Alectinib activity in chemotherapy-refractory metastatic RET-rearranged non-small cell lung carcinomas: A case series

Objectives: to report outcomes of four cases of chemo-refractory RET-rearranged non-small cell lung carcinomas (NSCLCs) treated with alectinib in a single center. Materials and methods: we retrospectively assessed and reported the activity and tolerability of alectinib 600 mg twice daily in advanced and chemo-refractory RET-rearranged NSCLC patients treated in a Brazilian institution. Identification of RET rearrangements was performed using the FoundationOne (R) next-generation sequencing (NGS) platform. Results: The four patients herein reported were white, female and non-smokers, ranging between 59-66 years of age. All patients had been previously treated with chemotherapy and were TKI naive; three of them presented disease progression to nivolumab as well. Molecular tumor profiling showed a KIF5B-RET fusion in three patients and a CCDC6-RET in the fourth. One patient exhibited disease progression and clinical deterioration two months after treatment initiation. Disease control was documented in two patients with PFS ranging from 4 to 5 months (one partial metabolic response and one stable disease). In one of the cases, which developed oligoprogression on alectinib, radiation therapy plus post-progression alectinib were able to provide additional disease control for 9 more months. No grade 3/4 adverse events, dose reductions or discontinuation due to toxicity were documented. Conclusion: Although this is a small single center evaluation, alectinib was well tolerated and demonstrated clinical activity against advanced RET-rearranged NSCLCs, suggesting its potential role in this specific subset of malignancies. Clinical trials addressing its efficacy and the optimal dosing schedule in the present context are underway, and results are eagerly awaited.