Bayer and Loxo Oncology’s Vitrakvi has become the first ever TRK inhibitor to be approved in the US, having been cleared to treat advanced solid tumours harbouring an NTRK gene fusion.

TRK fusion cancer occurs when an NTRK gene fuses with another unrelated gene, producing an altered TRK protein. This altered protein becomes constitutively active or overexpressed, triggering a signaling cascade. TRK fusion proteins act as oncogenic drivers promoting cell growth and survival, leading to TRK fusion cancer, regardless of where it originates in the body.

The approval allows for use of Vitrakvi (larotrectinib) in patients with TRK fusion cancer without a known acquired resistance mutation, who have metastatic disease or where surgical resection is likely to result in severe morbidity, and who have no satisfactory alternative treatments or have progressed following treatment.

The indication was cleared under accelerated approval, based on clinical data showing an overall response rate (ORR) of 75%, which included a 22 percent complete response rate.

The FDA’s approval of Vitrakvi “marks an important milestone in how we treat cancers that have an NTRK gene fusion – a rare driver of cancer," said David Hyman, chief of the Early Drug Development Service at Memorial Sloan Kettering Cancer Center and a global principal investigator for a larotrectinib clinical trial.

"I have seen firsthand how treatment with larotrectinib, which is designed specifically for this oncogenic driver, can deliver clinically meaningful responses in patients with TRK fusion cancer, regardless of patient age or tumor type."

"We now have the first therapy approved for this genomic alteration, regardless of cancer type."

Bayer and Loxo entered into an exclusive global collaboration for the development and commercialisation of the TRK inhibitors larotrectinib and LOXO-195 in November 2017.

The companies are jointly developing the two products with Loxo leading ongoing clinical studies as well as the US filing, and Bayer leading ex-US regulatory activities and worldwide commercial activities.

Vitrakvi is also currently under review in Europe.