The Food and Drug Administration (FDA) has granted accelerated approval for Vitrakvi (larotrectinib; Bayer and Loxo Oncology) for the treatment of patients with solid tumors that have neurotrophic receptor tyrosine kinase (NTRK) gene fusion without a known acquired resistance mutation, are metastatic or where surgical resection is likely to result in severe morbidity, and have no satisfactory alternative treatments or that have progressed following treatment. This approval is based on overall response rate (ORR) and duration of response (DOR); continued approval may be based upon verification and description of clinical benefit in confirmatory trials. 

Vitrakvi, a first-in-class oral TRK inhibitor, is also the first agent to receive a tumor-agnostic indication at the time of approval. NTRK gene fusions have been shown to promote cell proliferation and survival in tumor cell lines. By inhibiting these proteins, Vitrakvi has shown efficacy for various tumor types, including lung, thyroid, melanoma, GIST, colon, soft tissue sarcoma, salivary gland, and infantile fibrosarcoma. TRK fusion cancers are diagnosed through specific tests, including those that use next-generation sequencing (NGS) and fluorescence in situ hybridization (FISH). 

Vitrakvi was evaluated in the Phase 1 adult trial, Phase 2 NAVIGATE trial, and the Phase 1/2 pediatric SCOUT trial (N=55). Pooled data showed an ORR of 75% (95% CI, 61%, 85%) among patients treated with Vitrakvi, with 22% of patients having a complete response (CR) and 53% having a partial response (PR) across various tumor types. 

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Of the responders, 73% had a DOR of ≥6 months at the time of data cut-off; median DOR and progression-free survival (PFS) was not reached at the time of analysis. The median time to response was reported to be 1.84 months. 

Regardless of attribution, the most common adverse events (≥20%) were increased ALT/AST, anemia, fatigue, nausea, dizziness, cough, vomiting, constipation, and diarrhea. The majority of adverse events seen in ≥10% of patients were grade 1 or 2.

Vitrakvi will be available as 25mg and 100mg capsules in 60-count bottles, as well as a 20mg/mL oral solution. Vitrakvi will be commercially available immediately. 

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