Exhibit 10.61

                          LETTER OF INTENT

     THIS LETTER OF INTENT is made on the 19th day of June 1996, by and 
between Agouron Pharmaceuticals, Inc., a corporation duly organized and 
existing under the laws of the state of California, having a principal 
place of business at 10350 North Torrey Pines Road, La Jolla, 
California, United States of America (hereinafter called "Agouron"), 
and F. Hoffmann-La Roche Ltd, a corporation duly organized and 
existing under the laws of Switzerland, having its principal place of 
business at CH-4002-Basel, Switzerland and Hoffmann-La Roche Inc. 
("Roche"), a corporation duly organized and existing under the laws of 
the state of New Jersey, having a principal place of business at 340 
Kingsland Street, Nutley, New Jersey  07110 (hereinafter collectively 
called "Roche").  Agouron and Roche are sometimes hereinafter referred 
to as a party (collectively "parties") to this Agreement.

                              Background

     Agouron and Roche are interested in forming an alliance for the 
purpose of discovering, developing, manufacturing and marketing novel 
anti-cancer agents.  To confirm the commencement of this 
collaboration, the parties wish to initially enter into this Letter Of 
Intent which sets forth the basic terms of the understanding between 
the parties.  The full terms of the collaboration between the parties 
will be set forth in a definitive agreement to be prepared as 
described below.

       NOW THEREFORE, the parties agree as follows:

1.     Terms.  The parties hereby enter into this Letter of Intent to 
confirm their formation of a collaboration on terms substantially in 
accordance with those contained in Exhibit A hereto.  The parties 
acknowledge that the Exhibit A states the basic terms of the 
understanding between the parties and is subject to the further 
negotiation and preparation of an agreement containing the full terms 
of the collaboration between the parties (Definitive Agreement).  Each 
party agrees to act in good faith in an effort to negotiate, execute 
and deliver the Definitive Agreement on or before *

2.     Disclosure.       The parties shall jointly prepare and release 
a statement about the existence of this Letter of Intent and of the 
formation of the collaboration between Agouron and Roche.  Except as 
agreed to by the parties neither Agouron nor Roche shall release any 
further information to any third party who is not under an obligation 
of confidentiality with respect  thereto about any of the terms of 
this Letter of Intent or of the collaboration without the prior 
written consent of the other, which consent shall not unreasonably be 
withheld.  This prohibition includes, but is not limited to, press 
releases, educational and scientific conferences, promotional 
materials and discussions with the media.  If a party determines that 
it is required by law to release information to any third party 
regarding the terms of this Letter of Intent or the subject matter of 
the collaboration, it shall notify the other party of this fact prior 
to releasing the information.  The notice to the other party shall 
include the text of the information proposed for release.  The other 
party shall have the right to confer with the notifying party 
regarding the necessity for the disclosure and the text of the 
information proposed for release. 

[PAGE] 
3.     Miscellaneous.  This Letter of Intent contains the entire 
agreement between the parties  as to the matters set forth herein and 
shall be construed in accordance with the laws of the State of 
California, United States of America.  Exhibit A describes the 
parties' understanding with respect to the worldwide development and 
commercialization of Thymitaq (TM) and AG3340 products, and a 
collaborative research program focused on cell-cycle control.  Exhibit 
A also provides for the granting to Agouron of the right in North 
America to commercialize a Roche anti-cancer product to be designated 
in the future.  As set forth in Exhibit A, a termination of one or 
both of the Thymitaq or AG3340 Development Programs shall not be 
deemed a termination of the other Development Program, the Cell Cycle 
Research Program and/or Agouron's right to commercialize a Roche 
Cancer Product.  This Letter of Intent, including Exhibit A, shall not 
be amended, supplemented or otherwise modified, except by an 
instrument in writing signed by duly authorized officers of both 
parties.  Each party shall bear all of the expenses incurred by it in 
connection with the negotiation and preparation of this Letter of 
Intent and the Definitive Agreement. 


IN WITNESS WHEREOF, the parties hereto have executed this Letter of 
Intent, in duplicate originals, by their respective officers thereunto 
duly authorized, the day and year hereinabove written. 


F. HOFFMANN-LA ROCHE LTD          AGOURON PHARMACEUTICALS, INC.


By:   /s/ Werner Henrich          By:   /s/ R. Kent Snyder               
Name: Werner Henrich              Name: R. Kent Snyder                    
Title:Director                    Title:V.P Commercial Affairs          


By:   /s/ Rudolf Schaffner        By:   /s/ Gary Friedman               
Name: Rudolf Schaffner            Name: Gary Friedman               
Title:Deputy Director             Title:V.P. & General Counsel     


HOFFMANN-LA ROCHE INC.     


By:   /s/ William H. Epstein
Name: William H. Epstein
Title:Asst. Secretary


 [PAGE]


                                   EXHIBIT A


A.     THYMITAQ(TM) and AG3340 (MMP Inhibitor) Development Programs for 
Cancer Indications

     1.     Agouron, under the terms and conditions specified below, grants 
Roche the exclusive right to co-promote with Agouron Thymitaq and AG3340 
products for cancer indications in North America and the right to exclusively 
market such products for cancer indications in countries outside of North 
America.

     2.     A Joint Development Committee ("JDC"), comprised of 
representatives from Roche and Agouron, shall oversee development of Thymitaq 
and AG3340 products for cancer indications.  Decisions regarding development 
of Thymitaq and AG3340 products and the conduct of JDC activities shall be 
made as follows:

          a)     the JDC shall be chaired, *
     from Roche or Agouron.  The JDC shall meet in regular intervals, at 
least *         per year with the first meeting taking place within 30 
days after the signing of the Letter of Intent ("LOI");
     
          b)     *      shall establish development programs and development 
budgets for Thymitaq and AG3340 products, and shall, if necessary, modify 
such development programs and development budgets;
     
          c)     the Thymitaq development program shall provide, at a 
minimum,
 *
     












          d)     *

                    Each company's members of the JDC will reasonably 
consider the adoption of the other company's suggestions and will accept as 
many of such suggestions as are reasonable, based upon medical rationale, 
drug supply, and the need to conduct the studies in an expeditious manner; 
and
     
          e)     if the JDC is unable to reach agreement on any decision 
required of it, the issue shall be submitted for consideration *


          If they are unable to agree, then the issue shall be resolved *



     3.     Roche and Agouron shall collaborate to complete clinical studies
aimed at achieving registration of Thymitaq in an expeditious manner for 
hepatocellular carcinoma, head and neck cancer *                    and to 
conduct additional clinical studies agreed to by the parties in order to 
expand Thymitaq cancer indications and usage.  Under the direction of the 
JDC, Agouron shall be responsible for *

                    Roche and Agouron shall use reasonable diligence in the 
development and registration of Thymitaq in accordance with the Thymitaq 
development program.  Reasonable diligence shall mean *

                    Effective from the date of signing the LOI, Roche shall 
be responsible for payment of eighty percent of the Thymitaq development 
costs *

                                         and Agouron shall be responsible for 
payment  of twenty percent  of  such  Thymitaq  development  costs; 
     *

                                Prior to the convening of the first JDC 
meeting, Agouron *



     4.     Under the direction of the JDC, subsequent to completion of Phase 
I studies for AG3340, Roche *
                                                        in accordance with 
the following terms:

          a)     Roche shall be responsible for payment of eighty percent of 
the AG3340 development costs and Agouron shall be responsible for payment of 
twenty percent of the AG3340 development costs; provided however that Roche 
* 



          b)     Roche shall use reasonable diligence in the development and 
registration of AG3340 in accordance with AG3340 development program. 
Reasonable diligence shall mean *


          c)     *














     5.     *










     6.     *











     7.     A Joint Marketing Committee ("JMC"), comprised of representatives
from Roche and Agouron, shall oversee marketing of Thymitaq and AG3340 
products for cancer indications. Decisions regarding marketing of Thymitaq 
and AG3340 products and the conduct of JMC activities shall be made as 
follows:

          a)     the JMC shall be chaired, *
     from Roche or Agouron.   The JMC shall meet  in regular  intervals, at  
least *;
     
          b)     the JMC shall be responsible for the*
                           The JMC shall be responsible for *

                which shall, among other things, *
                                          The JMC shall also be responsible 
for *

                                         to the extent possible. 
Notwithstanding the preceding, Roche shall be responsible for *
     
                                To the extent possible, the local marketing 
plans shall be *
     
          c)     *



     
          d)     *



          e)     if the JMC is unable to reach agreement on any decision
required of it, the issue shall be submitted for consideration *




     and
     
          f)     *







     8.     Roche and Agouron shall collaborate to co-promote Thymitaq and 
AG3340 products for cancer indications in North America under the same 
trademark and based upon a marketing program to be agreed upon by the 
parties.  Profits from sales of Thymitaq and AG3340 products for cancer 
indications in North America shall be shared by Roche and Agouron on a fifty-
fifty basis, *



                                                         As soon as possible, 
Agouron and Roche agree to discuss and negotiate in good faith 
     *



                                          To the extent permitted by 
applicable accounting rules, sales of Thymitaq and AG3340 (and Backup MMP 
Inhibitors) products in North America shall be booked 50-50 each by Roche and 
Agouron; *

                                                            If the parties 
are co-promoting Thymitaq and AG3340 products, a Joint Finance Committee, 
comprised of representatives from Roche and Agouron, shall be established to 
oversee and approve the planning and budgeting of revenues and costs 
resulting from such co-promotional activities. 

     9.     Roche's rights to market Thymitaq and AG3340 products for cancer 
indications in all countries outside of North America shall be subject to 
diligent development and marketing efforts by Roche, on a country by country 
basis, and payment to Agouron of a royalty based upon net sales in the 
following amounts:  Thymitaq-
     *      and AG3340-*.  



















     10.     In consideration of the rights granted to Roche by Agouron for 
Thymitaq and AG3340 products, Roche shall also pay to Agouron license 
issuance fees as follows:

             Thymitaq                                   $(MM)

             *


















           AG3340 or a Backup MMP Inhibitor

           *











     11.     Roche and Agouron agree to discuss in good faith, future rights 
for Agouron to co-promote Thymitaq and AG3340 products in selected European 
countries, unless prohibited by law or regulation, based upon the following 
criteria: 

           a)*



           b)*




           c)*


           d)*



           e)*



           f)*






           g)*


     12.     During the period that Roche is participating in development 
and/or marketing of AG3340 *                    , Agouron agrees, on its own 
or with a third party other than Roche, *



                 Each company's members of the JDC will discuss in good faith 
the development of *

     13.     *








     14.     Roche and Agouron agree to cooperate to identify low-cost 
manufacturing sources for Thymitaq and AG3340.  *




     15.     *























16.     *







17.     *




B.     Cell Cycle Control Research Program

     1.     Roche and Agouron agree to collaborate to conduct a joint 
research program ("Research Program") focused on cell cycle control.  The 
initial focus of the Research Program will be the discovery, development, and 
commercialization of drugs which inhibit the activity of CDK4 for any 
indications.  The term of the Research Program ("Research Term") shall refer 
to the three year period commencing on the date of the signing of the LOI, 
unless such term is extended by the mutual written agreement of the parties. 
Compound(s) invented by Roche and/or Agouron, separately or jointly, in the 
Research Program during the Research Term are hereinafter referred to as 
"Program Compound(s)."
     
     2.     During the initial three year period of the Research Term, 
Agouron *



in return for the payment to Agouron by Roche of $3,000,000 per year of 
research support funding; *







     3.     A Joint Research Committee ("JRC"), comprised of representatives 
from Roche and Agouron, shall oversee the Research Program.  Decisions 
regarding the Research Program and the conduct of JRC activities shall be 
made as follows:

          a)     * shall be chaired, *
     from Roche or Agouron.  The JRC shall meet in regular intervals, at 
least                   *               with the first meeting taking place 
within 30 days after the signing of the LOI;
     
          b)     the JRC shall establish and modify a research plan 
("Research Plan") Which sets forth the goals and activities for the Research 
Program; and
     
          c)     the Research Plan shall * 

          as agreed to mutually by the parties.

          d)     decisions made by the JRC regarding the conduct of the 
Research Program *


     4.     Until the expiration of the Research Term, the parties agree to 
provide each other with *          written summaries of their data and 
results from the Research Program. 

     5.     Each party agrees, to the extent it is legally or contractually 
able to do so, to provide the other party *



                                        Each party agrees to keep the 
confidential Information of the other party in confidence and not to utilize 
such Information for any purpose other than for conducting the Research 
Program.  Unless the parties otherwise agree, termination of the Research 
Program for any reason will not give a party the right to utilize the 
confidential Information of the other party for any purpose and will not 
relieve a party of the obligation of confidentiality with respect to the 
Information of the other party.

     6.     Roche shall be responsible for payment of eighty percent of the 
development costs of Program Compounds from the Research Program and Agouron 
shall be responsible for payment of twenty percent of such development costs. 
The development program *
                                          The JDC shall oversee development 
of such Program Compounds.  Decisions regarding development of the Program 
Compounds *
     

     7.     In consideration for rights and obligations set forth elsewhere in 
this Exhibit A, the parties agree that Program Compounds shall be 
commercialized as follows:

          a)     Roche shall have the exclusive marketing rights in Program 
Compounds developed in the Research Program in all countries outside of North 
America, subject to diligent development and marketing efforts, on a country 
by country basis, and payment to Agouron of the following royalties: 

               (i) *


               (ii) *


               (iii) *












          b)     Roche and Agouron shall have co-promotion rights in Program 
Compounds developed in the Research Program in North America under the same 
trademark and based upon a marketing program to be agreed upon by the 
parties.  Profits from sales of Program Compounds in North America shall be 
shared by Roche and Agouron on a fifty-fifty basis, *

                    To the extent permitted by applicable accounting rules, 
sales of Program Compounds products in North America shall be booked 50-50 
each by Roche and Agouron; *

                                    If the parties are co-promoting Program 
Compounds, a Joint Finance Committee, comprised of representatives from Roche 
and Agouron, shall be established to oversee and approve the planning and 
budgeting of revenues and costs resulting from such co-promotional 
activities; and

          c)     the JMC shall oversee marketing of Program Compounds. 
Decisions regarding marketing of Program Compounds shall be made or resolved 
using the same procedures as described in Section A-6 above. 

     8.     Additionally, Roche and Agouron agree to discuss in good faith a 
future right for Agouron to co-promote a Program Compound(s) in selected 
European countries, unless prohibited by law or regulation, based upon the 
following criteria: 

          a)     *


     
          b)     *





          c)     *



          d)     *



          e)     *




          f)     *





          g)     *


     9.     In consideration of the rights granted to Roche by Agouron in 
Program Compound(s), Roche agrees pay to Agouron license issuance fees as 
follows:

          Program Compound                                   $(MM)

          *










          The above license fees shall be payable by Roche one time only.

     10.     Roche and Agouron agree to cooperate to identify low-cost 
manufacturing sources for Program Compounds.  Roche shall be responsible for 
the costs of inventory buildup in all countries where it holds exclusive 
marketing rights to Program 



Compounds; the parties shall share the costs of inventory buildup in North 
America.

     11.     *

























     12.     *






     13.     *



C.     Roche Cancer Product

     1.     Roche, *

                          shall offer such marketing or acquisition rights to 
such Roche Cancer Product in the United States to Agouron before offering 
such rights to an independent third party.  If Agouron declines such offer, 
Roche shall use its reasonable efforts to offer Agouron alternative Roche 
Cancer Product(s) in the United States provided it wishes to offer such 
rights to an independent third party.  For the purposes of this paragraph, a 
Roche Affiliated Company will not be considered an independent third party; 
an "Affiliated Company" is any company controlling, controlled by, or under 
common control with Roche as indicated by direct or indirect ownership or 
control of a least fifty percent (50%) of the voting stock or similar 
interest.  Without limiting the generality of the foregoing, F. Hoffmann-La 
Roche Ltd., Hoffmann-La Roche, Inc., Roche Products Limited and Genentech, 
Inc. are considered to be Affiliated Companies.

     2.     If Agouron has not accepted marketing or acquisition rights to a 
Roche Cancer Product before*



                                   then Roche will offer Agouron co-promotion
 rights in *                in North America.  The obligation to offer 
Agouron co-promotion rights *               in North America will also be 
applicable to *
     

     3.     If Agouron elects to accept co-promotion rights in North America 
in *            which is offered to it pursuant to the terms of Section C-2, 
then Agouron shall have the right to co-promote such *           in North 
America under the same trademark and based upon a marketing program agreed to 
by the parties.  If development of such *               is incomplete in 
North America, commencing on the date of such election, Roche shall be 
responsible for payment of eighty percent of the remaining worldwide 
development costs for *                and Agouron shall be responsible for 
payment of the lesser of:  *

                                                        in North America 
shall be shared by Roche and Agouron on a fifty-fifty basis, assuming *


     4.     In consideration of the rights granted to Agouron by Roche in a *
     Agouron shall also pay to Roche license issuance fees as follows:

     *








D.     Patent Costs

     1.     *