Daniel J. George

Activity of SU11248, a Multitargeted Inhibitor of Vascular Endothelial Growth Factor Receptor and Platelet-Derived Growth Factor Receptor, in Patients With Metastatic Renal Cell Carcinoma

PURPOSE Renal cell carcinoma (RCC) is characterized by loss of von Hippel Lindau tumor suppressor gene activity, resulting in high expression of pro-angiogenic growth factors: vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF). SU11248 (sunitinib malate), a small molecule inhibitor with high binding affinity for VEGF and PDGF receptors, was tested for clinical activity in patients with metastatic RCC. PATIENTS AND METHODS Patients with metastatic RCC and progression on first-line cytokine therapy were enrolled onto a multicenter phase II trial. SU11248 monotherapy was administered in repeated 6-week cycles of daily oral therapy for 4 weeks, followed by 2 weeks off. Overall response rate was the primary end point, and time to progression and safety were secondary end points. Results Twenty-five (40%) of 63 patients treated with SU11248 achieved partial responses; 17 additional patients (27%) demonstrated stable disease lasting > or = 3 months. Median time to progression in the 63 patients was 8.7 months. Dosing was generally tolerated with manageable toxicities. CONCLUSION SU11248, a multitargeted receptor tyrosine kinase inhibitor of VEGF and PDGF receptors, demonstrates antitumor activity in metastatic RCC as second-line therapy, a setting where no effective systemic therapy is presently recognized. The genetics of RCC and these promising clinical results support the hypothesis that VEGF and PDGF receptor-mediated signaling is an effective therapeutic target in RCC.

Abiraterone in Metastatic Prostate Cancer without Previous Chemotherapy

BACKGROUND Abiraterone acetate, an androgen biosynthesis inhibitor, improves overall survival in patients with metastatic castration-resistant prostate cancer after chemotherapy. We evaluated this agent in patients who had not received previous chemotherapy. METHODS In this double-blind study, we randomly assigned 1088 patients to receive abiraterone acetate (1000 mg) plus prednisone (5 mg twice daily) or placebo plus prednisone. The coprimary end points were radiographic progression-free survival and overall survival. RESULTS The study was unblinded after a planned interim analysis that was performed after 43% of the expected deaths had occurred. The median radiographic progression-free survival was 16.5 months with abiraterone-prednisone and 8.3 months with prednisone alone (hazard ratio for abiraterone-prednisone vs. prednisone alone, 0.53; 95% confidence interval [CI], 0.45 to 0.62; P<0.001). Over a median follow-up period of 22.2 months, overall survival was improved with abiraterone-prednisone (median not reached, vs. 27.2 months for prednisone alone; hazard ratio, 0.75; 95% CI, 0.61 to 0.93; P=0.01) but did not cross the efficacy boundary. Abiraterone-prednisone showed superiority over prednisone alone with respect to time to initiation of cytotoxic chemotherapy, opiate use for cancer-related pain, prostate-specific antigen progression, and decline in performance status. Grade 3 or 4 mineralocorticoid-related adverse events and abnormalities on liver-function testing were more common with abiraterone-prednisone. CONCLUSIONS Abiraterone improved radiographic progression-free survival, showed a trend toward improved overall survival, and significantly delayed clinical decline and initiation of chemotherapy in patients with metastatic castration-resistant prostate cancer. (Funded by Janssen Research and Development, formerly Cougar Biotechnology; ClinicalTrials.gov number, NCT00887198.).

Identification of endothelin–1 in the pathophysiology of metastatic adenocarcinoma of the prostate

Prostate cancer is the second most common cause of death from cancer in U.S. men, and advanced, hormone–refractory disease is characterized by painful osteoblastic bone metastases. Endothelin–1, more commonly known as a potent vasoconstrictor, is a normal ejaculate protein that also stimulates osteoblasts. We show here that plasma immunoreactive endothelin concentrations are significantly elevated in men with metastatic prostate cancer and that every human prostate cancer cell line tested produces endothelin–1 messenger RNA and secretes immunoreactive endothelin. Exogenous endothelin–1 is a prostate cancer mitogen in vitro and increases alkaline phosphatase activity in new bone formation, indicating that ectopic endothelin–1 may be a mediator of the osteoblastic response of bone to metastatic prostate cancer.

Circulating Tumor Cells from Patients with Advanced Prostate and Breast Cancer Display Both Epithelial and Mesenchymal Markers

During cancer progression, malignant cells undergo epithelial-mesenchymal transitions (EMT) and mesenchymal-epithelial transitions (MET) as part of a broad invasion and metastasis program. We previously observed MET events among lung metastases in a preclinical model of prostate adenocarcinoma that suggested a relationship between epithelial plasticity and metastatic spread. We thus sought to translate these findings into clinical evidence by examining the existence of EMT in circulating tumor cells (CTC) from patients with progressive metastatic solid tumors, with a focus on men with castration-resistant prostate cancer (CRPC) and women with metastatic breast cancer. We showed that the majority (>80%) of these CTCs in patients with metastatic CRPC coexpress epithelial proteins such as epithelial cell adhesion molecule (EpCAM), cytokeratins (CK), and E-cadherin, with mesenchymal proteins including vimentin, N-cadherin and O-cadherin, and the stem cell marker CD133. Equally, we found that more than 75% of CTCs from women with metastatic breast cancer coexpress CK, vimentin, and N-cadherin. The existence and high frequency of these CTCs coexpressing epithelial, mesenchymal, and stem cell markers in patients with progressive metastases has important implications for the application and interpretation of approved methods to detect CTCs. Mol Cancer Res; 9(8); 997–1007. ©2011 AACR.

Antitumor Activity and Biomarker Analysis of Sunitinib in Patients With Bevacizumab-Refractory Metastatic Renal Cell Carcinoma

PURPOSE To assess the safety and efficacy of sunitinib in patients with bevacizumab-refractory metastatic renal cell carcinoma (mRCC) and explore biomarkers for sunitinib response. PATIENTS AND METHODS Patients with mRCC and disease progression after bevacizumab-based therapy received oral sunitinib 50 mg once daily in 6-week cycles on a 4/2 schedule (4 weeks with treatment followed by 2 weeks without treatment) in a phase II multicenter study. The primary end point was objective response rate (ORR). Secondary end points included progression-free survival (PFS), duration of response (DR), overall survival (OS), and safety. Plasma soluble proteins (vascular endothelial growth factor [VEGF]-A, VEGF-C, soluble VEGF receptor [sVEGFR]-3, and placental growth factor [PlGF]) levels were measured. RESULTS Sixty-one patients were enrolled. The ORR was 23.0% (95% CI, 13.2% to 35.5%), median PFS was 30.4 weeks (95% CI, 18.3 to 36.7 weeks), median DR was 44.1 weeks (95% CI, 25.0 to 102.7 weeks), and median OS was 47.1 weeks (95% CI, 36.9 to 79.4 weeks). Mean plasma VEGF-A and PlGF levels significantly increased whereas VEGF-C and sVEGFR-3 levels decreased with sunitinib treatment. Lower baseline levels of sVEGFR-3 and VEGF-C were associated with longer PFS and ORR. Most treatment-related adverse events were of mild-to-moderate intensity and included fatigue, hypertension, and hand-foot syndrome. CONCLUSION Sunitinib has substantial antitumor activity in patients with bevacizumab-refractory mRCC and modulates circulating VEGF pathway biomarkers. These data support the hypothesis that sunitinib inhibits signaling pathways involved in bevacizumab resistance. Baseline levels of sVEGFR-3 and VEGF-C may have potential utility as biomarkers of clinical efficacy in this setting.

Randomized, Double-Blind, Placebo-Controlled Phase III Trial Comparing Docetaxel and Prednisone With or Without Bevacizumab in Men With Metastatic Castration-Resistant Prostate Cancer: CALGB 90401

PURPOSE A randomized, placebo-controlled study based on preclinical and clinical data that supports the potential role of vascular endothelial growth factor in prostate cancer was performed to evaluate the addition of bevacizumab to standard docetaxel and prednisone therapy in patients with metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS Patients with chemotherapy-naive progressive mCRPC with Eastern Cooperative Oncology Group performance status ≤ 2 and adequate bone marrow, hepatic, and renal function were randomly assigned to receive docetaxel 75 mg/m(2) intravenously (IV) over 1 hour for 21 days plus prednisone 5 mg orally twice per day (DP) with either bevacizumab 15 mg/kg IV every 3 weeks (DP + B) or placebo. The primary end point was overall survival (OS), and secondary end points were progression-free survival (PFS), 50% decline in prostate-specific antigen, objective response (OR), and toxicity. RESULTS In total, 1,050 patients were randomly assigned. The median OS for patients given DP + B was 22.6 months compared with 21.5 months for patients treated with DP (hazard ratio, 0.91; 95% CI, 0.78 to 1.05; stratified log-rank P = .181). The median PFS time was superior in the DP + B arm (9.9 v 7.5 months, stratified log-rank P < .001) as was the proportion of patients with OR (49.4% v 35.5%; P = .0013). Grade 3 or greater treatment-related toxicity was more common with DP + B (75.4% v 56.2%; P ≤ .001), as was the number of treatment-related deaths (4.0% v 1.2%; P = .005). CONCLUSION Despite an improvement in PFS and OR, the addition of bevacizumab to docetaxel and prednisone did not improve OS in men with mCRPC and was associated with greater toxicity.

Semuloparin for Thromboprophylaxis in Patients Receiving Chemotherapy for Cancer

BACKGROUND Patients receiving chemotherapy for cancer are at increased risk for venous thromboembolism. Limited data support the clinical benefit of antithrombotic prophylaxis. METHODS In this double-blind, multicenter trial, we evaluated the efficacy and safety of the ultra-low-molecular-weight heparin semuloparin for prevention of venous thromboembolism in patients receiving chemotherapy for cancer. Patients with metastatic or locally advanced solid tumors who were beginning to receive a course of chemotherapy were randomly assigned to receive subcutaneous semuloparin, 20 mg once daily, or placebo until there was a change of chemotherapy regimen. The primary efficacy outcome was the composite of any symptomatic deep-vein thrombosis, any nonfatal pulmonary embolism, and death related to venous thromboembolism. Clinically relevant bleeding (major and nonmajor) was the main safety outcome. RESULTS The median treatment duration was 3.5 months. Venous thromboembolism occurred in 20 of 1608 patients (1.2%) receiving semuloparin, as compared with 55 of 1604 (3.4%) receiving placebo (hazard ratio, 0.36; 95% confidence interval [CI], 0.21 to 0.60; P<0.001), with consistent efficacy among subgroups defined according to the origin and stage of cancer and the baseline risk of venous thromboembolism. The incidence of clinically relevant bleeding was 2.8% and 2.0% in the semuloparin and placebo groups, respectively (hazard ratio, 1.40; 95% CI, 0.89 to 2.21). Major bleeding occurred in 19 of 1589 patients (1.2%) receiving semuloparin and 18 of 1583 (1.1%) receiving placebo (hazard ratio, 1.05; 95% CI, 0.55 to 1.99). Incidences of all other adverse events were similar in the two study groups. CONCLUSIONS Semuloparin reduces the incidence of thromboembolic events in patients receiving chemotherapy for cancer, with no apparent increase in major bleeding. (Funded by Sanofi; ClinicalTrials.gov number, NCT00694382.).

Histone Deacetylase Inhibitor Panobinostat Induces Clinical Responses with Associated Alterations in Gene Expression Profiles in Cutaneous T-Cell Lymphoma

Purpose: Histone deacetylase inhibitors can alter gene expression and mediate diverse antitumor activities. Herein, we report the safety and activity of the histone deacetylase inhibitor panobinostat (LBH589) in cutaneous T-cell lymphoma (CTCL) and identify genes commonly regulated by panobinostat. Experimental Design: Panobinostat was administered orally to patients with CTCL on Monday, Wednesday, and Friday of each week on a 28-day cycle. A dose of 30 mg was considered excessively toxic, and subsequent patients were treated at the expanded maximum tolerated dose of 20 mg. Biopsies from six patients taken 0, 4, 8, and 24 h after administration were subjected to microarray gene expression profiling and real-time quantitative PCR of selected genes. Results: Patients attained a complete response (n = 2), attained a partial response (n = 4), achieved stable disease with ongoing improvement (n = 1), and progressed on treatment (n = 2). Microarray data showed distinct gene expression response profiles over time following panobinostat treatment, with the majority of genes being repressed. Twenty-three genes were commonly regulated by panobinostat in all patients tested. Conclusions: Panobinostat is well tolerated and induces clinical responses in CTCL patients. Microarray analyses of tumor samples indicate that panobinostat induces rapid changes in gene expression, and surprisingly more genes are repressed than are activated. A unique set of genes that can mediate biological responses such as apoptosis, immune regulation, and angiogenesis were commonly regulated in response to panobinostat. These genes are potential molecular biomarkers for panobinostat activity and are strong candidates for the future assessment of their functional role(s) in mediating the antitumor responses of panobinostat.

Prostate intraepithelial neoplasia induced by prostate restricted Akt activation: The MPAKT model

To determine whether Akt activation was sufficient for the transformation of normal prostate epithelial cells, murine prostate restricted Akt kinase activity was generated in transgenic mice (MPAKT mice). Akt expression led to p70S6K activation, prostatic intraepithelial neoplasia (PIN), and bladder obstruction. mRNA expression profiles from MPAKT ventral prostate revealed similarities to human cancer and an angiogenic signature that included three angiogenin family members, one of which was found elevated in the plasma of men with prostate cancer. Thus, the MPAKT model may be useful in studying the role of Akt in prostate epithelial cell transformation and in the discovery of molecular markers relevant to human disease.

Vaccination of Cancer Patients Against Telomerase Induces Functional Antitumor CD8+ T Lymphocytes

Purpose: High-level expression of the telomerase reverse transcriptase (hTERT) in >85% of human cancers, in contrast with its restricted expression in normal adult tissues, points to hTERT as a broadly applicable molecular target for anticancer immunotherapy. CTLs recognize peptides derived from hTERT and kill hTERT+ tumor cells of multiple histologies in vitro. Moreover, because survival of hTERT+ tumor cells requires functionally active telomerase, hTERT mutation or loss as a means of escape may be incompatible with sustained tumor growth. Experimental Design: A Phase I clinical trial was performed to evaluate the clinical and immunological impact of vaccinating advanced cancer patients with the HLA-A2-restricted hTERT I540 peptide presented with keyhole limpet hemocyanin by ex vivo generated autologous dendritic cells. Results: As measured by peptide/MHC tetramer, enzyme-linked immunospot, and cytotoxicity assays, hTERT-specific T lymphocytes were induced in 4 of 7 patients with advanced breast or prostate carcinoma after vaccination with dendritic cells pulsed with hTERT peptide. Tetramer-guided high-speed sorting and polyclonal expansion achieved highly enriched populations of hTERT-specific cells that killed tumor cells in an MHC- restricted fashion. Despite concerns of telomerase activity in rare normal cells, no significant toxicity was observed. Partial tumor regression in 1 patient was associated with the induction of CD8+ tumor infiltrating lymphocytes. Conclusions: These results demonstrate the immunological feasibility of vaccinating patients against telomerase and provide rationale for targeting self-antigens with critical roles in oncogenesis.