Statement authors recommend using immunotherapy prior to an androgen receptor-targeted agent in men with metastatic castration-resistant prostate cancer.
The authors of the first evidence-based consensus statement on the use of immunotherapy to treat prostate cancer recommend using immunotherapy first, followed by an androgen receptor-targeted agent, for metastatic castration-resistant disease.
The Society for Immunotherapy of Cancer published the consensus statement in the open-access Journal for ImmunoTherapy of Cancer (2016; 4:92).
“The new prostate cancer treatment guidelines, from a panel convened by the Society for Immunotherapy of Cancer (SITC), come at a time when immunotherapy is showing such promise across a wide range of cancers,” James L. Gulley, MD, PhD, of the National Institutes of Health, Center for Cancer Research and chair of the SITC Prostate Cancer Task Force, told Urology Times. “These guidelines are part of a programmatic effort to put forth our current understanding of the best practices vis-à-vis immunotherapy in multiple cancer types. Of interest, there are other guidelines that are just out from SITC [regarding] hematologic malignancies and renal cell cancer.”
The society’s statement on prostate cancer represents a consensus from a broad group, including medical oncology, radiation oncology, urology, nursing, and patient advocacy, with several being key opinion leaders in prostate cancer immunotherapy, according to Dr. Gulley.
“There is one FDA-approved immunotherapy in prostate cancer, sipuleucel-T [Provenge], and this is indicated for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer,” he said. “[The indication] was based on a statistically significant and clinically meaningful improvement in overall survival (level 1 evidence).”
Next: "The general consensus was that there are major characteristics of mCRPC that favor an immunotherapy approach."
According to the statement: “With respect to an overall role for immunotherapy in the treatment of mCRPC, the general consensus was that there are major characteristics of mCRPC that favor an immunotherapy approach. Therefore, the goals should be to define optimal patient and tumor characteristics, identify best immunotherapy approaches, and identify the optimal sequence of immunotherapy with other available treatments that will benefit patients.
“Given the importance of immunologic activation and the asymptomatic status of the patient, 100% of the panel recommended that when sipuleucel-T is used, it be used first if all other criteria are met.”
About 10% of U.S. patients with metastatic castration-resistant prostate cancer receive sipuleucel-T, according to Dr. Gulley.
“It is important that patients and providers understand that unlike enzalutamide [XTANDI] or abiraterone [ZYTIGA], the PSA may not decrease in treated patients, despite improvements in overall survival,” he said. “It is also important to note that [sipuleucel-T] has very little in terms of toxicity, and patients like the fact that their body’s immune system is helping fight the cancer.”
According to Dr. Gulley, the statement points out that a number of prostate cancer specialists elect, at least in some patients, to use sipuleucel-T with other treatments, such as enzalutamide. “Another key take home was that this group recommended using immunotherapy early on in the course of treatment of patients (front-line for mCRPC).”
The panel of experts suggests there is great opportunity for improvements in immunotherapy for prostate cancer. Immune checkpoint inhibitors, such as nivolumab (Opdivo), pembrolizumab (KEYTRUDA), or atezolizumab (Tecentriq), which recently were approved for other solid tumors, have significant activity but only in T-cell-inflamed tumors. And while prostate cancer is typically not a T-cell-inflamed tumor, therapeutic vaccines, such as sipuleucel-T, may be able to induce T-cell responses within the tumor. The responses could be further augmented with immune checkpoint inhibitors, according to Dr. Gulley.
“Other therapeutic vaccines in late-stage development, such as Prostvac, should have overall survival data soon,” he said. “Finally, these vaccines, because they are so well tolerated, could be used early on in the disease process. Indeed, a study of Prostvac versus placebo in patients eligible for active surveillance is ongoing, and another study recently opened combining Prostvac with immune checkpoint inhibitors in patients prior to prostatectomy.”
Dr. Gulley declared no competing interests. Several of the consensus statement’s co-authors have a financial relationship with Dendreon and/or other pharmaceutical companies.
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