Selpercatinib in Patients With RET Fusion-Positive Non-Small-Cell Lung Cancer: Updated Safety and Efficacy From the Registrational LIBRETTO-001 Phase I/II Trial

Abstract

Purpose: Selpercatinib, a first-in-class, highly selective, and potent CNS-active RET kinase inhibitor, is currently approved for the treatment of patients with RET fusion-positive non-small-cell lung cancer (NSCLC). We provide a registrational data set update in more than double (n = 316) of the original reported population (n = 144) and better characterization of long-term efficacy and safety.

Methods: Patients were enrolled to LIBRETTO-001, a phase I/II, single-arm, open-label study of selpercatinib in patients with RET-altered cancers. An analysis of patients with RET fusion-positive NSCLC, including 69 treatment-naive and 247 with prior platinum-based chemotherapy, was performed. The primary end point was objective response rate (ORR; RECIST v1.1, independent review committee). Secondary end points included duration of response (DoR), progression-free survival (PFS), overall survival, and safety.

Results: In treatment-naive patients, the ORR was 84% (95% CI, 73 to 92); 6% achieved complete responses (CRs). The median DoR was 20.2 months (95% CI, 13.0 to could not be evaluated); 40% of responses were ongoing at the data cutoff (median follow-up of 20.3 months). The median PFS was 22.0 months; 35% of patients were alive and progression-free at the data cutoff (median follow-up of 21.9 months). In platinum-based chemotherapy pretreated patients, the ORR was 61% (95% CI, 55 to 67); 7% achieved CRs. The median DoR was 28.6 months (95% CI, 20.4 to could not be evaluated); 49% of responses were ongoing (median follow-up of 21.2 months). The median PFS was 24.9 months; 38% of patients were alive and progression-free (median follow-up of 24.7 months). Of 26 patients with measurable baseline CNS metastasis by the independent review committee, the intracranial ORR was 85% (95% CI, 65 to 96); 27% were CRs. In the full safety population (n = 796), the median treatment duration was 36.1 months. The safety profile of selpercatinib was consistent with previous reports.

Conclusion: In a large cohort with extended follow-up, selpercatinib continued to demonstrate durable and robust responses, including intracranial activity, in previously treated and treatment-naive patients with RET fusion-positive NSCLC.

Trial registration: ClinicalTrials.gov NCT03157128.

FIG 1.

Response to selpercatinib. The waterfall plots of maximum change in tumor size are shown in (A) for the 69 patients who were treatment-naive and (B) for 226 with prior platinum chemotherapy and (C) the change in intracranial tumor size for the 26 patients with measurable CNS disease at baseline. Vertical bars represent the best percent change from baseline in the sum of diameters for all target lesions. Progressive disease (+20%) and partial response (–30%) are indicated with the dashed lines.

FIG 2.

Long-term outcomes with selpercatinib. Kaplan-Meier (KM) plots depict PFS for patients who (A) were treatment-naive or (B) had previous platinum chemotherapy. KM plots depict DoR for patients who (C) were treatment-naive or (D) had previous platinum chemotherapy. Median PFS is displayed in the Table inset. Tick marks indicate censored data. DoR, duration of response; IQR, interquartile range; PFS, progression-free survival.