Robert B. Sims

Sipuleucel-T Immunotherapy for Castration-Resistant Prostate Cancer

BACKGROUND Sipuleucel-T, an autologous active cellular immunotherapy, has shown evidence of efficacy in reducing the risk of death among men with metastatic castration-resistant prostate cancer. METHODS In this double-blind, placebo-controlled, multicenter phase 3 trial, we randomly assigned 512 patients in a 2:1 ratio to receive either sipuleucel-T (341 patients) or placebo (171 patients) administered intravenously every 2 weeks, for a total of three infusions. The primary end point was overall survival, analyzed by means of a stratified Cox regression model adjusted for baseline levels of serum prostate-specific antigen (PSA) and lactate dehydrogenase. RESULTS In the sipuleucel-T group, there was a relative reduction of 22% in the risk of death as compared with the placebo group (hazard ratio, 0.78; 95% confidence interval [CI], 0.61 to 0.98; P=0.03). This reduction represented a 4.1-month improvement in median survival (25.8 months in the sipuleucel-T group vs. 21.7 months in the placebo group). The 36-month survival probability was 31.7% in the sipuleucel-T group versus 23.0% in the placebo group. The treatment effect was also observed with the use of an unadjusted Cox model and a log-rank test (hazard ratio, 0.77; 95% CI, 0.61 to 0.97; P=0.02) and after adjustment for use of docetaxel after the study therapy (hazard ratio, 0.78; 95% CI, 0.62 to 0.98; P=0.03). The time to objective disease progression was similar in the two study groups. Immune responses to the immunizing antigen were observed in patients who received sipuleucel-T. Adverse events that were more frequently reported in the sipuleucel-T group than in the placebo group included chills, fever, and headache. CONCLUSIONS The use of sipuleucel-T prolonged overall survival among men with metastatic castration-resistant prostate cancer. No effect on the time to disease progression was observed. (Funded by Dendreon; ClinicalTrials.gov number, NCT00065442.)

Activated Lymphocyte Recruitment Into the Tumor Microenvironment Following Preoperative Sipuleucel-T for Localized Prostate Cancer

Background Sipuleucel-T is a US Food and Drug Administration–approved immunotherapy for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). Its mechanism of action is not fully understood. This prospective trial evaluated the direct immune effects of systemically administered sipuleucel-T on prostatic cancer tissue in the preoperative setting. Methods Patients with untreated localized prostate cancer were treated on an open-label Phase II study of sipuleucel-T prior to planned radical prostatectomy (RP). Immune infiltrates in RP specimens (posttreatment) and in paired pretreatment biopsies were evaluated by immunohistochemistry (IHC). Correlations between circulating immune response and IHC were assessed using Spearman rank order. Results Of the 42 enrolled patients, 37 were evaluable. Adverse events were primarily transient, mild-to-moderate and infusion related. Patients developed T cell proliferation and interferon-γ responses detectable in the blood following treatment. Furthermore, a greater-than-three-fold increase in infiltrating CD3+, CD4+ FOXP3-, and CD8+ T cells was observed in the RP tissues compared with the pretreatment biopsy (binomial proportions: all P < .001). This level of T cell infiltration was observed at the tumor interface, and was not seen in a control group consisting of 12 concurrent patients who did not receive any neoadjuvant treatment prior to RP. The majority of infiltrating T cells were PD-1+ and Ki-67+, consistent with activated T cells. Importantly, the magnitude of the circulating immune response did not directly correlate with T cell infiltration within the prostate based upon Spearman’s rank order correlation. Conclusions This study is the first to demonstrate a local immune effect from the administration of sipuleucel-T. Neoadjuvant sipuleucel-T elicits both a systemic antigen-specific T cell response and the recruitment of activated effector T cells into the prostate tumor microenvironment.

Treatment With Autologous Antigen-Presenting Cells Activated With the HER-2 –Based Antigen Lapuleucel-T: Results of a Phase I Study in Immunologic and Clinical Activity in HER-2–Overexpressing Breast Cancer

PURPOSE Lapuleucel-T (APC8024), an autologous active cellular immunotherapy, was prepared from peripheral-blood mononuclear cells, including antigen-presenting cells, that were activated in vitro with recombinant fusion protein BA7072. This antigen construct consisted of sequences from intracellular and extracellular domains of human epidermal growth factor receptor 2 (HER-2) linked to granulocyte-macrophage colony-stimulating factor. We conducted a phase I study to evaluate the safety and immunologic activity of lapuleucel-T in patients with HER-2-overexpressing metastatic breast cancer. PATIENTS AND METHODS Metastatic breast cancer patients whose tumors overexpressed or amplified HER-2 were eligible. Patients underwent leukapheresis and subsequent lapuleucel-T infusion 2 days later at weeks 0, 2, and 4. Patients who achieved a partial response (PR) or had stable disease (SD) lasting through week 48 were eligible for re-treatment using the same protocol and dose as their initial treatment. End points included safety, immunologic activity, and antitumor activity. RESULTS Nineteen patients were enrolled; 18 patients received treatment. Therapy was well tolerated, with no grade 3 or 4 adverse events associated with the treatment. Significant cellular immune responses specific for the immunizing antigen and HER-2 sequences were induced after treatment, as measured by lymphocyte proliferation and interferon gamma enzyme-linked immunospot assay. One patient experienced a PR lasting 6 months. Three additional patients had SD lasting more than 1 year. CONCLUSION Autologous active cellular immunotherapy with lapuleucel-T was feasible, safe, and well tolerated. The treatment stimulated significant immune responses, which were enhanced after boost infusions. Lapuleucel-T therapy was associated with tumor response or extended disease stabilization in some patients and warrants further investigation.

A Phase I Trial of Immunotherapy with Lapuleucel-T (APC8024) in Patients with Refractory Metastatic Tumors that Express HER-2/neu

Purpose: This study aimed to evaluate the safety of, immune response induced by, and efficacy of treatment with lapuleucel-T (APC8024) in patients with HER-2/neu–expressing tumors. Lapuleucel-T is an investigational active immunotherapy product consisting of autologous peripheral blood mononuclear cells, including antigen presenting cells, which are cultured ex vivo with BA7072, a recombinant fusion antigen consisting of portions of the intracellular and extracellular regions of HER-2/neu linked to granulocyte-macrophage colony-stimulating factor. Experimental Design: Patients with metastatic breast, ovarian, or colorectal cancer whose tumors expressed HER-2 were eligible. Patients underwent leukapheresis in week 0 and received lapuleucel-T infusions in weeks 0, 2, and 4. Patients who achieved a partial response or had stable disease through week 48 were eligible for re-treatment using the same protocol and dose as their initial treatment. Results: Eighteen patients were enrolled and treated. Patients showed an immune response to the immunizing antigen (BA7072) at week 8 compared with week 0 as measured by T lymphocyte proliferation and IFN-γ enzyme-linked immunospot assay. Therapy was well tolerated. The majority (94.7%) of adverse events associated with treatment were grade 1 or 2. Two patients experienced stable disease lasting >48 weeks. Conclusions: Autologous active cellular immunotherapy with lapuleucel-T stimulated an immune response specific to the immunizing antigen and seemed to be well tolerated. Further clinical studies to assess the clinical benefit for patients with HER/2-neu–expressing breast, ovarian, and colorectal cancer are warranted. (Clin Cancer Res 2009;15(18):5937–44)

Development of sipuleucel-T: Autologous cellular immunotherapy for the treatment of metastatic castrate resistant prostate cancer

Sipuleucel-T, the first autologous cellular immunotherapy approved by the United States Food and Drug Administration, is designed to stimulate an immune response to prostate cancer. Sipuleucel-T is manufactured by culturing a patients peripheral blood mononuclear cells, including autologous antigen presenting cells (APCs), with a recombinant protein comprising a tumor-associated antigen (prostatic acid phosphatase [PAP]) and granulocyte colony-macrophage stimulating factor (GM-CSF). A full course of treatment comprises 3 infusions of sipuleucel-T, given at approximately 2-week intervals. The pattern of APC activation is consistent with priming by the first infusion, and boosting by the second and third infusions. Preclinical and clinical studies have demonstrated evidence of a robust antigen-specific immune response that includes a progressive and persistent increase in antigen-specific cellular and humoral immune responses. Treatment with sipuleucel-T has demonstrated a survival benefit in Phase 3 studies of subjects with metastatic castrate resistant (hormone refractory) prostate cancer (mCRPC). Adverse events with sipuleucel-T were generally mild to moderate and resolved within 2 days. Serious adverse events, autoimmune events, and cerebrovascular events occurred at a similar rate to control subjects. As the first autologous cellular immunotherapy to demonstrate an improvement in overall survival in asymptomatic or minimally symptomatic mCRPC patients, sipuleucel-T represents a new treatment paradigm in oncology.

Integrated Safety Data From 4 Randomized, Double-Blind, Controlled Trials of Autologous Cellular Immunotherapy With Sipuleucel-T in Patients With Prostate Cancer

PURPOSE We describe the safety of sipuleucel-T using an integrated analysis of 4 randomized, controlled studies in patients with prostate cancer. MATERIALS AND METHODS Adverse events, survival data and laboratory evaluations were examined for common, rare and latent events. RESULTS In 5% or more of sipuleucel-T cases some adverse events were reported at a rate at least twice that in controls, including chills in 53.1%, pyrexia in 31.3%, headache in 18.1%, myalgia in 11.8%, influenza-like illness in 9.7% and hyperhidrosis in 5.0%. These events generally occurred within 1 day of infusion, were grade 1 or 2 in severity and resolved in 2 days or less. The incidence of serious adverse events reported was 24.0% in sipuleucel-T cases and 25.1% in controls. Grade 3 or greater adverse events were reported within 1 day of infusion in 40 of 601 sipuleucel-T cases (6.7%) and 7 of 303 controls (2.3%). The incidence rate of reported cerebrovascular events was 3.5% for sipuleucel-T cases and 2.6% in controls. CONCLUSIONS Sipuleucel-T therapy in patients with prostate cancer has a side effect profile that is characterized by mild to moderate, short-term, reversible adverse events. There was no evidence of a treatment related increase in autoimmune complications or secondary malignancies after treatment with sipuleucel-T. Sipuleucel-T can be administered safely in the outpatient setting.

A Transient Increase in Eosinophils Is Associated with Prolonged Survival in Men with Metastatic Castration- Resistant Prostate Cancer Who Receive Sipuleucel-T

McNeel and colleagues demonstrate that a transient increase in eosinophil counts following sipuleucel-T treatment was associated with therapy-induced immune responses and longer prostate cancer survival, suggesting this could be prospectively evaluated as a biomarker in clinical trials. Sipuleucel-T is an autologous cellular immunotherapy used to treat asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). Traditional short-term indicators of clinical response commonly used with chemotherapy have not correlated with survival in patients treated with sipuleucel-T. This retrospective study aimed to evaluate laboratory parameters as possible early biomarkers associated with clinical benefit following sipuleucel-T treatment. Patients treated with sipuleucel-T from three randomized, controlled, phase III clinical trials in mCRPC were considered: IMPACT (NCT00065442; n = 512), D9901 (NCT00005947; n = 127), and D9902A (NCT01133704; n = 98). Patients from these trials were included in this study if their samples were analyzed by the central laboratory and if data were available from baseline and ≥1 posttreatment time point (n = 377). We found that sipuleucel-T treatment was associated with a transient increase in serum eosinophil count at week 6 that resolved by week 14 in 28% of patients (105 of 377). This eosinophil increase correlated with induced immune response, longer prostate cancer–specific survival [HR, 0.713; 95% confidence interval (CI), 0.525–0.970; P = 0.031], and a trend in overall survival (HR, 0.753; 95% CI, 0.563–1.008; P = 0.057). Median serum globulin protein levels also increased transiently, which was associated with antigen-specific antibody responses; however, this finding did not correlate with longer survival. We conclude that transient increases in eosinophils at week 6 may be a useful, objective, short-term indicator of global immune activation and survival benefit with sipuleucel-T in patients with mCRPC. This observation warrants prospective evaluation in future clinical trials. Cancer Immunol Res; 2(10); 988–99. ©2014 AACR.

Combining Immunotherapy and Radiation for Prostate Cancer

Radiotherapy has conventionally been viewed as immunosuppressive, which has precluded its use in combination with immunotherapy for prostate and other cancers. However, the relationship between ionizing radiation and immune reactivity is now known to be more complex than was previously thought, and data on the use of radiotherapy and immunotherapy are accumulating. Herein, we review this topic in the light of recently available data in the prostate cancer setting. Recent research has shown no significant lymphopenia in patients undergoing radiotherapy for high-risk adenocarcinoma of the prostate. In addition, emerging evidence suggests that radiotherapy can have immunostimulatory effects, and that tumor cell death, coupled with related changes in antigen availability and inflammatory signals, can affect lymphocyte and dendritic cell activation. Initial studies have focused on combinations of tumor irradiation and immunotherapy, such as the autologous cellular immunotherapy sipuleucel-T and the monoclonal antibody ipilimumab, in metastatic castration-resistant prostate cancer. These combinations appear to have clinical promise, and further investigation of the potentially synergistic combination of radiotherapy and immunotherapy is continuing in clinical trials.

An analysis of leukapheresis and central venous catheter use in the randomized, placebo controlled, phase 3 IMPACT trial of Sipuleucel-T for metastatic castrate resistant prostate cancer.

PURPOSE Sipuleucel-T is an autologous cellular immunotherapy. We review the safety of the leukapheresis procedure required for sipuleucel-T preparation and complications related to venous catheter use in the randomized, placebo controlled phase 3 IMPACT (IMmunotherapy for ProstAte Cancer Trial) study (NCT 00065442). MATERIALS AND METHODS A total of 512 patients with asymptomatic or minimally symptomatic metastatic castrate resistant prostate cancer were enrolled in the study. All patients were scheduled to undergo 3 standard 1.5 to 2.0 blood volume leukapheresis procedures at 2-week intervals. Leukapheresis related adverse events and those related to venous catheter use were reviewed. Immune cell counts were examined throughout the treatment course. RESULTS Of 512 enrolled patients 506 underwent 1 or more leukapheresis procedures and were included in this analysis. Adverse events were comparable between the sipuleucel-T and control arms. Leukapheresis related adverse events were primarily associated with transient hypocalcemia (39.3%). Most leukapheresis related adverse events (97%) were of mild/moderate intensity. Median white blood cell count and absolute monocyte and lymphocyte counts were stable and within normal ranges throughout the treatment course. Of all patients 23.3% had a central venous catheter placed primarily for leukapheresis. Patients with vs without a central venous catheter had a higher risk of infection potentially related to catheter use (11.9% vs 1.3%, p <0.0001) and a trend toward a higher incidence of venous vascular events potentially related to catheter use, excluding the central nervous system (5.9% vs 2.1%, p = 0.06). CONCLUSIONS Adverse events related to leukapheresis are manageable and quickly reversible. The majority of patients can undergo leukapheresis without a central venous catheter. Central venous catheters are associated with an increased risk of infections and venous vascular events. Peripheral intravenous access should be used when feasible.

376 Preliminary results from a Phase 1 study of D-3263 HCl, a TRPM8 calcium channel agonist, in patients with advanced cancer

D-3263 HCl is a calcium channel agonist that induces calcium influx and subsequent apoptosis in cells that express TRPM8. TRPM8 was originally discovered as a gene expressed in the prostate and upregulated in prostate cancer, and was subsequently identified as the cold-menthol receptor (Tsavaler 2001). D3263-HCl, an orally administered small molecule agonist, showed evidence of activity in preclinical tumor models. BACKGROUND