{"success":true,"data":{"pressRelease":{"id":"74777","rtpr_id":"nGNX5BX7tG","ticker":"ABS","exchange":"Euronext Paris","all_tickers":["ABS"],"title":"AB Science reports completion of the step 3 of phase 1, evaluating the combination of AB8939 with venetoclax for the treatment of refractory or relapsed AML","author":"Globe Newswire","published_at":"2026-06-29T05:59:36.696Z","article_body":"PRESS RELEASE\n\nAB SCIENCE REPORTS COMPLETION OF THE STEP 3 OF PHASE 1, EVALUATING THE\nCOMBINATION OF AB8939 WITH VENETOCLAX FOR THE TREATMENT OF REFRACTORY OR\nRELAPSED ACUTE MYELOID LEUKEMIA\n\nTHE COMBINATION OF AB8939 WITH VENETOCLAX GENERATED A 67% OVERALL RESPONSE\nRATE (ORR) AND A 100% DISEASE CONTROL RATE (DCR), WITH NO DOSE-LIMITING\nTOXICITIES (DLT) OBSERVED, IN A POOR-PROGNOSIS POPULATION WITH ADVERSE\nGENETICS TREATED IN THE SECOND - TO FOURTH-LINE RELAPSED OR REFRACTORY SETTING\n\nParis, June 29, 2026, 8am CET\n\nAB Science SA (Euronext - FR0010557264 - AB) today provides an update on the\nPhase 1 study of the molecule AB8939 and the completion of Step 3, evaluating\nthe combination of AB8939 + venetoclax in patients with acute myeloid leukemia\n(AML) associated with a very unfavorable genetic profile.\n\nStep 3 evaluated the combination of AB8939 plus venetoclax administered over a\n14-day cycle. A total of six patients were treated across two dose levels of\nAB8939 (16 mg/m² and 21.3 mg/m²), each in combination with venetoclax. The\ncombination was well-tolerated, with no dose-limiting toxicity (DLT) and no\nhematological toxicity observed at either dose level, allowing selection of\nthe recommended Phase 2 dose (RP2D).\n\nEncouraging preliminary signs of efficacy were observed. Of the six patients\ntreated, four achieved an objective response (one complete remission with\nincomplete hematologic recovery and three partial responses), corresponding to\na 67% overall response rate (ORR). The two remaining patients achieved stable\ndisease, resulting in a 100% disease control rate (CDR). These responses were\nachieved after a single cycle of treatment (14 days) in heavily pre-treated\npatients receiving second- to fourth-line therapy. Notably, two of the\nresponding patients had previously progressed on venetoclax in combination\nwith other chemotherapies.\n\nThe patients treated all have very difficult to treat cytogenetic profiles,\nincluding complex karyotype, TP53 mutation, NRAS mutation, monosomy 5 and 7\nand MECOM-rearrangement, that typically have a poor prognosis due to their\naggressive disease course and treatment resistance\n\nThis is a high response rate in a population where standard-of-care therapies\nachieve ORR of 10–30% in adverse-risk, multiply pre-treated AML (Gill H, et\nal. Cancer Med. 2020;9(10):3371-3382).\n\nResponse after the first 14 days cycle in the six patients treated in Step 3\n(AB8939 + venetoclax)\n\n Patient    AB8939 dose  Line of therapy  Key adverse genetics                                      Best response  \n Patient 1  16 mg/m²     2nd              RUNX1 and NRAS mutations                                  CRi            \n Patient 2  16 mg/m²     2nd              MECOM-rearrangement, complex karyotype, monosomy 5 and 7  PR             \n Patient 3  16 mg/m²     4th              TP53 mutation, complex karyotype, monosomy 5 and 7        PR             \n Patient 4  21.3 mg/m²   3rd              TP53 mutation, complex karyotype, monosomy 5 and 7        PR             \n Patient 5  21.3 mg/m²   2nd              TP53 mutation                                             SD             \n Patient 6  21.3 mg/m²   2nd              TP53 mutation (very high-risk MDS)                        SD             \n\nComplete remission (CRc) is defined as CRc = CR + CRh + CRi + CRp\n* CR=Bone marrow blasts <5%; of circulating blasts; low level (<5%);\nextramedullary disease; ANC ≥1.0 x 109/L (1000/μL); platelet count ≥100 x\n109/L (100 000/μL). \n* CRh =ANC ≥ 0.5 × 109/L (500/μL) and platelet count ≥ 50 × 109/L (50\n000/μL), otherwise all other CR criteria met \n* CRi =All CR criteria except for residual neutropenia (<1.0 x 109/L\n[1000/μL]) or thrombocytopenia (<100 x 109/L [100 000/μL]). \n* CRp =All CR criteria except platelet count < 100 × 109/L (100 000/μL)\nPartial remission (PR) requires bone marrow response of at least 50% with a\nresidual % between 5% and 25%.\nProgressive disease (PD): > 50% increase in marrow blasts over baseline (a\nminimum 15% increase is required in cases <30% blasts at baseline).\n\nThis diversity of responsive patients appears to corroborate the mechanism of\naction of AB8939, which is capable of destabilizing microtubules while evading\nmulti-drug resistance and also targeting cancer stem cells without eliminating\nnon tumoral stem cells\n\nThese results corroborate the positioning of AB8939 in patients with adverse\ngenetics, complex karyotypes, TP53 mutations, NRAS and KRAS mutations,\nmonosomy 5 and 7, and MECOM-rearrangement, which represents the highest unmet\nmedical need.\n\nNicholas J. Short, MD, Associate Professor and Co-Lead of the Section of\nDevelopmental Therapeutics, Department of Leukemia, MD Anderson Cancer Center,\nsaid, \"This new data is very encouraging, particularly considering the very\nadverse risk profile of this patient’s leukemia. These early efficacy and\nsafety data suggest that AB8939 can be combined with venetoclax and could have\nsignificant activity in the highest-risk subtypes of AML. There is a strong\ninterest in continuing the development of this combination in patients whose\nAML has high-risk features that are expected to lead to resistance to\nvenetoclax + azacitidine.\"\n\nProfessor Olivier Hermine, MD, President of the Scientific Committee of AB\nScience and member of the Académie des Sciences in France, said, \"There is a\nstrong rationale to combine AB8939 and venetoclax as both molecules have low\nhematologic toxicity and complementary mode of actions. These first results\nare supportive of this rationale.\"\n\nWith Step 3 completed, the next step is Step 4, evaluating the triple\ncombination of AB8939 + venetoclax + azacitidine.\n\nAbout AB8939\n\nAB8939 is a drug candidate that targets (i) cancer cells by destabilizing\nmicrotubules (essential for cell division) and (ii) cancer stem cells by\ninhibiting ALDH1A1 and ALDH2 (enzymes essential for maintaining their\nphysiological state and survival).\n* AB8939 has shown in vitro activity in Ara-C (cytarabine, which is one of the\nstandards of care) resistant patient cell lines, including adverse genetic\nMECOM and TP53 mutations. \n* Analysis of cell lines responsive to AB8939 showed that AB8939 is effective\nin cell lines with TP53 mutations, MECOM, and complex karyotypes, whereas ARAC\nand azacitidine are not effective.\n* AB8939 increased survival and had an additive effect in combination with\nvenetoclax (another standard of care) in vivo in a MECOM-grafted PDX mouse\nmodel.\n* AB8939 increased survival and had an additive effect in combination with\nVidaza (azacitidine, another standard of care) in vivo in the MECOM PDX#C1005\nmouse model of leukemia.\n* AB8939 eradicated Leukemia Cancer Stem Cells in vivo in a human PDX AML\nmouse model, which is compatible with targeting stem cells via ALDH.\nAB8939 is currently being evaluated in a Phase 1 clinical trial (study\nAB18001, NCT05211570) in patients with refractory and relapsed AML.\n\nThe Phase 1 clinical trial of AB8939 has completed its first three steps. The\nfirst two steps determined the maximum tolerated dose (MTD) after 3 and 14\nconsecutive days of monotherapy. In both cases, the MTD was 21.3 mg/m².\n\nThe third step, now completed, evaluated the combination of AB8939 and\nvenetoclax. Six patients were treated across two dose levels (AB8939 14 days\nat a dose of 16 mg/m² + venetoclax 14 days, then AB8939 14 days at a dose of\n21.3 mg/m² + venetoclax 14 days), with no dose-limiting toxicity observed,\nsupporting selection of the recommended Phase 2 dose. The next step (Step 4)\nwill evaluate the triple combination of AB8939 + venetoclax + azacitidine.\n\nMedical need in AML and AB8939 mechanism of action\n\nAlthough several drugs have been registered for AML, 70% of patients still\nrelapse and die, creating a persistent unmet medical need for effective\ntreatments. Acute myeloid leukemia remains the most lethal form of leukemia in\nhumans.\n\nAML is a heterogeneous disease, and its outcome is highly dependent on genetic\nfactors. TP53 mutation has a very poor prognosis, with a median overall\nsurvival (OS) of 5.5 months. NRAS and KRAS mutants have a poor prognosis, with\na median OS of 12.1 months. MECOM also has a very poor prognosis in AML, with\na median OS of 5.5 months in relapsed or refractory settings.\n\nThe challenge in AML is the recurrence of tumors due to a combination of two\nfactors: the resistance of cancer cells to chemotherapy and relapse due to the\npersistence of cancer stem cells. This challenge may be overcome by AB8939’s\ndual mechanism of action.\n* First, AB8939 blocks the proliferation of leukemia cells through microtubule\ndisruption. It is not subject to multi-drug resistance as it does not bind to\nPgP, which is responsible for efflux outside the cells, and is not degraded by\nmyeloperoxidase. * Second, AB8939 targets leukemia cancer stem cells by\ninhibiting ALDH and promotes bone marrow repopulation of normal progenitors.\nAB8939 + venetoclax combination\n\nThere is a strong rationale to combine AB8939 with venetoclax\n* Both molecules exhibit low hematologic toxicity. This combination is\nexpected to be less toxic than azacitidine + venetoclax as first-line\ntreatment for AML\n* These molecules have different and complementary targets in cancer cells.\nThere is an additive, even synergistic, efficacy potential for the\ncombination, with three mechanisms of action in a single treatment. *\nVenetoclax’s mechanism of action inhibits the BCL2 pathway, a protein that\nprevents apoptosis (programmed cell death) in cancer cells. BCL2 is a key\nfactor in AML resistance, as it allows cancer cells to survive despite\ntreatment\n* AB8939 is pro-apoptotic, destabilizing microtubules, and would benefit from\nBCL2 inhibition to optimize apoptosis\n* In addition, AB8939 specifically targets cancer stem cells by inhibiting\nALDH, reducing resistance to treatment and limiting the risk of relapse\nNext steps\n\nFollowing completion of Step 3, the next step is to initiate Step 4,\nevaluating the triple combination of AB8939 + venetoclax + azacitidine, and to\nlaunch an expansion study in approximately 15 AML patients eligible for AB8939\n+ venetoclax at the appropriate dose. The expansion phase is expected to\ngenerate robust preliminary evidence of efficacy in the AML label, sufficient\nto support the clinical development plan and a beneficial partnership\nagreement.\n\nAB Science has started to discuss three possibilities for registration\nstudies, which are not mutually exclusive, with the European Medicines Agency\n(EMA) and US Food and Drug Administration (FDA):\n* AB8939 + venetoclax as first-line treatment, with aged patients and/or\npatients with adverse genetics (complex karyotypes, TP53 mutations, NRAS and\nKRAS mutations, monosomy 5 and 7, and MECOM-rearrangement)\n* AB8939 + venetoclax as a second- or third-line treatment, in all patients or\npatients with adverse genetics\n* AB8939 as a single agent in MECOM as a second or third-line treatment.\nAddressable market with AB8939 in relapsed/refractory AML\n\nTreatments for relapsed or refractory AML represent an estimated market size\npotential of greater than EUR 2 billion per annum.\n\n Region        Incidence Case (1)  % Relapse or Refractory (2,3)  % Insured Patients (4)  Drug Price (€)    Market Size (per in Mio EUR)  \n USA / CANADA  23,700              50%                            90%                     100,000 ((5))     1 000 000                     \n EUROPE        27,600                                             90%                     60,000            770 000                       \n APAC          27,800                                             30%                     60,000            250 000                       \n INDIA         11,000                                             30%                     60,000            100,000                       \n LATAM         7,200                                              30%                     60,000            65 000                        \n MENA          3,900                                              30%                     60,000            35 000                        \n TOTAL         90,200                                                                                       2 200 000                     \n\nEUROPE = EU27 + Norway + United Kingdom + Switzerland ; APAC = Australia,\nPeople’s Republic of China , Japan, New Zealand, Singapore, Taiwan ; LATAM =\nArgentina, Brazil, Chile, Colombia, Costa Rica, Mexico ; MENA = Algeria,\nBahrain, Egypt, Israel, Kuwait, Morocco, Oman, Qatar, Saudi Arabia, Tunisia,\nUnited Arab Emirates\n(1)    Zhou, Y et al. Global, regional, and national burden of acute\nmyeloid leukemia, 1990–2021: a systematic analysis for the global burden of\ndisease study 2021. Biomark Res 12, 101 (2024). \n(2)    Ravandi F. Relapsed acute myeloid leukemia: Why is there no\nstandard of care Best Pract Res Clin Haematol. 2013;26(3):253-9\n(3)    Walter RB et al. Resistance prediction in AML: analysis of 4601\npatients from MRC/NCRI, HOVON/SAKK, SWOG and MD Anderson Cancer Center.\nLeukemia (2015) 29:312–20. .\n(4)    Estimated\n(5)    Choi M. et al. Costs per patient achieving remission with\nvenetoclax-based combinations in newly diagnosed patients with acute myeloid\nleukemia ineligible for intensive induction chemotherapy. Journal of Managed\nCare & Specialty Pharmacy Volume 28, Number 9.\nhttps://doi.org/10.18553/jmcp.2022.22021\n\nIntellectual property\n\nAB8939 intellectual property rights in AML are secured until 2036 through a\n‘composition of matter’ patent and potentially until 2041 with a 5 years\nextension. Two additional ‘second medical use’ patent applications have\nbeen filed to protect the use of AB8939 in the treatment of AML with specific\nchromosomal abnormalities. If these applications are accepted, the protection\nfor AB8939 will be extended until 2044 and 2046 for these AML subpopulations.\n\nAB8939 has also received orphan drug designation for AML by both the EMA and\nFDA. This orphan drug designation confers 10 and 7 years of marketing\nexclusivity in Europe and the US, respectively, from the date of product\nregistration.\n\nAB Science is the sole proprietary holder of AB8939 and its family of\ncompounds.\n\nAbout AB Science\nFounded in 2001, AB Science is a pharmaceutical company specializing in the\nresearch, development and commercialization of protein kinase inhibitors\n(PKIs), a class of targeted proteins whose action are key in signaling\npathways within cells. Our programs target only diseases with high unmet\nmedical needs, often lethal with short term survival or rare or refractory to\nprevious line of treatment. \nAB Science has developed a proprietary portfolio of molecules and the\nCompany’s lead compound, masitinib, has already been registered for\nveterinary medicine and is developed in human medicine in oncology,\nneurological diseases, inflammatory diseases and viral diseases. The company\nis headquartered in Paris, France, and listed on Euronext Paris (ticker: AB).\n\nFurther information is available on AB Science’s website: \nwww.ab-science.com.\n\nForward-looking Statements - AB Science\nThis press release contains forward-looking statements. These statements are\nnot historical facts. These statements include projections and estimates as\nwell as the assumptions on which they are based, statements based on projects,\nobjectives, intentions and expectations regarding financial results, events,\noperations, future services, product development and their potential or future\nperformance.\n\nThese forward-looking statements can often be identified by the words\n\"expect\", \"anticipate\", \"believe\", \"intend\", \"estimate\" or \"plan\" as well as\nother similar terms. While AB Science believes these forward-looking\nstatements are reasonable, investors are cautioned that these forward-looking\nstatements are subject to numerous risks and uncertainties that are difficult\nto predict and generally beyond the control of AB Science and which may imply\nthat results and actual events significantly differ from those expressed,\ninduced or anticipated in the forward-looking information and statements.\nThese risks and uncertainties include the uncertainties related to product\ndevelopment of the Company which may not be successful or to the marketing\nauthorizations granted by competent authorities or, more generally, any\nfactors that may affect marketing capacity of the products developed by AB\nScience, as well as those developed or identified in the public documents\npublished by AB Science. AB Science disclaims any obligation or undertaking\nto update the forward-looking information and statements, subject to the\napplicable regulations, in particular articles 223-1 et seq. of the AMF\nGeneral Regulations.\n\nFor additional information, please contact:\n\nAB Science\nFinancial Communication & Media Relations \ninvestors@ab-science.com\n\nAttachment\n*     CP_AB8939_STEP3_VENG VF\n(https://ml-eu.globenewswire.com/Resource/Download/417938e5-f815-42c7-a064-a4f848648254)\n(https://www.globenewswire.com/NewsRoom/AttachmentNg/90d86a0e-7ea1-47ab-99d9-69985fa76ce0)\n\n\n\nGlobeNewswire, Inc. 2026","article_body_html":"","raw_payload":{"data":{"id":"nGNX5BX7tG","title":"AB Science reports completion of the step 3 of phase 1, evaluating the combination of AB8939 with venetoclax for the treatment of refractory or relapsed AML","author":"Globe Newswire","ticker":"ABS","created":"2026-06-29T05:59:36.696Z","tickers":["ABS"],"exchange":"Euronext Paris","article_body":"PRESS RELEASE\n\nAB SCIENCE REPORTS COMPLETION OF THE STEP 3 OF PHASE 1, EVALUATING THE\nCOMBINATION OF AB8939 WITH VENETOCLAX FOR THE TREATMENT OF REFRACTORY OR\nRELAPSED ACUTE MYELOID LEUKEMIA\n\nTHE COMBINATION OF AB8939 WITH VENETOCLAX GENERATED A 67% OVERALL RESPONSE\nRATE (ORR) AND A 100% DISEASE CONTROL RATE (DCR), WITH NO DOSE-LIMITING\nTOXICITIES (DLT) OBSERVED, IN A POOR-PROGNOSIS POPULATION WITH ADVERSE\nGENETICS TREATED IN THE SECOND - TO FOURTH-LINE RELAPSED OR REFRACTORY SETTING\n\nParis, June 29, 2026, 8am CET\n\nAB Science SA (Euronext - FR0010557264 - AB) today provides an update on the\nPhase 1 study of the molecule AB8939 and the completion of Step 3, evaluating\nthe combination of AB8939 + venetoclax in patients with acute myeloid leukemia\n(AML) associated with a very unfavorable genetic profile.\n\nStep 3 evaluated the combination of AB8939 plus venetoclax administered over a\n14-day cycle. A total of six patients were treated across two dose levels of\nAB8939 (16 mg/m² and 21.3 mg/m²), each in combination with venetoclax. The\ncombination was well-tolerated, with no dose-limiting toxicity (DLT) and no\nhematological toxicity observed at either dose level, allowing selection of\nthe recommended Phase 2 dose (RP2D).\n\nEncouraging preliminary signs of efficacy were observed. Of the six patients\ntreated, four achieved an objective response (one complete remission with\nincomplete hematologic recovery and three partial responses), corresponding to\na 67% overall response rate (ORR). The two remaining patients achieved stable\ndisease, resulting in a 100% disease control rate (CDR). These responses were\nachieved after a single cycle of treatment (14 days) in heavily pre-treated\npatients receiving second- to fourth-line therapy. Notably, two of the\nresponding patients had previously progressed on venetoclax in combination\nwith other chemotherapies.\n\nThe patients treated all have very difficult to treat cytogenetic profiles,\nincluding complex karyotype, TP53 mutation, NRAS mutation, monosomy 5 and 7\nand MECOM-rearrangement, that typically have a poor prognosis due to their\naggressive disease course and treatment resistance\n\nThis is a high response rate in a population where standard-of-care therapies\nachieve ORR of 10–30% in adverse-risk, multiply pre-treated AML (Gill H, et\nal. Cancer Med. 2020;9(10):3371-3382).\n\nResponse after the first 14 days cycle in the six patients treated in Step 3\n(AB8939 + venetoclax)\n\n Patient    AB8939 dose  Line of therapy  Key adverse genetics                                      Best response  \n Patient 1  16 mg/m²     2nd              RUNX1 and NRAS mutations                                  CRi            \n Patient 2  16 mg/m²     2nd              MECOM-rearrangement, complex karyotype, monosomy 5 and 7  PR             \n Patient 3  16 mg/m²     4th              TP53 mutation, complex karyotype, monosomy 5 and 7        PR             \n Patient 4  21.3 mg/m²   3rd              TP53 mutation, complex karyotype, monosomy 5 and 7        PR             \n Patient 5  21.3 mg/m²   2nd              TP53 mutation                                             SD             \n Patient 6  21.3 mg/m²   2nd              TP53 mutation (very high-risk MDS)                        SD             \n\nComplete remission (CRc) is defined as CRc = CR + CRh + CRi + CRp\n* CR=Bone marrow blasts <5%; of circulating blasts; low level (<5%);\nextramedullary disease; ANC ≥1.0 x 109/L (1000/μL); platelet count ≥100 x\n109/L (100 000/μL). \n* CRh =ANC ≥ 0.5 × 109/L (500/μL) and platelet count ≥ 50 × 109/L (50\n000/μL), otherwise all other CR criteria met \n* CRi =All CR criteria except for residual neutropenia (<1.0 x 109/L\n[1000/μL]) or thrombocytopenia (<100 x 109/L [100 000/μL]). \n* CRp =All CR criteria except platelet count < 100 × 109/L (100 000/μL)\nPartial remission (PR) requires bone marrow response of at least 50% with a\nresidual % between 5% and 25%.\nProgressive disease (PD): > 50% increase in marrow blasts over baseline (a\nminimum 15% increase is required in cases <30% blasts at baseline).\n\nThis diversity of responsive patients appears to corroborate the mechanism of\naction of AB8939, which is capable of destabilizing microtubules while evading\nmulti-drug resistance and also targeting cancer stem cells without eliminating\nnon tumoral stem cells\n\nThese results corroborate the positioning of AB8939 in patients with adverse\ngenetics, complex karyotypes, TP53 mutations, NRAS and KRAS mutations,\nmonosomy 5 and 7, and MECOM-rearrangement, which represents the highest unmet\nmedical need.\n\nNicholas J. Short, MD, Associate Professor and Co-Lead of the Section of\nDevelopmental Therapeutics, Department of Leukemia, MD Anderson Cancer Center,\nsaid, \"This new data is very encouraging, particularly considering the very\nadverse risk profile of this patient’s leukemia. These early efficacy and\nsafety data suggest that AB8939 can be combined with venetoclax and could have\nsignificant activity in the highest-risk subtypes of AML. There is a strong\ninterest in continuing the development of this combination in patients whose\nAML has high-risk features that are expected to lead to resistance to\nvenetoclax + azacitidine.\"\n\nProfessor Olivier Hermine, MD, President of the Scientific Committee of AB\nScience and member of the Académie des Sciences in France, said, \"There is a\nstrong rationale to combine AB8939 and venetoclax as both molecules have low\nhematologic toxicity and complementary mode of actions. These first results\nare supportive of this rationale.\"\n\nWith Step 3 completed, the next step is Step 4, evaluating the triple\ncombination of AB8939 + venetoclax + azacitidine.\n\nAbout AB8939\n\nAB8939 is a drug candidate that targets (i) cancer cells by destabilizing\nmicrotubules (essential for cell division) and (ii) cancer stem cells by\ninhibiting ALDH1A1 and ALDH2 (enzymes essential for maintaining their\nphysiological state and survival).\n* AB8939 has shown in vitro activity in Ara-C (cytarabine, which is one of the\nstandards of care) resistant patient cell lines, including adverse genetic\nMECOM and TP53 mutations. \n* Analysis of cell lines responsive to AB8939 showed that AB8939 is effective\nin cell lines with TP53 mutations, MECOM, and complex karyotypes, whereas ARAC\nand azacitidine are not effective.\n* AB8939 increased survival and had an additive effect in combination with\nvenetoclax (another standard of care) in vivo in a MECOM-grafted PDX mouse\nmodel.\n* AB8939 increased survival and had an additive effect in combination with\nVidaza (azacitidine, another standard of care) in vivo in the MECOM PDX#C1005\nmouse model of leukemia.\n* AB8939 eradicated Leukemia Cancer Stem Cells in vivo in a human PDX AML\nmouse model, which is compatible with targeting stem cells via ALDH.\nAB8939 is currently being evaluated in a Phase 1 clinical trial (study\nAB18001, NCT05211570) in patients with refractory and relapsed AML.\n\nThe Phase 1 clinical trial of AB8939 has completed its first three steps. The\nfirst two steps determined the maximum tolerated dose (MTD) after 3 and 14\nconsecutive days of monotherapy. In both cases, the MTD was 21.3 mg/m².\n\nThe third step, now completed, evaluated the combination of AB8939 and\nvenetoclax. Six patients were treated across two dose levels (AB8939 14 days\nat a dose of 16 mg/m² + venetoclax 14 days, then AB8939 14 days at a dose of\n21.3 mg/m² + venetoclax 14 days), with no dose-limiting toxicity observed,\nsupporting selection of the recommended Phase 2 dose. The next step (Step 4)\nwill evaluate the triple combination of AB8939 + venetoclax + azacitidine.\n\nMedical need in AML and AB8939 mechanism of action\n\nAlthough several drugs have been registered for AML, 70% of patients still\nrelapse and die, creating a persistent unmet medical need for effective\ntreatments. Acute myeloid leukemia remains the most lethal form of leukemia in\nhumans.\n\nAML is a heterogeneous disease, and its outcome is highly dependent on genetic\nfactors. TP53 mutation has a very poor prognosis, with a median overall\nsurvival (OS) of 5.5 months. NRAS and KRAS mutants have a poor prognosis, with\na median OS of 12.1 months. MECOM also has a very poor prognosis in AML, with\na median OS of 5.5 months in relapsed or refractory settings.\n\nThe challenge in AML is the recurrence of tumors due to a combination of two\nfactors: the resistance of cancer cells to chemotherapy and relapse due to the\npersistence of cancer stem cells. This challenge may be overcome by AB8939’s\ndual mechanism of action.\n* First, AB8939 blocks the proliferation of leukemia cells through microtubule\ndisruption. It is not subject to multi-drug resistance as it does not bind to\nPgP, which is responsible for efflux outside the cells, and is not degraded by\nmyeloperoxidase. * Second, AB8939 targets leukemia cancer stem cells by\ninhibiting ALDH and promotes bone marrow repopulation of normal progenitors.\nAB8939 + venetoclax combination\n\nThere is a strong rationale to combine AB8939 with venetoclax\n* Both molecules exhibit low hematologic toxicity. This combination is\nexpected to be less toxic than azacitidine + venetoclax as first-line\ntreatment for AML\n* These molecules have different and complementary targets in cancer cells.\nThere is an additive, even synergistic, efficacy potential for the\ncombination, with three mechanisms of action in a single treatment. *\nVenetoclax’s mechanism of action inhibits the BCL2 pathway, a protein that\nprevents apoptosis (programmed cell death) in cancer cells. BCL2 is a key\nfactor in AML resistance, as it allows cancer cells to survive despite\ntreatment\n* AB8939 is pro-apoptotic, destabilizing microtubules, and would benefit from\nBCL2 inhibition to optimize apoptosis\n* In addition, AB8939 specifically targets cancer stem cells by inhibiting\nALDH, reducing resistance to treatment and limiting the risk of relapse\nNext steps\n\nFollowing completion of Step 3, the next step is to initiate Step 4,\nevaluating the triple combination of AB8939 + venetoclax + azacitidine, and to\nlaunch an expansion study in approximately 15 AML patients eligible for AB8939\n+ venetoclax at the appropriate dose. The expansion phase is expected to\ngenerate robust preliminary evidence of efficacy in the AML label, sufficient\nto support the clinical development plan and a beneficial partnership\nagreement.\n\nAB Science has started to discuss three possibilities for registration\nstudies, which are not mutually exclusive, with the European Medicines Agency\n(EMA) and US Food and Drug Administration (FDA):\n* AB8939 + venetoclax as first-line treatment, with aged patients and/or\npatients with adverse genetics (complex karyotypes, TP53 mutations, NRAS and\nKRAS mutations, monosomy 5 and 7, and MECOM-rearrangement)\n* AB8939 + venetoclax as a second- or third-line treatment, in all patients or\npatients with adverse genetics\n* AB8939 as a single agent in MECOM as a second or third-line treatment.\nAddressable market with AB8939 in relapsed/refractory AML\n\nTreatments for relapsed or refractory AML represent an estimated market size\npotential of greater than EUR 2 billion per annum.\n\n Region        Incidence Case (1)  % Relapse or Refractory (2,3)  % Insured Patients (4)  Drug Price (€)    Market Size (per in Mio EUR)  \n USA / CANADA  23,700              50%                            90%                     100,000 ((5))     1 000 000                     \n EUROPE        27,600                                             90%                     60,000            770 000                       \n APAC          27,800                                             30%                     60,000            250 000                       \n INDIA         11,000                                             30%                     60,000            100,000                       \n LATAM         7,200                                              30%                     60,000            65 000                        \n MENA          3,900                                              30%                     60,000            35 000                        \n TOTAL         90,200                                                                                       2 200 000                     \n\nEUROPE = EU27 + Norway + United Kingdom + Switzerland ; APAC = Australia,\nPeople’s Republic of China , Japan, New Zealand, Singapore, Taiwan ; LATAM =\nArgentina, Brazil, Chile, Colombia, Costa Rica, Mexico ; MENA = Algeria,\nBahrain, Egypt, Israel, Kuwait, Morocco, Oman, Qatar, Saudi Arabia, Tunisia,\nUnited Arab Emirates\n(1)    Zhou, Y et al. Global, regional, and national burden of acute\nmyeloid leukemia, 1990–2021: a systematic analysis for the global burden of\ndisease study 2021. Biomark Res 12, 101 (2024). \n(2)    Ravandi F. Relapsed acute myeloid leukemia: Why is there no\nstandard of care Best Pract Res Clin Haematol. 2013;26(3):253-9\n(3)    Walter RB et al. Resistance prediction in AML: analysis of 4601\npatients from MRC/NCRI, HOVON/SAKK, SWOG and MD Anderson Cancer Center.\nLeukemia (2015) 29:312–20. .\n(4)    Estimated\n(5)    Choi M. et al. Costs per patient achieving remission with\nvenetoclax-based combinations in newly diagnosed patients with acute myeloid\nleukemia ineligible for intensive induction chemotherapy. Journal of Managed\nCare & Specialty Pharmacy Volume 28, Number 9.\nhttps://doi.org/10.18553/jmcp.2022.22021\n\nIntellectual property\n\nAB8939 intellectual property rights in AML are secured until 2036 through a\n‘composition of matter’ patent and potentially until 2041 with a 5 years\nextension. Two additional ‘second medical use’ patent applications have\nbeen filed to protect the use of AB8939 in the treatment of AML with specific\nchromosomal abnormalities. If these applications are accepted, the protection\nfor AB8939 will be extended until 2044 and 2046 for these AML subpopulations.\n\nAB8939 has also received orphan drug designation for AML by both the EMA and\nFDA. This orphan drug designation confers 10 and 7 years of marketing\nexclusivity in Europe and the US, respectively, from the date of product\nregistration.\n\nAB Science is the sole proprietary holder of AB8939 and its family of\ncompounds.\n\nAbout AB Science\nFounded in 2001, AB Science is a pharmaceutical company specializing in the\nresearch, development and commercialization of protein kinase inhibitors\n(PKIs), a class of targeted proteins whose action are key in signaling\npathways within cells. Our programs target only diseases with high unmet\nmedical needs, often lethal with short term survival or rare or refractory to\nprevious line of treatment. \nAB Science has developed a proprietary portfolio of molecules and the\nCompany’s lead compound, masitinib, has already been registered for\nveterinary medicine and is developed in human medicine in oncology,\nneurological diseases, inflammatory diseases and viral diseases. The company\nis headquartered in Paris, France, and listed on Euronext Paris (ticker: AB).\n\nFurther information is available on AB Science’s website: \nwww.ab-science.com.\n\nForward-looking Statements - AB Science\nThis press release contains forward-looking statements. These statements are\nnot historical facts. These statements include projections and estimates as\nwell as the assumptions on which they are based, statements based on projects,\nobjectives, intentions and expectations regarding financial results, events,\noperations, future services, product development and their potential or future\nperformance.\n\nThese forward-looking statements can often be identified by the words\n\"expect\", \"anticipate\", \"believe\", \"intend\", \"estimate\" or \"plan\" as well as\nother similar terms. While AB Science believes these forward-looking\nstatements are reasonable, investors are cautioned that these forward-looking\nstatements are subject to numerous risks and uncertainties that are difficult\nto predict and generally beyond the control of AB Science and which may imply\nthat results and actual events significantly differ from those expressed,\ninduced or anticipated in the forward-looking information and statements.\nThese risks and uncertainties include the uncertainties related to product\ndevelopment of the Company which may not be successful or to the marketing\nauthorizations granted by competent authorities or, more generally, any\nfactors that may affect marketing capacity of the products developed by AB\nScience, as well as those developed or identified in the public documents\npublished by AB Science. AB Science disclaims any obligation or undertaking\nto update the forward-looking information and statements, subject to the\napplicable regulations, in particular articles 223-1 et seq. of the AMF\nGeneral Regulations.\n\nFor additional information, please contact:\n\nAB Science\nFinancial Communication & Media Relations \ninvestors@ab-science.com\n\nAttachment\n*     CP_AB8939_STEP3_VENG VF\n(https://ml-eu.globenewswire.com/Resource/Download/417938e5-f815-42c7-a064-a4f848648254)\n(https://www.globenewswire.com/NewsRoom/AttachmentNg/90d86a0e-7ea1-47ab-99d9-69985fa76ce0)\n\n\n\nGlobeNewswire, Inc. 2026"},"type":"article","timestamp":"2026-06-29T05:59:36.741985992Z","server_sent_at_ms":1782712776741},"received_at":"2026-06-29T05:59:36.921Z","source_url":null},"analysis":{"id":"64135","press_release_id":"74777","analysis_json":{"industry":{"label":"Biotechnology","sector":"Health Care"},"redFlags":[],"eventType":"clinical_trial","narrative":"AB Science reported completion of Step 3 of its Phase 1 trial for AB8939 in combination with venetoclax for relapsed/refractory AML.\n\nThe combination achieved a 67% overall response rate and 100% disease control rate in six heavily pre-treated patients with adverse genetics, with no dose-limiting toxicities observed.\n\nThese results support the selection of a recommended Phase 2 dose and pave the way for a Step 4 expansion study and potential partnership discussions.","sentiment":"bullish","agentHooks":{"shouldPost":true,"suggestedAngle":"Strong Phase 1 data for AB8939+venetoclax in high-risk AML sets stage for partnership talks and Phase 2 expansion."},"keyFigures":{"drugName":"AB8939","phaseOfTrial":"Phase 1","customDimensions":{"dcr":"100%","orr":"67%","market_size_eur":"2.2 billion","patients_treated":6}},"quotedText":"This new data is very encouraging, particularly considering the very adverse risk profile of this patient’s leukemia. These early efficacy and safety data suggest that AB8939 can be combined with venetoclax and could have significant activity in the highest-risk subtypes of AML.","namedEntities":{"people":[{"name":"Nicholas J. Short","role":"Associate Professor, MD Anderson Cancer Center"},{"name":"Olivier Hermine","role":"President of the Scientific Committee, AB Science"}],"products":["AB8939","venetoclax","azacitidine","Vidaza"],"companies":[{"name":"AB Science SA","ticker":"AB","relationship":"filer"},{"name":"MD Anderson Cancer Center","relationship":"clinical site/expert"},{"name":"European Medicines Agency","relationship":"regulator"},{"name":"US Food and Drug Administration","relationship":"regulator"}],"dollarAmounts":[{"amount":"EUR 2 billion","context":"estimated annual market size for relapsed/refractory AML treatments"}]},"materialImpact":{"score":4,"reasoning":"Positive Phase 1 Step 3 data showing 67% ORR and 100% DCR in a high-risk, heavily pre-treated AML population with no dose-limiting toxicities. This de-risks the asset and supports progression to Phase 2 expansion and potential partnership discussions."},"tickerRelevance":{"others":[],"primary":"ABS"},"globalImportance":45,"audienceRelevance":35,"eventTypeSecondary":[],"importanceComponents":{"tickerTier":"small-cap","eventGravity":"positive_phase_1_data","sectorWeight":"high","householdBrandBoost":0,"marketCapAdjustment":"neutral","retailFavoriteBoost":0}},"event_type":"clinical_trial","event_type_secondary":null,"sentiment":"bullish","material_impact_score":4,"narrative":"AB Science reported completion of Step 3 of its Phase 1 trial for AB8939 in combination with venetoclax for relapsed/refractory AML.\n\nThe combination achieved a 67% overall response rate and 100% disease control rate in six heavily pre-treated patients with adverse genetics, with no dose-limiting toxicities observed.\n\nThese results support the selection of a recommended Phase 2 dose and pave the way for a Step 4 expansion study and potential partnership discussions.","key_figures":{"drugName":"AB8939","phaseOfTrial":"Phase 1","customDimensions":{"dcr":"100%","orr":"67%","market_size_eur":"2.2 billion","patients_treated":6}},"named_entities":{"people":[{"name":"Nicholas J. Short","role":"Associate Professor, MD Anderson Cancer Center"},{"name":"Olivier Hermine","role":"President of the Scientific Committee, AB Science"}],"products":["AB8939","venetoclax","azacitidine","Vidaza"],"companies":[{"name":"AB Science SA","ticker":"AB","relationship":"filer"},{"name":"MD Anderson Cancer Center","relationship":"clinical site/expert"},{"name":"European Medicines Agency","relationship":"regulator"},{"name":"US Food and Drug Administration","relationship":"regulator"}],"dollarAmounts":[{"amount":"EUR 2 billion","context":"estimated annual market size for relapsed/refractory AML treatments"}]},"model_name":"qwen3_6_27b_awq","prompt_hash":"sha256:727b4b9429a443af","schema_hash":"sha256:05005c02d9cffac9","created_at":"2026-06-29T05:59:51.782Z","global_importance":45,"audience_relevance":35,"importance_components":{"tickerTier":"small-cap","eventGravity":"positive_phase_1_data","sectorWeight":"high","householdBrandBoost":0,"marketCapAdjustment":"neutral","retailFavoriteBoost":0}},"durationMs":14852,"modelName":"george-droid-qwen-72b"}}