CStone Pharmaceuticals announced that the new drug application (NDA) for pralsetinib for the treatment of rearranged during transfection (RET) fusion-positive locally advanced or metastatic non-small cell lung cancer (NSCLC) has been accepted in Hong Kong, China. Pralsetinib is a potent and selective RET inhibitor discovered by CStone's partner Blueprint Medicines. CStone has an exclusive collaboration and license agreement with Blueprint Medicines for the development and commercialization of pralsetinib in Greater China, which encompasses Mainland China, Hong Kong, Macau and Taiwan.

The NDA acceptance of pralsetinib in Hong Kong, China is based on results from the global phase 1/2 ARROW study. This trial is designed to evaluate the safety, tolerability, and efficacy of pralsetinib in patients with RET-fusion positive NSCLC, RET-mutant medullary thyroid cancer (MTC), and other advanced solid tumors with RET fusions. Results from the ARROW trial in global patients with advanced RET fusion-positive NSCLC were presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting in June 2021.

As of a date cutoff date of November 6, 2020, pralsetinib showed durable clinical benefits in patients with RET fusion-positive NSCLC who had measurable disease at baseline and received a starting dose of 400 mg once daily. In 68 treatment-naïve patients, the overall response rate (ORR) was 79% (95% CI: 68%, 88%). The complete response (CR) rate was 6%, 10% of patients had complete regression of target tumors, and 74% of patients had a partial response (PR).

The median duration of response (DOR) was not reached (95% CI: 9.0 months, not reached). In 126 patients who previously received platinum-based chemotherapy, the ORR was 62% (95% CI: 53%, 70%). The CR rate was 4%, 12% of patients had complete regression of target tumors, and 58 %of patients had a PR.

The median DOR was 22.3 months (95% CI: 15.1 months, not reached). As of the data cutoff date, a total of 471 patients were enrolled across tumor types with a pralsetinib dose starting at 400 mg once daily. The most common treatment-related adverse events (AEs) reported by investigators were neutropenia, increased aspartate aminotransferase, anemia, decreased white blood cell count, increased alanine aminotransferase, hypertension, constipation and asthenia.