Eli Lilly’s selective RET kinase inhibitorRET kinase inhibitor Retevmo (selpercatinib) reduced the risk of disease progression or death by 53% compared to a combination of Merck & Co.'s Keytruda (pembrolizumab) plus chemotherapy in patients with advanced RET fusion-positive non-small-cell lung cancer. The results from the Phase III LIBRETTO-431 trial were presented Saturday at the European Society of Medical Oncology (ESMO) congress.
In August, EliLilly reported that the study met its primary endpoint, with Retevmo demonstrating a statistically significant and clinically meaningful improvement in progression-free survival (PFS), versus Keytruda plus chemotherapy. The trial enrolled 261 patients with advanced or metastatic RETfusion-positive non-squamous NSCLC who had received no prior systemic therapy for metastatic disease. Per the study's design, no more than 20% of patients were allowed to receive chemotherapy alone without Keytruda.
Detailed results presented at ESMO showed that at a median follow-up of around 19 months, median PFS was 24.8 months for Retevmo, compared to 11.2 months for Keytruda plus chemotherapy. Eli Lilly added that clinically meaningful improvements in overall response rate (83.7% versus 65.1%), duration of response (24.2 months versus 11.5 months) and intracranial response (82.4% versus 58.3%) were also observed with Retevmo versus Keytruda plus chemotherapy.
In terms of safety, results showed that adverse events (AEs) in patients given Retevmo were generally consistent with those previously reported and can be commonly managed with dose adjustments. However, 4.4% of those in the Retevmo arm died due to AEs, compared to none on Keytruda plus chemotherapy, while AEs leading to discontinuations were seen in the two groups at rates of 10.1% and 2%, respectively.
Retevmo scored an accelerated approval from the FDA in 2020 for RET-positive NSCLC and thyroid cancers that was subsequently converted to a full clearance last year, the same time it received another accelerated US nod – this time for locally advanced or metastatic solid tumours with a RET gene fusion. That decision was based on data from the Phase I/II LIBRETTO-001 trial where Retevmo showed an ORR of 44%.