On August 6, 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 the Cohort Safety Review Committee (CSRC) monitoring Aptose’s Phase 1/2 TUSCANY trial of TUS in combination with standard of care dosing of venetoclax and azacitidine (TUS+VEN+AZA triplet) has approved escalating from 120 mg TUS dose to 160 mg TUS dose based on its favorable review of safety and efficacy data from patients in the first three cohorts (40 mg, 80 mg, and 120 mg TUS dose levels) of the trial (Press release, Aptose Biosciences, AUG 6, 2025, View Source [SID1234654855]). Enrollment is open for dosing subjects at the 160 mg TUS dose level.

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Aptose also announced that it has received an additional advance of US$1.1M from Hanmi Pharmaceutical Co. Ltd. ("Hanmi"), as part of a US$8.5M loan facility agreement with Hanmi (the "Loan Agreement") announced prior on June 20, 2025 (press release here: View Source). To date, Aptose has received an aggregate of US$5.6M under the Loan Agreement.

The TUS+VEN+AZA triplet is being developed as a one-of-a-kind, safe and mutation agnostic frontline therapy to treat large, mutationally diverse populations of newly diagnosed AML patients who are ineligible to receive induction chemotherapy. Aptose reports that at the 120 mg TUS dose level, as with the prior reported 40 mg and 80 mg dose cohorts, no significant safety concerns or dose limiting toxicities (DLTs) have been reported in the TUSCANY trial, including no prolonged myelosuppression in Cycle 1 of subjects in remission.

All patients treated in the 120 mg dose cohort remain on study while enrollment is open for the 160 mg dose cohort. Aptose previously reported that the first two dose cohorts have demonstrated safety, CRs, and minimal residual disease (MRD) negativity across patients with diverse mutations in an oral presentation at the European Hematology Association (EHA) (Free EHA Whitepaper) Congress (EHA 2025) in June (press release here: View Source).

"Data from three cohorts, with a 40, 80 or 120 mg dose of TUS in the TUS+VEN+AZA triplet, continue to build a strong case for TUS as a therapeutic option for some of the most difficult to treat AML populations," said Rafael Bejar, M.D., Ph.D., Chief Medical Officer of Aptose. "In particular, patients with adverse biallelic TP53 or FLT3-ITD mutations, and those without FLT3 mutations, were able to safely achieve complete remissions with MRD negativity. After review of the most recent safety and efficacy data, our CSRC recommended that we continue to escalate dosing."

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. Earlier APTIVATE trials of TUS as a single agent and in combination as TUS+VEN demonstrated favorable safety and broad activity in diverse relapsed or refractory (R/R) AML populations that went beyond the more prognostically favorable NPM1 and IDH mutant subgroups. Indeed, responses were also noted in R/R AML patients with highly adverse TP53 and RAS mutations, and those with mutated or unmutated (wildtype) FLT3 genes.

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 late 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 (here: View Source).