Exelixis’ Phase II Cabometyx trial needs 30% PFS benefit to gain physician confidence for first-line RCC usage - experts

12 Jul 2016

Exelixis’ (NASDAQ:EXEL) Cabometyx (cabozantinib) would need at least a 30% progression-free survival (PFS) improvement to justify first-line use in metastatic renal cell cancer (mRCC) over approved tyrosine kinase inhibitors (TKIs) considering its toxicity profile, said experts.

The company is discussing the next steps with regulatory authorities for Cabometyx’s first-line use, said an Exelixis spokesperson. The firm announced on 23 May the Phase II (NCT01835158) trial, conducted in collaboration with the National Cancer Institute, met its primary PFS endpoint.

The Phase II CABOSUN trial meeting its primary endpoint in a difficult-to-treat population is significant, said experts. Nonetheless, they pointed to the importance of secondary endpoint data to guide their decision making process despite Cabometyx beating Pfizer’s (NYSE:PFE) TKI Sutent (sunitinib) in terms of PFS in CABOSUN.

The study, which was in poor- or intermediate-risk patients, is a more thorough representation of real-life clinical scenarios, they added, but its applicability in favorable-risk patients was not as clear.

Even if Cabometyx sees broad initial uptake, it will likely face further competition from immunotherapies being studied in the same space, said experts.

Sales of USD 50m are forecast for 2016 and USD 135 million in 2017, according to an analyst report, which noted half of 1Q16 sales were for RCC. In April, Cabometyx was approved for advanced RCC patients who have received prior anti-angiogenic therapy and as Cometriq for metastatic medullary thyroid cancer in November 2012.

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