Taxane analog shows ‘unequivocal benefit’ in prostate mets

Cabazitaxel, an investigational taxane, significantly extended survival among prostate cancer patients whose disease had progressed despite hormone therapy. This is good news for these patients who generally have very few treatment options, according to a study from the Tulane Cancer Center in New Orleans.

"Treatments with hormone therapy and multiple chemotherapy regimens, including docetaxel (Taxotere), have failed to control their disease," said Oliver Sartor, MD, Piltz Professor for Cancer Research at Tulane Cancer Center. "But we saw a treatment effect in these patients that was greater in second-line therapy than we saw with docetaxel in first-line therapy."

Currently, there are no "effective treatments available to help men with metastatic castration-resistant prostate cancer whose disease continues to grow despite standard chemotherapy, and this large study shows an unequivocal survival benefit for patients who received cabazitaxel," Dr. Sartor said.

"We saw a treatment effect in these patients that was greater in second-line therapy than we saw with docetaxel in first-line therapy." - Oliver Sartor, MD

In the phase III, randomized TROPIC study (Treatment of Hormone-Refractory Metastatic Prostate Cancer Previously Treated with a Taxotere-Containing Regimen), Dr. Sartor and colleagues from 132 institutions in 26 countries enrolled 755 men diagnosed with metastatic castration-refractory prostate cancer. Patients were recruited from January 2007 though October 2008. The subjects' median age was 68 years and 84% of the men were white (2010 Genitourinary Cancers Symposium abstract 9).

All patients in the study had been heavily pretreated for metastatic castration-resistant prostate cancer with docetaxel and some had undergone as many as seven chemotherapy treatments, according to Dr. Sartor.

Patients were assigned to receive cabazitaxel (25 mg/m² every three weeks) plus prednisone (10 mg daily) for 10 cycles or mitoxantrone (12 mg/m² every three weeks) with prednisone for 10 cycles.

After a median follow up of 12.8 months, men in the cabazitaxel group lived a median of 15.1 months, while those in the mitoxantrone group lived 12.7 months (P < .0001). Dr. Sartor said that the primary outcome indicated there was a 30% reduction in the risk of mortality with cabazitaxel.

Grade 3 toxicities associated with cabazitaxel therapy included febrile neutropenia, diarrhea, nausea, vomiting, and abdominal pain.

Based on these findings, sanofi-aventis will submit an application for marketing approval to the FDA for cabazitaxel, Dr. Sartor said. Other studies are being planned that will assess cabazitaxel earlier in the course of prostate cancer treatment, before patients stop responding to docetaxel.

"The results of this study are clinically meaningful for doctors and their patients," commented Howard Sandler, MD, Ronald H. Bloom Family Chair in Cancer Therapeutics and chair of radiation oncology at the Samuel Oschin Cancer Institute at Cedars-Sinai Medical Center in Los Angeles.

"Anecdotally, doctors at this meeting have already told me that they have received calls from patients who want to know when this drug will be available," Dr. Sandler said.