A practical guide to the appropriate analysis of eGFR data over time: A simulation study.

In several therapeutic areas, including chronic kidney disease (CKD) and immunoglobulin A nephropathy (IgAN), there is a growing interest in how best to analyze estimated glomerular filtration rate (eGFR) data over time in randomized clinical trials including how to best accommodate situations where the rate of change is not anticipated to be linear over time, often due to possible short term hemodynamic effects of certain classes of interventions. In such situations, concerns have been expressed by regulatory authorities that the common application of single slope analysis models may induce Type I error inflation. This article aims to offer practical advice and guidance, including SAS codes, on the statistical methodology to be employed in an eGFR rate of change analysis and offers guidance on trial design considerations for eGFR endpoints. A two-slope statistical model for eGFR data over time is proposed allowing for an analysis to simultaneously evaluate short term acute effects and long term chronic effects. A simulation study was conducted under a range of credible null and alternative hypotheses to evaluate the performance of the two-slope model in comparison to commonly used single slope random coefficients models as well as to non-slope based analyses of change from baseline or time normalized area under the curve (TAUC). Importantly, and contrary to preexisting concerns, these simulations demonstrate the absence of alpha inflation associated with the use of single or two-slope random coefficient models, even when such models are misspecified, and highlight that any concern regarding model misspecification relates to power and not to lack of Type I error control.

Conditional power and information fraction calculations at an interim analysis for random coefficient models.

Random coefficient (RC) models are commonly used in clinical trials to estimate the rate of change over time in longitudinal data. Trials utilizing a surrogate endpoint for accelerated approval with a confirmatory longitudinal endpoint to show clinical benefit is a strategy implemented across various therapeutic areas, including immunoglobulin A nephropathy. Understanding conditional power (CP) and information fraction calculations of RC models may help in the design of clinical trials as well as provide support for the confirmatory endpoint at the time of accelerated approval. This paper provides calculation methods, with practical examples, for determining CP at an interim analysis for a RC model with longitudinal data, such as estimated glomerular filtration rate (eGFR) assessments to measure rate of change in eGFR slope.

Sequencing of Sipuleucel-T and Androgen Deprivation Therapy in Men with Hormone-Sensitive Biochemically Recurrent Prostate Cancer: A Phase II Randomized Trial.

Purpose: STAND, a randomized, phase II, open-label trial (NCT01431391), assessed sequencing of sipuleucel-T (an autologous cellular immunotherapy) with androgen deprivation therapy (ADT) in biochemically recurrent prostate cancer (BRPC) patients at high risk for metastasis.Experimental Design: Men with BRPC following prostatectomy and/or radiotherapy, a PSA doubling time ≤12 months, and no metastasis were enrolled. Patients were randomized (34/arm) to sipuleucel-T followed by ADT (started 2 weeks after sipuleucel-T completion), or ADT followed by sipuleucel-T (started 12 weeks after ADT initiation); ADT continued for 12 months in both arms. The primary endpoint was PA2024-specific T-cell response [enzyme-linked immunospot (ELISPOT)] over time.Results: PA2024-specific ELISPOT responses over time were similar between groups, except at week 6, where responses were higher with sipuleucel-T→ADT versus ADT→sipuleucel-T (P = 0.013). PA2024-specific T-cell proliferation responses, averaged across time points, were approximately 2-fold higher with sipuleucel-T→ADT versus ADT→sipuleucel-T (P = 0.001). PA2024-specific cellular and humoral responses and prostatic acid phosphatase-specific humoral responses increased significantly versus baseline (P < 0.001) and were maintained for 24 months (both arms). Median time-to-PSA recurrence was similar between arms (21.8 vs. 22.6 months, P = 0.357). Development of a PA2024-specific humoral response correlated with prolonged time-to-PSA progression (HR, 0.22; 95% CI, 0.08-0.67; P = 0.007). Sipuleucel-T with ADT was generally well tolerated.Conclusions: Sipuleucel-T→ADT appears to induce greater antitumor immune responses than the reverse sequence. These results warrant further investigation to determine whether this sequence leads to improved clinical outcomes, as well as the independent contribution of ADT alone in terms of immune activation. Clin Cancer Res; 23(10); 2451-9. ©2016 AACR.

Clonotypic Diversification of Intratumoral T Cells Following Sipuleucel-T Treatment in Prostate Cancer Subjects.

Sipuleucel-T is an autologous cellular therapy for asymptomatic, or minimally symptomatic, metastatic castrate-resistant prostate cancer, designed to stimulate an immune response against prostate cancer. In a recent clinical trial (NCT00715104), we found that neoadjuvant sipuleucel-T increased the number of activated T cells within the tumor microenvironment. The current analysis examined whether sipuleucel-T altered adaptive T-cell responses by expanding pre-existing T cells or by recruiting new T cells to prostate tissue. Next-generation sequencing of the T-cell receptor (TCR) genes from blood or prostate tissue was used to quantitate and track T-cell clonotypes in these treated subjects with prostate cancer. At baseline, there was a significantly greater diversity of circulating TCR sequences in subjects with prostate cancer compared with healthy donors. Among healthy donors, circulating TCR sequence diversity remained unchanged over the same time interval. In contrast, sipuleucel-T treatment reduced circulating TCR sequence diversity versus baseline as measured by the Shannon index. Interestingly, sipuleucel-T treatment resulted in greater TCR sequence diversity in resected prostate tissue in sipuleucel-T-treated subjects versus tissue of nonsipuleucel-T-treated subjects with prostate cancer. Furthermore, sipuleucel-T increased TCR sequence commonality between blood and resected prostate tissue in treated versus untreated subjects with prostate cancer. The broadening of the TCR repertoire within the prostate tissue supports the hypothesis that sipuleucel-T treatment facilitates the recruitment of T cells into the prostate. Our results highlight the importance of assessing T-cell response to immunotherapy both in the periphery and in tumor tissue. Cancer Res; 76(13); 3711-8. ©2016 AACR.

Survival Outcomes of Sipuleucel-T Phase III Studies: Impact of Control-Arm Cross-Over to Salvage Immunotherapy.

Sipuleucel-T is an autologous cellular immunotherapy for asymptomatic/minimally symptomatic metastatic castrate-resistant prostate cancer (CRPC). After disease progression, control-arm patients on three double-blind, randomized phase III sipuleucel-T trials were offered, in nonrandomized open-label protocols, APC8015F, an autologous immunotherapy made from cells cryopreserved at the time of control manufacture. These exploratory analyses evaluated potential effects on survival outcomes associated with such treatment. Of 249 control-treated patients, 165 (66.3%) received APC8015F. We explored the effects of APC8015F on the overall survival (OS; Cox regression) of control-arm patients and treatment effects of sipuleucel-T versus control adjusted for APC8015F treatment [iterative parameter estimation model (IPE)]. The median time to first APC8015F infusion was 5.2 months (range, 1.8-33.1) after randomization and 2.2 months (0.5-14.6) after progression. After disease progression, median survival was longer for APC8015F-treated versus control-only treated patients [20.0 vs. 9.8 months; HR, 0.53; 95% confidence interval (CI), 0.38-0.74; P < 0.001]; however, baseline characteristics were more favorable for APC8015F-treated patients. Multivariate regression analyses identified lactate dehydrogenase, alkaline phosphatase, hemoglobin, ECOG status, age, and number of bone metastases as potential (P < 0.1) independent predictors of postprogression survival. After adjusting for these predictors, APC8015F (HR, 0.78; 95% CI, 0.54-1.11; P = 0.17) treatment trended toward improved survival. Estimated median OS benefit for sipuleucel-T versus control adjusted for APC8015F treatment was 3.9 months if APC8015F had no effect and was 8.1 months if APC8015F was equally as effective as sipuleucel-T. Exploratory analyses indicate that APC8015F treatment may have extended patient survival, suggesting the sipuleucel-T OS advantage in CRPC may be more robust than previously estimated.

A Randomized Phase II Trial of Sipuleucel-T with Concurrent versus Sequential Abiraterone Acetate plus Prednisone in Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: This phase II open-label study evaluated the effect of concurrent or sequential administration of abiraterone acetate plus prednisone (AA + P) on sipuleucel-T manufacture and immune responses in metastatic castration-resistant prostate cancer (mCRPC) patients. EXPERIMENTAL DESIGN: mCRPC patients received sipuleucel-T followed by AA + P 1 day (concurrent) or 10 weeks (sequential) after the first sipuleucel-T infusion. AA + P treatment continued for 26 weeks. The primary endpoint was cumulative antigen presenting cell (APC) activation, and secondary endpoints included cumulative APC number and total nucleated cell counts. Additional endpoints included in vivo peripheral immune responses to sipuleucel-T (T-cell responses, T-cell proliferation, humoral responses, and antigen spread) as well as safety. RESULTS: Sixty-nine mCRPC patients were enrolled, with 35 and 34 patients randomized to the concurrent and sequential arms, respectively. Ex vivo APC activation was significantly greater at the second and third infusions compared with baseline in both arms (P < 0.05), indicative of an immunologic prime-boost effect. In both arms, sipuleucel-T product parameter profiles and peripheral immune responses were consistent with previously conducted sipuleucel-T phase III trials. Antigen spread was similarly observed in both arms and consistent with the other immunologic endpoints. CONCLUSIONS: These data suggest that sipuleucel-T can be successfully manufactured during concurrent administration of AA + P without blunting immunologic effects or altering immune parameters that correlate with sipuleucel-T's clinical benefit. Combination of these agents was well tolerated, with no new safety signals emerging.

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.

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.

A transient increase in eosinophils is associated with prolonged survival in men with metastatic castration-resistant prostate cancer who receive sipuleucel-T.

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.

Phase I study of recombinant interleukin-21 in patients with metastatic melanoma and renal cell carcinoma.

PURPOSE: A phase I study of patients with metastatic malignant melanoma (MM) and renal cell carcinoma (RCC) evaluated the safety and maximum tolerated dose (MTD), pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of recombinant human interleukin-21 (rIL-21). PATIENTS AND METHODS: Patients who had one or fewer prior systemic treatments for metastatic MM or RCC were treated with rIL-21 administered for two 5-day cycles on days 1 through 5 and 15 through 19 of a treatment course; rIL-21 was administered by rapid intravenous infusion in an outpatient setting. Cohorts of patients received doses ranging from 3 to 100 microg/kg/dose, and an expanded cohort was treated at the MTD. Patients with stable disease (SD) or better could receive additional treatment cycles. RESULTS: Forty-three patients were treated (24 MM; 19 RCC), including 28 in the expanded cohort. Dose-limiting toxicities consisted primarily of transient grade 3 laboratory abnormalities. The MTD was estimated to be 30 microg/kg. The most common adverse events included flu-like symptoms, pruritus, and rash. Twelve patients received up to five additional two-cycle courses of treatment without cumulative toxicity, except for one patient with reversible grade 4 hepatotoxicity. Serum concentrations of rIL-21 increased in a dose-proportional manner. Dose-dependent increases in soluble CD25 reflected lymphocyte activation. Antitumor activity was observed in both MM (one complete response and 11 SD) and RCC (four partial responses, 13 SD). CONCLUSION: Outpatient therapy with rIL-21 at 30 microg/kg was well tolerated, had dose-dependent pharmacokinetics and pharmacodynamics, and was associated with antitumor activity in patients with MM and RCC.

Phase I clinical study of atacicept in patients with relapsed and refractory B-cell non-Hodgkin's lymphoma.

PURPOSE: B-lymphocyte stimulator and a proliferation-inducing ligand regulate B-cell homeostasis and immunoglobulin production and are overexpressed in B-cell malignancies. Atacicept (TACI-Ig), a recombinant fusion protein that inhibits both B-lymphocyte stimulator and a proliferation-inducing ligand, may be a novel treatment for B-cell malignancies. EXPERIMENTAL DESIGN: A phase 1, open-label, dose-escalation study of atacicept in patients with relapsed or refractory B-cell lymphoma was done. Atacicept was given s.c. weekly for 5 weeks to sequential patient cohorts at doses of 2, 4, 7, or 10 mg/kg. Patients responding or with stable disease were eligible for treatment on an extension study for up to 24 weeks or until disease progression. RESULTS: All patients were heavily pretreated (median number of previous treatments, 5; range, 1-10), and four patients had previously received a stem cell transplant. Four patients were treated at the 2, 4, or 7 mg/kg dose levels, and three patients received 10 mg/kg of atacicept. Atacicept was well tolerated at all doses. Three adverse events with grade 3 severity were reported for one patient, including jaw pain, gastrointestinal hemorrhage, and sepsis; all were considered unrelated to atacicept. Pharmacokinetic results were nonlinear, and treatment with atacicept resulted in dose-dependent decreases in immunoglobulin concentrations. Two patients had stable disease at 8 weeks, entered the extension study, and received additional doses of atacicept with no safety or tolerability concerns. CONCLUSION: Atacicept at doses of up to 10 mg/kg was well tolerated and showed biological activity by decreasing immunoglobulin concentrations, although tumor responses were not observed.

Pharmacokinetics of subcutaneously administered etanercept in subjects with psoriasis.

AIMS: To present the results of the pharmacokinetic analysis of the concentration-time profiles of etanercept, a soluble receptor tumour necrosis factor (TNF) antagonist, in more than 1300 subjects with psoriasis. METHODS: Pharmacokinetic samples were collected in one phase-2 and two phase-3 placebo-controlled, randomized clinical trials. Study 1 evaluated a 25-mg twice weekly (BIW) etanercept dosing regimen administered by subcutaneous (s.c.) injection for 24 weeks. Study 2 evaluated 25-mg BIW and 50-mg BIW s.c. doses for 12 weeks. Study 3 evaluated 25 mg once weekly (QW), 25 mg BIW and 50 mg BIW s.c. doses for 24 weeks. RESULTS: The mean +/- SD steady-state predose serum concentrations of etanercept for the 25-mg BIW arm at 12 weeks in study 1 were 1590 +/- 885 ng ml(-1). In study 2, mean +/- SD etanercept steady-state concentrations at 12 weeks were 1900 +/- 1110 ng ml(-1) in the 25-mg BIW group and 3830 +/- 1870 ng ml(-1) in the 50-mg BIW group. The mean +/- SD steady-state predose serum concentrations of etanercept at 12 weeks in study 3 were 768 +/- 475 ng ml(-1) for the 25-mg QW regimen, 1990 +/- 1030 ng ml(-1) for the 25-mg BIW regimen and 4020 +/- 2100 ng ml(-1) for the 50-mg BIW regimen. CONCLUSIONS: Pharmacokinetic results were highly consistent across clinical trials. The concentration-time profiles displayed dose proportionality. Etanercept concentrations in subjects with psoriasis are similar to the concentrations in subjects with rheumatoid arthritis.

Once-weekly administration of 50 mg etanercept in patients with active rheumatoid arthritis: results of a multicenter, randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To evaluate the safety, efficacy, and pharmacokinetics of 50 mg etanercept administered subcutaneously once weekly in adult patients with active rheumatoid arthritis (RA). METHODS: Four hundred twenty RA patients were randomized to receive, in a blinded manner, the study drug for up to 16 weeks: 214 patients received 50 mg etanercept once weekly, 153 received 25 mg etanercept twice weekly, and 53 received placebo for 8 weeks followed by 25 mg etanercept twice weekly for 8 weeks. Efficacy and safety were assessed at weeks 8 and 16. Pharmacokinetic analyses were performed on serum samples from patients at selected study sites. The primary efficacy end point was achievement of the American College of Rheumatology (ACR) 20% improvement criteria (ACR20 response) at week 8. RESULTS: An ACR20 response was achieved at week 8 by 50% of the patients receiving 50 mg etanercept once weekly, by 49% of the patients receiving 25 mg etanercept twice weekly, and by 19% of the patients in the placebo group (P