Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F2,F3	Mar 4, 2019	C	1,545,852	—	A	1,545,852	I	See Footnote
Common Stock^F2,F4	Mar 4, 2019	C	4,637,555	—	A	4,637,555	I	See Footnote
Common Stock^F5,F3	Mar 4, 2019	C	426,240	—	A	1,972,092	I	See Footnote
Common Stock^F5,F6	Mar 4, 2019	C	639,360	—	A	639,360	I	See Footnote
Common Stock^F7,F3	Mar 4, 2019	C	321,337	—	A	2,293,429	I	See Footnote
Common Stock^F7,F4	Mar 4, 2019	C	964,010	—	A	5,601,565	I	See Footnote
Common Stock^F7,F9	Mar 4, 2019	C	1,285,347	—	A	1,285,347	I	See Footnote
Common Stock^F8,F4	Mar 4, 2019	C	625,625	—	A	6,227,190	I	See Footnote
Common Stock^F8,F9	Mar 4, 2019	C	625,625	—	A	1,910,972	I	See Footnote
Common Stock^F3	Mar 4, 2019	P	266,667	$15.00	A	2,560,096	I	See Footnote
Common Stock^F4	Mar 4, 2019	P	333,333	$15.00	A	6,560,523	I	See Footnote
Common Stock^F9	Mar 4, 2019	P	333,333	$15.00	A	2,244,305	I	See Footnote
Common Stock^F1	holding	—	—		—	2,500,000	I	See Footnote

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
Series A Preferred Stock^F2,F3	—	Mar 4, 2019	C	3,091,704	D	—	—	Common Stock	1,545,852	I
Series A Preferred Stock^F2,F4	—	Mar 4, 2019	C	9,275,111	D	—	—	Common Stock	4,637,555	I
Series A-1 Preferred Stock^F5,F3	—	Mar 4, 2019	C	852,480	D	—	—	Common Stock	426,240	I
Series A-1 Preferred Stock^F5,F6	—	Mar 4, 2019	C	1,278,720	D	—	—	Common Stock	639,360	I
Series B Preferred Stock^F7,F3	—	Mar 4, 2019	C	642,674	D	—	—	Common Stock	321,337	I
Series B Preferred Stock^F7,F4	—	Mar 4, 2019	C	1,928,021	D	—	—	Common Stock	964,010	I
Series B Preferred Stock^F7,F9	—	Mar 4, 2019	C	2,570,694	D	—	—	Common Stock	1,285,347	I
Series C Preferred Stock^F8,F4	—	Mar 4, 2019	C	1,251,251	D	—	—	Common Stock	625,625	I
Series C Preferred Stock^F8,F9	—	Mar 4, 2019	C	1,251,251	D	—	—	Common Stock	625,625	I

Explanation of responses

F1Shares held by Flagship VentureLabs V LLC ("VentureLabs V"). Flagship Ventures Fund V, L.P. ("Flagship Fund V") is a member of VentureLabs V. Flagship Ventures Fund V General Partner LLC ("Flagship Fund V GP") is the general partner of Flagship Fund V. Flagship VentureLabs V Manager LLC ("VentureLabs V Manager") serves as manager of VentureLabs V. Flagship Pioneering, Inc. ("Flagship Pioneering") is the manager of VentureLabs V Manager. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and as sole director of Flagship Pioneering. Each of these entities and Noubar B. Afeyan, Ph.D. may be deemed to share voting and investment power with respect to all shares held by VentureLabs V. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.
F2Each share of Series A Preferred Stock converted into shares of the Issuer's common stock, par value $0.001 ("Common Stock"), on a one-for-two basis upon the closing of the Issuer's initial public offering.
F3Shares held by Flagship Fund V. Flagship Fund V GP is the general partner of Flagship Fund V. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and may be deemed to possess sole voting and investment power with respect to all shares held by Flagship Fund V. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.
F4Shares held by Nutritional Health Disruptive Innovation Fund, L.P. ("Nutritional Innovation Fund"). Flagship Fund V GP is the general partner of Nutritional Innovation Fund. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and may be deemed to possess sole voting and investment power with respect to all shares held by Nutritional Innovation Fund. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.
F5Each share of Series A-1 Preferred Stock converted into shares of the Issuer's Common Stock on a one-for-two basis upon the closing of the Issuer's initial public offering.
F6Shares held by Nutritional Health Side Fund, L.P. ("Nutritional Health Side Fund"). Flagship Fund V GP is the general partner of Nutritional Health Side Fund. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and may be deemed to possess sole voting and investment power with respect to all shares held by Nutritional Health Side Fund. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.
F7Each share of Series B Preferred Stock converted into shares of the Issuer's Common Stock on a one-for-two basis upon the closing of the Issuer's initial public offering.
F8Each share of Series C Preferred Stock converted into shares of the Issuer's Common Stock on a one-for-two basis upon the closing of the Issuer's initial public offering.
F9Shares held by Flagship Ventures Opportunities Fund I, L.P. ("Flagship Opportunities I"). Flagship Ventures Opportunities Fund I General Partner LLC ("Flagship Opportunities GP") is the general partner of Flagship Opportunities I. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Opportunities GP and may be deemed to possess sole voting and investment power with respect to all shares held by Flagship Opportunities I. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein.

Remarks

Due to limitations of the electronic filing system, each of Flagship Ventures Fund IV General Partner LLC, Flagship Ventures Fund IV, L.P., Flagship VentureLabs IV LLC, Flagship Ventures 2007 General Partner LLC, Flagship Ventures Fund 2007, L.P., Cadena LLC, Edwin M. Kania Jr. and Noubar B. Afeyan, Ph.D. are filing a separate Form 4 with respect to securities of the Issuer.