Kura surges on early readout in head and neck cancer trial

Study hits primary endpoint after only a third of patients are recruited.

Shares in Kura Oncology have rocketed more than 75% after the California biotech reported it had hit the mark in a phase 2 trial of lead drug tipifarnib in head and neck cancer—before the study was fully enrolled.

To hit the primary endpoint, Kura's drug needed to achieve at least four partial responses out of a total trial population of 18 patients, but tipifarnib managed that after just six patients were treated with the drug. The other two patients saw their disease stabilize, and to date, two subjects have responded for a year or more, said the company.

While still very early stage, it's an encouraging set of data for Kura's first drug candidate, which is a farnesyl transferase inhibitor designed to block HRAS, a signaling pathway that seems to initiate and drive some types of cancer. Kura—which came out of stealth mode two years ago—licenses the candidate from Johnson & Johnson.

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The trial involved patients with HRAS mutant relapsed or refractory squamous cell carcinomas of the head and neck (HNSCC), and Kura's chief medical officer Antonio Gualberto, M.D., Ph.D., said the results were remarkable with "rapid and, in some cases, dramatic responses" in this patient group.

Subjects recruited into the trial had seen their disease progress despite prior treatment with chemotherapy, Eli Lilly's Erbitux (cetuximab) and cancer immunotherapies, with one patient who progressed despite prior treatment with Merck & Co's PD-1 inhibitor Keytruda (pembrolizumab) responding to Kura's drug.

The company's CEO Troy Wilson said during the company's interim results call last month after five patients had been enrolled that the initial results from the study were compelling, as response rates for drugs approved by the FDA in second-line head and neck cancer are in the range of 13% to 16%, with overall survival generally up to 7.5 months.

The data provide the first clinical validation of HRAS as a cancer target in this cancer, according to Kura, and heightens expectations for three other phase 2 trials it is running with tipifarnib in peripheral T-cell lymphoma (PTCL), myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CML). Tipifarnib has been tested in a number of different cancer types in recent years but was unable to hit the mark in them, with failures in pancreatic cancer and acute myeloid leukemia, amongst others.

It's not the first win for the drug either, although certainly the most convincing. Earlier this year Kura reported preliminary clinical results in PTCL that 7 out of the 18 or almost 40% of patients in a heavily pretreated population who were treated with tipifarnib achieved either a partial response or disease stabilization. Meanwhile, a J&J-sponsored trial in MDS is due to report preliminary findings in the first half of 2018.