Why it can take us so long to develop new forms of treatment


A new report in the journal Human Vaccines and Immunotherapeutics exemplifies the problems associated with finding “the best” forms of treatment for men with progressive forms of prostate cancer.

Back in 2010, the Eastern Cooperative Oncology Group (EGOG), now re-named as the ECOG-ACRIN Cancer Research Group, put together a randomized, Phase II clinical trial designed to investigate whether men with metastatic, castration-resistant prostate cancer (mCRPC) would respond better to

  • Prostvac VF followed by docetaxel-based chemotherapy (an investigational drug combination) or
  • Simple chemotherapy with docetaxel + prednisone

In theory, this should have been an exciting trial. Early stage data had shown a high potential for Prostvac VF (now properly known as rimilogene-galacirepvec) in treatment of men with mCRPC, and so the question of whether combining this investigational drug with standard chemotherapy would have seemed to be of considerable importance. It was scheduled to randomize 144 men with mCRPC to one or other arm of the study.

So what were the results?

Basically, this study defines a “failed” clinical trial. It enrolled only 10 patients in the first 13 months of enrollment, of whom just eight actually received treatment. For those who are interested in the effects observed in the eight treated patients, please see here.

Why did this trial fail? There are probably many reasons but among the most important would have been the number of competing trials seeking to enroll men with mCRPC in the time period from 2010 to 2012. The available number of eligible patients for this trial would not have been huge to begin with, and any patient who had already received either chemotherapy or any other form of immunotherapy (e.g., Provenge) would not have been eligible. And then at the same time there were  a whole bunch of other trials seeking to enroll patients of the same type.

Now we are going to have to wait to see what happens with the ongoing Phase III trial of Prostvac VF before we can see whether a trial of this type can be “brought back to life” to explore whether the combination of Prostvac VF with docetaxel-based chemotherapy is more effective than either docetaxel alone or Prostvac VF alone.

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