# EDGAR Filing Document

**Accession Number:** 0001956827
**File Stem:** 0001104659-26-058492
**Filing Date:** 2026-5
**Character Count:** 31678
**Document Hash:** 1a3dee8d1cd98c183a7fe0985497b3e3
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-058492.hdr.sgml**: 20260511

**ACCESSION NUMBER**: 0001104659-26-058492

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260511

**DATE AS OF CHANGE**: 20260511

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Abivax S.A.
- **CENTRAL INDEX KEY:** 0001956827
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** I0
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-94198
- **FILM NUMBER:** 26961954

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 7 BD HAUSSMANN
- **CITY:** PARIS
- **PROVINCE COUNTRY:** I0
- **BUSINESS PHONE:** 01 53 83 09 63

**MAIL ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 7 BD HAUSSMANN
- **CITY:** PARIS
- **PROVINCE COUNTRY:** I0
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Sofinnova Crossover I
- **CENTRAL INDEX KEY:** 0001845105

**ORGANIZATION NAME:**
- **EIN:** 981420904
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 7-11 BOULEVARD HAUSSMAN
- **CITY:** PARIS
- **STATE:** I0
- **ZIP:** 75009
- **BUSINESS PHONE:** 33 (0) 1 76 23 41 00

**MAIL ADDRESS:**
- **STREET 1:** 7-11 BOULEVARD HAUSSMAN
- **CITY:** PARIS
- **STATE:** I0
- **ZIP:** 75009

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 5)**

**Abivax S.A.**

*(Name of Issuer)*

**Ordinary Shares, par value EUR0.01 per share**

*(Title of Class of Securities)*

**—**

*(CUSIP Number)*

**Armance Bordes**<br>7-11, boulevard Haussmann<br>Paris I0 75009<br>33 1 76 23 41 09

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**05/07/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Sofinnova Crossover I SLP** | Name of reporting person<br>**Sofinnova Crossover I SLP** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**I0** | Citizenship or place of organization<br>**I0** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

**Comment for Reporting Person:** Note in relation to Items 7 and 8: Sofinnova Partners SAS, a French corporation ("SP SAS"), the management company of Sofinnova Crossover I SLP ("SC"), may be deemed to have sole voting power, and Antoine Papiernik ("Papiernik"), Cedric Moreau ("Moreau"), Kinam Hong ("Hong"), Joseph Anderson ("Anderson") and Jacques Theurillat ("Theurillat"), the members of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note in relation to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Papiernik, Moreau, Hong, Anderson and Theurillat, the members of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,494 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Sofinnova Partners SAS** | Name of reporting person<br>**Sofinnova Partners SAS** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**I0** | Citizenship or place of organization<br>**I0** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

**Comment for Reporting Person:** Note in relation to Items 7 and 8: SP SAS, the management company of SC, may be deemed to have sole voting power, and Papiernik, Moreau, Hong, Anderson and Theurillat, the members of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note in relation to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Papiernik, Moreau, Hong, Anderson and Theurillat, the members of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,478 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Antoine Papiernik** | Name of reporting person<br>**Antoine Papiernik** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**I0** | Citizenship or place of organization<br>**I0** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** Note to Items 7 and 8: SP SAS, the management company of SC, may be deemed to have sole voting power, and Papiernik, a member of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Papiernik, a member of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,494 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Cedric Moreau** | Name of reporting person<br>**Cedric Moreau** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**I0** | Citizenship or place of organization<br>**I0** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** Note to Items 7 and 8: SP SAS, the management company of SC, may be deemed to have sole voting power, and Moreau, a member of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Moreau, a member of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,494 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Kinam Hong** | Name of reporting person<br>**Kinam Hong** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** Note to Items 7 and 8: SP SAS, the management company of SC, may be deemed to have sole voting power, and Hong, a member of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Hong, a member of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,494 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,844 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Joseph Anderson** | Name of reporting person<br>**Joseph Anderson** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X0** | Citizenship or place of organization<br>**X0** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** Note to Items 7 and 8: SP SAS, the management company of SC, may be deemed to have sole voting power, and Anderson, a member of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Anderson, a member of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,494 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Jacques Theurillat** | Name of reporting person<br>**Jacques Theurillat** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**V8** | Citizenship or place of organization<br>**V8** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**5499478.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**3377494.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | Aggregate amount beneficially owned by each reporting person<br>**5499478.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**6.7%** | Percent of class represented by amount in Row (11)<br>**6.7%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** Note to Items 7 and 8: SP SAS, the management company of SC, may be deemed to have sole voting power, and Theurillat, a member of the investment committee of SC, may be deemed to have shared power to vote these shares.

Note to Items 9 and 10: SP SAS, the management company of SC, may be deemed to have sole power to dispose of these shares, and Theurillat, a member of the investment committee of SC, may be deemed to have shared power to dispose of these shares.

Note in relation to Items 8, 10, 11 and 13: The Reporting Person beneficially owns 3,377,494 Ordinary Shares (including ordinary shares represented by American depositary shares) and has 5,499,478 voting rights related to such shares. The aggregate amount beneficially owned and percent of class reported above are based on the Reporting Person's voting rights and the 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement (as defined below).

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Ordinary Shares, par value EUR0.01 per share

**(b) Name of Issuer:**
Abivax S.A.

**(c) Address of Issuer's Principal Executive Offices:**
7-11, boulevard Haussmann, Paris, I0, 75009

Introductory Statement:

This Amendment No. 5 (this "Amendment"), being filed by Sofinnova Crossover I SLP ("SC"), Sofinnova Partners SAS, a French corporation ("SP SAS"), Antoine Papiernik ("Papiernik"), Cedric Moreau ("Moreau"), Kinam Hong ("Hong"), Joseph Anderson ("Anderson") and Jacques Theurillat ("Theurillat") the members of the investment committee of SC (collectively, the "Listed Persons" and together with SC and SP SAS, the "Reporting Persons"), amends and supplements the Schedule 13D filed with the Securities and Exchange Commission (the "SEC") on October 30, 2023, as amended by Amendment No. 1, filed with the SEC on February 14, 2025, as further amended by Amendment No. 2, filed with the SEC on July 31, 2025, as amended by Amendment No. 3, filed with the SEC on October 30, 2025, and as further amended by Amendment No. 4, filed with the SEC on January 14, 2026 (collectively, as amended, the "Schedule 13D").

This Schedule 13D relates to the Ordinary Shares, par value EUR0.01 per share (the "Ordinary Shares"), including ordinary shares represented by American Depositary Shares ("ADS"), of Abivax SA, a societe anonyme incorporated under the laws of the French Republic (the "Issuer"). Except as specifically provided herein, this Amendment No. 5 does not modify any of the information previously reported in the Schedule 13D.  Capitalized terms used herein shall have the meanings ascribed to them in the Schedule 13D.

**Item 4. Purpose of Transaction**

Item 4 of the Schedule 13D is hereby amended and supplemented as follows:

On May 4, 2026, SC, among various other shareholders, entered into a Purchase Agreement with the Issuer to repurchase royalty certificates issued to SC, and the other shareholders, on September 7, 2022. The Issuer repurchased the royalty certificates in full by paying an aggregate consideration of $90.0 million, $45.0 million of which was paid in cash and $45.0 million was paid in shares through the issuance of 403,347 ordinary shares, including in the form of ADS in a private placement (the "Private Placement"). In the Private Placement, SC received 42,755 ADSs. On May 7, 2026, the Issuer registered the offering and resale of the ADSs.

In addition to the Private Placement, Mr. Hong no longer serves as a member of the Board of Directors of the Issuer and no longer has influence over the corporate activities of the Issuer. Mr. Hong is no longer entitled to receive cash attendance fees.

All of the Ordinary Shares that are held of record by the Reporting Persons as reported herein were acquired for investment purposes. The Reporting Persons retain the right to change their investment intent, from time to time to acquire additional Ordinary Shares or other securities of the Issuer, or to sell or otherwise dispose of all or part of the Ordinary Shares or other securities of the Issuer, if any, beneficially owned by them, in any manner permitted by law. The Reporting Persons may engage from time to time in ordinary course transactions with financial institutions with respect to the securities described herein.

Except as set forth above, none of the Reporting Persons currently has any plans or proposals which would be related to or would result in any of the matters described in Items 4(a)-(j) of the Instructions to Schedule 13D. However, as part of the ongoing evaluation of investment and investment alternatives, the Reporting Persons may consider such matters and, subject to applicable law, may formulate a plan with respect to such matters, and, from time to time, may hold discussions with or make formal proposals to management or the board of directors of the Issuer or other third parties regarding such matters.

**Item 5. Interest in Securities of the Issuer**

**(a)**
Item 5(a) of the Schedule 13D is hereby amended and supplemented as follows:

As of May 11, 2026, SC held directly 3,377,494 Ordinary Shares representing approximately 4.3% of the Issuer's outstanding Ordinary Shares and 5,499,478 voting rights representing approximately 6.7% of the Issuer's outstanding voting rights. None of the other Reporting Persons hold any Ordinary Shares or ADSs directly.  SP SAS is the management company of SC and may be deemed to have shared voting and investment control over the Ordinary Shares and ADSs held by SC.  Each of Antoine Papiernik, Cedric Moreau, Kinam Hong, Joseph Anderson and Jacques Theurillat are the members of the investment committee of SC and may be deemed to have shared voting and investment control over the Ordinary Shares and ADSs held by SC. Each of such individuals disclaims beneficial ownership of such Ordinary Shares and ADSs except to the extent of their pecuniary interest therein.

The ownership percentages are based upon 79,694,535 of the Issuer's Ordinary Shares outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement. The voting percentages are based upon 82,047,884 voting rights outstanding as of March 31, 2026, as adjusted to reflect the shares issued in the Private Placement.

**(b)**
Item 5(b) of the Schedule 13D is hereby amended and supplemented as follows:

See the information contained on the cover pages of this Amendment, which is incorporated herein by reference.

**(c)**
Item 5(c) of the Schedule 13D is hereby amended and supplemented as follows:

Except as disclosed herein, there have been no other reportable transactions with respect to the Ordinary Shares or ADSs of the Issuer within the last 60 days by the Reporting Persons.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

On May 4, 2026, SC entered into a Purchase Agreement with Issuer to repurchase royalty certificates issued to SC, among other shareholders, on September 7, 2022, in exchange for 42,755 ADSs. Pursuant to the Purchase Agreement, the Issuer agreed to register the new ADSs for resale. The description of the Purchase Agreement herein is not complete and is qualified in its entirety by reference to the full text of the Purchase Agreement, which is filed herewith as Exhibit 99.2 and incorporated herein by reference.

Kinam Hong, a member of the investment committee of SC, is no longer a member of the Issuer's Board of Directors.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Sofinnova Crossover I SLP

**Signature:** /s/ Antoine Papiernik

**Name/Title:** Managing Partner

**Date:** 05/11/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Sofinnova Partners SAS

**Signature:** /s/ Antoine Papiernik

**Name/Title:** Managing Partner

**Date:** 05/11/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Antoine Papiernik

**Signature:** /s/ Antoine Papiernik

**Name/Title:** Antoine Papiernik

**Date:** 05/11/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Cedric Moreau

**Signature:** /s/ Cedric Moreau

**Name/Title:** Cedric Moreau

**Date:** 05/11/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Kinam Hong

**Signature:** /s/ Kinam Hong

**Name/Title:** Kinam Hong

**Date:** 05/11/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Joseph Anderson

**Signature:** /s/ Joseph Anderson

**Name/Title:** Joseph Anderson

**Date:** 05/11/2026

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Jacques Theurillat

**Signature:** /s/ Jacques Theurillat

**Name/Title:** Jacques Theurillat

**Date:** 05/11/2026