On December 6, 2025 Aptose Biosciences Inc. ("Aptose" or the "Company") (NASDAQ: APTO, TSX: APS), a clinical-stage precision oncology company developing highly differentiated targeted agents to treat hematologic malignancies, reported clinical data for its lead compound tuspetinib (TUS) combined with standard dosing of venetoclax (VEN) and azacitidine (AZA) in a poster presentation at the 67th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting in Orlando, FL. Updated data from patients in the TUSCANY trial across all three cohorts, 40 mg, 80 mg or 120 mg TUS dose in TUS+VEN+AZA, reveal promising clinical safety and antileukemic activity and support the use of TUS in combination with standard of care treatment across a broad range of AML populations, including those with adverse mutations regardless of FLT3 mutation status.
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Poster title: "TUSCANY study demonstrates safety and efficacy of tuspetinib plus standard of care venetoclax and azacitidine in patients with newly diagnosed AML ineligible for induction chemotherapy"
Key Findings and Messages:
In newly diagnosed AML patients, TUS+VEN+AZA shows promising safety, tolerability and resilient efficacy, including MRD-negative remissions across a broad mutational spectrum
High-quality clinical responses (CR/CRh):
90% across 40, 80 and 120 mg dose levels
100% at the higher 80 mg and 120 mg dose levels
Observed in FLT3-WT, FLT3-ITD, and NPM1c genetic subgroups
Observed in biallelic TP53/complex karyotype and RAS adverse genetic subgroups
Observed in AML with MDS-related mutations
MRD negativity: 78% by central flow cytometry in responding subjects
TUS targets VEN resistance mechanisms; inhibits kinase-driven abnormal signaling
Two subjects transitioned to stem cell transplantation and both returned for TUS maintenance
TUS+VEN+AZA triplet therapy was well tolerated with no dose-limiting toxicities (DLTs) across all evaluable TUS dose levels
No DLTs including no prolonged myelosuppression for subjects in remission in Cycle 1
No drug-related deaths, differentiation syndrome, QTc prolongation, or CPK elevation reported
8/10 evaluable subjects experienced red cell and platelet transfusion independence for > 8 weeks after their best response
Febrile neutropenia was reported in 2 subjects (16.7%), with 1 subject related to TUS
At the recently enrolled 160 mg dose level, preliminary findings show patients achieving early blast clearance with MRD-negativity and formal responses in the first few weeks of treatment (not included in poster data cut).
"Tuspetinib, as part of a triple drug therapy, continues to perform well, achieving 100% clinical response in the two higher doses we have evaluated to date," said Rafael Bejar, MD, PhD, Chief Medical Officer at Aptose. "We recently commenced treating patients at the highest dose level of 160 mg TUS and have already achieved early responses. With no dose-limiting toxicities and activity across diverse mutations, TUS+VEN+AZA targets AML’s greatest unmet needs and largest populations."
The ASH (Free ASH Whitepaper) poster presentation is available here.
About Tuspetinib
Aptose’s lead compound tuspetinib is a convenient once daily oral agent that potently targets SYK, mutated and wild type forms of FLT3, mutated KIT, JAK1/2, and RSK2 kinases, while avoiding many typical toxicity concerns observed with other agents. The ongoing TUSCANY triplet Phase 1/2 study is designed to test various doses and schedules of TUS in combination with standard dosing of azacitidine and venetoclax in newly diagnosed patients with AML who are ineligible to receive induction chemotherapy. Data from the first three dose cohorts demonstrate safety, CRs and minimal residual disease (MRD) negativity across patients with diverse mutations. The early data showed that 9 out of 10 patients responded to the TUS triplet therapy, with 100% complete remission (CR/CRh) achieved in the 80mg and 120mg cohorts. Notably, patients with difficult-to-treat mutations in TP53, RAS and FLT3 genes also achieved a 100% CR/CRh rate.
(Press release, Aptose Biosciences, DEC 6, 2025, View Source [SID1234661210])