We have previously reported the first randomized study of any kind in patients with nonmetastatic, castrate-resistant (D0.5) prostate cancer. The study employed vaccine, the hormone nilutamide, and the combined therapy (crossover for each arm) with an endpoint of time to progression. A follow-up survival analysis has been performed. Forty-two patients were randomized to receive either a poxvirus-based prostate-specific antigen (PSA) vaccine or nilutamide and median survival among all patients was 4.4 years from date of enrollment. Median survival exhibited a trend toward improvement for patients initially randomized to the vaccine arm (median, 5.1 versus 3.4 years;P = 0.13). A subset of 12 patients who initially received vaccine and then later received nilutamide suggested improved survival compared with the 8 patients who began with nilutamide and subsequently were treated with vaccine (median, 6.2 vs. 3.7 years;P = 0.045). These data suggest that patients with nonmetastatic castration-resistant prostate cancer (D0.5) who receive vaccine before second-line hormone therapy may potentially result in improved survival when compared with patients who received hormone therapy and followed by vaccine. Based on these findings, a follow-up study is being conducted. This study is currently enrolling patients with D0.5 prostate cancer on testosterone suppression therapy who have a rising PSA. Patients are stratified by PSA doubling time and randomized to androgen receptor antagonist alone (flutamide) or flutamide plus Prostavac. (Prostvac-VF is a vector-based, therapeutic cancer vaccine regimen consisting of recombinant poxviruses containing the transgenes for prostate-specific antigen (PSA) and 3 T-cell co-stimulatory molecules). A previous randomized, placebo-controlled phase II study demonstrated an 8.5-month improvement in median survival (25.1 months for Prostvac group vs. 16.6 months for control group) in men with metastatic castration resistant prostate cancer) Flutamide is given at the standard dose of 250 mg TID while Prostvac is given by monthly subcutaneous injections. The primary endpoint of the study is time to treatment failure (TTF) which is defined as biochemical recurrence (PSA rise) or development of metastatic lesions on scans. The first 26 patients enrolled are evaluated in this analysis. For flutamide alone (n = 13), the median age at enrollment was 64.7 years and median Gleason Score was 8. For flutamide + Prostvac (n = 13), the median age at enrollment was 67.1 years and median Gleason score was 8. Median time to progression is 223 days for Fluatmide + Prostvac (range 70-638) vs. 85 days for Flutamide alone (56-372). Progression for 11/12 flutamide alone patients and 9/10 fluatmide + Prostvac patients has been by PSA rise only. Preliminary evidence from this second randomized trial suggests improvement in time to treatment failure using combination of hormonal therapy with flutamide + PSA-TRICOM vaccine compared to fluatmide alone in patients with non-metastatic CRPC. This trial will continue to accrue a total of 62 patients and also will evaluate immunological responses. Preclinical models investigated in the LTIB suggest that vaccine induced anti-tumor effects can be enhanced by radiation. We are currently investigating a radiation/vaccine combination trial. A randomized phase 2.5 study of 153Sm-EDTMP (Quadramet) with or without a PSA/TRICOM vaccine in men with androgen-insensitive metastatic prostate cancer, MOB, CCR, NCI. This trial is the first clinical trial to combine vaccine with a bone seeking radionuclide for use in patients with androgen independent prostate cancer. This study has accrued half the total number of patients and there is preliminary suggestion of benefit for the combination of vaccine and radiation. We have previously conducted a study combining an anti-CTLA-4 molecule with vaccine, in the first clinical trial to combine an anti-CTLA-4 antibody and a vector-based vaccine in prostate cancer. This study suggested no increase in side effects vs. anti-CTLA4 therapy alone (based on previous studies.). The immune data from the study suggested that some patients had enhanced immune response and the median over survival was greater than in previous trials with vaccine alone. This hypothesis-generating study lays the ground work for future trials that may combine a vaccine with an immune checkpoint inhibitor such as anti-CTLA-4. Additional combination studies are ongoing: --A randomized Pilot Phase II study of Docetaxel alone or in combination with PANVAC-V (vaccinia) and PANVAC-F (fowlpox) in adults with metastatic breast cancer. MOB, CCR, NCI. This is the first randomized trial to combine vaccine with Docetaxel in this breast cancer patient population. --A Phase I-II study of tumor vaccine following chemotherapy in patients with previously untreated metastatic breast cancer: Vaccine-induced bias of T-cell repertoire reconstitution after T-cell reinfusion (Collaboration with Dr. Sportes) MOB, CCR, NCI. This trial combines the concepts of T-cell repertoire reconstitution with vaccine therapy. --An open label pilot study to evaluate the safety and tolerability of PANVAC-V (Vaccinia) and PANVAC-F (Fowlpox) in combination with Sargramostim (GM-CSF) in patients with metastatic adenocarcinoma, MOB, CCR, NCI. This trial employed vectors with transgenes of both multiple tumor antigens and multiple costimulatory molecules. A recent amendment allowed additional patients to further analyze the efficacy of the vaccine. --Collaborative Trials with Extramural Cancer Centers: A phase II study of PROSTVAC-V(Vaccinia)/TRICOM and PROSTVAC-F(fowlpox)/TRICOM with GM-CSF in patients with PSA progression after local therapy for prostate cancer (Eastern Cooperative Oncology Group). A Phase I study of sequential vaccinations with fowlpox-CEA(6D)-TRICOM and vaccinia-CEA(6D)-TRICOM, in combination with GM-CSF and Interferon-Alfa-2B in patients with CEA expressing carcinomas (Ohio State Comprehensive Cancer Center). --A Phase I study of regulatory T cell depletion with Denileukin Diftitox followed by active immunotherapy with autologous dendritic cells infected with CEA-6D expressing fowlpox-TRICOM in patients with advanced or metastatic malignancies expressing CEA (Duke Comprehensive Cancer Center). Phase I study of intravesical recombinant fowlpox-GM-CSF and or recombinant fowlpox-TRICOM in patients with bladder carcinoma scheduled for cystectomy (Cancer Institute of New Jersey, CINJ).
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