Humoral Immune Response against Nontargeted Tumor Antigens after Treatment with Sipuleucel-T and Its Association with Improved Clinical Outcome.

PURPOSE: Antitumor activity of cancer immunotherapies may elicit immune responses to nontargeted (secondary) tumor antigens, or antigen spread. We evaluated humoral antigen spread after treatment with sipuleucel-T, an immunotherapy for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC), designed to target prostatic acid phosphatase (PAP; primary antigen). EXPERIMENTAL DESIGN: Serum samples from patients with mCRPC enrolled in the placebo-controlled phase III IMPACT study (evaluable n = 142) were used to assess humoral antigen spread after treatment with sipuleucel-T. Immunoglobulin G (IgG) responses to self-antigens (including tumor antigens) were surveyed using protein microarrays and confirmed using Luminex xMAP. IgG responses were subsequently validated in ProACT (n = 33), an independent phase II study of sipuleucel-T. Association of IgG responses with overall survival (OS) was assessed using multivariate Cox models adjusted for baseline prostate-specific antigen (PSA) and lactate dehydrogenase levels. RESULTS: In patients from IMPACT and ProACT, levels of IgG against multiple secondary antigens, including PSA, KLK2/hK2, K-Ras, E-Ras, LGALS8/PCTA-1/galectin-8, and LGALS3/galectin-3, were elevated after treatment with sipuleucel-T (P < 0.01), but not control. IgG responses (≥ 2-fold elevation posttreatment) occurred in ≥ 25% of patients, appeared by 2 weeks after sipuleucel-T treatment, and persisted for up to 6 months. IgG responses to PSA and LGALS3 were associated with improved OS in sipuleucel-T-treated patients from IMPACT (P ≤ 0.05). CONCLUSIONS: Sipuleucel-T induced humoral antigen spread in patients with mCRPC. IgG responses were associated with improved OS in IMPACT. The methods and results reported may identify pharmacodynamic biomarkers of clinical outcome after sipuleucel-T treatment, and help in clinical assessments of other cancer immunotherapies. See related commentary by Hellstrom and Hellstrom, p. 3581.

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.

Quality of life after sipuleucel-T therapy: results from a randomized, double-blind study in patients with androgen-dependent prostate cancer.

OBJECTIVE: To collect and analyze quality-of-life (QOL) data from PROvenge Treatment and Early Cancer Treatment trial (PROTECT, NCT00779402), a phase III, randomized controlled trial of sipuleucel-T in patients with asymptomatic androgen-dependent prostate cancer. METHODS: Patients experiencing prostate-specific antigen relapse after radical prostatectomy entered a 3- to 4-month run-in phase of androgen-deprivation therapy (ADT), followed by 2:1 randomization to sipuleucel-T or control. QOL was assessed throughout the run-in and 26-week post-randomization phases using the Brief Fatigue Inventory (BFI), Linear Analog Self-Assessment (LASA) scale, Global Rating of Change (GRoC) scale, and an elicited symptoms list. RESULTS: One hundred seventy-six patients were randomized into 2 groups, the sipuleucel-T group (n = 117) or the control group (n = 59). The sample provided 80% power to detect a difference in fatigue interference score between treatment arms of 0.9 points. QOL declined predictably during ADT. At week 26, 26.2% of sipuleucel-T-treated patients and 21.6% of control-treated patients (P = .68) reported fatigue in the previous week, and the mean score for fatigue interference in the past 24 hours was 0.9 for both arms (P = .88). Results were comparable for usual fatigue (P = .91) and worst fatigue (P >.99). Mean LASA scores decreased in both groups (P = .26). The proportion of patients reporting better overall QOL on GRoC was similar (P = .62). CONCLUSION: There is no clinically significant negative impact on QOL after sipuleucel-T treatment compared with control after a period of ADT in patients with asymptomatic androgen-dependent prostate cancer.

Lower baseline prostate-specific antigen is associated with a greater overall survival benefit from sipuleucel-T in the Immunotherapy for Prostate Adenocarcinoma Treatment (IMPACT) trial.

OBJECTIVE: To explore the prognostic and predictive value of baseline variables in 512 patients with metastatic castration-resistant prostate cancer from the phase III Immunotherapy for Prostate Adenocarcinoma Treatment (IMPACT) trial who were randomized to receive sipuleucel-T or control. METHODS: The most powerful of these prognostic factors, baseline prostate-specific antigen (PSA), was subdivided into quartiles to evaluate treatment effect patterns. Cox regression analyses were used to assess predictors of overall survival (OS) and sipuleucel-T treatment effect within PSA quartiles. Median OS was estimated by the Kaplan-Meier method. RESULTS: PSA was the strongest baseline prognostic factor (P <.0001). Furthermore, the sipuleucel-T treatment effect appeared greater with decreasing baseline PSA. The OS hazard ratio for patients in the lowest baseline PSA quartile (≤22.1 ng/mL) was 0.51 (95% confidence interval, 0.31-0.85) compared with 0.84 (95% confidence interval, 0.55-1.29) for patients in the highest PSA quartile (>134 ng/mL). Estimated improvement in median survival varied from 13.0 months in the lowest baseline PSA quartile to 2.8 months in the highest quartile. Estimated 3-year survival in the lowest PSA quartile was 62.6% for sipuleucel-T patients and 41.6% for control patients, representing a 50% relative increase. CONCLUSION: The greatest magnitude of benefit with sipuleucel-T treatment in this exploratory analysis was observed among patients with better baseline prognostic factors, particularly those with lower baseline PSA values. These findings suggest that patients with less advanced disease may benefit the most from sipuleucel-T treatment and provide a rationale for immunotherapy as an early treatment strategy in sequencing algorithms for metastatic castration-resistant prostate cancer.

Sipuleucel-T immune parameters correlate with survival: an analysis of the randomized phase 3 clinical trials in men with castration-resistant prostate cancer.

PURPOSE: Sipuleucel-T, the first FDA-approved autologous cellular immunotherapy for treatment of advanced prostate cancer, is manufactured by activating peripheral blood mononuclear cells, including antigen presenting cells (APCs), with a fusion protein containing prostatic acid phosphatase. Analysis of data from three phase 3 trials was performed to immunologically characterize this therapy during the course of the three doses, and to relate the immunological responses to overall survival (OS). METHODS: Sipuleucel-T product characteristics [APC numbers, APC activation (CD54 upregulation), and total nucleated cell (TNC) numbers] were assessed in three randomized, controlled phase 3 studies (N = 737). Antigen-specific cellular and humoral responses were assessed in a subset of subjects. The relationships between these parameters and OS were assessed. RESULTS: APC activation occurred in the first dose preparation [6.2-fold, (4.65, 7.70); median (25th, 75th percentile)] and increased in the second [10.6-fold (7.83, 13.65)] and third [10.5-fold (7.89, 13.65)] dose preparations. Cytokines and chemokines associated with activated APCs were produced during the manufacture of each dose; T-cell activation-associated cytokines were detected in the second and third dose preparations. Antigen-specific T cells were detectable after administration of the first sipuleucel-T dose. Cumulative APC activation, APC number, and TNC number correlated with OS (P < 0.05). Antigen-specific immune responses were observed in 78.8 % of monitored subjects and their presence correlated with OS (P = 0.003). CONCLUSION: Sipuleucel-T broadly engages the immune system by activating APCs ex vivo and inducing long-lived immune responses in vivo. These data indicate antigen-specific immune activation as a mechanism by which sipuleucel-T prolongs OS.

Sipuleucel-T for the treatment of advanced prostate cancer.

Sipuleucel-T is an autologous cellular immunotherapy designed to stimulate an immune response to prostate cancer that prolongs the overall survival of men with asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer (CRPC). The clinical development program and key efficacy, safety, and immune response findings from the phase III studies are presented. The integration of sipuleucel-T into the treatment paradigm of advanced prostate cancer and future directions for research are discussed.

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.

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.

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.)

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-gamma 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.

Integrated data from 2 randomized, double-blind, placebo-controlled, phase 3 trials of active cellular immunotherapy with sipuleucel-T in advanced prostate cancer.

BACKGROUND: Sipuleucel-T is an investigational active cellular immunotherapy product designed to stimulate an immune response against prostate cancer. The safety and efficacy of sipuleucel-T was evaluated in 2 identically designed, randomized, double-blind, placebo-controlled trials (D9901 and D9902A) conducted in men with advanced prostate cancer. METHODS: A total of 225 patients were randomized in D9901 or D9902A to sipuleucel-T (n = 147) or placebo (n = 78), given as 3 intravenous infusions approximately 2 weeks apart. Patients were followed for survival until death or a prespecified cutoff of 36 months after randomization. RESULTS: In the integrated analysis of D9901 and D9902A, patients randomized to sipuleucel-T demonstrated a 33% reduction in the risk of death (hazard ratio, 1.50; 95% confidence interval, 1.10-2.05; P = .011; log-rank). The treatment effect remained strong after performing adjustments for imbalances in baseline prognostic factors, poststudy treatment chemotherapy use, and non-prostate cancer-related deaths. Additional support for the activity of sipuleucel-T is provided by the correlation between a measure of the product's potency, CD54 up-regulation, and overall survival. The most common adverse events associated with treatment were chills, pyrexia, headache, asthenia, dyspnea, vomiting, and tremor. These events were primarily grade 1 and 2, with durations of 1 to 2 days. CONCLUSIONS: The integrated results of D9901 and D9902A demonstrate a survival benefit for patients treated with sipuleucel-T compared with those treated with placebo. The generally modest toxicity profile, coupled with the survival benefit, suggests a favorable risk-benefit ratio for sipuleucel-T in patients with advanced prostate cancer.

A phase I trial of CD3/CD28-activated T cells (Xcellerated T cells) and interleukin-2 in patients with metastatic renal cell carcinoma.

PURPOSE: Xcellerated T Cells (Xcyte Therapies, Seattle, WA) are autologous T cells that have been activated and expanded ex vivo using antibodies to CD3 and CD28 coimmobilized on magnetic beads. This study assessed the safety, immunostimulatory effects, and antitumor activity of Xcellerated T Cells and interleukin-2 (IL-2) in patients with metastatic renal cell carcinoma (RCC). EXPERIMENTAL DESIGN: Twenty-six patients with measurable metastatic RCC after prior nephrectomy underwent leukapheresis. Peripheral blood lymphocytes were stimulated ex vivo for 8 days. Two cycles of therapy separated by 28 days were planned, with each cycle consisting of i.v. Xcellerated T Cells on day 1 and s.c. IL-2 at 10 x 10(6) units on days 1-10. RESULTS: Forty-nine cycles of therapy were administered to 25 patients. A mean (+/-SD) of 21.8 x 10(9) (+/-5.4 x 10(9)) Xcellerated T Cells were administered each cycle. The infused cells were 94% +/- 3% CD3(+), 64 +/- 12% CD4(+), and 25 +/- 12% CD8(+) (mean +/- SD). Adverse events (most commonly, fever and an influenza-like syndrome) were mild to moderate. Two patients developed significantly elevated human antimouse antibody titers (HAMA). No complete or partial clinical responses were observed. However, two patients experienced significant tumor regression in bone metastases. Median survival was 21 months. The number of cells infused correlated with the peak absolute lymphocyte count achieved, and there was a trend to increased postinfusion survival in patients achieving higher peak absolute lymphocyte counts. CONCLUSIONS: Adoptive immunotherapy with Xcellerated T Cells and IL-2 can be carried out safely on an outpatient basis in patients with advanced RCC. Further investigation of this therapy is warranted.