Targeted Immunotherapy for Prostate Cancer with PROSTVAC: Interview with Neal Shore, MD, FACS
Findings from the phase II PROSTVAC immunotherapy trial for prostate cancer patients.
Neal D. Shore, MD, FACS, of the Caroline Urologic Research Center in Myrtle Beach, South Carolina, is a member of Cancer Therapy Advisor's Advisory Board.
Dr. Shore recently published an article entitled “PROSTVAC® targeted immunotherapy candidate for prostate cancer” in the journal Immunotherapy and we sat down with him to discuss his research.
CTA: How has the treatment of castration-resistant prostate cancer evolved in the last several years?
Dr. Shore: The treatment for advanced prostate cancer has evolved dramatically in the last several years as there are now six new FDA- and EMA-approved therapies for patients with castration-resistant prostate cancer (CRPC) since 2010.
CTA: What are the benefits of immunotherapy for patients with castration-resistant prostate cancer?
Dr. Shore: The benefits of immunotherapy appear to be an attempt to harness the intact immune system of the patient in such a way that the natural defenses of the immune system are further stimulated to break tolerance to neoplastic antigens and therefore it's teleologically a more rational approach as opposed to traditional therapeutics which are geared toward non-immunologic targets.
CTA: What were the most promising outcomes of the PROSTVAC research that warrant further study of this therapy?
Dr. Shore: The phase II trial, as far as I can tell, for patients being studied in the pre-chemotherapy setting with asymptomatic or minimally symptomatic M1CRPC is the longest survival benefit demonstrated in a phase II study, which was approximately 8.5 months.
Neal D. Shore, MD, FACS
CTA: What are the implications of this research?
Dr. Shore: The implications of this research are to move forward with the registration trial in terms of a phase III development study. The study is multinational, global in its scope.
So in addition to the rather dramatic overall survival benefit in the phase II we also saw exceptional tolerability in the form of its administration as it only required subcutaneous injections, no infusional aspects to the therapy, and so the administration is easily clinic based and does not require any specific skill sets for administration.
CTA: Are there any other treatment considerations one should keep in mind?
Dr. Shore: I think overall the advantage of immunotherapeutic approaches for patients with CRPC is identifying them early in their development of CRPC when they have mild to moderate tumor burden and presumably less immunosuppression associated with more advanced disease, albeit still within the CRPC category.
Patients who are early on in their development of CRPC status may already have an immune system that demonstrates greater susceptibility to immunologic therapies and thus have a longer duration of time to respond to the immunotherapeutic agent while not precluding other CRPC therapies.
CTA: Are there any other additional comments you would like to share?
Dr. Shore: What's particularly provocative and exciting is the potential to combine immunobiologic therapies that can potentiate T-cell activation with other approved CRPC therapies, certainly ones that are not immunosuppressive.
Combinatorial strategiescould synergistically work on other pathways of neoplastic progression of CRPC patients, not only androgen receptor targets but also other downstream pathways.