Tuspetinib Myeloid Kinase Inhibitor Safety and Efficacy As Monotherapy and Combined with Venetoclax in Phase 1/2 Trial of Patients with Relapsed or Refractory (R/R) Acute Myeloid Leukemia (AML)

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.162-162
• Main Authors: Daver, Naval, Lee, Kyoo Hyung, Choi, Yunsuk, Jonas, Brian A., Arellano, Martha, Koller, Paul B., Jung, Chul W., Sohn, Sang Kyun, Fathi, Amir T., Lee, Jeong-Ok, Yoon, Sung-Soo, Watts, Justin M., Vachhani, Pankit, Shin, Ho-Jin, Hu, Jia, Sinha, Ranjeet, Khan, Nawazish, Rice, William G., Bejar, Rafael
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-182296

INTRODUCTION: Tuspetinib is a potent once daily oral myeloid kinase inhibitor of SYK, FLT3, JAK1/2, RSK1/2, mutant KIT, and TAK1-TAB1 kinases that mediate dysregulated cellular proliferation in AML. In an orthotopic mouse model of FLT3-mutant AML, tuspetinib exhibited greater antitumor activity than gilteritinib, entospletinib, venetoclax (VEN), and azacitidine (AZA) and combined favorably with VEN and AZA individually. Tuspetinib is being evaluated clinically as monotherapy (TUS) and in combination (VEN/TUS) in a global Phase 1/2 trial of patients with R/R AML. AIMS: Study objectives are to assess the safety, tolerability, and pharmacokinetics (PK) of TUS and VEN/TUS, to support selection of a recommended phase 2 dose (RP2D). METHODS: Dose escalation (Part A) and exploration (Part B) of single agent TUS have completed dosing of patients treated at 20 mg to 200 mg once daily. In dose expansion (Part C), 80 mg of TUS is administered continuously as once daily oral monotherapy in 28-day cycles, or in combination with daily VEN with a C1D15 marrow assessment and planned 28-day cycles. Treatment emergent adverse events (TEAE) and clinical responses are evaluated using CTCAE and Revised IWG criteria, respectively. RESULTS: As of May 30, 2023, 100 patients received TUS in Parts A/B (20mg to 200mg; n=77) and in Part C (n=23: TUS 120 mg (n=14) and TUS 80 mg + VEN 400 mg dose equivalent (n=9)). Patients are predominantly Asian (46%) and White (41%) with a median age of 63 (range 18 to 84); 60% FLT3 wild-type (FLT3-WT), 35% FLT3-mutated (FLT3m) of which 18 (51%) received prior FLT3 inhibitors, and 5% FLT3 undetermined. Patients received a mean of 2.6 prior lines of therapy (range 1-6) (Table 1). Sixty percent of patients have received prior venetoclax. In Parts A/B, clinical responses with TUS monotherapy (composite complete remission [CRc; including CR, CRh, CRp and CRi]; see Figure 1 for definitions), were observed at 40 mg (15.4%), 80 mg (29.4%), 120 mg (7.1%), and 160 mg (16.7%) in both FLT3-WT (n=33, CRc:15.2%,) and FLT3-mutated (n=23, CRc:21.7%) patients. Overall response rate (ORR, including CRc and PR) was 14.3% in prior VEN treated patients (n=28), 23.1% in FLT3-mutated patients with previous FLT3i treatment (n=13), and 66.7% in NPM1 and FLT3-mutated patients (n=6). Notably, responses were also seen in patients with TP53 (n=5; CRc:40%) and RAS (n=9; CRc:22.2%) mutations frequently associated with resistance to VEN and standard therapies. TUS was well tolera