A B S T R A C T PurposeTherapeutic prostate-specific antigen (PSA) -targeted poxviral vaccines for prostate cancer have been well tolerated. PROSTVAC-VF treatment was evaluated for safety and for prolongation of progression-free survival (PFS) and overall survival (OS) in a randomized, controlled, and blinded phase II study. Patients and MethodsIn total, 125 patients were randomly assigned in a multicenter trial of vaccination series. Eligible patients had minimally symptomatic castration-resistant metastatic prostate cancer (mCRPC). PROSTVAC-VF comprises two recombinant viral vectors, each encoding transgenes for PSA, and three immune costimulatory molecules (B7.1, ICAM-1, and LFA-3). Vaccinia-based vector was used for priming followed by six planned fowlpox-based vector boosts. Patients were allocated (2:1) to PROSTVAC-VF plus granulocyte-macrophage colony-stimulating factor or to control empty vectors plus saline injections. ResultsEighty-two patients received PROSTVAC-VF and 40 received control vectors. Patient characteristics were similar in both groups. The primary end point was PFS, which was similar in the two groups (P ϭ .6). However, at 3 years post study, PROSTVAC-VF patients had a better OS with 25 (30%) of 82 alive versus 7 (17%) of 40 controls, longer median survival by 8.5 months (25.1 v 16.6 months for controls), an estimated hazard ratio of 0.56 (95% CI, 0.37 to 0.85), and stratified log-rank P ϭ .0061. ConclusionPROSTVAC-VF immunotherapy was well tolerated and associated with a 44% reduction in the death rate and an 8.5-month improvement in median OS in men with mCRPC. These provocative data provide preliminary evidence of clinically meaningful benefit but need to be confirmed in a larger phase III study.

A concurrent multicenter, randomized Phase II trial employing a recombinant poxviral vaccine provided evidence of enhanced median overall survival (OS) (p=0.0061) in patients with metastatic castrate-resistant prostate cancer (mCRPC). The study reported here employed the identical vaccine in mCRPC to investigate the influence of GM-CSF with vaccine, and the influence of immunologic and prognostic factors on median OS. Thirty-two patients were vaccinated once with recombinant vaccinia containing the transgenes for prostate-specific antigen (PSA) and three costimulatory molecules (TRICOM). Patients received boosters with recombinant fowlpox containing the same four transgenes. Twelve of 32 patients showed declines in serum PSA post-vaccination and 2/12 showed decreases in index lesions. Median OS was 26.6 months (predicted median OS by the Halabi nomogram was 17.4 months). Patients with greater PSA-specific T-cell responses showed a trend (p=0.055) toward enhanced survival. There was no difference in T-cell responses or survival in cohorts of patients receiving GM-CSF vs no GM-CSF. Patients with a Halabi predicted survival of < 18 months (median predicted 12.3 months) had an actual median OS of 14.6 months, while those with a Halabi predicted survival of ≥ 18 months (median predicted survival 20.9 months) will meet or exceed 37.3 months, with 12/15 patients living longer than predicted (p=0.035). Treg suppressive function was shown to decrease following vaccine in patients surviving longer than predicted, and increase in patients surviving less than predicted. This hypothesis-generating study provides evidence that patients with more indolent mCRPC (Halabi predicted survival ≥ 18 months) may best benefit from vaccine therapy.

Purpose: Many patients with clinically localized prostate cancer develop biochemical failure despite excellent local therapy perhaps due to occult metastatic disease. One potential solution is the utilization of a well-tolerated systemic therapy (e.g., vaccine) in concert with local therapy. Experimental Design:We present a randomized phase II clinical trial designed to determine if a poxviral vaccine encoding prostate-specific antigen (PSA) can induce a PSA-specific T-cell response when combined with radiotherapy in patients with clinically localized prostate cancer. Thirty patients were randomized in a 2:1 ratio into vaccine plus radiotherapy or radiotherapyonly arms. Those patients in the combination arm received a ''priming'' vaccine with recombinant vaccinia (r V) PSA plus r V containing theT-cell costimulatory molecule B7.1 (r V-B7.1) followed by monthly booster vaccines with recombinant fowlpox PSA. The vaccines were given with local granulocyte-macrophage colony-stimulating factor andlow-dose systemicinterleukin-2. Standard external beam radiation therapy was given between the fourth and the sixth vaccinations. Results: Seventeen of 19 patients in the combination arm completed all eight vaccinations and 13 of these 17 patients had increases in PSA-specificTcells of at least 3-fold versus no detectable increases in the radiotherapy-only arm (P <0.0005).There was also evidence ofde novo generation of T cells to well-described prostate-associated antigens not found in the vaccine, providing indirect evidence of immune-mediated tumor killing. The vaccine was well tolerated. Conclusion:This vaccine regimen can be safely given in patients undergoing radiation therapy for localized prostate cancer, with the majority of patients generating a PSA-specific cellular immune response to vaccine.

US National Institutes of Health.

In this randomized phase II trial, the addition of thalidomide to docetaxel resulted in an encouraging PSA decline rate and overall median survival rate in patients with metastatic AIPC. After the prophylactic low-molecular-weight heparin was instituted to prevent venous thromboses, the combination regimen was well tolerated. Larger randomized trials are warranted to assess the impact of this combination.

We demonstrated that the CEA-TRICOM vaccines are safe and can generate significant CEA-specific immune responses, and they seem to have clinical benefit in some patients with advanced cancer.

Purpose: Docetaxel has activity against androgen-independent prostate cancer and preclinical studies have shown that taxane-based chemotherapy can enhance antitumor response of vaccines. The primary objective of this study was to determine if concurrent docetaxel (with dexamethasone) had any effect on generating animmune responseto the vaccine. Secondary endpoints were whether vaccine could be given safely with docetaxel and the clinical outcome of the treatment regimen. Experimental Design: The vaccination regimen was composed of (a) recombinant vaccinia virus (rV) that expresses the prostate-specific antigen gene (rV-PSA) admixed with (b) rV that expresses the B7.1 costimulatory gene (rV-B7.1), and (c) sequential booster vaccinations with recombinant fowlpox virus (rF-) containing the PSA gene (rF-PSA). Patients received granulocyte macrophage colony-stimulating factor with each vaccination. Twenty-eight patients with metastatic androgen-independent prostate cancer were randomized to receive either vaccine and weekly docetaxel or vaccine alone. Patients on the vaccine alone arm were allowed to cross over to receive docetaxel alone at time of disease progression. The ELISPOT assay was used to monitor immune responses for PSA-specificTcells. Results: The median increase in these T-cell precursors to PSA was 3.33-fold in both arms following 3 months of therapy. In addition, immune responses to other prostate cancerâ ssociated tumor antigens were also detected postvaccination. Eleven patients who progressed on vaccine alone crossed over to receive docetaxel at time of progression. Median progressionfree survival on docetaxel was 6.1months after receiving vaccine compared with 3.7 months with the same regimen in a historical control. Conclusion: This is the first clinical trial to show that docetaxel can be administered safely with immunotherapy without inhibiting vaccine specific T-cell responses. Furthermore, patients previously vaccinated with an anticancer vaccine may respond longer to docetaxel compared with a historical control of patients receiving docetaxel alone. Larger prospective clinical studies will be required to validate these findings.Adenocarcinoma of the prostate is the most common noncutaneous malignancy diagnosed in American males and the second leading cause of cancer death. One of six men will develop clinically significant prostate cancer in his lifetime.During 2005, an estimated 232,900 men will be diagnosed with prostate cancer and 30,350 will die from the disease in the United States (1). Overall survival for patients with metastatic androgen-independent prostate cancer has been improved with a docetaxel-based regimen. The clinical benefit shown in these recent studies is an f3-month increase in survival using an every-3-week regimen of docetaxel (2, 3). However, compared with the every-3-week schedule, weekly docetaxel is associated with significantly less grade 3 or 4 hematologic toxicity. Other studies have looked at combining weekly docetaxel with other agents (4, 5). A random...

The field of cancer vaccines is currently in an active state of preclinical and clinical investigations.Although no therapeutic cancer vaccine has to date been approved by the Food and Drug Administration, several new paradigms are emerging from recent clinical findings both in the use of combination therapy approaches and, perhaps more importantly, in clinical trial design and end point analyses. This article will review recent clinical trials involving several different cancer vaccines from which data are emerging contrasting classic ''tumor response'' (Response Evaluation Criteria in Solid Tumors) criteria with ''patient response'' in the manifestation of increased patient survival post-vaccine therapy. Also described are several strategies in which cancer vaccines can be exploited in combination with other agents and therapeutic modalities that are quite unique when compared with ''conventional'' combination therapies. This is most likely due to the phenomena that (a) cancer vaccines initiate a dynamic immune process that can be exploited in subsequent therapies and (b) both radiation and certain chemotherapeutic agents have been shown to alter the phenotype of tumor cells as to render them more susceptible to T-cell^mediated killing. Consequently, evidence is emerging from several studies in which patient cohorts who first receive a cancer vaccine (as contrasted with control cohorts) benefit clinically from subsequent therapies.The field of cancer vaccines is currently in a state of active preclinical and clinical investigations. Although no therapeutic cancer vaccine has been approved to date by the Food and Drug Administration, recent preclinical and clinical findings have shown that appropriate clinical trial design and end points, and the use of vaccines in new paradigms of combination therapies may well lead to cancer vaccines ultimately being used for the therapy of several cancer types.Cancer vaccines differ from other therapies in that they initiate a dynamic process of activating the host's own immune system. This process could potentially influence both how patient responses are evaluated and how responses to subsequent therapies post-vaccination are evaluated. Evaluation of Cancer Vaccines: New Paradigms for Responses toTherapyIt is proposed that cancer vaccines are a therapeutic modality where one should evaluate ''patient response'' more so than ''tumor response.'' The two phenomena are not always mutually inclusive. Standardization of response criteria is of course critical for any given clinical trial, but one must be aware that the use of only one criterion for all therapeutics, cancer types, and disease stages can be classic ''paradigm paralysis.'' Response Evaluation Criteria in Solid Tumors (RECIST; refs. 1, 2) has served the oncology community well in the evaluation of passive therapeutic modalities, such as chemotherapeutic agents and radiation therapy. With the advent of new targeted therapies, including cancer vaccines, however, the sole use of RECIST criteria as a clinical e...