POWER OF ATTORNEY

    Know all by these presents, that each of the undersigned hereby constitutes
and appoints each other undersigned, such person's true and lawful
attorney-in-fact, to:

    (1)	execute for and on behalf of each of such person Forms 3, 4, and 5 and
Schedules 13D or 13G, as appropriate, and any required amendments thereto
(collectively, the "Reports"), with respect to their current or future
beneficial ownership of securities of any public company, in accordance with
Section 13(d) and/or Section 16(a) of the Securities Exchange Act of 1934, as
amended, and the respective rules (including Rule 13d-1) promulgated thereunder;

    (2)	do and perform any and all acts for and on behalf of such person which
may be necessary or desirable to complete and execute any such Report and timely
file such form with the United States Securities and Exchange Commission and any
stock exchange or similar authority; and

    (3)	take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of an attorney-in-fact, may be of benefit to, in
the best interest of, or legally required by, such person, it being understood
that the documents executed by an attorney-in-fact on behalf of such person
pursuant to this Power of Attorney shall be in such form and shall contain such
terms and conditions as such attorney-in-fact may approve in such
attorney-in-fact's discretion.

    Each of the undersigned hereby grants to each attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that each
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted. Each of the undersigned hereby ratifies and
confirms each Report that has been signed by any other undersigned prior to the
date hereof. Each of the undersigned
acknowledges that each foregoing attorney-in-fact, in serving in such capacity
at the request of the undersigned, is not assuming any of the undersigneds'
responsibilities to comply with Section 13(d) or Section 16 of the Securities
Exchange Act of 1934.

    This Power of Attorney shall remain in full force and effect until the
undersigned are no longer required to file Reports with respect to the
undersigneds' current or future holdings of and transactions in securities
issued by any public company, unless earlier revoked by the undersigned in a
signed writing delivered to each foregoing attorney-in-fact.

    IN WITNESS WHEREOF, the undersigned have caused this Power of Attorney to be
executed as of dates set forth opposite their names.

Dated: 7/18/18                /s/ Otello Stampacchia
                              Otello Stampacchia

Dated: 7/18/18                /s/ Richard Lim
                              Richard Lim

Dated: 7/18/18                /s/ Anne-Mari Paster
                              Anne-Mari Paster