On October 16, 2025 Aptose Biosciences Inc. ("Aptose" or the "Company") (OTC: APTOF, TSX: APS), a clinical-stage precision oncology company developing the tuspetinib (TUS)-based triple drug frontline therapy to treat patients with newly diagnosed AML, reported that data from the ongoing TUSCANY trial of tuspetinib in combination with venetoclax and azacitidine (TUS+VEN+AZA) are being presented in a poster presentation, "TUSCANY Study of Safety and Efficacy of Tuspetinib plus Standard of Care Venetoclax and Azacitidine in Study Participants with Newly Diagnosed AML Ineligible for Induction Chemotherapy," at the European School of Haematology (ESH) 7th International Conference on Acute Myeloid Leukemia "Molecular and Translational": Advances in Biology and Treatment, being held from October 16-18, 2025 in Estoril, Portugal. Data to date from 10 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 with standard of care treatment across a broad range of AML populations, including those carrying adverse mutations regardless of FLT3 mutation status.

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The TUS+VEN+AZA triplet is being developed as a safe and well-tolerated, mutation agnostic frontline therapy to treat large, mutationally diverse populations of newly diagnosed AML patients who are ineligible to receive induction chemotherapy. Across all dose cohorts to date, no significant safety concerns or dose limiting toxicities (DLTs) have been observed in the TUSCANY trial, including no prolonged myelosuppression in Cycle 1 of subjects in remission, no reports of drug-related QTc prolongation or differentiation syndrome (DS), no CPK elevation and no treatment-related deaths. Dosing has begun at the 160 mg TUS dose level.

"We have observed that TUS can be safely added to a backbone VEN+AZA without needing to reduce the dose of these standard-of-care drugs. The activity we have observed with the TUS triplet in the first 10 patients has exceeded our expectations with 9 achieving complete remissions and 7 demonstrating MRD-negativity by central flow cytometry," said Rafael Bejar, M.D., Ph.D., Chief Medical Officer of Aptose. "In addition, these remissions are happening in diverse genetic subtypes including those with unmutated FLT3, FLT3-ITD, NPM1c, biallelic TP53 with complex karyotype, RAS, or myelodysplasia related mutations, making this a truly mutation agnostic therapy."

Data highlights:

TUS in combination with standard dosing of VEN+AZA has been well tolerated with no DLT, no treatment-related deaths, no differentiation syndrome, no QTc prolongation, no prolonged myelosuppression after remission in Cycle 1, and no CPK elevations reported at any dose levels to date in these newly diagnosed AML patients.
Addition of TUS to VEN+AZA achieved CR/CRh responses in 6/6 (100%) patients treated at the higher dose levels of 80 mg and 120 mg TUS, exceeding the 66% rate expected from VEN+AZA alone.
Overall, TUS+VEN+AZA CR/CRh responses were observed in 9/10 (90%) patients.
7 of 8 (88%) CR/CRh responses in FLT3 wildtype AML, representing 70% of AML population.
TUS+VEN+AZA MRD-negativity noted in 7/9 (78%) responding patients by central flow cytometry.
CR/CRh responses achieved across diverse mutational subtypes including: unmutated FLT3, FLT3-ITD, NPM1c, biallelic TP53 with complex karyotype, RAS, and myelodysplasia related mutations.
Dosing at the TUS 160 mg dose level is now ongoing.
See the ESH poster presentation here.

TUSCANY: TUS+VEN+AZA Triplet Phase 1/2 Study

The tuspetinib-based TUS+VEN+AZA triplet therapy is being advanced in the TUSCANY Phase 1/2 trial with the goal of creating an improved frontline therapy for newly diagnosed AML patients that is active across diverse AML populations, durable, and well tolerated.

The TUSCANY triplet Phase 1/2 study, being conducted at 10 leading U.S. clinical sites by elite clinical investigators, is designed to test various doses and schedules of TUS in combination with standard dosing of AZA and VEN for patients with AML who are ineligible to receive induction chemotherapy. A convenient, once daily oral agent, TUS is being administered in 28-day cycles. Multiple U.S. sites are enrolling in the TUSCANY trial with anticipated enrollment of 18-24 patients by the end of 2025. Data will be released as it becomes available.

More information on the TUSCANY Phase 1/2 study can be found on www.clinicaltrials.gov.

(Press release, Aptose Biosciences, OCT 16, 2025, View Source [SID1234656696])