Systematic literature review (SLR) and network meta-analysis (NMA) of first-line therapies (1L) for locally advanced/metastatic urothelial carcinoma (la/mUC)

570

Background: Standard of care (SOC) for 1L la/mUC is gemcitabine plus cisplatin (GC) or carboplatin (GCa), but the landscape is evolving with new therapies emerging. To compare outcomes of other approved/investigational 1L regimens with SOC in the context of recently published data on newer therapies, we updated a previously reported SLR/NMA of phase 2/3 randomized control trials. Methods: The SLR was conducted in line with PRISMA and NICE guidelines (01/2000-05/2020; updated 06/2020-06/2021). Three networks were formed: cisplatin (cis)-eligible/mixed eligibility; cis-ineligible (strict; studies including cis-ineligible patients only); and cis-ineligible (wide; expanded to also include study arms with an investigator’s choice of carboplatin in KEYNOTE-361, IMvigor130, and DANUBE). Comparative efficacy and safety were assessed under a Bayesian framework. Overall survival (OS) and progression-free survival (PFS) with 1L la/mUC regimens vs SOC (GC/GCa) are reported. Results: Among 2,312 citations identified, 55 unique trials were selected for data extraction. Of these, the NMA included 11 studies in the cis-eligible/mixed, 6 in the cis-ineligible (strict), and 8 in the cis-ineligible (wide) network. The NMA excluded therapies that were not effective or adopted in clinical practice; 6 maintenance trials were excluded due to differences in design precluding comparisons. Median OS in the SOC arms was 13.2 mo (95% confidence interval [CI] 12.4-14.0) for cis-eligible/mixed, 9.7 mo (95% CI 6.7-12.8) for cis-ineligible (strict), and 12.0 mo (95% CI 10.4-13.5) for cis-ineligible (wide); median PFS was 6.6 mo (95% CI 6.3-6.9) for cis-eligible/mixed and 5.6 mo (95% CI 5.0-6.3) for both cis-ineligible strict and wide. OS and PFS were similar to SOC across therapies in each network: hazard ratios (HR) ranged 0.7-1.4 for OS for cis-eligible/mixed, 0.9-1.4 for cis-ineligible (strict), and 0.8-1.4 for cis-ineligible (wide) (Table); HR for PFS ranged 0.5-1.6 for cis-eligible/mixed and 0.8-1.1 for both cis-ineligible strict and wide networks; all credible intervals (CrI) crossed or were close to 1. Conclusions: In this updated SLR/NMA, survival outcomes were similar and remained poor among established and emerging 1L la/mUC therapies, despite inclusion of recent trial data. This further highlights the unmet need in this population.[Table: see text]

Analysis of the PROCEED registry by baseline prostate-specific antigen (PSA) quartiles: Preliminary analysis of real-world sipuleucel-T (sip-T) use

193

Background: Sip-T is an FDA-approved, autologous cellular immunotherapy for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). Post-hoc analysis of the phase 3 IMPACT study revealed that compared with the highest baseline PSA quartile, patients (pts) in the lowest quartile treated with sip-T had a larger overall survival (OS) benefit, suggesting sip-T is most beneficial if administered earlier in the treatment of mCRPC (Schellhammer et al., Urology. 2013.). This analysis evaluated pt characteristics by PSA quartiles in PROCEED (NCT01306890). Methods: Pts enrolled in PROCEED with baseline PSA and ≥ 1 sip-T infusion were included in this analysis. PSA values were divided into quartiles, and trends in baseline pt characteristics were evaluated as well as time to first anticancer intervention (tACI) with approved mCRPC therapies (docetaxel [D], cabazitaxel, abiraterone [abi], or enzalutamide [enz]) following sip-T treatment. Radium-223 was approved too late in the conduct of PROCEED to be included in the tACI analysis. Results: PSA quartiles from 1880 eligible PROCEED pts were lower than those of IMPACT (Table). Pts in the highest PROCEED quartile were older, more likely to have ECOG performance status ≥ 1, > 10 bone metastases, visceral metastases, and higher ALP and LDH, and lower hemoglobin compared with the lowest PROCEED quartile. More African American men and greater prior systemic therapy use were observed in the highest PSA quartile. Following sip-T, the median tACI (11.0, 8.2, 7.6, and 6.6 mos) was inversely proportional to PSA quartile. Conclusions: Lower baseline PSA values in PROCEED relative to IMPACT suggest that in a real-world setting, clinicians are using sip-T earlier in the treatment of mCRPC. Pts in the lowest PSA quartile had the best prognostic features and longest tACI. Additional patient follow-up is ongoing to evaluate OS and survival by quartile from PROCEED. Clinical trial information: NCT01306890. [Table: see text]

Changing characteristics of patients treated with sipuleucel-T (sip-T) over time: Real-world experience from the PROCEED registry

320

Background: Sip-T is an autologous cellular immunotherapy approved by the FDA for the treatment of asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer. PROCEED (NCT01306890) is a phase 4 registry evaluating men receiving sip-T therapy in the US. Patient characteristics and treatment trends were assessed from 2011 to 2013, when several agents with an overall survival benefit became commercially available. Methods: For patients enrolled from 2011 to 2013, baseline patient and disease characteristics at the first sip-T infusion, trends in prior therapy, and pre–sip-T baseline prostate-specific antigen (PSA) levels were examined year over year. Results: From 2011 to 2013, 1902 patients were enrolled and received ≥ 1 sip-T infusion: 2011, n = 145; 2012, n = 967; 2013, n = 790. During this time period, enrollment of African American men nearly doubled from 6.9% to 13.4%, and central venous catheter use to facilitate sip-T infusion decreased (from 53.8% to 44.1%). Median baseline lactate dehydrogenase (LDH) levels and the number of lymph node metastases also decreased as well as median baseline PSA values (17.8 ng/mL to 11.9 ng/mL [P = 0.002]). Prior use of first-generation anti-androgens (from 73.1% to 60.5%), ketoconazole (17.2% vs. 6.3%), and estrogen (4.8% vs. 1.6%) decreased along with prior docetaxel use (19.3% vs. 7.5%). In contrast, prior investigational use of abiraterone acetate (from 3.4% to 8.9%) and enzalutamide (1.4% vs. 3.2%) increased over time. Conclusions: Over the duration of PROCEED, the decrease in baseline PSA, lower LDH, fewer nodal metastases, and decline in prior docetaxel use suggest that sip-T is being used earlier in the course of metastatic castration-resistant disease. Moreover, second-line hormonal therapy use with agents that do not improve overall survival appears to be substituted by therapies that do. This decrease in second-line hormonal therapies during PROCEED could suggest a real-world preference for earlier sip-T use. Clinical trial information: NCT01306890.

Real-world experience of therapeutic sequencing and time to first anticancer intervention (ACI) following sipuleucel-T (sip-T): Initial data from the PROCEED registry

194

Background: Sip-T is an autologous immunotherapy approved for asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC).Many therapeutic agents have been approved in a short time frame, and their optimal sequencing in mCRPC is under investigation. The sequencing of agents post–sip-T treatment on PROCEED (NCT01306890) and factors associated with a shorter time to first ACI (tACI) are described. Methods: The number of unique and most common sequences and sequence trends were analyzed. Post–sip-T ACIs evaluated were abiraterone (abi), enzalutamide (enz), docetaxel (D), and cabazitaxel (cbz), excluding radium-223 due to its late approval relative to PROCEED initiation. The tACI and factors associated with shorter tACI were assessed. Results: 1902 pts received ≥1 sip-T infusion, and an estimated 37.0% and 21.2%had not received an ACI at 1 and 2 y, respectively, post–sip-T. 1331 (70%) pts received abi, enz, D, or cbz after sip-T. 47 therapy sequences were recorded post–sip-T, with the most used therapies in order of prevalence: abi alone, enz alone, D alone, abi → enz, abi → D, D → enz, and D → abi. The most common post–sip-T sequences beginning with abi, enz, or D are below (Table). Only 25 pts received cbz as the first ACI post–sip-T. Pts who received abi prior to sip-T had a shorter median tACI (4.6 mos) compared with all pts (8.3 mos) or pts with D prior to sip-T (7.3 mos). Higher baseline alkaline phosphatase, lower hemoglobin, and prior radical prostatectomy were associated with shorter tACI. Conclusions: In the evolving mCRPC space, 47 unique ACI sequences were recorded post-sip-T. The most common sequences post–sip-T were abi, enz, and D as single agents. Prior abi was associated with a shorter tACI post–sip-T, which warrants longer follow-up. While many pts received subsequent therapy, ~20% had not received an ACI at 2 y post–sip-T. Clinical trial information: NCT01306890. [Table: see text]

Characteristics of African Americans (AAs) treated with sipuleucel-T (sip-T): Comparison of clinical trial and real-world experience

272

Background: AA men are underrepresented in randomized clinical trials (RCTs) for prostate cancer, despite an almost 2-fold greater incidence in AA vs Caucasian populations. Sip-T is an autologous cellular immunotherapy approved by the FDA and EMA for the treatment of certain patients (pts) with asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer. AA enrollment in three sip-T phase 3 RCTs was 5.8% (n=43). While no definitive conclusions were drawn, median overall survival (OS) suggested AAs benefit from sip-T. PROCEED, an ongoing phase 4 registry, expanded efforts to increase AA enrollment to better characterize this population and the safety, product parameters (PP), and OS of AAs treated with sip-T. Methods: PROCEED enrolled 1973 pts treated with commercial sip-T within 6 months of registration. Efforts, such as selecting racially diverse sites and highlighting AA enrollment in PROCEED communications and investigator meetings, were used to boost AA enrollment. Baseline Gleason score, Eastern Cooperative Oncology Group performance status (ECOG), prostate-specific antigen (PSA), and alkaline phosphatase (ALP) were compared between RCTs and PROCEED. Safety and survival analyses are ongoing. Results: PROCEED AA enrollment was 11.7% vs 7.1% US RCT nonwhite enrollment rate and approaches the US AA population of 13.7%. Baseline AA pt characteristics were: lower median PSA and ALP levels in PROCEED vs RCTs, higher ECOG >0 in PROCEED vs RCTs, and higher Gleason score ≥8 in PROCEED vs RCTs (Table). Conclusions: Efforts to boost AA enrollment in PROCEED to a proportion comparable to the US AA population succeeded. The lower baseline PSA of AAs in PROCEED is similar to the PSA observed in the entire PROCEED population. Safety, PP, and OS will be reported with longer follow-up. Clinical trial information: NCT01306890. [Table: see text]