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OA 12 - Emerging Genomic Targets (ID 679)
- Event: WCLC 2017
- Type: Oral
- Track: Advanced NSCLC
- Presentations: 1
OA 12.07 - LOXO-292, a Potent, Highly Selective RET Inhibitor, in MKI-Resistant RET Fusion-Positive Lung Cancer Patients with and without Brain Metastases (ID 10955)
11:00 - 12:30 | Author(s): M.E. Cabanillas
RET fusions are validated therapeutic targets in human lung cancers. However, the clinical activity of multikinase inhibitors (MKIs) with anti-RET activity is limited by a narrow therapeutic index from off-target effects and poor pharmacokinetics (PK). Moreover, MKIs have limited RET inhibition in the central nervous system (CNS), and patients often experience disease progression in the brain. LOXO-292 is a potent and highly selective RET inhibitor, with >100-fold selectivity versus important off-targets, and anti-tumor activity in the brain and periphery in RET-dependent tumor models in vivo.
Two RET fusion-positive lung cancer patients were treated with LOXO-292: a patient with CCDC6-RET-rearranged lung cancer with acquired resistance to RXDX-105; and a patient with KIF5B-RET-rearranged lung cancer with progressive disease in the brain while on alectinib treated under a single patient protocol with real-time, PK- guided intra-patient dose titration.
The first patient was enrolled on cohort 1 of the Phase 1 trial (20 mg daily) and was the first lung cancer patient to receive LOXO-292. She achieved a rapid, confirmed partial response (PR) by RECIST 1.1, with a 44% reduction in target lesion size. The second patient, the first to receive LOXO-292 in the setting of brain metastases, achieved a PR with escalating doses of LOXO-292 (20-60-100 mg twice daily) that included target lesion responses in both the lungs and brain (Figure 1), and resolution of cancer-related CNS symptoms. Early clinical experience with LOXO-292 has already established drug exposures that are consistent with significant RET inhibition in vitro and RET-dependent tumor regression in vivo. Importantly, LOXO-292 has been well-tolerated, with the majority of treatment-emergent adverse events reported as Grade 1-2, and none attributed to LOXO-292.
LOXO-292 has demonstrated proof-of-concept tolerability, significant exposure, and efficacy in two patients with MKI-resistant, RET-dependent cancers, including a patient with progressive brain metastases after alectinib.Figure 1