MO01.38 Registrational Dataset from the Phase 1/2 ARROW Trial of Pralsetinib (BLU-667) in Patients with Advanced RET Fusion+ Non-Small-Cell Lung Cancer (NSCLC)

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Conference Proceeding

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Journal of Thoracic Oncology


Background: Pralsetinib is an investigational, highly potent, selective RET inhibitor. We provide the registrational dataset for patients with RET fusion+ NSCLC with and without prior treatment from ARROW.

Methods: ARROW (75 sites/11 countries; NCT03037385) consists of phase 1 dose escalation to establish recommended phase 2 dose (400 mg once daily [QD] orally) and phase 2 expansion cohorts defined by tumor type and/or RET alteration. Primary objectives were overall response rate (ORR; blinded independent central review per RECIST v1.1) and safety. Efficacy is shown for response-evaluable patients (REP) with RET fusion+ NSCLC who initiated 400 mg QD pralsetinib by July 11, 2019 and safety for all patients (all diagnoses) who initiated 400 mg QD.

Results: As of November 18, 2019, 354 patients with advanced solid tumors had initiated 400 mg QD pralsetinib (median follow-up 8.8 months). Efficacy outcomes are shown (Table) for patients with metastatic RET fusion+ NSCLC (n=116; 72% KIF5B; 16% CCDC6; 12% other/fusion present but type unknown) with prior platinum treatment (n=80) or without prior systemic treatment (n=26). ORR was similar regardless of RET fusion partner, prior therapies, or central nervous system involvement. Overall there were 7 (6%) complete responses, 4 (5%) in prior platinum patients and 3 (12%) in treatment-naïve patients; median time to response overall was 1.8 months and median duration of response (DOR) was not reached (95% CI, 11.3–not reached). In the safety population (n=354; all tumor types), most treatment-related adverse events (TRAEs) were grade 1–2, and included increased aspartate aminotransferase (31%), anemia (22%), increased alanine aminotransferase (21%), constipation (21%) and hypertension (20%). 4% of patients in the safety population discontinued due to TRAEs.

Conclusions: Pralsetinib has rapid, potent, and durable clinical activity in patients with advanced RET fusion+ NSCLC regardless of RET fusion genotype or prior therapies, and QD oral dosing is well-tolerated.




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