Overall Survival with Adjuvant Pembrolizumab in Renal-Cell Carcinoma

BACKGROUND

Adjuvant pembrolizumab therapy after surgery for renal-cell carcinoma was approved on the basis of a significant improvement in disease-free survival in the KEYNOTE-564 trial. Whether the results regarding overall survival from the third prespecified interim analysis of the trial would also favor pembrolizumab was uncertain.

METHODS

In this phase 3, double-blind, placebo-controlled trial, we randomly assigned (in a 1:1 ratio) participants with clear-cell renal-cell carcinoma who had an increased risk of recurrence after surgery to receive pembrolizumab (at a dose of 200 mg) or placebo every 3 weeks for up to 17 cycles (approximately 1 year) or until recurrence, the occurrence of unacceptable toxic effects, or withdrawal of consent. A significant improvement in disease-free survival according to investigator assessment (the primary end point) was shown previously. Overall survival was the key secondary end point. Safety was a secondary end point.

RESULTS

A total of 496 participants were assigned to receive pembrolizumab and 498 to receive placebo. As of September 15, 2023, the median follow-up was 57.2 months. The disease-free survival benefit was consistent with that in previous analyses (hazard ratio for recurrence or death, 0.72; 95% confidence interval [CI], 0.59 to 0.87). A significant improvement in overall survival was observed with pembrolizumab as compared with placebo (hazard ratio for death, 0.62; 95% CI, 0.44 to 0.87; P = 0.005). The estimated overall survival at 48 months was 91.2% in the pembrolizumab group, as compared with 86.0% in the placebo group; the benefit was consistent across key subgroups. Pembrolizumab was associated with a higher incidence of serious adverse events of any cause (20.7%, vs. 11.5% with placebo) and of grade 3 or 4 adverse events related to pembrolizumab or placebo (18.6% vs. 1.2%). No deaths were attributed to pembrolizumab therapy.

CONCLUSIONS

Adjuvant pembrolizumab was associated with a significant and clinically meaningful improvement in overall survival, as compared with placebo, among participants with clear-cell renal-cell carcinoma at increased risk for recurrence after surgery. (Funded by Merck Sharp and Dohme, a subsidiary of Merck; KEYNOTE-564 ClinicalTrials.gov number, NCT03142334.).

Corrigendum: Phase 3 CLEAR study in patients with advanced renal cell carcinoma: outcomes in subgroups for the lenvatinib-plus-pembrolizumab and sunitinib arms

[This corrects the article DOI: 10.3389/fonc.2023.1223282.].

Phase 3 CLEAR study in patients with advanced renal cell carcinoma: outcomes in subgroups for the lenvatinib-plus-pembrolizumab and sunitinib arms

Introduction

The phase 3 CLEAR study demonstrated that lenvatinib plus pembrolizumab significantly improved efficacy versus sunitinib as first-line treatment for patients with advanced renal cell carcinoma (RCC). Prognostic features including presence and/or site of baseline metastases, prior nephrectomy, and sarcomatoid features have been associated with disease and treatment success. This subsequent analysis explores outcomes in patients with or without specific prognostic features.

Methods

In CLEAR, patients with clear cell RCC were randomly assigned (1:1:1) to receive either lenvatinib (20 mg/day) plus pembrolizumab (200 mg every 3 weeks), lenvatinib (18 mg/day) plus everolimus (5 mg/day), or sunitinib alone (50 mg/day, 4 weeks on, 2 weeks off). In this report, progression-free survival (PFS), overall survival (OS), and objective response rate (ORR) were all assessed in the lenvatinib-plus-pembrolizumab and the sunitinib arms, based on baseline features: lung metastases, bone metastases, liver metastases, prior nephrectomy, and sarcomatoid histology.

Results

In all the assessed subgroups, median PFS was longer with lenvatinib-plus-pembrolizumab than with sunitinib treatment, notably among patients with baseline bone metastases (HR 0.33, 95% CI 0.21-0.52) and patients with sarcomatoid features (HR 0.39, 95% CI 0.18-0.84). Median OS favored lenvatinib plus pembrolizumab over sunitinib irrespective of metastatic lesions at baseline, prior nephrectomy, and sarcomatoid features. Of interest, among patients with baseline bone metastases the HR for survival was 0.50 (95% CI 0.30-0.83) and among patients with sarcomatoid features the HR for survival was 0.91 (95% CI 0.32-2.58); though for many groups, median OS was not reached. ORR also favored lenvatinib plus pembrolizumab over sunitinib across all subgroups; similarly, complete responses also followed this pattern.

Conclusion

Efficacy outcomes improved following treatment with lenvatinib-plus-pembrolizumab versus sunitinib in patients with RCC-irrespective of the presence or absence of baseline lung metastases, baseline bone metastases, baseline liver metastases, prior nephrectomy, or sarcomatoid features. These findings corroborate those of the primary CLEAR study analysis in the overall population and support lenvatinib plus pembrolizumab as a standard of care in 1L treatment for patients with advanced RCC.

Clinical trial registration

ClinicalTrials.gov, identifier NCT02811861.

Phase 3 LITESPARK-022: Pembrolizumab (pembro) plus hypoxia-inducible factor 2α (HIF-2α) inhibitor belzutifan as adjuvant treatment for clear cell renal cell carcinoma (ccRCC)

TPS748

Background: Treatment with the PD-1 inhibitor pembro produced significant improvement in disease-free survival after surgery for patients (pts) with ccRCC in the phase 3 KEYNOTE-564 trial. Based on these results, pembro was approved by the US Food and Drug Administration and the European Medicines Agency for adjuvant treatment of pts with RCC at increased risk of recurrence following nephrectomy or following nephrectomy and resection of metastatic lesions. Despite advances in the treatment landscape for RCC, more effective adjuvant treatment strategies are needed for pts at risk of recurrence after surgery. HIF-2α is an established oncogenic driver in ccRCC, and promising antitumor activity in advanced ccRCC and von Hippel-Lindau disease–associated RCC has been demonstrated with the HIF-2α inhibitor belzutifan. The multicenter, double-blind, randomized, phase 3 LITESPARK-022 study (NCT05239728) will evaluate the efficacy and safety of pembro plus belzutifan compared with placebo plus pembro as adjuvant treatment following nephrectomy in pts with ccRCC. Methods: Key eligibility criteria include adults with histologically or cytologically confirmed intermediate-high risk, high risk, or M1 with no evidence of disease (NED) RCC with a clear cell component; pts with no prior systemic therapy, nephrectomy, and/or metastasectomy ≤12 weeks before randomization; and pts who are tumor free per computed tomography/magnetic resonance imaging. Approximately 1600 pts will be randomly assigned to receive belzutifan 120 mg orally once daily plus pembro 400 mg intravenously (IV) every 6 weeks (Q6W) for ≤9 administrations (~54 weeks) or oral placebo plus pembro 400 mg IV Q6W for ≤9 administrations (~54 weeks) or until verified disease recurrence by blinded independent central review, start of new anticancer treatment, unacceptable toxicity, or decision to withdraw. Stratification factors are tumor grade (1 or 2 vs 3 or 4) and risk type (intermediate-high risk versus high risk versus M1 NED). Pts will be radiologically evaluated Q12W from randomization through year 2, Q16W in years 3 to 5, and Q24W in years 6 and beyond. Adverse events will be monitored throughout the study and for 30 days following cessation of study treatment (90 days for serious adverse events). The primary end point is disease-free survival. Secondary end points include overall survival, safety, disease recurrence–specific survival, and patient-reported outcomes. Recruitment is underway in Asia, Australia, Europe, North America, and South America. © 2022 American Society of Clinical Oncology, Inc. Reused with permission. This abstract was accepted and previously presented at the 2022 ASCO Annual Meeting. All rights reserved. Clinical trial information: NCT05239728 .

Pembrolizumab versus placebo as post-nephrectomy adjuvant therapy for clear cell renal cell carcinoma (KEYNOTE-564): 30-month follow-up analysis of a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

The first interim analysis of the KEYNOTE-564 study showed improved disease-free survival with adjuvant pembrolizumab compared with placebo after surgery in patients with clear cell renal cell carcinoma at an increased risk of recurrence. The analysis reported here, with an additional 6 months of follow-up, was designed to assess longer-term efficacy and safety of pembrolizumab versus placebo, as well as additional secondary and exploratory endpoints.

METHODS

In the multicentre, randomised, double-blind, placebo-controlled, phase 3 KEYNOTE-564 trial, adults aged 18 years or older with clear cell renal cell carcinoma with an increased risk of recurrence were enrolled at 213 hospitals and cancer centres in North America, South America, Europe, Asia, and Australia. Eligible participants had an Eastern Cooperative Oncology Group performance status of 0 or 1, had undergone nephrectomy 12 weeks or less before randomisation, and had not received previous systemic therapy for advanced renal cell carcinoma. Participants were randomly assigned (1:1) via central permuted block randomisation (block size of four) to receive pembrolizumab 200 mg or placebo intravenously every 3 weeks for up to 17 cycles. Randomisation was stratified by metastatic disease status (M0 vs M1), and the M0 group was further stratified by ECOG performance status and geographical region. All participants and investigators involved in study treatment administration were masked to the treatment group assignment. The primary endpoint was disease-free survival by investigator assessment in the intention-to-treat population (all participants randomly assigned to a treatment). Safety was assessed in the safety population, comprising all participants who received at least one dose of pembrolizumab or placebo. As the primary endpoint was met at the first interim analysis, updated data are reported without p values. This study is ongoing, but no longer recruiting, and is registered with ClinicalTrials.gov, NCT03142334.

FINDINGS

Between June 30, 2017, and Sept 20, 2019, 994 participants were assigned to receive pembrolizumab (n=496) or placebo (n=498). Median follow-up, defined as the time from randomisation to data cutoff (June 14, 2021), was 30·1 months (IQR 25·7-36·7). Disease-free survival was better with pembrolizumab compared with placebo (HR 0·63 [95% CI 0·50-0·80]). Median disease-free survival was not reached in either group. The most common all-cause grade 3-4 adverse events were hypertension (in 14 [3%] of 496 participants) and increased alanine aminotransferase (in 11 [2%]) in the pembrolizumab group, and hypertension (in 13 [3%] of 498 participants) in the placebo group. Serious adverse events attributed to study treatment occurred in 59 (12%) participants in the pembrolizumab group and one (<1%) participant in the placebo group. No deaths were attributed to pembrolizumab.

INTERPRETATION

Updated results from KEYNOTE-564 support the use of adjuvant pembrolizumab monotherapy as a standard of care for participants with renal cell carcinoma with an increased risk of recurrence after nephrectomy.

FUNDING

Merck Sharp & Dohme LLC, a subsidiary of Merck & Co, Inc, Rahway, NJ, USA.

LITESPARK-022: A phase 3 study of pembrolizumab + belzutifan as adjuvant treatment of clear cell renal cell carcinoma (ccRCC)

TPS4602

Background: Patients with locally advanced renal cell carcinoma (RCC) may experience recurrence after surgery. In the phase 3 KEYNOTE-564 (NCT03142334) trial, adjuvant pembrolizumab demonstrated significant improvement in disease-free survival (DFS) in ccRCC, leading to FDA approval of pembrolizumab (November 17, 2021) for adjuvant treatment of patients with RCC at intermediate-high or high risk for recurrence following nephrectomy or following nephrectomy and resection of metastatic lesions. Despite benefit of pembrolizumab, there is an unmet need for more effective adjuvant treatment for patients at risk for recurrence after definitive surgery. The HIF-2α inhibitor belzutifan (MK-6482) has shown activity and good tolerability in patients with advanced ccRCC and von Hippel-Lindau (VHL) disease–associated RCC. Combining belzutifan with pembrolizumab may be a therapeutic option as adjuvant treatment of ccRCC. This global, multicenter, double-blind, randomized, phase 3 study LITESPARK-022 (NCT05239728) is designed to compare the efficacy and safety of belzutifan + pembrolizumab with that of placebo + pembrolizumab as adjuvant treatment of ccRCC after nephrectomy. Methods: Approximately 1600 patients with histologically or cytologically confirmed RCC (intermediate-high [pT2, grade 4 or sarcomatoid, N0, M0 or pT3, any grade, N0, M0], high [pT4, any grade, N0, M0 or pT, any stage/grade, N+, M0] or M1 NED [patients who present with the primary kidney tumor and solid, isolated, soft tissue metastases that can be resected at the time of nephrectomy or ≤2 years from nephrectomy) with a clear cell component and had not previously received systemic therapy will be enrolled. Patients must have undergone nephrectomy and/or metastasectomy ≤12 weeks before randomization and be tumor free, confirmed by CT/MRI. Stratification factors are tumor grade (1 or 2 vs 3 or 4) and risk type (intermediate-high vs high vs M1 NED). Patients will be randomly assigned 1:1 to receive belzutifan 120 mg orally once daily + pembrolizumab 400 mg IV every 6 weeks (Q6W) or oral placebo + pembrolizumab 400 mg IV Q6W. Pembrolizumab treatment will be administered for up to 9 doses (̃1 year); belzutifan and placebo may be continued for a maximum of 54 weeks. Disease recurrence will be evaluated radiologically Q12W from randomization through year 2, Q16W in years 3-5, and Q24W in years 6 and beyond. Adverse events (AEs) will be monitored by NCI CTCAE v5.0 through 30 days (90 days for serious AEs) after cessation of study drug. The primary end point is DFS, as assessed by investigator, defined as time from randomization to first documented event of local recurrence, occurrence of distant kidney cancer metastasis, or death from any cause, whichever occurs first. The key secondary end point is overall survival. Other secondary end points are safety, disease recurrence–specific survival and patient-reported outcomes. Clinical trial information: NCT05239728.

Pembrolizumab (pembro) plus axitinib (axi) versus sunitinib as first-line therapy for advanced clear cell renal cell carcinoma (ccRCC): Analysis of progression after first subsequent therapy in KEYNOTE-426

4513

Background: The randomized, open-label, phase 3 KEYNOTE-426 study (NCT02853331) met its primary and key secondary end points of improved OS, PFS, and ORR with pembro + axi versus sunitinib as first-line treatment for patients with advanced ccRCC. Extended follow-up (42.8-mo median follow-up) continued to show the superior efficacy of pembro + axi versus sunitinib in this patient population. We describe the results of PFS2 for all randomly assigned patients and across IMDC risk categories. Methods: Treatment-naive patients with advanced ccRCC, Karnofsky Performance Status Scale score ≥70% and measurable disease per RECIST v1.1 were randomly assigned 1:1 to receive pembro 200 mg IV every 3 weeks for up to 35 doses (̃2 y) + axi 5 mg orally twice daily or sunitinib 50 mg orally once daily on a 4-wk on/2-wk off schedule. The end point of this exploratory analysis was PFS2, defined as time from randomization to progression after first subsequent therapy or any-cause death. The Kaplan-Meier method was used to estimate PFS2 and hazard ratios were estimated using a Cox regression model. Results: Of 861 patients, 432 were assigned to receive pembro + axi; 429, to sunitinib. Median time from randomization to the database cutoff date (January 11, 2021) was 42.8 mo (range, 35.6-50.6). Overall, 47.2% of patients (204/432) in the pembro + axi arm and 65.5% of patients (281/429) in the sunitinib arm received ≥1 line of subsequent anticancer therapy. For patients who received subsequent therapy, anti–PD-1/PD-L1 agents were the first subsequent treatment for 11.3% of patients (23/204) in the pembro + axi arm and 54.8% of patients (154/281) in the sunitinib arm. In the pembro + axi arm, 82.8% of patients (169/204) received a VEGF/VEGFR inhibitor as first subsequent therapy, as did 43.4% (122/281) in the sunitinib arm. PFS2 results are displayed in the Table. Conclusions: In this exploratory analysis, PFS2 was longer for patients randomized to pembro + axi compared to sunitinib. Results were consistent across IMDC risk groups. These data support use of pembro + axi for the first-line treatment of patients with advanced ccRCC. Clinical trial information: NCT02853331. [Table: see text]

Pembrolizumab (pembro) plus axitinib (axi) versus sunitinib as first-line therapy for advanced clear cell renal cell carcinoma (ccRCC): Results from 42-month follow-up of KEYNOTE-426

4500

Background: In the first interim analysis of the randomized, multicenter, open-label, phase 3 KEYNOTE-426 study (NCT02853331), treatment with pembro + axi significantly improved OS, PFS, and ORR vs sunitinib monotherapy in treatment-naive advanced ccRCC. Extended follow-up (median, 30.6 mo) continued to demonstrate the superior efficacy of pembro + axi vs sunitinib monotherapy in this patient population. Here, we present the results of the prespecified final analysis with 42.8-mo median follow-up. Methods: Treatment-naive patients (pts) with advanced ccRCC, KPS ≥70%, and measurable disease (RECIST v1.1) were randomly assigned 1:1 to receive pembro 200 mg IV Q3W for up to 35 doses + axi 5 mg orally BID or sunitinib 50 mg orally QD on a 4-wk on/2-wk off schedule until progression, intolerable toxicity, or withdrawal. Randomization was stratified by IMDC risk (favorable vs intermediate vs poor) and geographic region (North America vs Western Europe vs Rest of World). Dual primary endpoints were OS and PFS. Secondary endpoints were ORR, DOR, and safety. The protocol-specified final analysis was based on a target of 404 OS events. No formal hypothesis testing was performed because all efficacy endpoints were met previously at the first interim analysis; nominal P values are reported. Results: Overall, 861 pts were randomly assigned to receive pembro + axi (n=432) or sunitinib (n=429). Median duration of follow-up, defined as time from randomization to the database cutoff date, was 42.8 mo (range, 35.6-50.6). At data cutoff, 418 pts had died: 193 (44.7%) of 432 pts in the pembro + axi arm vs 225 (52.4%) of 429 pts in the sunitinib arm. Compared with sunitinib, pembro + axi improved OS (median: 45.7 vs 40.1 mo; HR, 0.73 [95% CI, 0.60-0.88]; P<0.001) and PFS (median: 15.7 vs 11.1 mo; HR, 0.68 [95% CI, 0.58-0.80]; P<0.0001). The 42-mo OS rate was 57.5% with pembro + axi vs 48.5% with sunitinib; the 42-mo PFS rate was 25.1% with pembro + axi vs 10.6% with sunitinib. For pembro + axi vs sunitinib, ORR was 60.4% vs 39.6% ( P<0.0001); CR rate was 10.0% vs 3.5%; median DOR was 23.6 mo (range 1.4+ to 43.4+) vs 15.3 mo (range, 2.3-42.8+). Subsequent anticancer therapy was administered to 47.2% of pts in pembro + axi arm vs 65.5% of pts in sunitinib arm. Although a similar proportion of pts in each arm received VEGF/VEGFR inhibitors, only 10.2% of pts in the pembro + axi arm received subsequent treatment with a PD-1/L1 inhibitor compared to 48.7% of pts in the sunitinib arm. No new safety signals were observed. Conclusions: With a median follow-up of 42.8 mo, this is the longest follow-up of an anti-PD–1/L1 immunotherapy combined with a VEGF/VEGFR inhibitor for first-line RCC. These results show that pembro + axi continues to demonstrate superior efficacy over sunitinib with respect to OS, PFS, and ORR, with no new safety signals. Clinical trial information: NCT02853331.

Exploratory gene-by-gene analysis of olaparib in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): PROfound

126

Background: The Phase 3 PROfound trial (NCT02987543) met its primary endpoint and key secondary endpoints, including improved overall survival (OS) for olaparib in men with mCRPC with alterations in BRCA1, BRCA2, or ATM (Cohort A). We report gene-by-gene analysis of olaparib antitumor activity among the 15 prespecified homologous recombination repair (HRR) genes. Methods: Pts were randomized to olaparib (300 mg bid; n=256) or physician’s choice of enzalutamide or abiraterone (control; n=131). Exploratory analyses in pts with alterations in BRCA1 and/or BRCA2 (BRCA, regardless of co-occurring alterations with other HRR genes) or in single genes were conducted. Results: Evidence of olaparib antitumor activity was observed in subgroups with >10 pts (table). Data for pts with alterations in only BRCA1, BRCA2, PPP2R2A, RAD51B, RAD54L, PALB2, BRIP1, CHEK1, BARD1, and RAD51D will be reported (no FANCL or RAD51C enrolled). Conclusions: Small subgroups limit interpretation for some genes. Olaparib antitumor activity is greatest in pts with BRCA alterations, with a spectrum of clinical sensitivity to olaparib as defined by rPFS and OS across the broader population with alterations in other HRR genes. Clinical trial information: NCT02987543. [Table: see text]

Pembrolizumab (pembro) plus enzalutamide (enza) and androgen deprivation therapy (ADT) for patients (pts) with metastatic hormone-sensitive prostate cancer (mHSPC): The phase III KEYNOTE-991 study

TPS184

Background: The combination of pembro, an anti–PD-1 antibody, added to enza, a nonsteroidal antiandrogen agent, has shown antitumor activity in abiraterone-resistant metastatic castration-resistant prostate cancer (mCRPC) in the KEYNOTE-365 trial (NCT02861573) and in pts with mCRPC for whom enza was ineffective in the KEYNOTE-199 trial (NCT02787005). The efficacy of enza may be proimmunogenic, suggesting that it may be additive or synergistic in antitumor activity when combined with pembro. These data indicate that pembro + enza with ADT warrants phase 3 evaluation. Methods: KEYNOTE-991 (NCT04191096) is a randomized, double-blind, placebo-controlled, multicenter phase 3 trial evaluating the efficacy and safety of enza + ADT (luteinizing hormone-releasing hormone agonist/antagonist during study treatment or bilateral orchiectomy) + pembro or placebo in pts with mHSPC. Eligibility criteria include age ≥18 years, mHSPC, ≥2 bone lesions or visceral disease, no prior treatment with next-generation hormone agents, adequate organ function, and ECOG PS 0 or 1. Pts must provide tissue for biomarker analysis. Approximately 1232 pts will be randomized in a 1:1 ratio to receive enza 160 mg orally once daily + ADT + pembro 200 mg intravenously (IV) every 3 weeks (Q3W) or enza 160 mg orally once daily + ADT + placebo IV Q3W. Treatment will continue with pembro up to 35 cycles and treatment with enza will proceed continuously from day 1 of cycle 1 until disease progression, unacceptable toxicity, or withdrawal of consent. The stratification factors are prior docetaxel therapy (yes or no) and presence of high-volume disease (yes or no). Computed tomography or magnetic resonance imaging and radionuclide bone imaging will be used to assess response according to Prostate Cancer Working Group 3 (PCWG3)–modified RECIST v1.1 by blinded independent central review (BICR) every 12 weeks (Q12W) from the date of randomization. Imaging will continue until the end of treatment and will resume Q12W during the posttreatment period. The dual-primary endpoints are BICR-assessed radiographic progression-free survival (rPFS; according to PCWG3-modified RECIST v1.1) and overall survival (OS). Key secondary endpoints are time to first subsequent anticancer therapy (TFST) and time to symptomatic skeletal-related event (TTSSRE). Safety and tolerability will be evaluated using a tiered approach. The dual-primary (rPFS and OS) and key secondary (TFST and TTSSRE) endpoints will be evaluated using a stratified log-rank test. Event rates will be summarized using the Kaplan-Meier method, and hazard ratios will be estimated using a stratified Cox regression model. KEYNOTE-991 is enrolling at 40 sites in Australia, Chile, Colombia, Germany, Israel, Japan, Poland, South Korea, Spain, Switzerland, Taiwan, and the United States. Clinical trial information: NCT04191096.

Genomic/genetic testing patterns for patients with metastatic castrate-resistant prostate cancer: Results from a real-world study in the United States

49

Background: In May 2020, Olaparib was approved for HRRm mCRPC post progression on abiraterone and enzalutamide, and rucaparib was approved for BRCAm mCPRC following progression on androgen receptor targeted inhibitors and prior taxane therapy for mCRPC. HRRm are associated with approximately 25% of mCRPC and may be derived from germline or somatic origin. Somatic and germline alterations can be detected by tumour testing, but to differentiate between these, independent germline testing is needed. This study examined real-world genomic/genetic testing (GT) patterns in patients (pts) diagnosed with mCRPC in the United States (US). Methods: Data were drawn from the Adelphi Prostate Cancer Disease Specific Programme; a point-in-time survey administered to oncologists (onc), urologists (uro) and surgeons (sur) between January and August 2020 in the US. Physicians (phys) completed an attitudinal survey and a patient record form for the next four to nine mCRPC pts seen. Study variables included patient demographics, clinical factors and GT patterns. HRRm testers were defined as phys who tested for HRRm. Pts were identified as positive, negative or unknown depending on the outcome of the HRRm test. Results: A total of 72 phys (69% onc/ 29% uro/ 1% sur; 40% academic vs. 60% community) reported on 346 mCRPC pts. 41% of phys were based in the Northeast, 24% Midwest, 23% South and 13% in the West region of the US. 65 phys (90%) reported having access to overall GT; of these 5% identified as having access to germline tests only, while 94% were able to test for germline and somatic mutations. Challenges to conducting GT overall were ‘cost per test’ (50%), ‘having to send out for the tests (within country)’ (25%), ‘inadequate sample available’ (25%) and ‘patient refusal’ (25%). GT was typically conducted at identification of castrate-resistance (52%), metastases (51%) and at initial diagnosis (49%). 72% of total phys were HRRm testers; for these, patient characteristics primarily driving HRRm testing included Ashkenazi Jewish heritage (63%) and ECOG of 2-4 (58%). Other common drivers were family history, young diagnosis age and hormone therapy failure (all 46%). 132 (38% of 326) mCRPC pts were tested for HRRm; 39% of tested pts were identified with a HRRm. Most common HRRm tested were BRCA1 (90%), BRCA2 (89%) and ATM (55%). Conclusions: In this study majority of US phys had access to GT, but testing was only performed in 38% of pts with mCRPC. The higher than expected % of pts identified with an HRRm suggest that molecular testing was prioritised in high risk populations, as identified by the phys. With the recent approval of olaparib and rucaparib, GT may become more routine in clinical practice to identify eligible pts. Broader testing may also depend on addressing other barriers to testing including cost and testing logistics/practicalities.

Health-related quality of life (HRQoL) for olaparib versus enzalutamide or abiraterone in metastatic castration-resistant prostate cancer (mCRPC) with homologous recombination repair (HRR) gene alterations: PROfound

5539

Background: In the randomized Phase III PROfound trial (NCT02987543), olaparib significantly prolonged radiographic progression-free survival compared with physician’s choice of new hormonal agent (pcNHA, enzalutamide or abiraterone) in men with mCRPC and HRR gene alterations, whose disease had progressed on prior NHA. Olaparib significantly improved time to pain progression in Cohort A. We report additional patient reported outcome measures of HRQoL in the overall study population (Cohorts A+B). Methods: HRQoL was assessed in the overall study population using the Functional Assessment of Cancer Therapy-Prostate (FACT-P) questionnaire, comprising 5 subscales: physical wellbeing (PWB), functional wellbeing (FWB), emotional wellbeing, social wellbeing, and prostate cancer subscale (PCS). The Trial Outcome Index (TOI; PWB+FWB+PCS) and FACT Advanced Prostate Symptom Index (FAPSI-6: derived from 6 FACT-P items) were also calculated. Adjusted mean change and time to deterioration in scores were statistically analyzed. Results: Baseline FACT-P total score was similar for both treatment arms. FACT-P total and subscale scores during treatment were all higher for olaparib vs pcNHA, with clinically meaningful differences between treatment arms in the adjusted least square (LS) mean changes from baseline in all but FWB and FAPSI-6 (Table). The time to deterioration in FACT-P total and TOI, FAPSI-6, PWB and PCS scores favored olaparib but were not statistically significant, with hazard ratios ranging from 0.68 to 0.94. Further HRQoL results for cohort A will also be presented. Conclusions: Olaparib delayed deterioration in HRQoL scores vs pcNHA and was associated with better HRQoL functioning over time compared with pcNHA in men with mCRPC and HRR gene alterations. Clinical trial information: NCT02987543 . [Table: see text]

Impact of olaparib vs physician’s choice of new hormonal agent (pcNHA) on burden of pain in metastatic castration-resistant prostate cancer (mCRPC): PROfound

5538

Background: In the Phase III PROfound study (NCT02987543) olaparib significantly improved radiographic progression-free survival (primary endpoint) vs pcNHA (enzalutamide or abiraterone) in patients (pts) with mCRPC and homologous recombination repair (HRR) gene alterations. In pts with alterations in BRCA1, BRCA2 and/or ATM (cohort A), time to pain progression was also significantly improved by olaparib vs pcNHA. We report additional pain analyses evaluated in the overall study population (cohort A and B). Methods: Pts were randomized to olaparib tablets (300 mg bid; n=256) or pcNHA (n=131). Pts completed the Brief Pain Inventory-Short Form (BPI–SF) questionnaire (electronic administration) every 4 weeks up to 6 months after progression or treatment crossover. Responses were analysed to determine time to progression to worst pain, pain severity and first opiate use for cancer-related pain (Kaplan-Meier), and also pain interference in daily activity (mixed model for repeated measures). Results: 85% and 76% of olaparib pts were free of pain progression (worst pain item) compared with 75% and 51% in the pcNHA arm, respectively at 6 and 12 months. The proportion of pts without pain progression (overall pain severity) also favoured olaparib (Table). Median time to first opiate use was significantly prolonged in olaparib arm compared with pcNHA arm; 18 months for olaparib vs 9 months for pcNHA (Table). BPI-SF pain interference scores were also more favourable for olaparib than pcNHA; difference in overall adjusted mean change from baseline score −0.75 (95% CI: −1.14, −0.36) P=0.0002. Further pain burden results for cohort A will also be presented. Conclusions: Olaparib reduced the burden of pain and time to first opiate use in pts with mCRPC and HRR gene alterations vs pcNHA, demonstrating a clinical and symptomatic patient benefit. Clinical trial information: NCT02987543 . [Table: see text]

Phase III study of pembrolizumab (pembro) plus enzalutamide (enza) and androgen deprivation therapy (ADT) for patients (pts) with metastatic hormone-sensitive prostate cancer (mHSPC): KEYNOTE-991

TPS5595

Background: Pembro, an anti–PD-1 antibody, has shown antitumor activity as monotherapy and in combination with other agents in metastatic castration-resistant prostate cancer (mCRPC). As the antitumor effects of enza may be pro-immunogenic, we hypothesized that combining pembro and enza could show additive or synergistic antitumor activity. Furthermore, pembro + enza previously showed antitumor activity in pts with mCRPC for whom abiraterone failed (KEYNOTE-365, NCT02861573) and in pts with mCRPC for whom enza monotherapy failed (KEYNOTE 199, NCT02787005). These data warrant further evaluation of the combination of pembro + enza when given at the initiation of ADT. Methods: KEYNOTE-991 (NCT04191096) is a phase III trial to evaluate the efficacy and safety of enza + ADT + either pembro or placebo in patients with mHSPC. Approximately 1232 pts will be randomly assigned 1:1 to receive enza 160 mg orally once daily + ADT + pembro 200 mg IV every 3 weeks (Q3W) or enza 160 mg orally once daily + ADT + placebo IV Q3W. ADT is receipt of an LHRH agonist or antagonist during study treatment or bilateral orchiectomy. Treatment will be stratified by prior docetaxel therapy (yes or no) and presence of high-volume disease (yes or no). Pts with mHSPC, with ≥2 bone lesions and/or visceral disease, who are naive to next-generation hormone agents, and who have ECOG PS 0 or 1 are eligible. Pts must provide tissue for biomarker analysis. Responses will be assessed by CT or MRI and radionuclide bone imaging per Prostate Cancer Working Group 3 (PCWG3)–modified RECIST v1.1 by blinded independent central review (BICR) Q12W from the date of randomization. Treatment will continue with pembro for up to 35 cycles, and treatment with enza will proceed continuously from day 1 of cycle 1 until disease progression, unacceptable toxicity, or withdrawal of consent. Dual primary end points are radiographic progression-free survival (PFS) per PCWG3-modified RECIST v1.1 assessed by BICR and overall survival. Secondary end points are time to first subsequent anticancer therapy, time to symptomatic skeletal-related event, PFS2 (progression after next line of therapy or death), prostate-specific antigen (PSA) response rate, time to PSA progression, PSA undetectable rate, objective response rate, duration of response, and time to radiographic soft tissue progression. Other end points are safety and patient-reported outcomes (eg, time to pain progression). Clinical trial information: NCT04191096 .

Migratory properties of pulmonary dendritic cells are determined by their developmental lineage

The chemokine receptor, CCR7, directs the migration of dendritic cells (DCs) from peripheral tissue to draining lymph nodes (LNs). However, it is unknown whether all pulmonary DCs possess migratory potential. Using novel Ccr7(gfp) reporter mice, we found that Ccr7 is expressed in CD103⁺ and a CD14(med/lo) subset of CD11b(hi) classical (c)DCs but not in monocyte-derived (mo)DCs, including Ly-6C(hi)CD11b(hi) inflammatory DCs and CD14(hi)CD11b(hi) DCs. Consequently, cDCs migrated to lung-draining LNs but moDCs did not. Mice lacking the chemokine receptor, CCR2, also lacked inflammatory DCs in the lung after lipopolysaccharide inhalation but retained normal levels of migratory DCs. Conversely, the lungs of fms-like tyrosine kinase 3 ligand (Flt3L)-deficient mice lacked cDCs but retained moDCs, which were functionally mature but did not express Ccr7 and were uniformly non-migratory. Thus, the migratory properties of pulmonary DCs are determined by their developmental lineage.

The inflammasome component NLRP3 impairs antitumor vaccine by enhancing the accumulation of tumor-associated myeloid-derived suppressor cells

The inflammasome is a proteolysis complex that generates the active forms of the proinflammatory cytokines interleukin (IL)-1β and IL-18. Inflammasome activation is mediated by NLR proteins that respond to microbial and nonmicrobial stimuli. Among NLRs, NLRP3 senses the widest array of stimuli and enhances adaptive immunity. However, its role in antitumor immunity is unknown. Therefore, we evaluated the function of the NLRP3 inflammasome in the immune response using dendritic cell vaccination against the poorly immunogenic melanoma cell line B16-F10. Vaccination of Nlrp3(-/-) mice led to a relative 4-fold improvement in survival relative to control animals. Immunity depended on CD8(+) T cells and exhibited immune specificity and memory. Increased vaccine efficacy in Nlrp3(-/-) hosts did not reflect differences in dendritic cells but rather differences in myeloid-derived suppressor cells (MDSC). Although Nlrp3 was expressed in MDSCs, the absence of Nlrp3 did not alter either their functional capacity to inhibit T cells or their presence in peripheral lymphoid tissues. Instead, the absence of Nlrp3 caused a 5-fold reduction in the number of tumor-associated MDSCs found in host mice. Adoptive transfer experiments also showed that Nlrp3(-/-) MDSCs were less efficient in reaching the tumor site. Depleting MDSCs with an anti-Gr-1 antibody increased the survival of tumor-bearing wild-type mice but not Nlrp3(-/-) mice. We concluded that Nlrp3 was critical for accumulation of MDSCs in tumors and for inhibition of antitumor T-cell immunity after dendritic cell vaccination. Our findings establish an unexpected role for Nlrp3 in impeding antitumor immune responses, suggesting novel approaches to improve the response to antitumor vaccines by limiting Nlrp3 signaling.

Alphaviral vector-transduced dendritic cells are successful therapeutic vaccines against neu-overexpressing tumors in wild-type mice

While dendritic cell (DC) vaccines can protect hosts from tumor challenge, their ability to effectively inhibit the growth of established tumors remains indeterminate. Previously, we have shown that human DCs transduced with Venezuelan equine encephalitis virus replicon particles (VRPs) were potent stimulators of antigen-specific T cells in vitro. Therefore, we investigated the ability of VRP-transduced DCs (VRP-DCs) to induce therapeutic immunity in vivo against tumors overexpressing the neu oncoprotein. Transduction of murine DCs with VRPs resulted in high-level transgene expression, DC maturation and secretion of proinflammatory cytokines. Vaccination with VRP-DCs expressing a truncated neu oncoprotein induced robust neu-specific CD8(+) T cell and anti-neu IgG responses. Furthermore, a single vaccination with VRP-DCs induced the regression of large established tumors in wild-type mice. Interestingly, depletion of CD4(+), but not CD8(+), T cells completely abrogated inhibition of tumor growth following vaccination. Taken together, our results demonstrate that VRP-DC vaccines induce potent immunity against established tumors, and emphasize the importance of the generation of both CD4(+) T cell and B cell responses for efficient tumor inhibition. These findings provide the rationale for future evaluation of VRP-DC vaccines in the clinical setting.

Expression profiles of Na+,K+-ATPase during acute and chronic hypo-osmotic stress in the blue crab Callinectes sapidus

During acclimation to dilute seawater, the specific activity of Na+,K+-ATPase increases substantially in the posterior gills of the blue crab Callinectes sapidus. To determine whether this increase occurs through regulation of pre-existing enzyme or synthesis of new enzyme, mRNA and protein levels were measured over short (<24 h) and long (18 days) time courses. Na+,K+-ATPase expression, both mRNA and protein, did not change during the initial 24-h exposure to dilute seawater (10 ppt salinity). Thus, osmoregulation in C. sapidus during acute exposure to low salinity likely involves either modulation of existing enzyme or mechanisms other than an increase in the amount of Na+,K+-ATPase enzyme. However, crabs exposed to dilute seawater over 18 days showed a 300% increase in Na+,K+-ATPase specific activity as well as a 200% increase in Na+,K+-ATPase protein levels. Thus, it appears that the increase in Na+,K+-ATPase activity during chronic exposure results from the synthesis of new enzyme. The relative amounts of mRNA for the alpha-subunit increased substantially (by 150%) during the acclimation process, but once the crabs had fully acclimated to low salinity, the mRNA levels had decreased and were not different from levels in crabs fully acclimated to high salinity. Thus, there is transient induction of the Na+,K+-ATPase mRNA levels during acclimation to dilute seawater.

Effects of hypoxia and hypercapnic hypoxia on the localization and the elimination of Vibrio campbellii in Litopenaeus vannamei, the Pacific white shrimp

Low oxygen (hypoxia) and elevated CO2 (hypercapnia, are characteristic of estuarine environments. Although hypoxia and hypercapnic hypoxia decrease the resistance of shrimp to bacterial pathogens, their direct effects on the immune system are unknown. Here we present evidence demonstrating in the penaeid shrimp Litopenaeus vannamei that both hypoxia and hypercapnic hypoxia affect the localization of bacteria, their conversion from culturable to non-culturable status (bacteriostasis), and their elimination from hemolymph and selected tissues. Shrimp were injected with a sublethal dose of a pathogenic strain of Vibrio campbellii expressing green fluorescent protein and resistance to kanamycin. Real-time polymerase chain reaction was used to determine the number of intact V. campbellii in hemolymph, gills, hepatopancreas, heart, and lymphoid organ. Selective plating was used to quantify the injected bacteria that remained culturable. We found that both hypercapnic hypoxia and hypoxia increased the percentage of culturable bacteria recovered from the hemolymph and tissues, suggesting an overall decrease in bacteriostatic activity. Hypoxia and hypercapnic hypoxia generally increased the distribution of intact V. campbellii to the hepatopancreas and the gills, which are major targets for the pathogenic effects of Vibrio spp., without affecting the number of intact bacteria in the lymphoid organ, a main site of bacterial accumulation and bacteriostatic activity.

Localization and bacteriostasis of Vibrio introduced into the Pacific white shrimp, Litopenaeus vannamei

Although numerous mechanisms of immune defense have been described in crustaceans, the tissue distribution and fate of live bacteria introduced into the host remain unclear. In the present study, Litopenaeus vannamei were injected with a sub-lethal dose of kanamycin-resistant Vibrio campbellii expressing green fluorescent protein. Accumulation of intact bacteria was quantified by real-time PCR, while bacteriostasis was quantified as the percentage of intact bacteria that could not be recovered by selective plating. Over the 240 min examined, the lymphoid organ contained the greatest number of intact V. campbellii per gram tissue as well as the lowest percentage of culturable V. campbellii compared to other tissues, including the hemolymph. In contrast, the gills and hepatopancreas accumulated intact bacteria, but contained a significantly greater percentage of culturable bacteria than the hemolymph after 240 min. These data suggest that the lymphoid organ plays a major role in bacterial uptake and bacteriostasis in penaeid shrimp.