RET-MAP: An International Multicenter Study on Clinicobiologic Features and Treatment Response in Patients With Lung Cancer Harboring a RET Fusion

Abstract

Chemotherapy; Non–small cell lung cancer; RET inhibitors

Quimioteràpia; Càncer de pulmó de cèl·lules no petites; Inhibidors de RET

Quimioterapia; Cáncer de pulmón de células no pequeñas; Inhibidores de RET

Introduction Nearly 1% to 2% of NSCLCs harbor RET fusions. Characterization of this rare population is still incomplete. Methods This retrospective multicenter study included patients with any-stage RET positive (RET+) NSCLC from 31 cancer centers. Molecular profiling included DNA/RNA sequencing or fluorescence in situ hybridization analyses. Clinicobiological features and treatment outcomes (per investigator) with surgery, chemotherapy (CT), immune checkpoint blockers (ICBs), CT-ICB, multityrosine kinase inhibitors, and RET inhibitors (RETis) were evaluated. Results For 218 patients included between February 2012 and April 2022, median age was 63 years, 56% were females, 93% had adenocarcinoma, and 41% were smokers. The most frequent fusion partner was KIF5B (72%). Median tumor mutational burden was 2.5 (range: 1–4) mutations per megabase, and median programmed death-ligand 1 expression was 10% (range: 0%–55%). The most common metastatic sites were the lung (50%), bone (43%), and pleura (40%). Central nervous system metastases were found at diagnosis of advanced NSCLC in 21% of the patients and at last follow-up or death in 31%. Overall response rate and median progression-free survival were 55% and 8.7 months with platinum doublet, 26% and 3.6 months with single-agent CT, 46% and 9.6 months with CT-ICB, 23% and 3.1 months with ICB, 37% and 3 months with multityrosine kinase inhibitor, and 76% and 16.2 months with RETi, respectively. Median overall survival was longer in patients treated with RETi versus no RETi (50.6 mo [37.7–72.1] versus 16.3 mo [12.7–28.8], p < 0.0001). Conclusions Patients with RET+ NSCLC have mainly thoracic and bone disease and low tumor mutational burden and programmed death-ligand 1 expression. RETi markedly improved survival, whereas ICB may be active in selected patients.

Writing assistance was provided by Mrs. Sarah Mackenzie. Dr. Marinello was the recipient for the grant for DUERTECC/EURONCO (Diplôme Universitaire Européen de Recherche Translationnelle Et Clinique en Cancérologie). Dr. Mezquita received support from the Contrato Juan Rodes 2020 (ISCIII, Ministry of Health); Ayuda de la Acción Estratégica en Salud-ISCIII FIS 2021 (PI21/01653); Ayuda SEOM-Juan Rodés 2020. Dr. Cortellini acknowledges the support from the National Institute for Health Research Imperial Biomedical Research Centre. Dr. Pinato acknowledges the support from the Wellcome Trust Strategic Fund (PS3416), Associazione Italiana per la Ricerca sul Cancro (Associazione Italiana per la Ricerca sul Cancro MFAG Grant ID 25697), National Institute for Health Research Imperial Biomedical Research Centre, Imperial Experimental Cancer Medicine Centre, and the Imperial College Tissue Bank.