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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                            ------------------------
                                    FORM 10-Q


     [X] QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
                              EXCHANGE ACT OF 1934

                For the quarterly period ended December 31, 1999

                                       OR

          [ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                                   SECURITIES
                              EXCHANGE ACT OF 1934

For the transition period from                    to

Commission file number  0-17999

                                 ImmunoGen, Inc.
             (Exact name of registrant as specified in its charter)


       Massachusetts                                     04-2726691
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
 incorporation or organization)


                             333 Providence Highway
                                Norwood, MA 02062
          (Address of principal executive offices, including zip code)

                                 (781) 769-4242
              (Registrant's telephone number, including area code)


         (Former               name,  former  address and former fiscal year, if
                               changed since last report.)

     Indicate  by check mark  whether the  registrant  (1) has filed all reports
required to be filed by Section 13 or 15(d) of the  Securities  Exchange  Act of
1934  during  the  preceding  12 months  (or for such  shorter  period  that the
registrant was required to file such reports),  and (2) has been subject to such
filing requirements for the past 90 days.

Yes  x   No

     Indicate the number of shares  outstanding of each of the issuer's  classes
of common stock, as of the latest practicable date.

     At February  10, 2000 there were  32,118,439  shares of common  stock,  par
value $.01 per share, of the registrant outstanding.


                           Exhibit Index at Page: 18


  2

                                 IMMUNOGEN, INC.
                                TABLE OF CONTENTS

                                                                         Page
                                                                         ----
PART I. FINANCIAL INFORMATION

Item 1. Condensed Consolidated Financial Statements:

     a.  Condensed Consolidated Balance Sheets as of
         December 31, 1999 and June 30, 1999.........................     3

     b.  Condensed Consolidated Statements of Operations
         for the three months and six months ended
         December 31, 1999 and 1998..................................     4

     c.  Condensed Consolidated Statements of Stockholders'
         Equity for the year ended June 30, 1999 and the
         six months ended December 31, 1999..........................     5

     d.  Condensed Consolidated Statements of Cash Flows
         for the six months ended December 31, 1999 and 1998.........     6

     e.  Notes to Condensed Consolidated Financial Statements........     7

Item 2.  Management's Discussion and Analysis of Financial Condition
         and Results of Operations...................................     10

Item 3.  Quantitative and Qualitative Disclosures about Market Risk..     14

PART II. OTHER INFORMATION ..........................................     14


SIGNATURES...........................................................     17

                                       2
  3


                                IMMUNOGEN, INC.
                     CONDENSED CONSOLIDATED BALANCE SHEETS
                     AS OF DECEMBER 31, AND JUNE 30, 1999
                                  (UNAUDITED)


                                                             DECEMBER 31,     JUNE 30,
                                                                1999             1999
                                                            ------------    -------------
                                                                      
ASSETS
Cash and cash equivalents.................................  $  4,941,470    $  4,225,580
Marketable securities.....................................     4,051,875             -
Due from related parties..................................     3,388,715         910,108
Current portion of note receivable........................           -           350,000
Prepaid and other current assets..........................        90,078          57,915
                                                            ------------    ------------
       Total current assets...............................    12,472,138       5,543,603
                                                            ------------    ------------
Property and equipment, net of accumulated depreciation...     1,482,473       1,583,350
Other assets..............................................        43,700          43,700
                                                            ------------    ------------

          Total assets....................................  $ 13,998,311    $  7,170,653
                                                            ============    ============

LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable..........................................  $    811,822    $    869,996
Accrued compensation......................................       145,915         282,390
Other current accrued liabilities.........................       526,099         528,969
Current portion of deferred lease and
 capital lease obligations................................        69,523          91,911
                                                            ------------    ------------
       Total current liabilities..........................     1,553,359       1,773,266
                                                            ------------    ------------
Capital lease obligations.................................        36,825          68,220
                                                            ------------    ------------
          Total liabilities...............................     1,590,184       1,841,486
                                                            ------------    ------------

Commitments and contingencies
Stockholders' equity:
 Preferred stock, $.01 par value; authorized 5,000,000
  shares as of December 31, 1999 and June 30, 1999:
   Convertible preferred stock, Series E, $.01 par
    value; issued and outstanding 2,400 as of
    December 31, 1999 and June 30, 1999 (liquidation
    preference - stated value)............................            24              24
 Common stock, $.01 par value;  authorized  50,000,000
  shares as of December 31, 1999 and June 30, 1999;
  issued and outstanding 28,724,522 and 25,668,797 as
  of December 31, 1999 and June 30 1999, respectively ....       287,245         256,687

Additional paid-in capital................................   163,954,916     158,790,821
Accumulated deficit.......................................  (151,863,018)   (153,718,365)
Accumulated other comprehensive income....................        28,960             -
                                                            ------------    ------------
       Total stockholders' equity.........................    12,408,127       5,329,167
                                                            ------------    ------------
          Total liabilities and stockholders' equity......  $ 13,998,311    $  7,170,653
                                                            ============    ============

           The accompanying notes are an integral part of the condensed
                       consolidated financial statements.

                                       3

  4



                                 IMMUNOGEN, INC.
                 CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
      FOR THE THREE MONTHS AND SIX MONTHS ENDED DECEMBER 31, 1999 AND 1998
                                   (UNAUDITED)




                                                         THREE MONTHS ENDED          SIX MONTHS ENDED
                                                            DECEMBER 31,               DECEMBER 31,
                                                     ------------------------    ------------------------
                                                         1999        1998           1999         1998
                                                     -----------  -----------    -----------  -----------
                                                                                  
Revenues:
  Revenue earned under collaboration agreement....   $ 2,500,000                 $ 6,500,000
  Development fees................................           -    $   157,623          4,800  $   262,295
  Interest........................................        74,793       72,787        134,089      143,913
  Licensing.......................................           195          300            485          828
                                                     -----------  -----------    -----------  -----------
       Total revenues.............................     2,574,988      230,710      6,639,374      407,036
                                                     -----------  -----------    -----------  -----------
Expenses:
  Research and development........................     1,890,695    1,420,868      3,721,716    2,846,082
  General and administrative......................       643,212      472,713      1,146,278      817,130
  Interest........................................         4,862          986         10,131        2,428
                                                     -----------  -----------    -----------  -----------
       Total expenses.............................     2,538,769    1,894,567      4,878,125    3,665,640
                                                     -----------  -----------    -----------  -----------
Earnings/(loss) from operations...................        36,219   (1,663,857)     1,761,249   (3,258,604)
                                                     -----------  -----------    -----------  -----------

  Gain on the sale of assets......................         1,645        1,000          1,488        4,200
  Other income....................................        42,030          333         42,030       25,280
                                                     -----------  -----------    -----------  -----------
Net earnings/(loss) before minority interest......        79,894   (1,662,524)     1,804,767   (3,229,124)
                                                     -----------  -----------    -----------  -----------
  Minority interest in net loss of consolidated
   subsidiary.....................................        25,290       25,290         50,580       50,580
                                                     -----------  -----------    -----------  -----------
Net earnings/(loss)...............................       105,184   (1,637,234)     1,855,347   (3,178,544)
                                                     -----------  -----------    -----------  -----------
  Non-cash dividends on convertible
   preferred stock................................           -            -              -       (917,583)
                                                     -----------  -----------    -----------  -----------

Net earnings/(loss) to common stockholders........   $   105,184  $(1,637,234)   $ 1,855,347  $(4,096,127)
                                                     ===========  ===========    ===========  ===========

Earnings/(loss) per common share
  Basic...........................................   $      0.00  $     (0.06)   $      0.07  $     (0.16)
                                                     ===========  ===========    ===========  ===========
  Diluted.........................................   $      0.00  $     (0.06)   $      0.06  $     (0.16)
                                                     ===========  ===========    ===========  ===========
Average common shares outstanding
  Basic...........................................    27,143,460   25,494,552     26,528,658   25,488,845
                                                     ===========  ===========    ===========  ===========
  Diluted.........................................    33,463,758   25,494,552     32,848,956   25,488,845
                                                     ===========  ===========    ===========  ===========


          The accompanying notes are an integral part of the condensed
                       consolidated financial statements.

                                       4

  5


                                 IMMUNOGEN, INC.
            CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY
   FOR THE YEAR ENDED JUNE 30, 1999 AND THE SIX MONTHS ENDED DECEMBER 31, 1999
                                   (UNAUDITED)



                                                                                                         ACCUMULATED
                                     COMMON STOCK      PREFERRED STOCK    ADDITIONAL                       OTHER         TOTAL
                                 --------------------  ----------------    PAID-IN      ACCUMULATED    COMPREHENSIVE  STOCKHOLDERS'
                                   SHARES     AMOUNT    SHARES   AMOUNT    CAPITAL        DEFICIT         INCOME         EQUITY
                                 ----------  --------  -------  -------  ------------  -------------   -------------  ------------
                                                                                              
Balance at June 30, 1998.......  25,419,552  $254,195    1,200  $    12  $152,782,585  $(148,725,822)  $        -     $  4,310,970
                                 ==========  ========  =======  =======  ============  =============   =============  ============

Comprehensive loss:
  Net loss.....................         -         -        -        -             -       (4,074,960)           -       (4,074,960)
                                                                                                                      ------------
  Comprehensive loss...........         -         -        -        -             -              -              -       (4,074,960)


Issuances of Common Stock......     174,245     1,742      -        -         313,545            -              -          315,287
Issuance of Series E
 Convertible Preferred Stock,
 net of financing costs........         -         -      1,200       12     1,495,193            -              -        1,495,205
Issuance of Common Stock in
 exchange for Series E
 Preferred Stock placement
 services......................      75,000       750      -        -            (750)           -              -              -
Value of Common Stock
 purchase warrants issued......         -         -        -        -         917,583            -              -          917,583
Compensation for stock
 option vesting acceleration
 for retired director..........         -         -        -        -          13,275            -              -           13,275
Value ascribed to ImmunoGen
 warrants issued to BioChem,
 net of financing costs........         -         -        -        -       3,269,390            -              -        3,269,390
Non-cash dividends on
 convertible preferred stock...         -         -        -        -             -         (917,583)           -         (917,583)
                                 ----------  --------  -------  -------  ------------  -------------   -------------  ------------
Balance at June 30, 1999.......  25,668,797  $256,687    2,400  $    24  $158,790,821  $(153,718,365)  $        -     $  5,329,167
                                 ==========  ========  =======  =======  ============  =============   =============  ============

Comprehensive income:
  Net earnings.................         -         -        -        -             -        1,855,347            -        1,855,347
  Unrealized gains on
   marketable securities, net..         -         -        -        -             -              -           28,960         28,960
                                                                                                                      ------------
Comprehensive income...........         -         -        -        -             -              -              -        1,884,307

Issuance of Common Stock.......   3,055,725    30,558      -        -       3,515,256            -              -        3,545,814
Tax benefit from stock options
 exercised.....................         -         -        -        -          13,419            -              -           13,419
Value ascribed to ImmunoGen
 warrants issued to BioChem,
 net of financing costs........         -         -        -        -       1,635,420            -              -        1,635,420
                                 ----------  --------  -------  -------  ------------  -------------   -------------  ------------
Balance at December 31, 1999...  28,724,522  $287,245    2,400  $    24  $163,954,916  $(151,863,018)  $      28,960  $ 12,408,127
                                 ==========  ========  =======  =======  ============  =============   =============  ============


          The accompanying notes are an integral part of the condensed
                       consolidated financial statements.

                                       5
  6

                                 IMMUNOGEN, INC.
                CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
              FOR THE SIX MONTHS ENDED DECEMBER 31, 1999 AND 1998
                                  (UNAUDITED)


                                                             SIX MONTHS ENDED
                                                               DECEMBER 31,
                                                       -------------------------
                                                          1999           1998
                                                       -----------   -----------
                                                               
CASH FLOWS FROM OPERATING ACTIVITIES:
 Net earnings/(loss) to common stockholders..........  $ 1,855,347   $(4,096,127)
 Adjustments to reconcile net loss to net cash
  used for operating activities:
   Depreciation and amortization.....................      244,567       334,657
   Gain on sale of property and equipment............       (1,488)       (4,200)
   Interest earned on note receivable................          -         (50,297)
   Compensation for stock option vesting
    acceleration for retired director................          -          13,275
   Tax benefit from stock options exercised..........       13,419           -
   Non-cash dividend on convertible preferred stock..          -         917,583
   Minority interest in net loss of consolidated
    subsidiary.......................................      (50,580)      (50,580)
   Amortization of deferred lease....................      (26,376)      (26,376)
   Changes in operating assets and liabilities:
    Due from related parties.........................   (2,478,607)       41,417
    Prepaid and other current assets.................      (32,163)       20,262
    Accounts payable.................................      (58,174)       33,432
    Accrued compensation.............................     (136,475)     (116,577)
    Other current accrued liabilities................       (2,870)     (153,861)
                                                       -----------   -----------
        Net cash used for operating activities.......     (673,400)   (3,137,392)
                                                       -----------   -----------

CASH FLOWS FROM INVESTING ACTIVITIES:
  Payments received on note receivable...............      350,000       260,000
  Purchase of marketable securities..................   (4,022,915)          -
  proceeds from sale of property and equipment.......        1,745         4,200
  Capital expenditures...............................     (143,947)       (8,500)
                                                       -----------   -----------
        Net cash (used for) provided by investing
         activities..................................   (3,815,117)      255,700
                                                       -----------   -----------

CASH FLOWS FROM FINANCING ACTIVITIES:
  Common Stock issuances, net........................    3,545,814           -
  Proceeds from convertible preferred stock, net.....          -       1,495,205
  Proceeds from issuance of subsidiary
   convertible preferred stock, net..................    1,686,000     1,685,252
  Principal payments on capital lease obligations....      (27,407)          -
                                                       -----------   -----------
        Net cash provided by financing activities....    5,204,407     3,180,457
                                                       -----------   -----------
Net change in cash and cash equivalents..............      715,890       298,765
                                                       -----------   -----------
Cash and cash equivalents, beginning balance.........    4,225,580     1,741,825
                                                       -----------   -----------
Cash and cash equivalents, ending balance............  $ 4,941,470   $ 2,040,590
                                                       ===========   ===========


SUPPLEMENTAL DISCLOSURE OF NONCASH FINANCING ACTIVITIES:
  Due from related party for quarterly investment
   payment...........................................  $   843,000   $   843,000
                                                       ===========   ===========
  Issuance  of Common  Stock in exchange  for
   Series E Preferred Stock placement services.......  $       -     $   107,812
                                                       ===========   ===========


          The accompanying notes are an integral part of the condensed
                       consolidated financial statements.

                                       6
  7


                                IMMUNOGEN, INC.
             NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS



A.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

NATURE OF BUSINESS

     ImmunoGen,   Inc.  ("ImmunoGen"  or  the  "Company")  was  incorporated  in
Massachusetts in 1981 to develop,  produce and market commercial anti-cancer and
other pharmaceuticals  based on molecular  immunology.  The Company continues to
research and develop its various products and technologies,  and does not expect
to derive revenue from  pharmaceutical  product sales in the foreseeable future.
It is  anticipated  that the Company's  existing  capital  resources will enable
current  and  planned  operations  to be  maintained  through  at least the next
twelve-month  period.  However,  if the Company is unable to achieve  subsequent
milestones  under its  collaborative  agreement (see Note B), the Company may be
required to pursue additional  strategic  partners,  secure alternative  funding
arrangements  and/or defer or limit some or all of its research and  development
projects.

      The Company is subject to risks common to  companies in the  biotechnology
industry  including,  but not limited to, the  development by the Company or its
competitors  of new  technological  innovations,  dependence  on key  personnel,
protection of proprietary  technology,  manufacturing and marketing limitations,
collaboration  arrangements,  third-party  reimbursements,  the  need to  obtain
additional funding, and compliance with governmental regulations.

BASIS OF PRESENTATION

      The accompanying  condensed  consolidated financial statements at December
31, 1999 and June 30, 1999 and for the three-month  and six-month  periods ended
December  31,  1999  and  1998  include  the  accounts  of the  Company  and its
subsidiaries, ImmunoGen Securities Corp. and Apoptosis Technology, Inc. ("ATI").
Although the condensed  consolidated  financial  statements are unaudited,  they
include all of the adjustments, consisting only of normal recurring adjustments,
which management  considers  necessary for a fair  presentation of the Company's
financial position in accordance with generally accepted  accounting  principles
for interim financial information.  Certain information and footnote disclosures
normally  included  in the  Company's  annual  financial  statements  have  been
condensed or omitted.  The preparation of interim financial  statements requires
the use of  management's  estimates  and  assumptions  that affect the  reported
amounts  of assets and  liabilities  and  disclosure  of  contingent  assets and
liabilities  at the date of the interim  financial  statements  and the reported
amounts of revenues and expenditures during the reported period. The Company has
been unprofitable since inception and expects to incur significant  research and
development  expenses  that may result in a net loss for the  fiscal  year ended
June 30, 2000. The results of the interim periods are not necessarily indicative
of  the  results  for  the  entire  year.  Accordingly,  the  interim  financial
statements should be read in conjunction with the audited  financial  statements
and notes thereto  included in the Company's  Annual Report on Form 10-K for the
year ended June 30, 1999.

CASH AND CASH EQUIVALENTS

     The Company  considers all  investments  purchased  with maturity  dates of
three months or less from the date of acquisition to be cash equivalents.

MARKETABLE SECURITIES

     In  accordance  with  the  Company's  investment  policy,  surplus  cash is
invested in  investment-grade  corporate  and U.S.  Government  debt  securities
typically with maturity dates of less than one year. The Company  determines the
appropriate  classification of marketable securities at the time of purchase and
reevaluates  such  designation  as  of  each  balance  sheet  date.   Marketable
securities which meet the criteria for classification as available-for-sale  are
carried at fair value based on quoted market prices. Unrealized gains and losses
are reported net, as comprehensive income, within shareholders' equity. The cost
of debt  securities  is adjusted for  amortization  of premiums and accretion of
discounts  to  maturity  with all  amortization/accretion  included  in interest
income.

                                        7
  8

     As of June 30, 1999, $4,225,580 in cash and overnight government repurchase
agreements  were  classified as cash and cash  equivalents.  The Company's cash,
cash  equivalents  and  marketable  securities  as of  December  31, 1999 are as
follows:



                                                GROSS       GROSS
                                   AMORTIZED  UNREALIZED  UNREALIZED   ESTIMATED
                                     COST       GAINS       LOSSES    FAIR VALUE
                                  ----------  ----------  ----------  ----------
                                                          
DECEMBER 31, 1999
 Cash and money market funds....  $2,553,656  $      -    $      -    $2,553,656
 Commercial paper...............   2,628,842      56,159         -     2,685,001
 Government treasury notes......   3,806,121         -       (51,433)  3,754,688
                                  ----------  ----------  ----------  ----------
   Total........................   8,988,619      56,159     (51,433)  8,993,345
 Less amounts classified as
  cash and cash equivalents.....  (4,965,704)    (10,526)     34,760  (4,941,470)
                                  ----------  ----------  ----------  ----------
   Total marketable securities..  $4,022,915  $   45,633  $  (16,673) $4,051,875
                                  ==========  ==========  ==========  ==========


     No  realized  gains  or  losses  on   available-for-sale   securities  were
recognized during the three-month and six-month periods ended December 31, 1999.

COMPUTATION OF LOSS PER COMMON SHARE

     Basic and diluted  earnings/(loss)  per share is calculated  based upon the
weighted average number of common shares outstanding during the period.  Diluted
earnings per share  incorporates the dilutive effect of stock options,  warrants
and other  convertible  securities.  As of December 31, 1999 and 1998, the total
number  of  stock  options,  warrants  and  other  securities  convertible  into
ImmunoGen  Common Stock,  as calculated  in accordance  with the  treasury-stock
accounting method, equaled 11,737,133 and 14,461,528,  respectively.  Components
of  calculating  net  earnings/(loss)  per share are set forth in the  following
table:



                                                        SIX MONTHS ENDED
                                                           DECEMBER 31,
                                                    --------------------------
                                                        1999           1998
                                                    -----------    -----------
                                                             
  Net earnings/(loss) to common shareholders.....   $ 1,855,347    $(4,096,127)
                                                    ===========    ===========
  Weighted  average common shares
   outstanding, basic...........................     26,528,658     25,488,845
  Net effect of dilutive instruments:
   Convertible preferred stock.................       4,692,984      5,978,781
   Options.....................................       1,234,384        657,060
   Warrants....................................         392,930            -
                                                    -----------    -----------
  Weighted average common shares
   outstanding, diluted.........................     32,848,956     32,124,686 *
                                                    ===========    ===========

  Earnings/(loss) per common share, basic.......    $      0.07   $     (0.16)
                                                    ===========    ===========
  Earnings/(loss) per common share, dilutive *..    $      0.06   $     (0.16)
                                                    ===========    ===========


  * The dilutive  effects of common stock  equivalents  were not included in the
    December 31, 1998 calculation, as their effect was antidilutive.

COMPREHENSIVE INCOME

     The Company presents  comprehensive  income in accordance with Statement of
Financial  Accounting  Standard No. 130, "Reporting  Comprehensive  Income." For
both the  three-month  and six-month  periods ended  December 31, 1999 and 1998,
total comprehensive income equaled $28,960 and $0,  respectively.  Comprehensive
income   was   comprised    entirely   of   unrealized   gains   recognized   on
available-for-sale debt securities.

                                       8
  9

B.  AGREEMENTS

     In February 1999, the Company entered into an exclusive  license  agreement
with  SmithKline  Beecham  plc,  London  and  SmithKline  Beecham,  Philadelphia
(collectively,  "SB")  to  develop  and  commercialize  ImmunoGen's  lead  tumor
activated prodrug ("TAP"),  huC242-DM1/SB-408075 (the "SB Agreement"). Under the
terms  of the  agreement,  the  Company  could  receive  up to a total  of $41.5
million,   subject  to  the   achievement  by  the  Company  of   predetermined,
nonrefundable  scientific  and/or  regulatory  milestones.  The  Company is also
entitled to receive  royalty  payments on future product sales, if and when they
commence.

     Under a separate Stock Purchase  Agreement,  ImmunoGen was also granted the
right to sell up to $5.0 million of ImmunoGen Common Stock to SB in two separate
transactions, subject to certain conditions (the "put options"). On September 1,
1999,  the  Company  exercised  the first of these two put  options  and  issued
1,023,039 shares of Common Stock to SB in exchange for $2.5 million.

     The SB Agreement is expected to provide the Company  with  sufficient  cash
funding to carry out its responsibilities in developing huC242-DM1/SB-408075. To
that end,  the Company will be primarily  responsible  for all costs  associated
with  the  Phase I  clinical  study  that  began in  December  1999.  All  costs
subsequent to this initial  assessment will be the  responsibility of SB. The SB
Agreement  is also  expected  to provide  enough  additional  funding to support
further  development  of the Company's  other  current and planned  research and
development  efforts.  As of December 31, 1999, the Company had recognized  four
milestones  under the SB Agreement,  resulting in $9.5 million in  collaboration
revenue. Pursuant to the SB Agreement, these payments represented nonrefundable,
unrestricted cash transfers where no future obligation to perform exists. Of the
$9.5  million  collaboration  revenue  recorded to date,  $7.0  million had been
received and $2.5 million remained  outstanding and included in the asset titled
"Due from  related  parties" on the  December  31, 1999  condensed  consolidated
balance  sheet.  In January  2000,  the  outstanding  $2.5  million  balance was
received in full.

C.  MINORITY INTEREST

     In July 1997,  ATI entered  into a  collaboration  agreement  with  BioChem
Pharma Inc. ("BioChem"), a large Canadian biopharmaceutical company. The BioChem
agreement  grants BioChem an exclusive  worldwide  license to ATI's  proprietary
screens  based on two  families of proteins  involved in  apoptosis,  for use in
identifying leads for anti-cancer drug development.

     Under the BioChem agreement,  BioChem will invest a total of $11,125,000 in
non-voting,  non-dividend-bearing convertible preferred stock of ATI in a series
of quarterly  private  placements,  through March 2000.  Proceeds are to be used
exclusively  to  support  the  research  and   development   activities  of  the
collaboration.  The BioChem agreement also establishes  certain  restrictions on
the  transferability  of assets between ATI and the Company.  As of December 31,
1999,  BioChem had invested  $10,282,000,  of which $9,439,000 had been received
and $843,000  remained  outstanding  and included within the asset entitled "Due
from related  parties" on the December 31, 1999 condensed  consolidated  balance
sheet. The outstanding  $843,000  payment was  subsequently  received in January
2000. The preferred stock issued to BioChem is convertible into ATI common stock
at any time after three years from the first date of  issuance,  at a conversion
price equal to the then current market price of the ATI common stock, but in any
event at a price that will result in BioChem  acquiring at least 15% of the then
outstanding ATI common stock.  Through  December 31, 1999,  10,282 shares of ATI
preferred  stock  were  issued or  issuable  to  BioChem,  representing  a 13.9%
minority interest (on an if-converted and fully-diluted basis) in the net equity
of ATI. This minority  interest  portion of ATI's loss reduced  ImmunoGen's  net
loss in each of the  six-month  periods  ended  December  31,  1999  and 1998 by
$50,580.  Based  upon  an  independent   appraisal,   approximately  3%  of  the
$10,282,000 invested to date, or approximately  $308,000,  has been allocated to
the minority interest in ATI, with the remainder,  or approximately  $9,974,000,
allocated to the  Company's  equity.  Under the BioChem  agreement,  the initial
three-year research term will expire in July 2000. However, the agreement may be
extended beyond the initial three-year term, at BioChem's  discretion,  on terms
substantially  similar to those for the  original  term.  BioChem will also make
milestone  payments up to $15.0  million for each product over the course of its
development.  In addition, if and when product sales commence,  ATI will receive
royalties  on  any  future  worldwide  sales  of  products  resulting  from  the
collaboration.  BioChem's obligation to provide additional financing to ATI each
quarter is subject  to the  satisfaction  of  special  conditions,  including  a
condition that ATI maintain  sufficient  cash and other resources to allow it to
continue its planned operations (other than performance of its obligations under
the research  agreement)  for a minimum  period of time. Of the Company's  total
$9.0 million in cash, cash equivalents and marketable  securities as of December
31, 1999, $1.5 million represents funds restricted to support ATI's research and
administrative expenditures.

                                       9
  10

     As part  of the  BioChem  agreement,  BioChem  also  receives  warrants  to
purchase  shares of ImmunoGen  Common Stock equal to the amount  invested in ATI
during the three-year  research term.  These warrants will be exercisable  for a
number of shares of ImmunoGen  Common Stock determined by dividing the amount of
BioChem's investment in ATI by the market price of ImmunoGen Common Stock on the
exercise date, subject to certain limitations imposed by the Nasdaq Stock Market
rules,  which limit the sale or issuance by an issuer of certain securities at a
price less than the  greater of book or market  value.  Consequently,  BioChem's
ability to convert all of its ImmunoGen  warrants into ImmunoGen Common Stock is
limited to a total of 20% of the number of shares of  ImmunoGen's  Common  Stock
outstanding  on the  date of the  initial  transaction  to the  extent  that the
conversion  price would be less than the market price of ImmunoGen  Common Stock
on that date, unless  stockholder  approval for such conversion is obtained,  if
required,  or unless the Company has obtained a waiver of that requirement.  The
exercise  price is  payable  in cash or  shares  of ATI's  preferred  stock,  at
BioChem's  option.  The warrants are expected to be exercised  only in the event
that the  shares of ATI  common  stock do not become  publicly  traded.  In such
event,  ImmunoGen  expects  that  BioChem  will use its shares of ATI  preferred
stock, in lieu of cash, to exercise the warrants.

D.  CAPITAL STOCK

     In December 1999, holders of warrants  originally issued in connection with
a private  placement  of the  Company's  Series C  Convertible  Preferred  Stock
exercised  their right to acquire  443,200  shares of Common  Stock at $2.31 per
share. In exchange for the issued shares of Common Stock,  the Company  received
$1,023,792.  Proceeds from this warrant  exercise are to be used to fund current
operations.

     In December 1999, holders of warrants  originally issued in connection with
a private  placement  of the  Company's  Series E  Convertible  Preferred  Stock
exercised their right to acquire  2,823,528 shares of Common Stock at $2.125 per
share.  In lieu of cash,  the  holders  elected to  utilize a cashless  exercise
provision contained in the warrant  agreements,  resulting in a net distribution
to such holders of 1,584,819  shares of Common Stock. The total number of shares
required  to effect  the  exercise  of the  warrants  was  determined  using the
aggregate exercise value divided by the closing price of the Common Stock on the
date of exercise.

     In July 1997, the Company's majority-owned subsidiary,  ATI, entered into a
collaboration with a biopharmaceutical  company.  As part of the agreement,  the
collaborator  receives  warrants to purchase  shares of  ImmunoGen  Common Stock
equal to the amount  invested  in ATI by the  collaborator  during a  three-year
research  term.  These warrants will be exercisable at any time on or after July
31,  2000,  until  and  including  July 31,  2002,  into a number  of  shares of
ImmunoGen  Common Stock determined by dividing the amount invested in ATI by the
market price of the  ImmunoGen  Common Stock on the  exercise  date,  subject to
certain limitations.  On December 31, 1999, the quarterly investment of $843,000
was made in ATI,  and  warrants  corresponding  to that  amount  were  issued on
January  6,  2000  in  connection  with  such  investment.  Proceeds  from  this
investment are restricted to fund the ongoing ATI research collaboration.

E.    SUBSEQUENT EVENTS

     In January 2000,  holders of the Company's  Series E Convertible  Preferred
Stock  ("Series E Stock")  exercised  their right to convert all 2,400 shares of
Series E Stock into 2,823,528 shares of the Company's Common Stock.

     In January 2000, holders of warrants originally issued in connection with a
private  placement  of  the  Company's  Series  C  Convertible  Preferred  Stock
exercised  their  right to  acquire  128,200  shares of  Common  Stock at $2.31.
Proceeds from this warrant exercise are to be used to fund current operations.

     In January 2000, holders of warrants originally issued in connection with a
private  placement  of  the  Company's  Series  D  Convertible  Preferred  Stock
exercised  their  right to  acquire  427,272  shares of  Common  Stock at $1.94.
Proceeds from this warrant exercise are to be used to fund current operations.


ITEM 2.  MANAGEMENT'S  DISCUSSION  AND  ANALYSIS  OF  FINANCIAL  CONDITION  AND
         RESULTS OF OPERATIONS

OVERVIEW

     Since inception, ImmunoGen has been principally engaged in the research and
development  of  immunoconjugate   products  which  the  Company  believes  have
significant commercial potential as human therapeutics.  The Company's 97%-owned
subsidiary,  Apoptosis  Technology,  Inc.  ("ATI"),  focuses  its efforts on the
discovery and development of anti-cancer and anti-viral  therapeutics based upon
regulation of programmed cell death, or apoptosis.

     In February 1999, the Company entered into an exclusive  license  agreement
with  SmithKline  Beecham  plc,  London  and  SmithKline  Beecham,  Philadelphia
(collectively,  "SB")  to  develop  and  commercialize  ImmunoGen's  lead  tumor
activated   prodrug   ("TAP"),   huC242-DM1/SB-408075,   for  the  treatment  of
colorectal,  pancreatic and non-small-cell lung cancers (the "SB Agreement"). In
December   1999,   the  Company  began  a  Phase  I  human   clinical  study  of

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huC242-DM1/SB-408075.  The start of this Phase I clinical study triggered a $2.5
million milestone  payment to ImmunoGen,  which represented the fourth milestone
to be achieved in ImmunoGen's  collaboration  with SB to date.  Through December
31,  1999,  the Company  received  $12.0  million  under the SB Agreement - $9.5
million in milestone-based collaborative agreement revenue and $2.5 million upon
issuance of ImmunoGen Common Stock to SB.

     The Company  continues  developing  huN901-DM1,  a TAP for the treatment of
small-cell lung cancer, as well as pursuing additional  antibodies to be used to
develop  TAP's  effective  against  other  cancers.  In July  1997,  ATI began a
three-year  research and  development  collaboration  with  BioChem  Pharma Inc.
("BioChem"),  a large Canadian  biopharmaceutical  company. At BioChem's option,
this collaboration may be extended beyond its initial three-year term.

     To date, the Company has not generated revenues from product sales and does
not anticipate having a commercially approved product in the foreseeable future.
The  Company  expects  to incur  significant  future  research  and  development
expenses  which  may not be  offset  by  collaboration  derived  revenues.  Such
research and development  expenses are expected to increase over the foreseeable
future as the Company continues its development efforts. Accordingly,  period to
period  results may  fluctuate  dramatically.  The Company  believes that the SB
Agreement,   while  subject  to  the  achievement  by  the  Company  of  certain
milestones,  will provide  cash-based  milestone  payments  sufficient  to allow
current and planned operations to continue beyond the next twelve-month  period.
Furthermore,  the Company is also  actively  pursuing  additional  collaboration
partners in support of its other product candidates and TAP technology. However,
no assurances can be given that such SB Agreement  milestones  and/or additional
partnerships  will, in fact, be realized.  If the Company is unable to meet some
or all of the terms and  conditions in the SB  Agreement,  it may be required to
pursue additional strategic partners, secure alternative financing arrangements,
and/or defer or limit some or all of its research and development projects.

RESULTS OF OPERATIONS

   THREE MONTHS ENDED DECEMBER 31, 1999 AND 1998

   Revenues

     The Company's  total  revenues for the three months ended December 31, 1999
("1999") were $2.57  million,  compared with $231,000 for the three months ended
December 31, 1998 ("1998").  The  significant  increase in revenues from 1998 to
1999 is primarily  attributable to the $2.5 million milestone payment recognized
in  December  1999 as  collaboration  revenue  under the SB  Agreement.  No such
collaboration revenue was earned during 1998. The $2.5 million milestone payment
was recorded upon initiation of Phase I clinical studies of  huC242-DM1/SB408075
for the treatment of  colorectal,  pancreatic and  non-small-cell  lung cancers.
Milestones  earned  under  the SB  Agreement  represent  one-time,  unrestricted
payments   recognized   upon   predetermined    scientific   and/or   regulatory
achievements.  Additional  collaboration  revenues of up to approximately  $32.0
million  will  be  earned  if the  Company  achieves  certain  predetermined  SB
Agreement milestones.  Therefore, historically recognized collaboration revenues
should not be used as indicators as to the timing or extent of future  milestone
payments.

     In the  three-month  period ended  December 31, 1998,  revenues of $158,000
were also  derived  from  development  fees  received  under the Small  Business
Innovation  Research  Program ("SBIR") of the National Cancer  Institute.  As of
July 1999, all funds available under authorized SBIR programs had been received.
Therefore,  no material  development  fees are expected to be earned through the
remainder of fiscal year 2000.

     Interest  income was $75,000 in 1999 compared to $73,000 in 1998.  Interest
earned in the three-month period ended December 31, 1999 primarily resulted from
earnings on invested  cash  balances.  Interest  earned  during the  three-month
period ended  December 31, 1998  included  earnings on invested cash balances as
well as  interest  earned on a note  receivable  from an  assignee of one of the
Company's  facilities.  As the note receivable was paid in full on July 1, 1999,
no related interest has been earned in 1999.


   Research and Development Expenses

     Research  and  development   expenses,   which  constituted  the  principal
component of the Company's total operational  expenditures (75% in both quarters
ended December 31, 1999 and 1998),  were $1.89 million in 1999 compared to $1.42
million in 1998. The $470,000,  or 33%, increase from 1998 to 1999 was primarily
due to increased costs  associated with the  development  and  manufacturing  of
huC242-DM1/SB-408075   components,   as  well  as  the  further  development  of
huN901-DM1.  Total 1999  increases  were  offset by  significant  reductions  in
depreciation and, to a lesser extent, decreased salary and related costs. Future
research and development expenses are expected to significantly  increase as the
Company   continues   to  fund   the   initial   Phase  1   clinical   study  of
huC242-DM1/SB-408075.   Similarly,   additional  preclinical  development  costs
associated  with the Company's  huN901-DM1 and other TAP product  candidates are
also expected to increase future research and development spending.

                                       11
  12

   General and Administrative Expenses

     General and  administrative  expenses  were  $643,000  in 1999  compared to
$473,000 in 1998. The $170,000,  or 36%, increase was primarily due to increased
administrative  and  business  development   staffing,   as  well  as  increased
expenditures  associated with investor relations,  business  development and the
Company's  information  system.  Future general and administrative  expenses are
also  expected  to  increase  in support  of the  continued  development  of the
Company's product candidates and technologies.

   Minority Interest

     ATI operating  losses of $25,290 in each of the  three-month  periods ended
December 31, 1999 and 1998 were allocated to ATI's minority  stockholder  within
the Company's condensed consolidated financial statements.

  SIX MONTHS ENDED DECEMBER 31, 1999 AND 1998

   Revenues

     The  Company's  total  revenues for the six months ended  December 31, 1999
("1999")  were $6.64  million,  compared  with $407,000 for the six months ended
December 31, 1998 ("1998").  The  significant  increase in revenues from 1998 to
1999 is  primarily  attributable  to the  $6.5  million  in  milestone  payments
recognized as collaboration  revenue under the SB Agreement.  The  collaboration
revenue was comprised of the following: $4.0 million on acceptance by the United
States Food and Drug  Administration of the Company's  Investigational  New Drug
application for huC242-DM1/SB408075, and $2.5 million on initiation of the Phase
I human clinical study. No such collaboration revenues were earned during 1998.

     In 1998,  revenues of $262,000  were also  derived  from  development  fees
received  under the SBIR grant  program.  As of July 1999,  all funds  available
under  authorized  SBIR  programs had been  received.  Accordingly,  no material
development  fees are expected to be earned through the remainder of fiscal year
2000.

     Interest income was $134,000 in 1999 compared to $144,000 in 1998. Interest
earned in 1999  primarily  resulted  from  earnings on invested  cash  balances.
Interest  earned in 1998 included  earnings on invested cash balances as well as
interest  earned on a note  receivable  from an assignee of one of the Company's
facilities.  As the note receivable was paid in full on July 1, 1999, no related
interest has been earned in 1999.

   Research and Development Expenses

     Research and  development  expenses  were $3.72 million in 1999 compared to
$2.85 million in 1998. The $870,000,  or 31%,  increase from 1998 to 1999 is due
to the increased costs  associated with the  development  and  manufacturing  of
huC242-DM1/SB-408075   components,   as  well  as  the  further  development  of
huN901-DM1.  Total 1999  increases  were  offset by  significant  reductions  in
depreciation and, to a lesser extent, decreased salary and related costs.

   General and Administrative Expenses

     General and administrative  expenses were $1.15 million in 1999 compared to
$817,000 in 1998. Similar to the results for the three months ended December 31,
1999 and 1998,  the  $333,000,  or 41%,  increase was primarily due to increased
administrative   and  business   development   staffing  as  well  as  increased
expenditures  associated with investor relations,  business  development and the
Company's information system.

   Minority Interest

     ATI  operating  losses of $50,580 in 1999 and 1998 were  allocated to ATI's
minority  stockholder  within the  Company's  condensed  consolidated  financial
statements.

                                       12
  13

   Non-cash Dividends

     Non-cash  dividends were  approximately  $918,000 in 1998. No such non-cash
dividends were recognized in 1999. The $918,000 non-cash  dividends  represented
the  Black-Scholes  option  pricing  model  derived  fair value of  warrants  to
purchase 1.4 million shares of ImmunoGen  Common Stock issued in connection with
the July 1998 sale of the Company's Series E Convertible Preferred Stock.

LIQUIDITY AND CAPITAL RESOURCES

     Since July 1, 1999, the Company has primarily financed the net cash used to
support operating  activities from various  collaborative and financing sources.
These sources include milestone  revenues earned under the SB agreement,  issues
of equity  securities  to SB and  BioChem,  the exercise of warrants to purchase
Common Stock,  amounts received from the assignment of facilities and equipment,
and income earned on invested assets.  To a lesser extent,  the Company has also
received  proceeds from the SBIR grant program as well as cash payments from the
exercise of employee  stock  options.  Cash used in operations in the six months
ended December 31, 1999 primarily  supported the Company's  various research and
development efforts.

     Net cash used in operations  in the six months ended  December 31, 1999 was
$673,000  compared  to  $3.14  million  used in the six  months  ended  December
31,1998.  This significant  decrease in operational cash use is primarily due to
the  recognition  of $6.5 million in  collaboration  revenue earned under the SB
agreement.  Offsetting the $2.46 million period to period total decrease in cash
used in operating  activities  was a $2.5 million  increase in "Due from related
parties,"  which   represents  the  outstanding   huC242-DM1/SB408075   Phase  I
initiation  milestone  earned on  December  9, 1999.  Additionally,  for the six
months ended  December 31, 1999,  $230,000 in  operational  cash was used to pay
various current assets and liabilities.

     Net cash used in investing  activities  was $3.8 million for the six months
ended December 31, 1999, and primarily  represents purchases of higher-yielding,
investment-grade   corporate  and  U.S.   Government  debt  securities.   Future
marketable  security  purchases  are expected to increase,  consistent  with the
Company's intentions to enhance overall returns via investment of available cash
in higher yielding debt securities.

     Capital purchases were $144,000 for the six months ended December 31, 1999,
and consisted  primarily of information  system  upgrades.  Although the Company
anticipates   further  research  related  equipment   acquisitions,   cash-based
expenditures for property and equipment through the remainder of fiscal 2000 are
not expected to be significant.

     On  September  1, 1999,  the Company  exercised  a $2.5  million put option
available  to it under  the SB  Agreement.  In  exchange  for the  $2.5  million
received, 1,023,039 shares of the Company's Common Stock were issued to SB.

     In December 1999, holders of warrants  originally issued in connection with
a private  placement  of the  Company's  Series C  Convertible  Preferred  Stock
exercised  their right to acquire  443,200  shares of Common  Stock at $2.31 per
share.  Also  in  December  1999,  holders  of  warrants  originally  issued  in
connection  with a  private  placement  of the  Company's  Series E  Convertible
Preferred  Stock  exercised  their right to acquire  2,823,528  shares of Common
Stock at $2.125 per share.  In lieu of cash,  the  holders  elected to utilize a
cashless exercise provision contained in the warrant agreements,  resulting in a
net distribution of 1,584,819 shares of Common Stock. The total number of shares
required  to effect  the  exercise  of the  warrants  was  determined  using the
aggregate exercise value divided by the closing price of the Common Stock on the
date of exercise.

     For the  six-month  period ended  December 31, 1999, a total of 4,667 stock
options  were   exercised,   resulting  in  cash  receipts  to  the  Company  of
approximately $6,000.

     From July 1, 1999 to December 31, 1999, an aggregate of $1.686  million was
received  from BioChem with respect to the June 30, 1999 and  September 30, 1999
quarterly  investments.  As  previously  described,  in  January  2000,  another
$843,000  payment  was  received  as  payment  of the  December  1999  quarterly
investment.

     In January  2000,  and  subsequent  to the balance  sheet date,  holders of
warrants  originally  issued  in  connection  with a  private  placement  of the
Company's Series C Convertible  Preferred Stock exercised their right to acquire
128,200  shares of Common  Stock at $2.31.  Also in  January  2000,  holders  of
warrants  originally  issued  in  connection  with a  private  placement  of the
Company's Series D Convertible  Preferred Stock exercised their right to acquire
427,272 shares of Common Stock at $1.94.

                                       13
  14

     The Company anticipates that its existing capital resources,  which include
the $2.5 million Phase I initiation milestone payment, the $843,000 December 31,
1999 BioChem  investment,  and the  proceeds  from the  above-mentioned  warrant
exercises will enable the Company to maintain its current and planned operations
through at least the next twelve-month  period.  Moreover,  the Company believes
that the SB Agreement,  while subject to the  achievement of future  development
milestones,  will not only provide  sufficient equity and milestone  payments to
carry out its  responsibilities  in  developing  huC242-DM1/SB-408075,  but also
provide  enough  additional  funding to support the Company's  other current and
planned  research and  development  expenditures.  The Company is also  actively
seeking   partners   to   support    aggressive    clinical    development   and
commercialization of both huN901-DM1,  and the Company's other TAP technologies.
However, no assurances can be given that such third-party  relationships will be
consummated  or that future  milestone  payments  under the SB agreement will in
fact be  realized.  If the  Company is unable to  achieve  some or all of the SB
Agreement milestones and/or not consummate additional third-party relationships,
it may be required to seek alternative  financing  arrangements  and/or defer or
limit some or all of its research and development projects.

CERTAIN FACTS THAT MAY AFFECT FUTURE RESULTS OF OPERATIONS

     This report  contains  certain  forward-looking  statements as that term is
defined in the Private Securities Litigation Reform Act of 1995. Such statements
are based on management's  current  expectations  and are subject to a number of
factors and uncertainties  which could cause actual results to differ materially
from those described in the  forward-looking  statements.  The Company  cautions
investors  that  there can be no  assurance  that  actual  results  or  business
conditions will not differ  materially from those projected or suggested in such
forward-looking  statements as a result of various factors,  including,  but not
limited to, the following: the uncertainties associated with preclinical studies
and  clinical  trials;   the  early  stage  of  the  Company's  initial  product
development  and lack of product  revenues;  the Company's  history of operating
losses and accumulated  deficit;  the Company's limited financial  resources and
uncertainty as to the availability of additional capital to fund its development
on acceptable  terms, if at all; the Company's lack of commercial  manufacturing
experience  and  commercial  sales,  distribution  and  marketing  capabilities;
reliance on suppliers of key materials  necessary for production of the products
and technologies; the potential development by competitors of competing products
and   technologies;   the   Company's   dependence  on  existing  and  potential
collaborative  partners, and the lack of assurance that the Company will receive
any  funding  under  such   relationships  to  develop  and  maintain  strategic
alliances;  the lack of assurance  regarding patent and other protection for the
Company's  proprietary  technology;  governmental  regulation  of the  Company's
activities, facilities, products and personnel; the dependence on key personnel;
uncertainties as to the extent of  reimbursement  for the costs of the Company's
potential  products and related  treatments  by  government  and private  health
insurers   and   other   organizations;   the   potential   adverse   impact  of
government-directed  health care reform;  the risk of product  liability claims;
unreported Year 2000 problems; and economic conditions, both generally and those
specifically related to the biotechnology  industry.  As a result, the Company's
future  development   efforts  involve  a  high  degree  of  risk.  For  further
information,  refer to the  more  specific  risks  and  uncertainties  discussed
throughout  the  Company's  Annual Report on Form 10-K for the fiscal year ended
June 30, 1999 as filed with the Securities and Exchange Commission.

YEAR 2000 ISSUES

     Prior to January 1, 2000, the Company had completed all upgrades  necessary
to ensure that its information systems,  facilities and research and development
equipment  containing   date-sensitive  hardware  and  software  was  Year  2000
compliant. Also prior to January 1, 2000, the Company sent questionnaires to its
currently engaged third-party suppliers, vendors, administrators and custodians,
inquiring  of their  progress  in  identifying  and  addressing  their Year 2000
issues. The Company received responses from all surveyed vendors and, based upon
the information  contained in those  responses,  the Company  believes that Year
2000 issues have been addressed by the Company's critical vendors.  To date, the
Company has not encountered any problems as a result of the Year 2000.  Expenses
related to Year 2000 have not been material,  and the Company does not expect to
incur any significant Year 2000 expenses in the future.


ITEM 3.  QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

     In the normal course of business,  the financial position of the Company is
subject to certain risks,  including  market risk  associated with interest rate
movements.  The  Company  regularly  assesses  these  risks and has  established
policies and business practices designed to mitigate such exposures. The Company
invests surplus cash in low-risk debt securities, typically maturing in one year
or less,  pending use in operations.  The Company manages these funds by seeking
principal  preservation  while  concurrently  enhancing  rates  of  return.  The
Company's interest income is therefore sensitive to changes in the general level
of  domestic  interest  rates.  Based on the  Company's  overall  interest  rate
exposure at December 31, 1999,  a near-term  change in interest  rates would not
materially affect the fair value of interest rate sensitive instruments.


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  15

                          PART II. OTHER INFORMATION


Item 1.    Legal Proceedings.

      The Company is not a party to any material legal proceedings.

Item 2.    Changes in Securities and Use of Proceeds.

      In December 1999, holders of warrants originally issued in connection with
      a private placement of the Company's Series C Convertible  Preferred Stock
      exercised  their right to acquire  443,200 shares of Common Stock at $2.31
      per share.  Proceeds  from this  warrant  exercise  are to be used to fund
      current operations.

      In December 1999, holders of warrants originally issued in connection with
      a private placement of the Company's Series E Convertible  Preferred Stock
      exercised  their  right to  acquire  2,823,528  shares of Common  Stock at
      $2.125  per  share.  In lieu of cash,  the  holders  elected  to utilize a
      cashless exercise provision contained in the warrant agreements, resulting
      in a net  distribution  of  1,584,819  shares of Common  Stock.  The total
      number of shares  required  to effect the  exercise  of the  warrants  was
      determined using the aggregate exercise value divided by the closing price
      of the Common Stock on the date of exercise.

      In  July  1997,  the  Company's   majority-owned   subsidiary,   Apoptosis
      Technology,   Inc.   ("ATI"),   entered  into  a   collaboration   with  a
      biopharmaceutical  company.  As part of the  agreement,  the  collaborator
      receives  warrants to purchase  shares of ImmunoGen  Common Stock equal to
      the  amount  invested  in ATI  by the  collaborator  during  a  three-year
      research term.  These warrants will be exercisable at any time on or after
      July 31, 2000,  until and including July 31, 2002, into a number of shares
      of ImmunoGen  Common Stock  determined by dividing the amount  invested in
      ATI by the market  price of the  ImmunoGen  Common  Stock on the  exercise
      date, subject to certain  limitations.  On December 31, 1999 the quarterly
      investment of $843,000 was made in ATI and warrants corresponding to those
      amounts  were  issued  on  January  6,  2000  in   connection   with  such
      investments.  All warrants were issued in accordance  with Regulation D of
      the  Securities  Exchange Act of 1933.  Proceeds from this  investment are
      restricted to fund the ongoing ATI research collaboration.

      In January 2000, and subsequent to the balance sheet date,  holders of the
      Company's Series E Stock exercised their right to convert all 2,400 shares
      of Series E Stock into 2,823,528 shares of the Company's Common Stock.

      In January 2000, holders of warrants  originally issued in connection with
      a private placement of the Company's Series C Convertible  Preferred Stock
      exercised  their right to acquire 128,200 shares of Common Stock at $2.31.
      Proceeds  from  this  warrant  exercise  are to be used  to  fund  current
      operations.

      In January 2000 holders of warrants originally issued in connection with a
      private  placement of the Company's  Series D Convertible  Preferred Stock
      exercised  their right to acquire 427,272 shares of Common Stock at $1.94.
      Proceeds  from  this  warrant  exercise  are to be used  to  fund  current
      operations.


Item 3.  Defaults Upon Senior Securities.

      Not applicable.


Item 4.    Submission of Matters to a Vote of Security Holders.

      The Company's Annual Meeting of Shareholders was held on November 9, 1999.
      At the Meeting, the following matters were voted upon:

      1) The  proposal  to elect five (5)  directors  was  approved by a vote of
         22,176,897 shares FOR and 594,562 shares WITHHELD.

                                       15
  16

      2) The following  persons were elected as Directors of the Company and the
         record votes cast is as set forth below:


                 Name              Votes Cast     Votes For   Votes Withheld
          ------------------       ----------    ----------   --------------
                                                        
          Mitchel Sayare           22,771,459    22,166,897      604,562
          Walter A. Blattler       22,771,459    22,171,597      599,862
          David W. Carter          22,771,459    22,174,797      596,662
          Michael R. Eisenson      22,771,459    22,160,696      610,763
          Stuart F. Feiner         22,771,459    22,166,496      604,963



      3) The  proposal  to amend the  Company's  Restated  Stock  Option Plan to
         increase  the number of shares  reserved  for the grant of options from
         3.525 million to 4.850 million was approved by the following vote:

                      Shares FOR            21,157,802
                      Shares AGAINST         1,472,059
                      Shares ABSTAINED         141,598


Item 5.    Other Information.

      Not applicable.


Item 6.    Exhibits and Reports on Form 8-K.

      (a)  Exhibits

           10.1 Form of Warrant  Certificate issued by the Registrant to BioChem
                Pharma  Inc.   (previously   filed  as  exhibit   10.5  to,  and
                incorporated   herein  by  reference   from,  the   Registrant's
                Registration  Statement on Form 10-Q, as amended by form 10-Q/A,
                for the quarter ended December 31, 1997)

           27   Financial Data Schedule

      (b)  Reports on Form 8-K

           None.




                                       16
  17



                                  SIGNATURES


      Pursuant to the  requirements  of the Securities  Exchange Act of 1934, as
amended,  the  Registrant has duly caused this report to be signed on its behalf
by the undersigned thereunto duly authorized.



                                    IMMUNOGEN, INC.




Date: February 10, 2000             By:  /s/ Mitchel Sayare
                                        -------------------------------
                                        Mitchel Sayare
                                          President and Chief Executive
                                          Officer
                                          (principal executive officer)







Date: February 10, 2000             By:  /s/ Kathleen A. Carroll
                                        -------------------------------
                                        Kathleen A. Carroll
                                          Vice President,
                                          Finance and Administration
                                          (principal financial officer)






                                       17



  18
                               INDEX TO EXHIBITS

EXHIBIT
  NO.           DESCRIPTION
- -------         -----------

  27            Financial Data Schedule