0000899243-17-026400.txt : 20171115 0000899243-17-026400.hdr.sgml : 20171115 20171115172631 ACCESSION NUMBER: 0000899243-17-026400 CONFORMED SUBMISSION TYPE: 3 PUBLIC DOCUMENT COUNT: 7 CONFORMED PERIOD OF REPORT: 20171115 FILED AS OF DATE: 20171115 DATE AS OF CHANGE: 20171115 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: SV LIFE SCIENCES FUND V LP CENTRAL INDEX KEY: 0001460732 STATE OF INCORPORATION: DE FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38295 FILM NUMBER: 171206067 BUSINESS ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 BUSINESS PHONE: 617-973-2708 MAIL ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: SV Life Sciences Fund VI Strategic Partners, L.P. CENTRAL INDEX KEY: 0001667605 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38295 FILM NUMBER: 171206070 BUSINESS ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 BUSINESS PHONE: 617-367-8100 MAIL ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: SVLSF V, LLC CENTRAL INDEX KEY: 0001644160 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38295 FILM NUMBER: 171206072 BUSINESS ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 BUSINESS PHONE: 617-367-8100 MAIL ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: SV Life Sciences Fund V Strategic Partners, L.P. CENTRAL INDEX KEY: 0001482194 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38295 FILM NUMBER: 171206068 BUSINESS ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 BUSINESS PHONE: 617-973-2708 MAIL ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS, LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: SVLSF VI, LLC CENTRAL INDEX KEY: 0001717728 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38295 FILM NUMBER: 171206071 BUSINESS ADDRESS: STREET 1: C/O SV HEALTH INVESTORS, LLC STREET 2: ONE BOSTON PLC, 201 WASHINGTON ST. #3900 CITY: BOSTON STATE: MA ZIP: 02108 BUSINESS PHONE: 6173678100 MAIL ADDRESS: STREET 1: C/O SV HEALTH INVESTORS, LLC STREET 2: ONE BOSTON PLC, 201 WASHINGTON ST. #3900 CITY: BOSTON STATE: MA ZIP: 02108 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: SV Life Sciences Fund VI, L.P. CENTRAL INDEX KEY: 0001642251 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38295 FILM NUMBER: 171206069 BUSINESS ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 BUSINESS PHONE: (617) 367-8100 MAIL ADDRESS: STREET 1: C/O SV LIFE SCIENCES ADVISERS LLC STREET 2: ONE BOSTON PLACE, SUITE 3900 CITY: BOSTON STATE: MA ZIP: 02108 ISSUER: COMPANY DATA: COMPANY CONFORMED NAME: Arsanis, Inc. CENTRAL INDEX KEY: 0001501697 STANDARD INDUSTRIAL CLASSIFICATION: BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836] IRS NUMBER: 273181608 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 BUSINESS ADDRESS: STREET 1: 890 WINTER STREET, SUITE 230 CITY: WALTHAM STATE: MA ZIP: 02451 BUSINESS PHONE: 781-819-5704 MAIL ADDRESS: STREET 1: 890 WINTER STREET, SUITE 230 CITY: WALTHAM STATE: MA ZIP: 02451 3 1 doc3.xml FORM 3 SUBMISSION X0206 3 2017-11-15 0 0001501697 Arsanis, Inc. ASNS 0001644160 SVLSF V, LLC ONE BOSTON PLACE, SUITE 3900 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001717728 SVLSF VI, LLC ONE BOSTON PLACE, SUITE 3900 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001667605 SV Life Sciences Fund VI Strategic Partners, L.P. ONE BOSTON PLACE, SUITE 3900, 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001642251 SV Life Sciences Fund VI, L.P. ONE BOSTON PLACE, SUITE 3900, 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001482194 SV Life Sciences Fund V Strategic Partners, L.P. ONE BOSTON PLACE, SUITE 3900, 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 0001460732 SV LIFE SCIENCES FUND V LP ONE BOSTON PLACE, SUITE 3900, 201 WASHINGTON STREET BOSTON MA 02108 0 0 1 0 Series A-1 Convertible Preferred Stock Common Stock 19128 D Series A-1 Convertible Preferred Stock Common Stock 404 D Series A-2 Convertible Preferred Stock Common Stock 247010 D Series A-2 Convertible Preferred Stock Common Stock 5219 D Series B Convertible Preferred Stock Common Stock 322102 D Series B Convertible Preferred Stock Common Stock 6806 D Series C Convertible Preferred Stock Common Stock 111955 D Series C Convertible Preferred Stock Common Stock 2365 D Series D Convertible Preferred Stock Common Stock 202915 D Series D Convertible Preferred Stock Common Stock 4288 D Series D Convertible Preferred Stock Common Stock 431980 D Series D Convertible Preferred Stock Common Stock 14789 D The Series A-1 Convertible Preferred Stock is convertible into Common Stock on a 0.29300-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date. The Series A-2 Convertible Preferred Stock is convertible into Common Stock on a 0.35785-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date. The Series B Convertible Preferred Stock is convertible into Common Stock on a 0.44650-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date. The Series C Convertible Preferred Stock is convertible into Common Stock on a 0.49832-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date. The Series D Convertible Preferred Stock is convertible into Common Stock on a 0.29300-for-one basis into the number of shares of Common Stock shown in column 3 at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering without payment of further consideration. The shares have no expiration date. These shares are owned directly by SV Life Sciences Fund V, L.P. ("SVLS V LP"). SV Life Sciences Fund V (GP), LP ("SVLS V GP") is the general partner of SVLS V LP. The general partner of SVLS V GP is SVLSF V, LLC. Kate Bingham, James Garvey, Eugene D. Hill, III and Michael Ross are members of the investment committee of SVLSF V, LLC. SVLS V GP, SVLSF V, LLC and each of the individuals comprising the SVLSF V, LLC investment committee may be deemed to share voting, dispositive and investment power over the shares held of record by SVLS V LP. Each of SVLS V GP, SVLSF V, LLC and the individual members of the SVLSF V, LLC investment committee disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their pecuniary interest therein. These shares are owned directly by SV Life Sciences Fund V Strategic Partners, L.P. ("SVLS V SPP"). SVLS V GP is the general partner of SVLS V SPP. The general partner of SVLS V GP is SVLSF V, LLC. Kate Bingham, James Garvey, Eugene D. Hill, III and Michael Ross are members of the investment committee of SVLSF V, LLC. SVLS V GP, SVLSF V, LLC and each of the individuals comprising the SVLSF V, LLC investment committee may be deemed to share voting, dispositive and investment power over the shares held of record by SVLS V SPP. Each of SVLS V GP, SVLSF V, LLC and the individual members of the SVLSF V, LLC investment committee disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their pecuniary interest therein. These shares are owned directly by SV Life Sciences Fund VI, L.P. ("SVLS VI LP"). SV Life Sciences Fund VI (GP), LP ("SVLS VI GP") is the general partner of SVLS VI LP. The general partner of SVLS VI GP is SVLSF VI, LLC. Kate Bingham, James Garvey, Eugene D. Hill, III, Paul LaViolette, Thomas Flynn and Michael Ross are members of the investment committee of SVLSF VI, LLC. SVLS VI GP, SVLSF VI, LLC and each of the individuals comprising the SVLSF VI, LLC investment committee may be deemed to share voting, dispositive and investment power over the shares held of record by SVLS VI LP. Each of SVLS VI GP, SVLSF VI, LLC and the individual members of the SVLSF VI, LLC investment committee disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their pecuniary interest therein. These shares are owned directly by SV Life Sciences Fund VI Strategic Partners, L.P. ("SVLS VI SPP"). SVLS VI GP is the general partner of SVLS VI SPP. The general partner of SVLS VI GP is SVLSF VI, LLC. Kate Bingham, James Garvey, Eugene D. Hill, III, Paul LaViolette, Thomas Flynn and Michael Ross are members of the investment committee of SVLSF VI, LLC. SVLS VI GP, SVLSF VI, LLC and each of the individuals comprising the SVLSF VI, LLC investment committee may be deemed to share voting, dispositive and investment power over the shares held of record by SVLS VI SPP. Each of SVLS VI GP, SVLSF VI, LLC and the individual members of the SVLSF VI, LLC investment committee disclaims beneficial ownership of these securities and this report shall not be deemed to be an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or any other purpose, except to the extent of their pecuniary interest therein. Exhibit Index: 24.1 Power of Attorney 24.2 Power of Attorney 24.3 Power of Attorney 24.4 Power of Attorney 24.5 Power of Attorney 24.6 Power of Attorney /s/ Mike Gray, as attorney-in-fact on behalf of SVLSF V, LLC 2017-11-15 /s/ Mike Gray, as attorney-in-fact on behalf of SVLSF VI, LLC 2017-11-15 /s/ Mike Gray, as attorney-in-fact on behalf of SV Life Sciences Fund V, L.P. 2017-11-15 /s/ Mike Gray, as attorney-in-fact on behalf of SV Life Sciences Fund V Strategic Partners, L.P. 2017-11-15 /s/ Mike Gray, as attorney-in-fact on behalf of SV Life Sciences Fund VI, L.P. 2017-11-15 /s/ Mike Gray, as attorney-in-fact on behalf of SV Life Sciences Fund VI Strategic Partners, L.P. 2017-11-15 EX-24.1 2 attachment1.htm EX-24.1 DOCUMENT 
                                                                    EXHIBIT 24.1

         LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

    Know all by these presents, that the undersigned hereby makes, constitutes
and appoints each of Rene Russo and Mike Gray, signing singly and each acting
individually, as the undersigned's true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

    (1)  execute for and on behalf of the undersigned, Forms 3, 4, and 5
(including any amendments thereto) in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder (the "Exchange Act");

    (2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to prepare, complete and execute any such
Form 3, 4, or 5, prepare, complete and execute any amendment or amendments
thereto, and timely deliver and file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar authority,
including without limitation the filing of a Form ID or any other application
materials to enable the undersigned to gain or maintain access to the Electronic
Data Gathering, Analysis and Retrieval system of the SEC;

    (3)  seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information regarding transactions in the securities of
Arsanis, Inc. (the "Company") from any third party, including brokers, employee
benefit plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to such attorney-in-fact and
approves and ratifies any such release of information; and

    (4)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned 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.

    The undersigned hereby grants to each such 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 such 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.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming nor
relieving, nor is the Company assuming nor relieving, any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.  The undersigned
acknowledges that neither the Company nor the foregoing attorneys-in-fact assume
(i) any liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any obligation or liability
of the undersigned for profit disgorgement under Section 16(b) of the Exchange
Act.

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 13th day of November, 2017.

                                        SVLSF V, LLC.


                                        By: /s/ Denise W. Marks
                                            ------------------------------
                                        Name: Denise W. Marks
                                        Title: SVLSF V, LLC, Member
EX-24.2 3 attachment2.htm EX-24.2 DOCUMENT 
                                                                    EXHIBIT 24.2

           LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

    Know all by these presents, that the undersigned hereby makes, constitutes
and appoints each of Rene Russo and Mike Gray, signing singly and each acting
individually, as the undersigned's true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

    (1)  execute for and on behalf of the undersigned, Forms 3, 4, and 5
(including any amendments thereto) in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder (the "Exchange Act");

    (2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to prepare, complete and execute any such
Form 3, 4, or 5, prepare, complete and execute any amendment or amendments
thereto, and timely deliver and file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar authority,
including without limitation the filing of a Form ID or any other application
materials to enable the undersigned to gain or maintain access to the Electronic
Data Gathering, Analysis and Retrieval system of the SEC;

    (3)  seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information regarding transactions in the securities of
Arsanis, Inc. (the "Company") from any third party, including brokers, employee
benefit plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to such attorney-in-fact and
approves and ratifies any such release of information; and

    (4)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned 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.

    The undersigned hereby grants to each such 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 such 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.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming nor
relieving, nor is the Company assuming nor relieving, any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.  The undersigned
acknowledges that neither the Company nor the foregoing attorneys-in-fact assume
(i) any liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any obligation or liability
of the undersigned for profit disgorgement under Section 16(b) of the Exchange
Act.

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 13th day of November, 2017.

                                        SVLSF VI, LLC

                                        By: /s/ Denise W. Marks
                                            ------------------------------------
                                        Name: Denise W. Marks
                                        Title: SVLSF VI, LLC, Member
EX-24.3 4 attachment3.htm EX-24.3 DOCUMENT 
                                                                    Exhibit 24.3

           LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

    Know all by these presents, that the undersigned hereby makes, constitutes
and appoints each of Rene Russo and Mike Gray, signing singly and each acting
individually, as the undersigned's true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

    (1)  execute for and on behalf of the undersigned, Forms 3, 4, and 5
(including any amendments thereto) in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder (the "Exchange Act");

    (2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to prepare, complete and execute any such
Form 3, 4, or 5, prepare, complete and execute any amendment or amendments
thereto, and timely deliver and file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar authority,
including without limitation the filing of a Form ID or any other application
materials to enable the undersigned to gain or maintain access to the Electronic
Data Gathering, Analysis and Retrieval system of the SEC;

    (3)  seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information regarding transactions in the securities of
Arsanis, Inc. (the "Company") from any third party, including brokers, employee
benefit plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to such attorney-in-fact and
approves and ratifies any such release of information; and

    (4)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned 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.

    The undersigned hereby grants to each such 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 such 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.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming nor
relieving, nor is the Company assuming nor relieving, any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.  The undersigned
acknowledges that neither the Company nor the foregoing attorneys-in-fact assume
(i) any liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any obligation or liability
of the undersigned for profit disgorgement under Section 16(b) of the Exchange
Act.

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 31st day of October, 2017.

                                        SV LIFE SCIENCES FUND V, L.P.

                                        By:  SV Life Sciences Fund V (GP), L.P.,
                                             Its sole General Partner

                                        By:  SVLSF V, LLC,
                                             Its sole General Partner


                                        By: /s/ Denise W. Marks
                                            ------------------------------------
                                        Name: Denise W. Marks
                                        Title: SVLSF V, LLC, Member
EX-24.4 5 attachment4.htm EX-24.4 DOCUMENT 
                                                                    EXHIBIT 24.4

           LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

    Know all by these presents, that the undersigned hereby makes, constitutes
and appoints each of Rene Russo and Mike Gray, signing singly and each acting
individually, as the undersigned's true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

    (1)  execute for and on behalf of the undersigned, Forms 3, 4, and 5
(including any amendments thereto) in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder (the "Exchange Act");

    (2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to prepare, complete and execute any such
Form 3, 4, or 5, prepare, complete and execute any amendment or amendments
thereto, and timely deliver and file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar authority,
including without limitation the filing of a Form ID or any other application
materials to enable the undersigned to gain or maintain access to the Electronic
Data Gathering, Analysis and Retrieval system of the SEC;

    (3)  seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information regarding transactions in the securities of
Arsanis, Inc. (the "Company") from any third party, including brokers, employee
benefit plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to such attorney-in-fact and
approves and ratifies any such release of information; and

    (4)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned 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.

    The undersigned hereby grants to each such 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 such 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.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming nor
relieving, nor is the Company assuming nor relieving, any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.  The undersigned
acknowledges that neither the Company nor the foregoing attorneys-in-fact assume
(i) any liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any obligation or liability
of the undersigned for profit disgorgement under Section 16(b) of the Exchange
Act.

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 31st day of October, 2017.

                              SV LIFE SCIENCES FUND V STRATEGIC
                              PARTNERS, L.P.

                              By:  SV Life Sciences Fund V (GP), L.P.,
                                   Its sole General Partner

                              By:  SVLSF V, LLC,
                                   Its sole General Partner


                              By: /s/ Denise W. Marks
                                  ----------------------------------------------
                              Name: Denise W. Marks
                              Title: SVLSF V, LLC, Member
EX-24.5 6 attachment5.htm EX-24.5 DOCUMENT 
                                                                    EXHIBIT 24.5

           LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

    Know all by these presents, that the undersigned hereby makes, constitutes
and appoints each of Rene Russo and Mike Gray, signing singly and each acting
individually, as the undersigned's true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

    (1)  execute for and on behalf of the undersigned, Forms 3, 4, and 5
(including any amendments thereto) in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder (the "Exchange Act");

    (2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to prepare, complete and execute any such
Form 3, 4, or 5, prepare, complete and execute any amendment or amendments
thereto, and timely deliver and file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar authority,
including without limitation the filing of a Form ID or any other application
materials to enable the undersigned to gain or maintain access to the Electronic
Data Gathering, Analysis and Retrieval system of the SEC;

    (3)  seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information regarding transactions in the securities of
Arsanis, Inc. (the "Company") from any third party, including brokers, employee
benefit plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to such attorney-in-fact and
approves and ratifies any such release of information; and

    (4)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned 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.

    The undersigned hereby grants to each such 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 such 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.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming nor
relieving, nor is the Company assuming nor relieving, any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.  The undersigned
acknowledges that neither the Company nor the foregoing attorneys-in-fact assume
(i) any liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any obligation or liability
of the undersigned for profit disgorgement under Section 16(b) of the Exchange
Act.

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 31st day of October, 2017.

                              SV LIFE SCIENCES FUND VI, L.P.

                              By:  SV Life Sciences Fund VI (GP), L.P.,
                                   Its sole General Partner

                              By:  SVLSF VI, LLC,
                                   Its sole General Partner


                              By: /s/ Denise W. Marks
                                  --------------------------------
                              Name: Denise W. Marks
                              Title: SVLSF VI, LLC, Member
EX-24.6 7 attachment6.htm EX-24.6 DOCUMENT 
                                                                    EXHIBIT 24.6

           LIMITED POWER OF ATTORNEY FOR SECTION 16 REPORTING OBLIGATIONS

    Know all by these presents, that the undersigned hereby makes, constitutes
and appoints each of Rene Russo and Mike Gray, signing singly and each acting
individually, as the undersigned's true and lawful attorney-in-fact with full
power and authority as hereinafter described to:

    (1) execute for and on behalf of the undersigned, Forms 3, 4, and 5
(including any amendments thereto) in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder (the "Exchange Act");

    (2)  do and perform any and all acts for and on behalf of the undersigned
which may be necessary or desirable to prepare, complete and execute any such
Form 3, 4, or 5, prepare, complete and execute any amendment or amendments
thereto, and timely deliver and file such form with the United States Securities
and Exchange Commission (the "SEC") and any stock exchange or similar authority,
including without limitation the filing of a Form ID or any other application
materials to enable the undersigned to gain or maintain access to the Electronic
Data Gathering, Analysis and Retrieval system of the SEC;

    (3)  seek or obtain, as the undersigned's representative and on the
undersigned's behalf, information regarding transactions in the securities of
Arsanis, Inc. (the "Company") from any third party, including brokers, employee
benefit plan administrators and trustees, and the undersigned hereby authorizes
any such person to release any such information to such attorney-in-fact and
approves and ratifies any such release of information; and

    (4)  take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of the
undersigned 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.

    The undersigned hereby grants to each such 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 such 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.  The undersigned acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming nor
relieving, nor is the Company assuming nor relieving, any of the undersigned's
responsibilities to comply with Section 16 of the Exchange Act.  The undersigned
acknowledges that neither the Company nor the foregoing attorneys-in-fact assume
(i) any liability for the undersigned's responsibility to comply with the
requirement of the Exchange Act, (ii) any liability of the undersigned for any
failure to comply with such requirements, or (iii) any obligation or liability
of the undersigned for profit disgorgement under Section 16(b) of the Exchange
Act.

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4, and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 31st day of October, 2017.

                              SV LIFE SCIENCES FUND VI STRATEGIC
                              PARTNERS, L.P.

                              By:  SV Life Sciences Fund VI (GP), L.P.,
                                   Its sole General Partner

                              By:  SVLSF VI, LLC,
                                   Its sole General Partner

                              By: /s/ Denise W. Marks
                                  --------------------------------------
                              Name: Denise W. Marks
                              Title: SVLSF VI, LLC, Member