What’s the idea behind slamming high-risk prostate cancer with a battery of treatments: surgery plus a finite course of androgen deprivation therapy (ADT) plus an androgen-directed drug such as abiraterone, apalutamide or enzalutamide? Catching cancer when it’s less prepared for battle.
Over time, prostate cancer acquires genomic alterations that help it to be more aggressive. Each tiny mutation gives the cancer extra protection, maybe starting out with the genetic equivalent of a bullet-proof vest or stronger helmet, then becoming much more sophisticated – imagine a fighter jet deploying decoy flares or chaff as missile countermeasures.
Is it more vulnerable, and easier to kill, early on? PCF-funded investigator Rana McKay, M.D., a medical oncologist at the University of California-San Diego (UCSD), and colleagues believe the answer is yes, and they’re testing this idea in several clinical trials. One phase II study at UCSD still in progress, in collaboration with PCF-funded investigator Mary-Ellen Taplin, M.D., of the Dana Farber Cancer Institute involved 119 men with “unfavorable intermediate or high-risk disease. “More than 90 percent of the patients had high-risk disease, and all of them, from the get-go, had very aggressive tumors,” says McKay. “Over one-third of patients had Gleason 9 or 10 disease, and about 60 percent of patients had stage 3 cancer,” that had spread slightly beyond the prostate but with no evidence of distant metastases. Men in the trial received either neoadjuvant abiraterone and prednisone plus leuprolide (Lupron), vs. abiraterone and prednisone, Lupron, and apalutamide.
One major reason why McKay and colleagues are testing this approach with surgery rather than radiation is to study the pathologic response: looking at how much residual tumor is present in the surgical specimen that has been removed after treatment. Have they seen any changes? Not in all men, but in about 20 percent, there’s a remarkable change: “The primary tumor was dead and necrotic.” The pathologists “looked at every little sliver of the prostate,” and found that these exceptional responders had either “less than 5 mm of tumor left behind, or no tumor left behind.”
Just think about that for a minute: the surgeon removes the prostate, gives the tissue to the pathologist, who starts looking at it under the microscope and sees only corpses of cancer cells!
One patient who participated in this study is Pat Sheffler (see his story and video), who was diagnosed at age 53 with stage 3 prostate cancer and had a PSA of 37. He received abiraterone and prednisone, Lupron, and apalutamide for six months before prostatectomy, and started to see results right away. In monthly blood tests before his surgery, his PSA levels dropped: “34, 27, 21, 10, 4, 2, and 0.2.” At surgery, he had “very minimal remaining tumor,” says McKay. Then he underwent one more year of hormone therapy after surgery. Two months after he stopped taking the trial medications, not only was his PSA undetectable, but his testosterone levels were coming back to normal. “My hope for Pat is that he’s cured, that he can go on just being an amazing dad, husband, and advocate for prostate cancer awareness.”
In another phase II study led by Taplin, published in the Journal of Clinical Oncology, McKay and colleagues at UCSD, Dana-Farber, Beth Israel Deaconess Medical Center, Johns Hopkins, and the University of Washington reported a complete pathologic response (no remaining live cancer cells in the prostate) or minimal residual disease in 30 percent of patients treated with neoadjuvant enzalutamide, Lupron, abiraterone and prednisone before prostatectomy.
But what about the men who were not exceptional responders to big-gun hormone therapy? The scientists have identified some key genetic changes in men who were non-responders, and they have some ideas about how to help these men, as well.