L. Michael Glode

Overall Survival Analysis of a Phase II Randomized Controlled Trial of a Poxviral-Based PSA-Targeted Immunotherapy in Metastatic Castration-Resistant Prostate Cancer

PURPOSE Therapeutic 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 METHODS In 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. RESULTS Eighty-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 = .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 = .0061. CONCLUSION PROSTVAC-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.

Trastuzumab, Paclitaxel, Carboplatin, and Gemcitabine in Advanced Human Epidermal Growth Factor Receptor-2/neu–Positive Urothelial Carcinoma: Results of a Multicenter Phase II National Cancer Institute Trial

PURPOSE We investigated the safety and efficacy (response rates, time to disease progression, survival) of trastuzumab, carboplatin, gemcitabine, and paclitaxel in advanced urothelial carcinoma patients and prospectively evaluated human epidermal growth factor receptor-2 (Her-2/neu) overexpression rates. PATIENTS AND METHODS Advanced urothelial carcinoma patients were screened for Her-2/neu overexpression. Eligibility for therapy required human epidermal growth factor receptor-2 (Her-2/neu) overexpression by immunohistochemistry (IHC), gene amplification and/or elevated serum Her-2/neu, no prior chemotherapy for metastasis, and adequate organ function including a normal cardiac function. Treatment consisted of trastuzumab (T) 4 mg/kg loading dose followed by 2 mg/kg on days 1, 8, and 15; paclitaxel (P) 200 mg/m2 on day 1; carboplatin (C; area under the curve, 5) on day 1; and gemcitabine (G) 800 mg/m2 on days 1 and 8. The primary end point was cardiac toxicity. RESULTS Fifty-seven (52.3%) of 109 registered patients were Her-2/neu positive, and 48.6% were positive by IHC. Her-2/neu-positive patients had more metastatic sites and visceral metastasis than did Her-2/neu negative patients. Forty-four of 57 Her-2/neu-positive patients were treated with TPCG. The median number of cycles was six (range, 1 to 12 cycles). The most common grade 3/4 toxicity was myelosuppression. Grade 3 sensory neuropathy occurred in 14% of patients, and 22.7% experienced grade 1 to 3 cardiac toxicity (grade 3, n = 2: one left ventricular dysfunction, one tachycardia). There were three [corrected] therapy-related deaths. Thirty-one (70%) of 44 patients responded (five complete and 26 partial), and 25 (57%) of 44 were confirmed responses. Median time to progression and survival were 9.3 and 14.1 months, respectively. CONCLUSION We prospectively characterized Her-2/neu status in advanced urothelial carcinoma patients. TPCG is feasible; cardiac toxicity rates were higher than projected, but the majority were grade two or lower. Determining the true contribution of trastuzumab requires a randomized trial.

PROTECTION FROM CYCLOPHOSPHAMIDE-INDUCED TESTICULAR DAMAGE WITH AN ANALOGUE OF GONADOTROPIN-RELEASING HORMONE

Abstract A mouse model for cyclophosphamideinduced testicular damage has been created which produces severe damage to both spermatogonia and maturing spermatocytes. Pretreatment and continued administration of [D-leu 6 ]-des-Gly-NH 2 10 pro-ethylamide GnRH, a synthetic analogue of gonadotropin-releasing hormone, produces striking protection from the histologically detectable cyclophosphamide-induced damage. These results suggest that temporary interruption of the pituitarygonadal axis may ameliorate the gonadal toxicity of systemic chemotherapy.

Metronomic therapy with cyclophosphamide and dexamethasone for prostate carcinoma

The current study was designed to evaluate the efficacy and toxicity of the continuous oral administration of a combination of cyclophosphamide (50 mg/day given in the morning) and dexamethasone (1 mg/day given in the evening) in patients with prostate specific antigen (PSA) progression despite single or multiagent hormone therapy and antiandrogen withdrawal.

Adjuvant Androgen Deprivation for High-Risk Prostate Cancer After Radical Prostatectomy: SWOG S9921 Study

PURPOSE Men with high-risk features (extraprostatic extension or high Gleason grade) face a high risk of prostate cancer recurrence after radical prostatectomy. Clinical trials of adjuvant systemic therapy for such patients have been limited. PATIENTS AND METHODS The SWOG (Southwest Oncology Group) S9921 study randomly assigned 983 men with high-risk features at prostatectomy to receive adjuvant therapy with androgen deprivation (ADT) alone or in combination with mitoxantrone chemotherapy. ADT consisted of goserelin and bicalutamide for 2 years. RESULTS Although the final primary treatment comparison results are not ready for publication, this article reports results in the ADT-alone control arm with a median follow-up of 4.4 years. For these 481 men, the estimated 5-year biochemical failure-free survival is 92.5% (95% CI, 90 to 95), and 5-year overall survival is 95.9% (95% CI, 93.9 to 97.9). CONCLUSION The results of this trial, taken in context, make a compelling argument for counseling all high-risk patients with prostate cancer about adjuvant ADT. This article discusses the challenges in the design and implementation of clinical trials to take the next step forward in adjuvant therapy for prostate cancer because of the excellent survival achieved with currently available therapies and highlights the need for better molecular markers to personalize care.

Clinical Study of Leuprolide Depot Formulation in the Treatment of Advanced Prostate Cancer

In a phase III, open, multicenter study we evaluated the safety and efficacy of the depot formulation of leuprolide (7.5 mg. injected intramuscularly every 4 weeks) in patients with stage D2 prostate cancer who had not previously received systemic treatment. Serum testosterone, luteinizing hormone and plasma leuprolide levels were monitored during the 24-week study period. Median interval to onset of castrate testosterone levels was 21 days and mean testosterone levels decreased to within the castrate range by week 3 of treatment. After onset of castrate levels there were no escapes (defined as 2 consecutive values of greater than 50 ng./dl.) of testosterone levels during the 24 weeks. Suppression of testosterone did not differ significantly from that observed in patients receiving the daily subcutaneous injection of leuprolide acetate in the first 24 weeks of another study. Objective response (no progression) to treatment occurred in 81% of 53 evaluable patients and adverse (related and unrelated) events were reported in 45 of the 56 patients. The response rate and incidence of adverse events in this study did not differ significantly from those occurring with the daily formulation. We conclude that the depot formulation of leuprolide is safe and effective in the treatment of advanced prostatic cancer, and that the safety and efficacy of this formulation do not differ significantly from those of the daily subcutaneous formulation.

Randomized trial of autologous cellular immunotherapy with sipuleucel-T in androgen-dependent prostate cancer

Purpose: Sipuleucel-T, an autologous cellular immunotherapy, was investigated in a randomized, double-blind, controlled trial to determine its biologic activity in androgen-dependent prostate cancer (ADPC). Experimental Design: Patients with prostate cancer detectable by serum prostate-specific antigen (PSA) following radical prostatectomy received 3 to 4 months of androgen suppression therapy, and were then randomized (2:1) to receive sipuleucel-T (n = 117) or control (n = 59). The primary endpoint was time to biochemical failure (BF) defined as serum PSA ≥ 3.0 ng/mL. PSA doubling time (PSADT), time to distant failure, immune response, and safety were also evaluated. Results: Median time to BF was 18.0 months for sipuleucel-T and 15.4 months for control (HR = 0.936, P = 0.737). Sipuleucel-T patients had a 48% increase in PSADT following testosterone recovery (155 vs. 105 days, P = 0.038). With only 16% of patients having developed distant failure, the treatment effect favored sipuleucel-T (HR = 0.728, P = 0.421). The most frequent adverse events in sipuleucel-T patients were fatigue, chills, and pyrexia. Immune responses to the immunizing antigen were greater in sipuleucel-T patients at Weeks 4 and 13 (P < 0.001, all) and were sustained prior to boosting as measured in a subset of patients a median of 22.6 months (range: 14.3–67.3 months) following randomization. Conclusions: No significant difference in time to BF could be shown. The finding of increased PSADT in the sipuleucel-T arm is consistent with its biologic activity in ADPC. Long-term follow-up will be necessary to determine if clinically important events, such as distant failure, are affected by therapy. Treatment was generally well tolerated. Clin Cancer Res; 17(13); 4558–67. ©2011 AACR.

Dietary Feeding of Silibinin Inhibits Prostate Tumor Growth and Progression in Transgenic Adenocarcinoma of the Mouse Prostate Model

Herein, for the first time, we evaluated the chemopreventive efficacy of dietary silibinin against prostate cancer (PCa) growth and progression in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice from two different genetic backgrounds [C57BL/6 (TRAMP) x FVB; C57BL/6 (TRAMP) x C57BL/6]. At 4 weeks of age, mice were fed control or 0.1% to 1% silibinin-supplemented diets until 23 to 24 weeks of age. Silibinin-fed groups had a lower tumor grade and higher incidence of prostatic intraepithelial neoplasia (PIN) at the expense of a strong decrease in adenocarcinoma incidence. Prostate tissue showed a 47% (P < 0.001) decrease in proliferating cell nuclear antigen (PCNA)-positive cells and an approximately 7-fold (P < 0.001) increase in apoptotic cells at the highest silibinin dose. As potential mechanisms of silibinin efficacy, an approximately 50% (P < 0.05) decrease in insulin-like growth factor (IGF) receptor type I beta and an approximately 13-fold (P < 0.001) increase in IGF-binding protein 3 (IGFBP-3) protein levels were also observed. These changes were specific to tumors as they were not reflected in circulating IGF-IGFBP-3 system. Additionally, silibinin decreased protein expression of cyclin-dependent kinases (Cdk) by more than 90% (P < 0.001) with a concomitant increase in Cdk inhibitors, Cip1/p21 and Kip1/p27 (P < 0.05, for both). A dose-dependent decrease was also observed in cyclin B1, cyclin E, and cyclin A protein levels by silibinin. Together, these findings suggest that oral silibinin blocks PCa growth and progression at PIN stage in TRAMP mice via modulation of tumor IGF-IGFBP-3 axis and cell cycle regulation, and therefore it has practical and translational potential in suppressing growth and neoplastic conversion of PIN to PCa in humans.

Clinical effects of gonadotropin-releasing hormone analogue in metastatic carcinoma of prostate

Leuprolide is a new, potent analogue of gonadotropin-releasing hormone which, after an initial transient stimulation, causes a profound suppression of serum gonadotropins and testosterone. One hundred eighteen patients with advanced carcinoma of the prostate have undergone treatment with leuprolide in a multi-institutional trial. Minimal evidence of objective response was seen in patients who had failed prior endocrine therapy with orchiectomy or estrogens. In patients without previous hormonal treatment, leuprolide induced an objective disease response (72%) comparable to alternative primary endocrine therapy. Considering the lack of significant side effects seen with long-term GnRH agonists, compounds such as leuprolide may prove to be the preferred initial endocrine therapy for selected patients with metastatic carcinoma of the prostate.

SILIBININ SENSITIZES HUMAN PROSTATE CARCINOMA DU145 CELLS TO CISPLATIN- AND CARBOPLATIN-INDUCED GROWTH INHIBITION AND APOPTOTIC DEATH

In several recent studies, we have shown that silibinin inhibits the growth of human prostate cancer cells (PCA) both in vitro and in vivo. Here, we investigated the effect of silibinin in combination with cisplatin and carboplatin on human PCA DU145 cell growth and apoptosis. Cisplatin alone at 2 μg/ml dose produced 48% cell growth inhibition, whereas a combination with 50–100 μM silibinin resulted in 63–80% (p<0.05–0.001) growth inhibition. Similarly, compared to 68% growth inhibition at 20 μg/ml carboplatin, addition of 50–100 μM doses of silibinin caused 80–90% inhibition (p<0.005–0.001). In the studies assessing the effect of these combinations on cell cycle progression, a combination of cisplatin or carboplatin with silibinin resulted in a stronger G2‐M arrest, compared to these agents alone showing a moderate G2‐M and G1 arrests in case of cisplatin and silibinin, and a complete S phase arrest with carboplatin, respectively. A stronger G2‐M arrest by these combinations was accompanied by a substantial decrease in the levels of cdc2, cyclin B1 and cdc25C. Silibinin/platinum compound combinations were also effective in inducing apoptosis where cisplatin and carboplatin when combined with silibinin enhanced apoptosis from 8 to 15% and from 20 to 40%, respectively. Apoptosis induction was further confirmed by PARP and caspases 3, 9 and 7 whose cleaved levels were also enhanced by combination treatment. In addition, there was a significant increase in cytochrome c release in the cytosol following treatment of DU145 cells with these combinations. Together, these results show a substantial increase in the efficacy of platinum compounds on human PCA cells, when combined with silibinin, which provide a rationale for further investigations with these combinations.