Pembrolizumab Monotherapy for Recurrent or Metastatic Cutaneous Squamous Cell Carcinoma: A Single-Arm Phase II Trial (KEYNOTE-629)

PURPOSE

Treatment options are limited for patients with recurrent and/or metastatic (R/M) cutaneous squamous cell carcinoma (cSCC); mortality rates exceed 70% in patients with distant metastases. Here, we present the first interim analysis of the R/M cSCC cohort from the 2-cohort-locally advanced and R/M-phase II KEYNOTE-629 study.

PATIENTS AND METHODS

Patients with R/M cSCC not amenable to surgery or radiation received pembrolizumab 200 mg every 3 weeks. The primary end point was objective response rate per RECIST v1.1. Secondary end points were duration of response, disease control rate, progression-free survival, overall survival, and safety.

RESULTS

At data cutoff (April 8, 2019), median follow-up of 105 enrolled patients in the R/M cohort was 11.4 months (range, 0.4 to 16.3 months). Objective response rate was 34.3% (95% CI, 25.3% to 44.2%; 4 complete responses, 32 partial responses), and disease control rate was 52.4% (95% CI, 42.4% to 62.2%). Median duration of response was not reached (range, 2.7 to 13.1+ months; '+' refers to ongoing response at data cutoff). Median progression-free survival was 6.9 months (95% CI, 3.1 months to 8.5 months). Median overall survival was not reached (95% CI, 10.7 months to not reached). Treatment-related adverse events occurred in 66.7% of patients (n = 70), the most common of which were pruritus (n = 15; 14.3%), asthenia (n = 14; 13.3%), and fatigue (n = 13; 12.4%). Grade 3 to 5 treatment-related adverse events occurred in 5.7% (n = 6) of patients. One patient died of treatment-related cranial nerve neuropathy.

CONCLUSION

Pembrolizumab demonstrated effective antitumor activity; clinically meaningful, durable responses; and acceptable safety in primarily elderly patients with R/M cSCC, supporting its use in clinical practice. Pembrolizumab adverse events in this study were consistent with its established safety profile.

Rucaparib in Men With Metastatic Castration-Resistant Prostate Cancer Harboring a BRCA1 or BRCA2 Gene Alteration

PURPOSE

BRCA1 or BRCA2 (BRCA) alterations are common in men with metastatic castration-resistant prostate cancer (mCRPC) and may confer sensitivity to poly(ADP-ribose) polymerase inhibitors. We present results from patients with mCRPC associated with a BRCA alteration treated with rucaparib 600 mg twice daily in the phase II TRITON2 study.

METHODS

We enrolled patients who progressed after one to two lines of next-generation androgen receptor–directed therapy and one taxane-based chemotherapy for mCRPC. Efficacy and safety populations included patients with a deleterious BRCA alteration who received ≥ 1 dose of rucaparib. Key efficacy end points were objective response rate (ORR; per RECIST/Prostate Cancer Clinical Trials Working Group 3 in patients with measurable disease as assessed by blinded, independent radiology review and by investigators) and locally assessed prostate-specific antigen (PSA) response (≥ 50% decrease from baseline) rate.

RESULTS

Efficacy and safety populations included 115 patients with a BRCA alteration with or without measurable disease. Confirmed ORRs per independent radiology review and investigator assessment were 43.5% (95% CI, 31.0% to 56.7%; 27 of 62 patients) and 50.8% (95% CI, 38.1% to 63.4%; 33 of 65 patients), respectively. The confirmed PSA response rate was 54.8% (95% CI, 45.2% to 64.1%; 63 of 115 patients). ORRs were similar for patients with a germline or somatic BRCA alteration and for patients with a BRCA1 or BRCA2 alteration, while a higher PSA response rate was observed in patients with a BRCA2 alteration. The most frequent grade ≥ 3 treatment-emergent adverse event was anemia (25.2%; 29 of 115 patients).

CONCLUSION

Rucaparib has antitumor activity in patients with mCRPC and a deleterious BRCA alteration, but with a manageable safety profile consistent with that reported in other solid tumor types.

Incidence and characteristics of neurotoxicity in immune checkpoint inhibitors with focus on neuromuscular events: Experience beyond the clinical trials

Immune checkpoint inhibitors (ICIs) are associated with various neurological adverse events (NAEs). We herein explored the incidence and clinical phenotype of immune-related NAEs in cancer patients. Medical records of ICI-treated cancer patients were reviewed between the years 2010 and 2018, with an aim to characterize immuno-related NAEs. A total of 1185 ICIs-treated patients were identified, 63.7% of which were males and 36.3% were females, with a mean age of 63.4 ± 7.3 years. Twenty-four from the overall ICIs-treated patients (2%) developed NAEs. No differences were identified in terms of age, sex, tumor type and class of ICIs between the patients who developed NAEs and those who did not. The median number of cycles of ICI treatment before NAEs onset were 4.5 (1-10), and the median time was 102 days. Peripheral nervous system (PNS) involvement was present in 14 patients (58.4%) and central nervous system (CNS) involvement in 10 (33.3%), including 2 patients with aseptic meningitis and polyradicular involvement. Amongst PNS complications, there were five (20.8%) with axonal sensory neuropathies, four (16.7%) with Guillain-Barre-like syndromes, and four (16.7%) with myositis and/or myasthenic syndromes. The majority of patients with PNS-related NAEs (n = 11; 78.6%) improved after ICIs discontinuation and treatment with immune-modulating therapies. The time to neuromuscular toxicities onset was significantly shorter, compared to CNS NAEs (median 70 vs 119 days, P = .037). Immune-related NAEs mostly present with neuromuscular complications. Discontinuation of ICIs and appropriate treatment should be commenced early throughout the process, in order to maximize a favorable outcome.

KEYNOTE-365 cohort A updated results: Pembrolizumab (pembro) plus olaparib in docetaxel-pretreated patients (pts) with metastatic castration-resistant prostate cancer (mCRPC)

100

Background: KEYNOTE-365 (NCT02861573) is a phase 1b/2 study evaluating pembro + other agents in mCRPC. Updated results from cohort A (pembro + olaparib) are reported. Methods: Docetaxel-pretreated, molecularly unselected pts with mCRPC with progression within 6 mo of screening per PSA or radiologic bone/soft tissue progression enrolled. Pts may have received 1 other chemotherapy and ≤2 2nd-generation hormone therapy (HT). Pts received pembro 200 mg IV Q3W + olaparib 400 mg PO BID. Primary end points: safety, PSA response rate (confirmed PSA decline ≥50%), and ORR per blinded independent central review. Results: Of 84 treated pts, 42 discontinued, primarily due to progression (n=29). Median age was 71 y (range, 47-83); 26% were PD-L1+, 26% had visceral disease, and 57% had RECIST-measurable disease. Median follow-up was 3 mo for all pts (n=81) and 14 mo for pts with ≥27 wks’ follow-up (n=41). See Table for efficacy outcomes. Treatment-related AEs occurred in 70 (83%) pts. Most frequent (≥30%) were nausea (33%) and anemia (31%). Grade 3-5 treatment-related AEs occurred in 29 (35%) pts. Three pts died of AEs (2 treatment related [l myocardial infarction, 1 unknown cause]). Conclusions: With additional follow-up, pembro + olaparib continued to show activity in docetaxel-pretreated, molecularly unselected pts who previously received HT for mCRPC. Safety of the combination was consistent with individual profiles of each agent. Clinical trial information: NCT02861573. [Table: see text]

Update on KEYNOTE-199, cohorts 1-3: Pembrolizumab (pembro) for docetaxel-pretreated metastatic castration-resistant prostate cancer (mCRPC)

104

Background: The KEYNOTE-199 multicohort phase 2 study (NCT02787005) showed that pembro monotherapy has antitumor activity and acceptable safety in patients (pts) with mCRPC previously treated with a next-generation hormonal agent (NHA) and docetaxel in cohort 1 (C1) (RECIST-measurable, PD-L1+ disease), C2 (RECIST-measurable, PD-L1− disease), and C3 (bone-predominant disease, irrespective of PD-L1). Updated results with additional follow-up for C1-3 are presented. Methods: Pts previously received ≥1 NHAs and 1 or 2 chemotherapies, including docetaxel. Pts received pembro 200 mg Q3W for 35 cycles or until progression or intolerable toxicity. Primary end point was ORR. Key secondary end points were DCR, DOR, PSA (≥50%) response rate, rPFS, OS, and safety. Results: Of 258 pts enrolled (C1=133; C2=67; C3=58), 6 completed (C1=4; C3=2) and 252 discontinued (C1=129; C2=67; C3=56) therapy, primarily due to progression (C1=106; C2=61; C3=45). Median follow-up was 9.6 mo (C1, 9.5; C2, 7.9; C3, 14.2). ORR (95% CI) for pts with measurable disease was 6% (2.6-11.5) in C1 and 3% (0.4-10.4) in C2 (Table; includes other efficacy results). Treatment-related AEs of any grade/grade 3-5 occurred in 57%/16% in C1, 60%/15% in C2, and 71%/17% in C3. 1 pt in each cohort died of a treatment-related AE (C1, sepsis; C2, unknown; C3, immune-related pneumonitis). Conclusions: With additional follow-up, pembro monotherapy continued to show antitumor activity and disease control in pts with RECIST-measurable and bone-predominant mCRPC previously treated with both NHA and docetaxel. Pts experienced durable responses. Safety was consistent with the known safety profile of pembro. Clinical trial information: NCT02787005. [Table: see text]

KEYNOTE-365 cohort B updated results: Pembrolizumab (pembro) plus docetaxel and prednisone in abiraterone (abi) or enzalutamide (enza)-pretreated patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC)

103

Background: KEYNOTE-365 (NCT02861573) is a phase 1b/2 study to evaluate pembro in combination with other agents in mCRPC. Here we report updated results from cohort B (pembro + docetaxel and prednisone). Methods: Cohort B enrolled pts who failed or were intolerant to ≥4 wk of abi or enza in the prechemotherapy mCRPC state and whose disease progressed within 6 mo of screening as determined by PSA progression or radiologic bone/soft tissue progression. Pts received pembro 200 mg IV + docetaxel 75 mg/m2 IV Q3W and prednisone 5 mg orally twice daily. Primary end points were safety, PSA response rate (confirmed PSA decrease >50%), and ORR per blinded independent central review (BICR). Results: Of 104 treated pts, 72 discontinued, primarily due to progression (55%). Median age was 68 y (range 50-86), 24% were PD-L1+, 25% had visceral disease, and 50% had measurable disease. Median follow-up was 13 mo for all pts (n=104) and 19 mo for pts who had ≥27 wk of follow up (n=72). See table for efficacy outcomes. Treatment-related AEs occurred in 100 pts (96%); most frequent (≥30%) were alopecia, diarrhea, and fatigue (39% each). Grade 3-5 treatment-related AEs occurred in 42 pts (40%). Five pts died of AEs; 2 deaths were from treatment-related AEs (pneumonitis). Conclusions: With additional follow-up, pembro + docetaxel and prednisone continued to show activity in pts with mCRPC who failed previous antihormonal therapy. Safety of the combination was consistent with the known profiles of the individual agents and will be further evaluated in a phase 3 study (KEYNOTE-921). Clinical trial information: NCT02861573. [Table: see text]

KEYNOTE-365 cohort C updated results: Pembrolizumab (pembro) plus enzalutamide (enza) in abiraterone (abi)-pretreated patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC)

102

Background: KEYNOTE-365 (NCT02861573) is a phase 1b/2 study evaluating pembro in combination with other agents in mCRPC. An earlier report of cohort C showed activity and acceptable safety with pembro + enza. Updated results from cohort C are reported. Methods: Pts who failed or became intolerant to ≥4 wks of abi in prechemotherapy mCRPC state and whose disease progressed within 6 mo of screening per PSA progression or radiologic bone or soft tissue progression enrolled. Pts received pembro 200 mg IV Q3W with enza 160 mg/day PO. Primary end points: safety, PSA response rate (confirmed PSA decline ≥50%), and objective response rate (ORR) per blinded independent central review. Key secondary end points: disease control rate (DCR), duration of response (DOR), time to PSA progression, rPFS, and OS. Results: Of 102 treated pts, 73 discontinued, primarily due to progression (60%). Median age was 70 y (range, 43-87), 29% were PD-L1+, 17% had visceral disease, and 39% had measurable disease. Median follow up was 13 mo for all patients (n=102) and 17 mo for patients with ≥27 wks’ follow-up (n=69). See Table for efficacy outcomes. Treatment-related AEs occurred in 92 pts (90%); most frequent (≥20%) were fatigue (38%), nausea (22%), and rash (20%). Grade 3-5 treatment-related AEs occurred in 40 pts (39%). Three pts died of AEs (1 AE was treatment related [cause unknown]). Conclusions: With additional follow-up, pembro + enza continued to show activity in pts with abi-pretreated mCRPC. Safety of the combination was consistent with known profiles of pembro and enza. Clinical trial information: NCT02861573. [Table: see text]

Phase III study of pembrolizumab (pembro) plus docetaxel and prednisone for enzalutamide (enza)- or abiraterone acetate (abi)–pretreated patients (pts) with metastatic castration-resistant prostate cancer (mCRPC): KEYNOTE-921

TPS262

Background: Docetaxel is an established treatment for pts with mCRPC. Pembro, a PD-1 inhibitor, showed single-agent antitumor activity in mCRPC. In the phase 1b/2 KEYNOTE-365 study (NCT02861573), docetaxel + pembro and prednisone showed activity in pts treated with abi or enza for mCRPC, warranting further evaluation. Methods: KEYNOTE-921 (NCT03834506) is a phase 3 trial to evaluate efficacy and safety of pembro + docetaxel and prednisone in chemotherapy-naive pts who progressed with enza or abi therapy for mCRPC. An estimated 1000 pts will be randomly assigned 1:1 to receive docetaxel 75 mg/m2 IV every 3 weeks (Q3W) + prednisone/prednisolone orally 5 mg twice daily (BID) and pembrolizumab 200 mg IV Q3W or docetaxel 75 mg/m2 IV Q3W + prednisone/prednisolone 5 mg orally BID + placebo IV Q3W. Treatment will be stratified by previous next-generation hormone agent (abi or enza) and metastases location (bone only, liver, other). Adults (≥18 years) with histologically or cytologically confirmed mCRPC who progressed with androgen deprivation therapy (or postbilateral orchiectomy) ≤6 months of screening, have ECOG PS 0 or 1, and have adequate organ function are eligible. Pts must have experienced either progression after ≥8 weeks (≥14 weeks for bone progression) or intolerance after ≥4 weeks of abi or enza (but not both) in a chemotherapy-naive mCRPC state. Pts will be required to 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) Q9W during the first year and Q12W thereafter. Treatment will continue with docetaxel and prednisone for up to 10 cycles and with pembro for up to 35 cycles or until disease progression, unacceptable toxicity, or consent withdrawal. Primary end points are rPFS by BICR and OS. Secondary end points are time to initiation of subsequent anticancer therapy or death, PSA response rate, time to PSA progression, ORR and DOR per PCWG3-modified RECIST v1.1 assessed by BICR, and safety. Accrual began May 2, 2019. Clinical trial information: NCT03834506.

Pembrolizumab for Treatment-Refractory Metastatic Castration-Resistant Prostate Cancer: Multicohort, Open-Label Phase II KEYNOTE-199 Study

PURPOSE

Pembrolizumab has previously shown antitumor activity against programmed death ligand 1 (PD-L1)-positive metastatic castration-resistant prostate cancer (mCRPC). Here, we assessed the antitumor activity and safety of pembrolizumab in three parallel cohorts of a larger mCRPC population.

METHODS

The phase II KEYNOTE-199 study included three cohorts of patients with mCRPC treated with docetaxel and one or more targeted endocrine therapies. Cohorts 1 and 2 enrolled patients with RECIST-measurable PD-L1-positive and PD-L1-negative disease, respectively. Cohort 3 enrolled patients with bone-predominant disease, regardless of PD-L1 expression. All patients received pembrolizumab 200 mg every 3 weeks for up to 35 cycles. The primary end point was objective response rate per RECIST v1.1 assessed by central review in cohorts 1 and 2. Secondary end points included disease control rate, duration of response, overall survival (OS), and safety.

RESULTS

Two hundred fifty-eight patients were enrolled: 133 in cohort 1, 66 in cohort 2, and 59 in cohort 3. Objective response rate was 5% (95% CI, 2% to 11%) in cohort 1 and 3% (95% CI, < 1% to 11%) in cohort 2. Median duration of response was not reached (range, 1.9 to ≥ 21.8 months) and 10.6 months (range, 4.4 to 16.8 months), respectively. Disease control rate was 10% in cohort 1, 9% in cohort 2, and 22% in cohort 3. Median OS was 9.5 months in cohort 1, 7.9 months in cohort 2, and 14.1 months in cohort 3. Treatment-related adverse events occurred in 60% of patients, were of grade 3 to 5 severity in 15%, and led to discontinuation of treatment in 5%.

CONCLUSION

Pembrolizumab monotherapy shows antitumor activity with an acceptable safety profile in a subset of patients with RECIST-measurable and bone-predominant mCRPC previously treated with docetaxel and targeted endocrine therapy. Observed responses seem to be durable, and OS estimates are encouraging.

T-Type Calcium Channels as Potential Therapeutic Targets in Vemurafenib-Resistant BRAFV600E Melanoma

Melanoma is a malignant neoplasia that is highly resistant to chemotherapy and radiotherapy and is associated with poor prognosis in advanced stage. Targeting melanoma that harbors the common BRAF^V600E mutation with kinase inhibitors, such as vemurafenib, reduces tumor burden, but these tumors frequently acquire resistance to these drugs. We previously proposed that T-type calcium channel (TTCC) expression may serve as a biomarker for melanoma progression and prognosis, and we showed that TTCC blockers reduce migration and invasion rates because of autophagy blockade only in BRAF^V600E-mutant melanoma cells. Here, we demonstrated that high expression of the TTCC Cav3.1 isoform is related to autophagic status in vemurafenib-resistant BRAF^V600E-mutant melanoma cells and human biopsies, and in silico analysis revealed an enrichment of Cav3.1 expression in post-treatment melanomas. We also demonstrated that the TTCC blocker mibefradil induces apoptosis and impairs migration and invasion via inhibition of autophagy in resistant melanoma cells and mouse xenograft models. Moreover, we identified an association between PTEN status and Cav3.1 expression in these cells as a marker of sensitivity to combination therapy in resistant cells. Together, our results suggest that TTCC blockers offer a potential targeted therapy in resistant BRAF^V600E-mutant melanoma and a therapeutic strategy to reduce progression toward BRAF inhibitor resistance.

P10.04 Incidence and characteristics of neurological adverse events secondary to immunotherapy with checkpoint inhibitors

BACKGROUND

To explore the incidence and clinical phenotype of serious neurological adverse events (NAEs) in cancer patients who received immunotherapy with checkpoint inhibitors (ICIs) at two institutions.

MATERIAL AND METHODS

We reviewed files of cancer patients who were treated with ICIs from 2010 to 2018 and then searched for ICIs-related NAEs.

RESULTS

We identified 1185 ICIs-treated patients. Males and females were 63.7% and 36.3%, respectively, with a mean age of 63.4±7.3 years-old. Nivolumab was given to 536 (45.2%) patients, Pembrolizumab to 301 (25.4%) patients, Atezolizumab to 135 (11.4%), Ipilimumab to 104 (8.8%), Durvalumab-Tremelimumab to 77 (6.5%), and other ICIs to 32 (2.8%). Of those patients, 24 (2%) developed a ICI-related NAE. No differences were identified in age, sex, tumor type and class of ICIs between patients who developed neurotoxicity compared to those without neurologic adverse events. The distribution of NAE by agent was: Nivolumab (2.1%), Pembrolizumab (2%), Atezolizumab (1.5%), Ipilimumab (1%), Durvalumab-Tremelimumab (3.9%), and others (2.8%). The median number of cycles received before NAEs onset were 4.5 (1–10), and the median time was 110 days. PNS involvement was evident in 14 patients (58.3%) and CNS involvement in 41.7%, while 2 patients with aseptic meningitis also presented polyradicular involvement. Among PNS complications, there were 5 cases (20.8%) with axonal sensory neuropathies, 4 (16.7%) with Guillain-Barre-like syndromes, 4 (16.7%) with muscle involvement (myositis and myasthenias), and one with other syndromes. Seven patients (50%) with PNS-related NAEs were treated with steroids, 2 (14.3%) with IVIG, and 5 (35.7%) remained untreated. In general the outcome was good after ICIs discontinuation, with about half of patients improving or completely resolving NAEs.

CONCLUSION

ICIs-related NAE although rare overall, might be severe, and are mostly represented by neuromuscular complications. Early discontinuation of ICIs and possibly treatment with immune-modulating therapies should early be initiated to achieve a favourable neurological outcome

New perspectives on screening and early detection of endometrial cancer

Due to the anatomical continuity of the uterine cavity with the cervix, genomic exploitation of material from routine Pap smears and other noninvasive sampling methods represent a unique opportunity to detect signs of disease using biological material shed from the upper genital tract. Recent research findings offer a promising perspective in the detection of endometrial cancer, but certain questions need to be addressed in order to accelerate the implementation of novel technologies in a routine screening or clinical setting. We discuss here new perspectives on detection of endometrial cancer using genomic and other biomarkers in minimally invasive sampling methods with a special focus on public health classic screening criteria, highlighting current gaps in knowledge.

KEYNOTE-629: Phase 2 study of pembrolizumab for recurrent/metastatic or locally advanced unresectable cutaneous squamous cell carcinoma (cSCC)

TPS9598

Background: Findings from phase 1 and 2 studies suggest that targeting programmed death 1 (PD-1)/PD-L1 pathway can provide durable antitumor activity in patients with local/regionally advanced or metastatic cSCC and may be a promising treatment option. The open-label, single-arm, phase 2 KEYNOTE-629 trial (NCT03284424) will be conducted to test the clinical activity of the PD-1 inhibitor pembrolizumab in locally advanced, unresectable, and recurrent or metastatic cSCC. Methods: Patients will receive intravenous pembrolizumab 200 mg every 3 weeks for up to 35 infusions (≤24 months) or until protocol-specified treatment discontinuation. Treatment will not be stratified in this study. Eligibility criteria include age ≥18 years; locally advanced cSCC for which the patient is ineligible for resection or radiotherapy (RT) or for which the patient previously underwent RT to the index site or systemic therapy for curative intent; presence of measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1; and Eastern Cooperative Oncology Group performance status 0 or 1. Treatment will be discontinued for progressive disease, unacceptable toxicity, intercurrent illness preventing administration, investigator’s decision, patient withdrawal of consent, pregnancy, or cessation for administrative reasons. Response will be assessed by imaging 6 weeks after treatment initiation, every 6 weeks through year 1, and every 9 weeks thereafter or more frequently if clinically indicated. After disease progression or the start of new anticancer therapy, the patient will be followed up every 12 weeks until death, consent withdrawal, or study end, whichever occurs first. Safety will be monitored throughout the study and for 30 days after treatment end or 90 days if the patient experiences serious adverse events. The primary end point is objective response rate (RECIST v1.1). Secondary end points include response duration, disease control rate, progression-free survival, overall survival, and safety. Recruitment is ongoing in 10 countries and will continue until approximately 50 additional patients with locally advanced, unresectable cSCC are enrolled. Clinical trial information: NCT03284424.

Pamiparib, an investigational PARP inhibitor, in patients with metastatic castration-resistant prostate cancer (mCRPC) and a circulating tumor cell (CTC) homologous recombination deficiency (HRD) phenotype or BRCA defects: A trial in progress

TPS5086

Background: Men with mCRPC who have a BRCA1/2 mutation ( BRCA1/2mut) or mutations in other genes resulting in HRD have a poor prognosis. A novel liquid biopsy test (EPIC Sciences) identifies CTCs with an HRD phenotype. Preliminary studies showed that these men may respond to treatment with a PARP inhibitor. Pamiparib, an investigational PARP1/2 inhibitor, has shown brain penetration and potent PARP–DNA complex trapping in nonclinical studies. In early phase clinical studies (NCT02361723; NCT03333915), pamiparib was generally well tolerated and showed preliminary antitumor activity; 60 mg orally twice daily (BID) was established as the recommended investigational dose. Methods: This open-label, global, phase 2 study (NCT03712930) evaluates the antitumor activity and safety/tolerability of pamiparib in mCRPC patients (pts) with CTC-HRD, assessed by the CTC-HRD assay, or deleterious germline/somatic mutations in BRCA1/2. Patients must have progressed on/after ≥1 androgen receptor-targeted therapy, received ≥1 taxane-based therapy, and have prostate-specific antigen (PSA) progression per PCWG3 criteria. Four cohorts of pts will receive pamiparib 60 mg BID in 28-day cycles. Cohort 1 will include ~50 pts with CTC-HRD+ +/- BRCA1/2mut mCRPC with measurable metastatic disease; Cohort 2 will include ~30 pts with CTC-HRD+ +/- BRCA1/2mut mCRPC with bone-only disease; Cohorts 3 & 4 will include ~20 pts with CTC-HRD-/unk + BRCA1/2mut mCRPC with measurable metastatic disease (Cohort 3), or bone-only disease (Cohort 4). Disease status will be assessed every 8 wks for 24 wks, then every 12 wks; PSA levels will be tested every 4 wks. Co-primary endpoints are radiographic ORR assessed by IRC (pts with measurable disease) and confirmed PSA response rate per PCWG3 criteria (pts +/- measurable disease). Secondary endpoints include ORR, time to PSA response/progression, duration of PSA response, time to symptomatic skeletal event, radiographic progression-free survival, overall survival, and safety. As of 05 December 2018, this study is actively enrolling. Clinical trial information: NCT03712930.

Pembrolizumab (pembro) plus olaparib in docetaxel-pretreated patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC): Cohort A of the phase 1b/2 KEYNOTE-365 study

5027

Background: Individual activity with pembro or olaparib has been observed in mCRPC pts who progressed on second-generation hormone therapy (HT) and chemotherapy. Data from cohort A (pembro+olaparib) of KEYNOTE-365 (NCT02861573), a phase 1b/2 umbrella study to test combinations in mCRPC, are presented. Methods: Pts with mCRPC who progressed within 6 mo before screening, were docetaxel-pretreated (up to 1 other chemotherapy permitted) for mCRPC and had ≤2 second-generation HTs were eligible. Pts received pembro 200 mg IV Q3W+olaparib 400 mg orally twice daily. Primary end points: safety and PSA response rate (confirmed PSA decrease ≥50%). Key secondary end points: ORR per RECIST v1.1 (investigator review), disease control rate (DCR: CR+PR+SD ≥6 mo), time to PSA progression, composite response rate, rPFS, and OS. Results: Median (95% CI) follow-up was 11 (6-15) mo. 41 pts initiated treatment (median age, 69 y; visceral disease, 42%; RECIST-measurable, 68%; homologous recombination deficient detected, 0%). Efficacy is outlined in the table. Treatment-related AEs occurred in 39 (95%) pts; most frequent (≥30%) were anemia (37%), fatigue (34%), and nausea (34%). Grade 3-5 treatment-related AEs occurred in 21 (51%) pts. There were 2 deaths; 1 was treatment-related (cause unknown). Conclusions: Pembro+olaparib had activity in pts with mCRPC who were molecularly unselected and were previously treated with docetaxel and second-generation HT. The observed safety profile for the combination is consistent with individual profiles of pembro and olaparib. Clinical trial information: NCT02861573. [Table: see text]

Pembrolizumab (pembro) plus docetaxel and prednisone in abiraterone (abi) or enzalutamide (enza)-pretreated patients (pts) with metastatic castrate resistant prostate cancer (mCRPC): Cohort B of the phase 1b/2 KEYNOTE-365 study

5029

Background: Pembro had activity as monotherapy in pretreated advanced mCRPC. Data are presented here from cohort B (pembro + docetaxel/prednisone) of KEYNOTE-365 (NCT02861573), a phase 1b/2 umbrella study to test combinations in mCRPC. Methods: Pts who progressed on or became intolerant to ≥4 wk of abi or enza in the prechemotherapy mCRPC state and progressed within 6 mo before screening were eligible. Pts received pembro 200 mg IV with docetaxel 75 mg/m2 IV Q3W plus prednisone 5 mg orally twice daily. The primary end points were safety and PSA response rate (confirmed PSA decrease ≥50%). Key secondary end points were investigator-determined ORR (RECIST v1.1), disease control rate (DCR: CR+PR+SD ≥6 mo), time to PSA progression, rPFS, and OS. Results: 72 pts (median age, 68 y; visceral disease, 36%; measurable disease, 50%) began pembro + docetaxel. Median (95% CI) follow-up was 10 (8-12) mo. Efficacy is outlined in the table. Treatment-related AEs occurred in 69 (96%) pts; most frequent (≥30%) were alopecia (43%), fatigue (40%), and diarrhea (39%). Grade 3-5 treatment-related AEs occurred in 27 (38%) pts, including 2 deaths from treatment-related AEs (pneumonitis). Most commonly reported immune-mediated AEs were infusion-related reactions (11%) and colitis (10%). Conclusions: Pembro + docetaxel/prednisone has activity in pts with mCRPC who previously progressed on second-generation hormone therapy. AEs were considered mild for the treatment combination. Clinical trial information: NCT02861573. [Table: see text]

Keynote-365 cohort b: Pembrolizumab (pembro) plus docetaxel and prednisone in abiraterone (abi) or enzalutamide (enza)-pretreated patients (pts) with metastatic castrate resistant prostate cancer (mCRPC)

170

Background: Pembro had antitumor activity as monotherapy in pretreated advanced mCRPC (KEYNOTE-028; KEYNOTE-199). KEYNOTE-365 (NCT02861573) is a phase 1b/2 umbrella study testing combinations in mCRPC; we report early results from cohort B combining pembro + docetaxel in mCRPC. Methods: Pts who failed or became intolerant to ≥4 weeks of abi or enza in the pre-chemotherapy mCRPC state received pembro 200 mg IV with docetaxel 75 mg/m2 IV Q3W plus prednisone 5 mg orally twice daily. Pts also progressed within 6 months prior to screening as determined by either PSA progression or radiologic progression in bone or soft tissue. Response was evaluated by PSA levels Q3W and imaging Q9W for first year and Q12W thereafter. Primary end points: safety and PSA response rate (confirmed PSA decline ≥50%). Key secondary end points: investigator-determined ORR (RECIST v1.1), disease control rate (DCR: CR+PR+SD ≥6 mo), time to PSA progression, rPFS, and OS. Results: 72 pts (median age 68 years; PD-L1+ 29%; visceral disease 36%; measurable disease 50%) initiated pembro + docetaxel. Median (95% CI) follow-up was 10 (8-12) mo. Efficacy is outlined in table below. Treatment-related AEs occurred in 69 (96%) pts; most frequent (≥30%) were alopecia (43%), fatigue (40%), and diarrhea (39%). Grade 3-5 treatment-related AEs occurred in 27 (38%) pts, including 2 deaths due to treatment-related AEs (pneumonitis). Conclusions: Combination of pembro + docetaxel/prednisone has activity in pts with mCRPC previously failing anti-hormonal therapy. Observed safety profile for the combination was consistent with known safety profile of each component. Clinical trial information: NCT02861573. [Table: see text]

Keynote-365 cohort a: Pembrolizumab (pembro) plus olaparib in docetaxel-pretreated patients (pts) with metastatic castrate-resistant prostate cancer (mCRPC)

145

Background: Activity with pembro or olaparib has been observed in mCRPC pts who progressed on 2nd-generation hormonal therapy (HT) and chemotherapy. From KEYNOTE-365 (NCT02861573), a phase 1b/2 umbrella study testing combinations in mCRPC, we report early results from cohort A combining pembro + olaparib. Methods: Pts with mCRPC were eligible if they progressed within 6 months prior to screening determined by either PSA progression or radiologic progression in bone or soft tissue. Pts were docetaxel-pretreated for mCRPC, may have received 1 other chemotherapy, and had ≤2 2nd-generation HT. Pts received pembro 200 mg IV Q3W + olaparib 400 mg orally twice daily. Primary end points: safety and PSA response rate (confirmed PSA decline ≥50%). Key secondary end points: ORR RECIST v1.1 (investigator review), disease control rate (DCR: CR+PR+SD ≥6 mo), time to PSA progression, composite response rate (ORR RECIST v1.1, confirmed PSA response, or confirmed decrease in circulating tumor cell count from ≥5 to <5 cells/7.5 mL blood), rPFS, and OS. Results: Median follow-up was 11 mo. 41 initiated treatment (median age 69 years; PD-L1+ 27%; visceral disease 42%; RECIST-measurable 68%; homologous recombination repair mutation [HRR] 0%). See efficacy in table below. Treatment-related AEs occurred in 39 (95%) pts. Most frequent (≥30%) were anemia (37%), fatigue (34%), and nausea (34%). Grade 3-5 treatment-related AEs were in 21 (51%) pts. There were 2 deaths; only 1 was treatment-related (cause unknown). Conclusions: Combination of pembro + olaparib has activity in pts previously treated with docetaxel and ≤2 2nd-generation HT for mCRPC and who are HRR wild type. Observed safety profile for the combination is consistent with individual profiles of pembro and olaparib. Clinical trial information: NCT02861573. [Table: see text]

A phase II trial in progress: Pamiparib, an investigational PARP inhibitor, in patients with metastatic castration-resistant prostate cancer and a circulating tumor cell homologous recombination deficiency (HRD) phenotype or BRCA defects

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Background: Men with metastatic castration-resistant prostate cancer (mCRPC) who have a BRCA1/2 mutation ( BRCA1/2mut) or mutations in other HRD genes have a poor prognosis. The EPIC liquid biopsy test is a novel assay that can identify circulating tumor cells (CTC) with HRD associated phenotypes. Preliminary studies have shown that these men may respond to treatment with a PARP inhibitor. Pamiparib is an investigational PARP1/2 inhibitor that has shown brain penetration and potent PARP–DNA complex trapping in nonclinical studies. In early phase clinical studies (NCT02361723; NCT03333915), pamiparib was generally well tolerated and showed preliminary antitumor activity; 60 mg orally twice daily (BID) was established as the recommended investigational dose. Methods: This open-label, global, phase 2 study (NCT03712930) will evaluate antitumor activity and safety of pamiparib in mCRPC pts with CTC-HRD, assessed by the EPIC CTC-HRD assay, or deleterious germline/somatic BRCA1/2mut status. Patients must have progressed on/after ≥1 androgen receptor-targeted therapy, have received ≥1 taxane-based therapy, and have prostate-specific antigen (PSA) progression per PCWG3 criteria. Four cohorts of patients will receive pamiparib 60 mg BID in 28-day cycles. Cohort 1 will include ~50 pts with CTC-HRD+ +/- BRCA1/2mut mCRPC with measurable metastatic disease; Cohort 2 will include ~30 pts with CTC-HRD+ +/- BRCA1/2mut mCRPC with bone-only disease; Cohorts 3 & 4 will include ~20 pts with CTC-HRD-/unknown + BRCA1/2mut mCRPC with measurable metastatic disease (Cohort 3), or bone-only disease (Cohort 4). Disease status will be assessed every 8 wks for 24 wks, then every 12 wks; PSA levels will be tested every 4 wks. Co-primary endpoints are radiographic ORR assessed by IRC (pts with measurable disease) and confirmed PSA response rate per PCWG3 criteria (pts +/- measurable disease). Secondary endpoints include ORR, time to PSA response/progression, duration of PSA response, time to symptomatic skeletal event, radiographic progression-free survival, overall survival, and safety. Clinical trial information: NCT03712930.

Pembrolizumab for metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel: Updated analysis of KEYNOTE-199

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Background: Previously presented data from cohorts (C) 1-3 of the phase 2 KEYNOTE-199 study (n = 258; NCT02787005) showed that pembrolizumab monotherapy had antitumor activity and acceptable safety in patients (pts) with mCRPC previously treated with next-generation hormonal agents (NHAs; eg, abiraterone, enzalutamide) and docetaxel. Activity was observed for both PD-L1–positive and negative cohorts and in RECIST-measurable and bone-predominant disease. We present data from KEYNOTE-199 C1, C2, and C3 based on longer-follow-up. Methods: C1 enrolled 133 pts with RECIST-measurable, PD-L1–positive disease, C2 enrolled 66 pts with RECIST-measurable, PD-L1–negative disease, and C3 enrolled 59 pts with nonmeasurable, bone-predominant disease. All pts had ECOG PS 0-2 and received ≥1 NHA and 1-2 prior chemotherapies including docetaxel. Pembrolizumab 200 mg Q3W was given for 35 cycles or until PD or intolerable toxicity. Response was assessed Q9W in yr 1, then Q12W. Primary end point was ORR per RECIST v1.1 by central review. Key secondary end points included DCR (CR + PR + SD ≥6 mo), duration of response (DOR), OS, and safety. Results: Median follow-up as of Aug 21, 2018, was 9.5 mo in C1, 7.9 mo in C2, and 14.1 mo in C3. ORR (95% CI) was 5% (2-11) in C1 and 3% ( < 1-11) in C2. DCR was 10% in C1, 9% in C2, and 22% in C3 per RECIST v1.1. Median (range) DOR was not reached (1.9-21.8+ mo) in C1 and 10.6 mo (4.4-16.8) in C2; KM estimates of DOR ≥12 mo were 71% and 50%. Median (95% CI) OS was 9.5 mo (6.4-11.9) in C1, 7.9 mo (5.9-10.2) in C2, and 14.1 (10.8-17.6) in C3. 12-mo OS rates were 41% in C1, 35% in C2, and 62% in C3; 18-mo rates were 30%, 21%, and 36%. Grade 3-5 drug-related AE rates were 15% in C1, 14% in C2, and 17% in C3. There were 2 drug-related deaths (n = 1 each sepsis and pneumonitis). Conclusions: Pembrolizumab shows antitumor activity and disease control with acceptable safety in RECIST-measurable and bone-predominant mCRPC previously treated with NHAs and docetaxel. Responses are durable, and the observed OS benefit is promising. Clinical trial information: NCT02787005.

Impact of treatment sequence in metastatic castration-resistant prostate cancer (mCRPC) on outcome in a prospective cohort study

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Background: Abiraterone (Abi), enzalutamide (Enza) and docetaxel (Doc) are all valid first-line (1L) mCRPC treatment options. Evidence suggests a degree of cross-resistance between agents, which may impact the efficacy of subsequent lines of therapy. Evidence on the optimal treatment sequence is lacking. Methods: We evaluated the outcome of patients (pts) treated with 1L Doc, Abi or Enza in the prospective PROREPAIR-B cohort study. We assessed the impact of 1L treatment option (Doc vs Abi/Enza) on overall survival (OS), progression-free survival (PFS) to 1L-therapy (PCWG2) and PFS2 (time from initiation of 1L-therapy to progression on second-line [2L] therapy). Uni- (UV) and multivariable (MV) cox-regression models were used. MV model covariates included age (≥75 years), local therapy, Gleason Score, metastases at diagnosis, visceral metastases, ALP (≥ULN), LDH (≥ULN), haemoglobin (≤LNL), albumin (≤LNL) and ECOG PS. Results: 406 pts received 1L-Doce (N=188) or Abi/Enza (N=218). Pts receiving Doc were younger (p=0.002), had higher rates of visceral metastases (17.6 vs 8.7%; p=0.008), ALP (52.1% vs 40.4%; p=0.018), LDH (48.1% vs 31.2%; p<0.001) and lower Hb (7.4 vs 2.8%; p=0.029) and albumin (11.3 vs 4.6%). PFS was higher in pts receiving 1L-Abi/Enza (10.8 vs 8.3 months; HR:0.5; p<0.001). Pts receiving 1L Abi/Enza had higher rates of radiographic progression (88.4 vs 80%; p=0.032). 123/188 pts treated with 1L-Doc received 2L-Abi/Enza: 30 received other 2L and 35 had not started 2L. 111/216 pts treated with 1L-Abi/Enza received 2L-Doc, 26 were started on other 2L and 79 had not initiated 2L. A significant difference between pts treated with initial Abi/Enza vs Doc was observed in PFS2 (20.6 vs 16.6m; HR:0.78; p=0.006) but not OS (31.3 vs 29.9 m; HR:1.05; p=0.725). Choice of first-line agent was not associated with OS in the MV model. Conclusions: Despite longer PFS to 1L and PFS2 in pts treated with initial Abi/Enza, no differences in OS were observed between treatment sequences starting with Doc vs Abi/Enza. Pts treated with 1L-Doc had worse baseline prognostic features. Molecular stratification may enable biomarker-driven patient selection to optimize benefit in pts. (NCT03075735).

Correlation between time to PSA progression (TTPP), radiographic progression-free survival (rPFS) and overall survival (OS) in first-line abiraterone/enzalutamide (Abi/Enza) and docetaxel (Doc) treated patients in a prospective cohort study

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Background: Abiraterone, enzalutamide and docetaxel represent first-line (1L) treatment options in mCRPC. A significant correlation between rPFS and OS has been reported for patients treated with 1L abi and enza in mCRPC. It is however unclear whether TTPP or rPFS present a similar magnitude of correlation with OS in Doc-treated pts. Methods: We evaluated the association of TTPP and rPFS with OS in pts treated with 1L Abi/Enza or Doc in a prospective multicenter observational cohort study. TTPP and rPFS were defined as per PCWG2. Correlation between TTPP and rPFS with OS was evaluated with Spearman rho coefficients (r), and by calculating the concordance index (c-index) in Cox-regression models. Results: 406 out of 419 pts received 1L Abi/Enza or Doc. After a median follow-up of 40 months (m), 253 mCRPC-related deaths were observed, with a median OS of 31.3 m (95% CI: 27.6-35). Median rPFS and TTPP were 10.8 m (95% CI:9.7-11.9) and 7.2 m (95% CI:6.7-7.7), respectively. Significant correlations between rPFS/TTPP and OS were observed in all pts treated at 1L, as well as in Abi/Enza and Doc treated pts (Table). R and c-index were consistently higher in Abi/Enza treated pts than in Doc treated pts, with a higher difference in predictive accuracy of the Cox regression model observed when comparing the association between TTPP and OS (c-index 0.788 in Abi/Enza treated pts vs 0.627 in Doc treated pts). Conclusions: Differences in r and c-index were observed when evaluating the association between TTPP/rPFS and OS in Abi/Enza and Doc treated pts, suggesting rPFS and TTPP may better predict OS in Abi/Enza than in Doc-treated pts. Indirect comparisons of TTPP in Abi/Enza vs Doc pts may therefore not reflect their true impact on OS. Further insight on the exact significance of TTPP is needed. Clinical trial information: NCT03075735. [Table: see text]

Treatment efficacy of abiraterone (abi), enzalutamide (enza) or cabazitaxel (caba) in metastasic castration-resistant prostate cancer patients (mCRPC) after progression to docetaxel plus androgen deprivation therapy (ADT) in hormone sensible disease

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Background: Different treatments efficacy for mCRPC when progression after docetaxel x 6 cycles + ADT (as CHAARTED scheme) are unknown as all pivotal trials where performed in patients who progressed to mCPRC after ADT. Methods: A retrospective analysis of 175 mCRPC patients of 10 spanish hospitals who were treated with docetaxel + ADT as first line treatment was performed. Patients characteristics at diagnosis (age, gleason) and at progression to mCRPC were analyzed (PSA, presence of visceral mets, type of progression). As efficacy endpoints, clinical and objective response, and survival from progression to mCRPC were analyzed. Results: Median age at diagnosis 65.2 years old (range 44-84). Metastatic at diagnosis 173. Bone metastasis 155 (88,5%), visceral 31 (17.7%), gleason >7 130 (74,3%), number docetaxel cycles: 6 (80%), 5 (5,7%), <5 (14,3 %). Median survival from diagnosis: 35 months. Progression to CRPC 78pts (44.5%) Type of progression: PSA 74/78 (94,9%), clinical 45/78 (57.7%), radiological 59/78 (75.6%). Median survival from progression to CRPC: 10.3 months. Treatments frequency, clinical benefit (RP/EE) and median survival: abi 30 (38.4%)/ 7(23.3%)/ 15.7 m; enza 12 (15.4%)/ 4 (33.3%)/ 10.4 m, caba 14(17.9%)/ 3(21.4%)/ 6.4m; Other treatments frequency: Ra223 4 (5.1%), docetaxel 4 (5.1%), others/no treatment/BSC 14 (17.8%). Clinical and radiological progression before treatment was 36.7%/63.3% in abi patients, 58.3%/63.7% in enza and 93.9%/93.9% in caba pts. Visceral (mostly hepatic) metastasis were more frequent in caba (57.1%) than in abi (11.8%) or enza (0%) pts. Median PSA value abi 375/ caba 1633. Conclusions: Although AA seems be more effective than cabazitaxel in mCRPC progressed after docetaxel + ADT in HSPC, patients treated with caba are of worse prognosis.

Selumetinib in Combination With Dacarbazine in Patients With Metastatic Uveal Melanoma: A Phase III, Multicenter, Randomized Trial (SUMIT)

Purpose Uveal melanoma is the most common primary intraocular malignancy in adults with no effective systemic treatment option in the metastatic setting. Selumetinib (AZD6244, ARRY-142886) is an oral, potent, and selective MEK1/2 inhibitor with a short half-life, which demonstrated single-agent activity in patients with metastatic uveal melanoma in a randomized phase II trial. Methods The Selumetinib (AZD6244: ARRY-142886) (Hyd-Sulfate) in Metastatic Uveal Melanoma (SUMIT) study was a phase III, double-blind trial ( ClinicalTrial.gov identifier: NCT01974752) in which patients with metastatic uveal melanoma and no prior systemic therapy were randomly assigned (3:1) to selumetinib (75 mg twice daily) plus dacarbazine (1,000 mg/m2 intravenously on day 1 of every 21-day cycle) or placebo plus dacarbazine. The primary end point was progression-free survival (PFS) by blinded independent central radiologic review. Secondary end points included overall survival and objective response rate. Results A total of 129 patients were randomly assigned to receive selumetinib plus dacarbazine (n = 97) or placebo plus dacarbazine (n = 32). In the selumetinib plus dacarbazine group, 82 patients (85%) experienced a PFS event, compared with 24 (75%) in the placebo plus dacarbazine group (median, 2.8 v 1.8 months); the hazard ratio for PFS was 0.78 (95% CI, 0.48 to 1.27; two-sided P = .32). The objective response rate was 3% with selumetinib plus dacarbazine and 0% with placebo plus dacarbazine (two-sided P = .36). At 37% maturity (n = 48 deaths), analysis of overall survival gave a hazard ratio of 0.75 (95% CI, 0.39 to 1.46; two-sided P = .40). The most frequently reported adverse events (selumetinib plus dacarbazine v placebo plus dacarbazine) were nausea (62% v 19%), rash (57% v 6%), fatigue (44% v 47%), diarrhea (44% v 22%), and peripheral edema (43% v 6%). Conclusion In patients with metastatic uveal melanoma, the combination of selumetinib plus dacarbazine had a tolerable safety profile but did not significantly improve PFS compared with placebo plus dacarbazine.