Loxo Oncology announces LOXO-292 durability update in RET-Mutant MTC
Loxo Oncology announced updated interim clinical data for LOXO-292 from the global Phase 1/2 LIBRETTO-001 trial in patients with RET-mutant medullary thyroid cancer and RET fusion-positive thyroid cancer who were initially included in the LOXO-292 presentation at the 2018 ASCO Annual Meeting. In these 38 patients, approximately 3.5 months of additional patient follow-up were available, as were first follow-up scans for the nine patients most recently enrolled. Sixteen of 17 responding RET-mutant MTC patients remained on therapy, with median follow-up of 8.4 months. Seven of seven responding RET fusion-positive thyroid cancer patients remained on therapy, with median follow-up of 8.5 months. Inclusion of new restaging data for the most recently enrolled patients resulted in a 59% overall response rate in the presented subset of RET-mutant MTC patients, and a 78% confirmed overall response rate in the presented subset of RET fusion-positive thyroid cancer patients. These data were presented at the 88th Annual Meeting of the American Thyroid Association. The data presented were based on a July 19, 2018 data cut-off date and included the 29 patients with RET-mutant MTC and the nine patients with RET fusion-positive thyroid cancer who were initially included in the LOXO-292 presentation at the 2018 ASCO Annual Meeting. Patients were heavily pretreated, having received a median of three prior systemic treatment regimens. Of the patients with RET-mutant MTC, 79% had previously received cabozantinib or vandetanib and 45% had received prior treatment with both agents. Of the patients with RET fusion-positive thyroid cancer, 78% had previously received radioactive iodine and 78% had previously received sorafenib or lenvatinib. Anti-tumor activity was observed regardless of RET mutation, RET fusion partner, and prior multikinase inhibitor treatment. One patient, with RET fusion-positive thyroid cancer, had RECIST target lesions in the central nervous system and exhibited an intracranial partial response by RECIST 1.1, pending confirmation. Of the 82 patients in the safety analysis, most treatment-emergent adverse events were Grade 1 in severity and judged by the investigator as not related to LOXO-292.