AB Science today reports its revenues for the first half of 2026 and provides an update on its activities

PRESS RELEASE        

AB SCIENCE REPORTS ITS FINANCIAL RESULTS FOR THE FIRST HALF OF 2026 AND KEY EVENTS OF THE PERIOD

• Change in AB Science's governance and implementation of a new strategy
  • Appointment of Stéphane Ledermann as Chairman and Chief Executive Officer
  • In-depth overhaul of the Company's organisation and strategy
  • Priority given to the development of a new quality assurance system
  • Web conference to be held on Wednesday 14 October 2026 at 6:00 pm to present the Company's new ambitions in detail
    
    
• Financial and corporate situation
  
  
  • Operating loss of €10.4 million as of 30 June 2026, mainly due to the recognition of a €6.5 million provision relating to the Research Tax Credit (Crédit d'Impôt Recherche, CIR)
  • Cash position of €8.9 million as of 30 June 2026, in addition to which €16.5 million was raised through private placements completed in July and August 2026
  • Final agreement on the renegotiation of the repayment terms of its loans with all financial creditors

• Clinical development
  • Masitinib:
    • Update on the development plan following a sponsor inspection on Good Clinical Practice
    • Clinical trial insurance obtained for the Phase 3 study in Amyotrophic Lateral Sclerosis (Lou Gehrig's disease) covering up to €39 million
    • Identification of a potential biomarker to assess the activity of masitinib on the pathological involvement of microglia in Amyotrophic Lateral Sclerosis
  • AB8939:
    • Update on the Phase 1 study of AB8939 and completion of Stage 3 of Phase 1, evaluating the combination of AB8939 and Venetoclax in the treatment of relapsed or refractory acute myeloid leukaemia
      
      

Paris, 9 October 2026, 6.15pm CET

AB Science SA (Euronext - FR0010557264 - AB) today announces its half-year financial results as of 30 June 2026 and provides an update on its activities.

IMPLEMENTATION OF A NEW GOVERNANCE AND A NEW STRATEGY

Change in AB Science's governance and appointment of Stéphane Ledermann as Chairman and Chief Executive Officer

On 8 July 2026, AB Science announced the decision of its Board of Directors to change the Company's governance in order to enter a new stage of its development, as well as the co-optation of Stéphane Ledermann as Chairman and Chief Executive Officer. The Board of Directors decided to entrust its new Chairman and Chief Executive Officer with conducting a strategic review of the Company's activities, assets and prospects. On this occasion, Mr Alain Moussy, co-founder of AB Science, stepped down from his position as Chairman and Chief Executive Officer and remains a director and shareholder. He no longer holds any other operational role.

Implementation of a new organisation and a new ambition

Stéphane Ledermann initiated a transformation plan for AB Science as early as 13 July 2026. The main lines of this “Relaunch AB Science” plan were announced to all employees on 2 September 2026

The ambition is now to create value from all of the Company's assets, whatever their stage of development, to relaunch research and development and to finance the necessary clinical studies, in particular the AB8939 programme in acute myeloid leukaemia and masitinib in amyotrophic lateral sclerosis (Lou Gehrig's disease). This new strategy is built around the following pillars:

• Priority given to the development of a new quality assurance system: led by the Quality department but involving every department, this initiative will ensure compliance with Good Clinical Practice for future studies.
• In-depth overhaul of the Company's organisation in order to secure its activities and meet regulatory requirements: in August 2026, AB Science put in place a new, evolving organisation chart based on the creation of new key functions, aimed at improving the Company's productivity and operational efficiency. Several internal committees have been set up.
• Development and value creation:
  • Raising the Company's profile beyond its current 28,000 shareholders,
  • Developing veterinary sales and thereby validating a complete process from pre-sales through to customer delivery,
  • Securing existing and undisclosed assets through patent filings. Patent protection opens a secure door to partnerships,
  • Entering into partnerships with public institutions renowned for the rigour of their teams and their research,
  • Searching for possible “hits” among the Company's assets, including an analysis of the 10,000 molecules created by AB Science, using AI where appropriate,
  • Reconsidering the scientific choices imposed by the lack of resources. Prioritising the best scientific option, with cost being a consequence rather than the starting constraint,
  • The position of Vice President Corporate Development was created as early as July with this objective of creating value from these assets.
• Strengthening financial visibility: breaking with repeated capital increases that add no value, restoring market confidence through a precise and credible roadmap, following on from the €14.2 million capital increase completed in August 2026, and opening up the capital to institutional investors.
• Respect for all shareholders: in September 2026, AB Science carried out an identifiable bearer share survey (TPI, Titre au Porteur Identifiable), which showed that the Company is owned by more than 28,000 bearer shareholders. The exercise of their rights will be facilitated by the introduction of electronic voting at General Meetings. In addition, a new website went live on 9 October, with a new logo, a new visual identity and simplified scientific language that improves understanding of the medical value created over many years.

A web conference in French will be held on Wednesday 14 October 2026 at 6:00 pm to present the Company's new roadmap in detail. Connection details will be communicated at a later date.

CONSOLIDATED FINANCIAL INFORMATION FOR THE FIRST HALF OF 2026

The operating result as of 30 June 2026 corresponds to a loss of €10.4 million, compared with a loss of €2.7 million as of 30 June 2025.

• Operating income consists exclusively of revenue from the sale of the drug Masivet in veterinary medicine. Revenue amounted to €498 thousand as of 30 June 2026, compared with €515 thousand as of 30 June 2025.
• The €7.6 million increase in costs between 2025 and 2026 is mainly explained by the recognition of a €6.5 million provision relating to the Research Tax Credit (CIR), in the dispute between AB Science and the French tax authorities (Direction Générale des Finances Publiques, DGFiP). This provision reflects the risk relating to the recovery of the €8.2 million CIR receivable, estimated following the unfavourable decision handed down by the Paris Administrative Court on 22 September 2026. Excluding this exceptional item, R&D costs remained essentially stable over the period, rising from €1.8 million to €2.0 million, reflecting the continuity of R&D work over the period.
• Administrative costs increased by €1 million – the main factor being a €497 thousand provision for labour court (Prud'hommes) risk, the remainder being reversals of exceptional provisions in 2025. Recurring administrative costs are essentially unchanged year on year.
• Cost of goods sold benefited from a positive impact related to year-on-year movements in veterinary inventories. Masivet's commercial activity remains stable, with however a slight increase in marketing costs, which rose from €150 thousand to €170 thousand.
• Other operating expenses relate to the discontinuation of patents deemed non-essential and to the expensing of patent maintenance fees.
• The financial result corresponds to a gain of €1.4 million for the first half of 2026, compared with a loss of €2.5 million for the first half of 2025. It includes in particular the change in conditional advances of €2.0 million relating to an advance repayable in the event of success (ROMANE – ROle du MAstocyte en NEurologie), reflecting the updating of assumptions on the basis of the new financing agreement finalised in April 2026, which defers the repayment dates to the period 2027 to 2030 subject to commercial success. If the programme fails, the conditional advances are not repaid.
• As of 30 June 2026, income from financial assets consisted of investment income of €111 thousand.
• Interest on borrowings and financial debt of €674 thousand relates to loans from the EIB, Bpifrance, Société Générale and Banque Populaire. As a reminder, a conciliation agreement resulted in a repayment holiday of 18 to 24 months on these repayments. For the most part, the interest recorded here is payable under amortisation schedules running from 2027 to 2030 and has no immediate impact on AB Science's cash position.

Net income came to -€9.0 million as of 30 June 2026, compared with –€5.2 million as of 30 June 2025, for the reasons set out above.

The following table summarises the half-year consolidated financial statements for the first half of 2026, prepared in accordance with IFRS, and the comparative information for the first half of 2025:

KEY CLINICAL DEVELOPMENT EVENTS DURING THE FIRST HALF OF 2026 AND SINCE 30 JUNE 2026

Update on the development plan following a sponsor inspection on Good Clinical Practice

Following a Good Clinical Practice inspection conducted from 21 to 25 September 2026 by three European health authorities, AB Science is revising its operational plan. The final inspection report is expected before the end of the year. The preliminary findings support management in its priority of establishing a new quality management system. The finalisation of this system and its external audit are planned by the end of 2026, before clinical trials resume. AB Science anticipates resuming the Phase 1 study in acute myeloid leukaemia (AB8939) in the first quarter of 2027. The resumption of the Phase 3 study in amyotrophic lateral sclerosis (masitinib) is planned for the fourth quarter of 2027. This timeframe will make it possible to optimise the design and methodology of these two studies. The masitinib programme in sickle cell disease, sponsored by AP-HP, would not be affected and is expected to start in early 2027.

In addition, as announced in July 2026, the Company announced that three clinical studies considered non-priority at this stage, and whose recruitment had been suspended, are being discontinued, namely:

• Phase 2 study (AB20006) of masitinib in mast cell activation syndrome
• Phase 3 study (AB15003) of masitinib in mastocytosis
• Phase 3 study (AB20009) of masitinib in progressive forms of multiple sclerosis
  
  

The Company specified that the discontinuation of these studies was not related to any safety concern regarding masitinib.

Clinical trial insurance of €25 to €39 million obtained for the Phase 3 study in Amyotrophic Lateral Sclerosis

AB Science announced that it had received a firm offer to underwrite a clinical trial financing insurance policy from Medical & Commercial International Ltd. (MCI), Lloyd's Syndicate 1902, for its pivotal Phase III trial AB23005 evaluating masitinib (AB1010) in combination with standard of care in amyotrophic lateral sclerosis (ALS – Lou Gehrig's disease). The placement was arranged by Acrisure Re UK, in collaboration with its subsidiary Acrisure Re Netherlands. The policy provides coverage with no deductible, with a liability limit of €25 million that can be increased to €39 million, intended to cover all financial costs associated with a clinical failure. It takes effect on the date of enrolment of the first patient, subject to AB Science securing the financing required for the study and to payment of the premium of approximately €8 million (an amount including the insurance premium, taxes and brokerage fees, for a liability limit of €25 million; this premium may amount to approximately €13 million for a liability limit of €39 million).

The covered events include an efficacy failure according to FDA/EMA criteria, a safety failure, a recruitment failure, a regulatory suspension, a breach of GCP or of data integrity, early termination recommended by the independent committee, as well as manufacturing (CMC) issues.

This structure represents a significant reduction in the risk profile of the ALS programme and of the Company, with three benefits for shareholders: (i) protection of the capital invested up to €25 million in the event of failure; (ii) external validation of the trial design and regulatory pathway through the independent due diligence conducted by the insurer; (iii) improved capital efficiency and better conditions of access to debt and equity financing.

Identification of a potential biomarker to assess the activity of masitinib on the pathological involvement of microglia in amyotrophic lateral sclerosis

In February 2026, AB Science announced the identification of a potential biomarker to assess the activity of masitinib on the pathological involvement of microglia in amyotrophic lateral sclerosis.

The main characteristics of this newly identified biomarker are as follows:

• It is a blood (plasma) biomarker, which has the advantage of being easy to collect and of being accurately measured by ELISA (enzyme-linked immunosorbent assay).
• It is produced by pro-inflammatory microglia.
• It activates microglia and astrocytes and is therefore an activator contributing to a harmful feedback loop of neuroinflammation.
• It is also released by mast cells, thereby establishing a link between mast cells and microglia, which are the two main cellular targets of masitinib.
• It predicts survival in ALS, which could explain why masitinib may prolong survival in certain specific patients.
• Internal experiments showed that this biomarker was reduced by masitinib when mast cells and microglia were activated in vitro, highlighting the specific and potent activity of masitinib on mast cells and microglia.

Update on the Phase 1 study of AB8939 and completion of Stage 3 of Phase 1, evaluating the combination of AB8939 and Venetoclax in the treatment of relapsed or refractory acute myeloid leukaemia

In January 2026, AB Science reviewed the status of the Phase 1 study of AB8939 and the fourth consecutive response with the combination of AB8939 and Venetoclax in patients with acute myeloid leukaemia (AML) associated with a very unfavourable genetic profile.

• The combination treatment was well tolerated, with no haematological toxicity or dose-limiting toxicity
• The fourth patient had a complex karyotype including monosomy of chromosome 5 and a TP53 mutation, and was in third-line treatment. The patient achieved a near-complete response after 14 days of treatment with AB8939 at 21 mg/m2 combined with Venetoclax
• This is the fourth patient showing signs of response to the combination out of a total of 4 patients treated
• The rate of partial response signals is 100% (4/4), including one patient in complete remission, one in near-complete response and two in partial response according to the clinical approach
• The results were obtained after the first treatment cycle (14 days) in patients receiving third- or fourth-line treatment, two of whom had previously progressed on Venetoclax in combination with other chemotherapies
• These four patients all have cytogenetic profiles that are very difficult to treat, including complex karyotype, TP53 mutation, NRAS mutation, monosomy 5 and MECOM rearrangement, which are generally associated with a poor prognosis due to the aggressive course of the disease and resistance to treatment
• This diversity of responding patients appears to corroborate the mechanism of action of AB8939, which is able to destabilise microtubules while bypassing multidrug resistance and also by targeting cancer stem cells without eliminating non-tumour stem cells
• These results support the positioning of AB8939 in patients with unfavourable genetics, complex karyotypes, TP53, NRAS and KRAS mutations, monosomy 5 and 7, and MECOM rearrangement, who represent the greatest unmet medical needs

In addition, in June 2026 AB Science announced the completion of Stage 3 of Phase 1 evaluating the combination of AB8939 + Venetoclax in patients with acute myeloid leukaemia (AML) associated with a very unfavourable genetic profile. Stage 3 evaluated the combination of AB8939 and Venetoclax administered over a 14-day cycle. In total, six patients were treated at two dose levels of AB8939 (16 mg/m² and 21.3 mg/m²), each in combination with Venetoclax. The combination was well tolerated, with no dose-limiting toxicity (DLT) or haematological toxicity observed at either dose level, which made it possible to select the recommended Phase 2 dose (RP2D).

Encouraging preliminary signs of efficacy were observed. Of the six patients treated, four achieved an objective response (one complete remission with incomplete haematological recovery and three partial responses), corresponding to an overall response rate (ORR) of 67% according to the clinical approach. The remaining two patients had stable disease, resulting in a disease control rate (DCR) of 100%. These responses were obtained after a single treatment cycle (14 days) in heavily pretreated patients receiving second- to fourth-line treatment. Notably, two of the responding patients had previously progressed on Venetoclax in combination with other chemotherapies. The patients treated all have cytogenetic profiles that are very difficult to treat, including complex karyotype, TP53 mutation, NRAS mutation, monosomy 5 and 7 and MECOM rearrangement, which are generally associated with a poor prognosis due to the aggressive course of the disease and resistance to treatment. This is a high response rate in a population where standard treatments achieve an ORR of 10 to 30% in heavily pretreated, adverse-risk AML.

Grant of patents protecting the use of masitinib in the treatment of progressive forms of multiple sclerosis and in the treatment of metastatic castration-resistant prostate cancer

In January 2026, AB Science announced that the Japan Patent Office had officially granted a patent for methods of treating progressive multiple sclerosis (MS) with its lead compound, masitinib. This new patent (JP 7788154) secures intellectual property protection for masitinib until February 2041. Japan is the first country to grant a patent protecting the use of masitinib in progressive forms of MS.

For the protection of masitinib in progressive forms of MS, AB Science followed the same methodology as for the use of masitinib in ALS. The latter patent has been granted worldwide. AB Science is optimistic about its chances of obtaining protection for the use of masitinib in progressive MS on a global scale.

In January 2026, AB Science also announced that the United States Patent and Trademark Office (USPTO) had issued a Notice of Allowance (NOA) for a patent relating to methods of treating metastatic castration-resistant prostate cancer (mCRPC) with its lead compound, masitinib (US 18/040884). Once granted, this new US secondary medical use patent will secure intellectual property (IP) protection for masitinib in mCRPC until May 2042. An NOA means that the USPTO intends to grant the patent application once certain procedural formalities have been completed. The US NOA is issued after an examiner has confirmed that the patent application meets all patentability requirements. This new US patent adds to the coverage already granted in Europe (EP4175639) [1]. Equivalent patent applications have also been filed in other major international markets. The US Patent Office officially granted a patent in June 2026.

OTHER CORPORATE INFORMATION FOR THE FIRST HALF OF 2026 AND SINCE 30 JUNE 2026

Capital increase through private placements for a total amount of €19.7 million

In April, July and August 2026, AB Science successively announced capital increases for amounts of €3.2 million, €2.3 million and €14.2 million respectively.

The proceeds of these private placements will thus enable the Company to carry out the first stages of its “Relaunch AB Science” plan without additional financing in the short term.

Final agreement on the renegotiation of the repayment terms of its loans with all financial creditors

In April 2026, AB Science announced that it had reached a final agreement with its financial creditors. This agreement provides for a two-year deferral of the repayment of the State-Guaranteed Loans (PGE) and a 12-month deferral of the repayment date of the EIB Covid loan. The savings over the period will be invested in R&D.

Unanimous agreement of the financial creditors was obtained on the following restructuring terms:

• PGE with an outstanding balance of €2.3 million: i) a 24-month principal repayment holiday from the date of opening of the first conciliation procedure for the benefit of AB Science, i.e. 17 January 2025, with amortisation resuming from 31 January 2027 for Société Générale and from 2 February 2027 for Banque Populaire respectively; ii) a 24-month extension of maturity, postponing the final maturity date from 2 April 2027 to 2 April 2029 for Banque Populaire and from 31 March 2027 to 31 March 2029 for Société Générale; iii) an increase in the interest rate solely to reflect the change in the cost of refinancing.
• Bpifrance innovation support loan with an outstanding balance of €1.25 million: i) a 24-month principal repayment holiday from 1 November 2024 (instalment due on 31 January 2025) up to and including 31 October 2026 (principal instalment due on 31 January 2027); ii) a 24-month extension of maturity, postponing the final maturity date from 30 April 2027 to 30 April 2029; iii) an increase in the interest rate solely to reflect the change in the cost of refinancing.
• Bpifrance framework agreement for strategic industrial innovation project support with an outstanding balance of €5.8 million: for this agreement, which provides, in the event of commercial success of masitinib in neurology, for the repayment of the support provided by Bpifrance under the research project entitled ROMANE, the restructuring terms are as follows: i) an 18-month principal repayment holiday from 30 June 2026 to 31 December 2027; ii) an extension of the lump-sum repayment period from 10 years to 15 years from the last payment of this advance; iii) an extension of the additional repayment period from 15 years to 20 years; iv) a change in the amounts of the annual instalments.
• EIB Covid loan: 12-month postponement of the final maturity date of the EIB loan (with a 100 bps increase in the interest rate), such that the final maturity date of the first tranche is postponed from 21 December 2028 to 21 December 2029 and the final maturity date of the second tranche is postponed from 28 January 2028 to 30 January 2029.

About AB Science
Founded in 2001, AB Science is a pharmaceutical company specialising in the research, development and commercialisation of protein kinase inhibitors (PKIs), a class of targeted proteins whose action is key in cell signalling. Our programmes target only diseases with a high unmet medical need, which are often fatal with a low survival rate, rare, or resistant to first-line treatment.
AB Science has developed a proprietary portfolio of molecules, and AB Science's lead compound, masitinib, has already been registered for veterinary medicine and is being developed in humans in oncology, neurodegenerative diseases, inflammatory diseases and viral diseases. The Company is headquartered in Paris and is listed on Euronext Paris (Ticker: AB).

Further information is available on the Company's website: www.ab-science.com

Forward-looking statements – AB Science
This press release contains forward-looking statements. These statements are not historical facts. These statements include projections and estimates as well as the assumptions on which they are based, statements relating to projects, objectives, intentions and expectations regarding financial results, events, operations, future services, product development and their potential, or future performance.
These forward-looking statements can often be identified by the words “expect”, “anticipate”, “believe”, “intend”, “estimate” or “plan”, as well as other similar terms. Although AB Science believes that these forward-looking statements are reasonable, investors are cautioned that these forward-looking statements are subject to numerous risks and uncertainties, which are difficult to predict and generally beyond the control of AB Science, and which may cause actual results and events to differ materially from those expressed, implied or anticipated in the forward-looking information and statements. These risks and uncertainties include in particular the uncertainties inherent in the development of the Company's products, which may not succeed, or in the granting of marketing authorisations by the competent authorities or, more generally, any factors that may affect the ability to commercialise the products developed by AB Science, as well as those developed or identified in the public documents published by AB Science. AB Science undertakes no obligation to update the forward-looking information and statements, subject to the applicable regulations, in particular Articles 223-1 et seq. of the General Regulation of the AMF.

For further information, please contact:

Financial Communication
investors@ab-science.com

Attachment

• AB SCIENCE press release S1 2026 VENG VF