“Adding abiraterone acetate (Zytiga) to enzalutamide (Xtandi) did not improve progression-free survival (PFS) after prostate-specific antigen (PSA) progression in men on enzalutamide monotherapy for chemotherapy-naive metastatic castration-resistant prostate cancer (mCRPC), researchers found.
“In the randomized, double-blind PLATO trial, the median PFS in patients treated with enzalutamide plus abiraterone and prednisone was 5.7 months. By comparison, the PFS was 5.6 months in the control group treated with abiraterone and prednisone plus placebo (hazard ratio [HR] 0.83; P=0.22).”
“The FDA has approved enzalutamide (Xtandi) for the treatment of patients with nonmetastatic castration-resistant prostate cancer (CRPC), according to Pfizer and Astellas, the codevelopers of the antiandrogen agent.
“The approval is based on the phase III PROSPER trial, in which the combination of enzalutamide (Xtandi) and androgen deprivation therapy (ADT) reduced the risk of metastases or death by 71% compared with ADT alone for patients with nonmetastatic CRPC. In the double-blind study, the median metastasis-free survival (MFS) was 36.6 months with enzalutamide plus ADT versus 14.7 months with ADT alone (HR, 0.29; 95% CI, 0.24-0.35; P <.0001).”
“Detection of circulating tumor cells (CTCs) positive for the nuclear-specific AR-V7 protein was an independent predictor of shortened progression-free survival (PFS) and overall survival (OS) when treating metastatic castration-resistant prostate cancer (mCRPC) with abiraterone or enzalutamide, according to results of the PROPHECY study (abstract 5004). The findings were presented at the 2018 Annual Meeting of the American Society of Clinical Oncology (ASCO), held June 1–5 in Chicago.
“’Men with AR-V7–positive CTCs have a very low probability of benefit from abiraterone or enzalutamide, ranging from 0% to 11%,’ said Andrew J. Armstrong, MD, of Duke Cancer Institute. ‘However, a lack of AR-V7 detection does not guarantee response or benefit’ where these therapies are concerned, he added.”
“The Food and Drug Administration granted Xtandi (enzalutamide) a priority review to a supplemental new drug application for the treatment of patients with nonmetastatic castration-resistant prostate cancer, according to the companies developing the drug, Pfizer and Astellas.
“The sNDA is based on data from the phase 3 PROSPER trial in which the combination of Xtandi and androgen deprivation therapy (ADT) reduced the risk of metastases or death by 71 percent compared with ADT alone for patients with nonmetastatic CRPC. In the double-blind study, the median metastasis-free survival (MFS) was 36.6 months with Xtandi plus ADT versus 14.7 months with ADT alone.”
“Fifteen years ago, Michael Jung was already an eminent scientist when his wife asked him a question that would change his career, and extend the lives of many men with a particularly lethal form of prostate cancer.
” ‘When I turned 55—I’m now 70—my wife, Alice, said to me, “What do you want to do for the rest of your life, more of the same?” ‘ recalled Jung, a UCLA distinguished professor of chemistry and biochemistry. ‘I said that didn’t sound like such a bad idea until you put it that way.’ ”
“In two separate trials presented at the 2018 Genitourinary Cancers Symposium, apalutamide and enzalutamide (Xtandi), respectively, reduced the risk of metastasis and prolonged metastasis-free survival in men with high-risk nonmetastatic castrate-resistant prostate cancer. In the SPARTAN trial, apalutamide reduced the risk of developing metastasis and death by 72% compared with placebo, and in the PROSPER trial,enzalutamide reduced the risk of metastasis or death by 71% compared with placebo. In both studies, men were treated with ongoing androgen-deprivation therapy.”
“Enzalutamide (Xtandi) demonstrated early signs of efficacy in patients with androgen receptor (AR)-positive triple-negative breast cancer (TNBC), according to findings from the phase II MDV3100-11 study published in the Journal of Clinical Oncology.
“A total of 118 patients were enrolled in the single-arm, 2-stage trial, and 78 were evaluable for response. At 16 weeks, the clinical benefit rate (CBR) was 25% (95% CI, 17-33) in the intent-to-treat (ITT) population and 33% (95% CI, 23-45) in the evaluable subgroup. The median progression-free survival (PFS) was 2.9 months (95% CI, 1.9-3.7) in the ITT population and 3.3 months (95% CI, 1.9-4.1) in the evaluable subgroup. Median overall survival (OS) was 12.7 months (95% CI, 8.5 – not yet reached) in the ITT population and 17.6 months (95% CI, 11.6 – not yet reached) in the evaluable subgroup.”
“The use of bipolar androgen therapy (BAT), involving rapid cycling between high and low serum concentrations, was safe and resulted in responses and resensitization to enzalutamide in men with metastatic castration-resistant prostate cancer (CRPC) who progressed after initial enzalutamide therapy, according to a new study.
“ ‘Clinically, metastatic CRPC that has progressed after enzalutamide treatment is minimally responsive to further therapy that inhibits androgen receptor signaling,’ wrote study authors led by Benjamin A. Teply, MD, of Johns Hopkins School of Medicine in Baltimore. ‘Theoretically, rapidly varying the androgen concentrations between the extremes of supraphysiological and near-castrate, a strategy termed BAT, provides insufficient time for CRPC cells to adaptively regulate androgen receptor concentrations,’ and thus may promote cancer cell death and prevent resistance.”
“In patients with hormone receptor (HR)-positive advanced breast cancer and no prior endocrine therapy who were positive for a gene signature-based biomarker indicating androgen receptor (AR)-signaling, the addition of enzalutamide (Xtandi) to exemestane was found to significantly improve progression-free survival (PFS) from 4 months to 16.5 months.
“Moreover, the phase II trial showed no effect of enzalutamide on PFS in the overall cohort of patients nor in the biomarker-positive population who received prior endocrine therapy, said Denise Yardley, MD, at the 2017 San Antonio Breast Cancer Symposium.”