Cabozantinib not sufficiently effective in treatment of mCRPC

According to a media release from Exelixis in the past hour, it appears that we have seen the end of all attempts to develop cabozantinib as a treatment for metastatic, castration-resistant prostate cancer (mCRPC).

The company has announced that the final results of the COMET-2 trial did not meet the primary endpoint of alleviation of bone pain, which was determined by comparing the percentage of patients in the two treatment arms who achieved a pain response at week 6 of treatment which was then confirmed at week 12 without increase in narcotic medication.

According to the company’s media release:

  • 15 percent of patients in the cabozantinib treatment arm reported a pain response.
  • 17 percent of patients in the mitoxantrone + prednisone (control) arm reported a pain response.
  • The difference in pain response between the arms was not statistically significant.
  • The safety profile of cabozantinib in this trial was consistent with that observed in earlier studies in men with mCRPC.

Cabozantinib was approved a while ago (under the brand name Cometriq) as a treatment for progressive, metastatic medullary thyroid cancer, and it is still in Phase III trials designed to investigate its potential in the treatment of metastatic renal cell carcinoma and advanced hepatocellular carcinoma. However, the failure of this drug to demonstrate significant efficacy in either one of two Phase III trials for the treatment of mCRPC has surely ended any attempt to develop this drug for the treatment of prostate cancer.

3 Responses

  1. Your death knell is premature, and I hope that Exelixis won’t give up on it entirely for mCRPC just yet. It is in a Phase I trial combined with docetaxel and prednisone (NCT01683994). I think that all such growth factor inhibitors are unlikely to show efficacy as single agents. They are more likely to be effective as part of a cocktail.

  2. Dear Allen:

    The NCT01683994 trial is a small, NCI-sponsored study that has no backing from Exelixis other than (I suspect) provision of some free drug. I am not a naysayer but I am a realist. Exelixis’ shareholders have ridden this horse as far as they are willing to go.

  3. Typically the existing trials that are going on can still move ahead. But the right people to ask on the trial Allen alludes to are William Dahut (PI) and/or Guinevere Chun (RN at NIH) and their contact information is on the website for this NCT trial number.

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