Exelixis on Monday said its cancer drug Cabometyx, when combined with Roche’s Tecentriq, shrank or eliminated tumors in nearly one-third of tested patients with advanced prostate cancer. The study, called COSMIC-021, enrolled patients who progressed following treatment with hormone therapy and chemotherapy.The news comes as Cabometyx has been under increasing pressure in its main kidney cancer indication from Pfizer’s Inlyta, which won Food and Drug approval in first-line disease in combination with Merck & Co.’s Keytruda last year. Pfizer said sales of Inlyta rose 60% in 2019 thanks to that approval.Full data are set to be released at a genitourinary meeting of the American Society of Clinical Oncology on Thursday. Exelixis said it hopes to ask the FDA for approval in prostate cancer in 2021, based on data from this trial and an expansion.
Exelixis is, for now, primarily dependent on sales of Cabometyx (cabozantinib), and must work hard to protect and expand that franchise. In renal cell carcinoma, the entry of first-line combination treatment with Keytruda (pembrolizumab) and Inlyta (axitinib) has disrupted treatment regimens.
Exelixis executives have been going to great pains to point out that Cabometyx is still being used extensively on patients who progress following treatment with the Keytruda-Inlyta pairing. Yet winning a place in prostate cancer treatment would still come as a relief to Exelixis and its investors.
The data comes from a cohort of the Phase 1 COSMIC-021 trial treating prostate cancer patients whose disease is defined as advanced or has spread to other parts of the body. The study tested whether the combination of Cabometyx plus Roche’s immuno-oncology agent Tecentriq (atezolizumab) can shrink or eliminate tumors.
The patients enrolled in the trial needed to have progressed following treatment with hormone therapies like Xtandi (enzalutamide) and in some cases chemotherapy.
The data being presented at the meeting come from an interim analysis of 44 patients followed for a median of nearly 13 months. Fourteen patients had their tumors shrink, and of those, two had their tumors disappear. When combined with patients whose tumors did not grow, the disease control rate was 80%, Exelixis said.
One patient died from drug-related causes, a 90-year-old who suffered from dehydration.
Earlier this year, Exelixis decided to expand the prostate cancer cohort to 130 patients. Based on this interim data and that coming from the expansion, the company said it plans on asking FDA for accelerated approval in early 2021 if results continue to be positive.
Exelixis shares rose 3% today, trading at $19.83 apiece.