144: Filer Information

Filer CIK

0001845105

Filer CCC

XXXXXXXX

Is this a LIVE or TEST Filing?

LIVE

TEST

Submission Contact Information

Name

Phone

E-Mail Address

144: Issuer Information

Name of Issuer

Abivax S.A.

SEC File Number

001-41842

Address of Issuer

7-11 boulevard Haussmann
Paris
FRANCE
75009

Phone

330-153830963

Name of Person for Whose Account the Securities are To Be Sold

Sofinnova Crossover I SLP

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

Affiliate

144: Securities Information

Title of the Class of Securities To Be Sold

Name and Address of the Broker

Number of Shares or Other Units To Be Sold

Aggregate Market Value

Number of Shares or Other Units Outstanding

Approximate Date of Sale

Name the Securities Exchange

ADS

Leerink Partners
53 State St., 40th Floor
Boston � MA � 02109

1000000

133700000.00

77800000

01/08/2026

NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class

Date you Acquired

Nature of Acquisition Transaction

Name of Person from Whom Acquired

Is this a Gift?

Date Donor Acquired

Amount of Securities Acquired

Date of Payment

Nature of Payment *

ADS

07/11/2019

Private Placement

Issuer

1000000

07/15/2019

Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller

Title of Securities Sold

Date of Sale

Amount of Securities Sold

Gross Proceeds

Sofinnova Crossover I SLP
7-11, boulevard Haussman
Paris � I0 � 75009

ADS

10/28/2025

590877

55638897.00

Sofinnova Crossover I SLP
7-11, boulevard Haussman
Paris � I0 � 75009

ADS

10/29/2025

609123

57261354.00

144: Remarks and Signature

Remarks

Date of Notice

01/08/2026

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

/s/ Christophe Blanche

SEC Form 144 filed by Abivax SA