Aptose Presents Highlights from Corporate Update and KOL Event

On June 2, 2022 Aptose Biosciences, Inc. (NASDAQ: APTO, TSX: APS), reported that in the section of updated clinical findings with HM43239, the fifth bullet point should read "Eight total responses, including seven CRs and one PR, and favorable safety achieved at three separate dose levels (80 mg, 120 mg, 160 mg)" (Press release, Aptose Biosciences, JUN 2, 2022, View Source [SID1234615524]). The corrected release follows:

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Aptose Biosciences Inc. ("Aptose" or the "Company") (NASDAQ: APTO, TSX: APS), a clinical-stage precision oncology company developing highly differentiated oral kinase inhibitors to treat hematologic malignancies, today released highlights from a key opinion leader (KOL) and corporate update event held today, June 2, 2022. The event included an up-to-date review of clinical data for Aptose’s two investigational products under development for hematologic malignancies: HM43239, an oral, myeloid kinome inhibitor in an international Phase 1/2 trial in patients with relapsed or refractory acute myeloid leukemia (AML); and luxeptinib, an oral, dual lymphoid and myeloid kinome inhibitor in a Phase 1 a/b trial in patients with relapsed or refractory B-cell malignancies, and in a separate Phase 1 a/b trial in patients with relapsed or refractory AML or high risk myelodysplastic syndrome (MDS).

Guest KOLs included Brian Druker, M.D., of the Oregon Health & Science University, Naval G. Daver, M.D., of The University of Texas MD Anderson Cancer Center, and Brian Andrew Jonas, M.D., Ph.D., of the University of California, Davis, Comprehensive Cancer Center, who discussed the current treatment landscape and unmet medical need in treating patients with acute myeloid leukemia (AML), as well as their experiences with Aptose’s investigational therapies.

The webcast of the presentation, including the Q&A with the guest KOLs, is available on Aptose’s website here.

Aptose provided updated clinical findings with HM43239, a potent suppressor of FLT3, SYK, JAK 1/2 and mutant forms of cKIT kinases operative in AML:

Clinically validated in a highly diverse set of relapsed/refractory (R/R) AML patients
Fast Track Designation supported by multiple complete remissions (CRs) in FLT3-mutant refractory R/R AML, including those who failed prior therapy with other FLT3 inhibitors
New CRi at 160 mg dose in a R/R AML patient with wildtype FLT3 and other adverse mutations
Patient with CRi at 120 mg dose bridged to hematopoietic stem cell transplantation
Eight total responses, including seven CRs and one PR, and favorable safety achieved at three separate dose levels (80 mg, 120 mg, 160 mg)
One DLT of muscle weakness (not rhabdomyolysis) reported at 200 mg
Three separate doses (80 mg, 120 mg, 160 mg) selected for Expansion Clinical Trials
Single agent Expansion Clinical Trials in FLT3-mutated and FLT3-unmutated AML expected to begin in the second half of 2022
Combination (HM43239 with venetoclax) Expansion Clinical Trials in FLT3-mutated and FLT3-unmutated AML expected to begin in the first half of 2023
Aptose also reviewed clinical findings with the new G3 formulation of luxeptinib (Lux):

G3 formulation was designed to increase plasma exposure and lower pill burden
Patients already administered G3 formulation at 50 mg, 100 mg and 200 mg
G3 formulation is being tested in patients with R/R B-cell malignancies and R/R AML
G3 formulation encouraging with rapid absorption and exposures maintained over 3 days
Plan transition from G1 to G3 continuous dosing if PK modeling studies are supportive
"We’re pleased to announce a new complete remission (CRi) today with HM43239 in a relapsed AML patient with wildtype FLT3 and mutations in diverse genes (RAS, BCOR, U2AF1, SETBP1), expanding the genotypes and R/R AML patient population that may respond to this drug that has thus far been generally well tolerated," said William G. Rice, Ph.D., Chairman, President and Chief Executive Officer. "We’ve identified three doses and target patient populations for our next stage of Expansion Clinical Trials with HM43239, as we move along a pathway toward registrational studies. For Lux, our new G3 formulation appears to be significantly better absorbed than the original formulation and we continue to believe in its potential as a unique dual lymphoid and myeloid kinome inhibitor."