Pembrolizumab for advanced urothelial carcinoma: exploratory ctDNA biomarker analyses of the KEYNOTE-361 phase 3 trial.

Circulating tumor DNA (ctDNA) is emerging as a potential biomarker in early-stage urothelial cancer but its utility in metastatic disease remains unknown. In the phase 3 KEYNOTE-361 study, pembrolizumab with and without chemotherapy was compared with chemotherapy alone in patients with metastatic urothelial cancer. The study did not meet prespecified efficacy thresholds for statistical significance. To identify potential biomarkers of response, we retrospectively evaluated association of pre- and post-treatment ctDNA with clinical outcomes in a subset of patients who received pembrolizumab (n = 130) or chemotherapy (n = 130) in KEYNOTE-361. Baseline ctDNA were associated with best overall response (BOR;P = 0.009), progression-free survival (PFS;P < 0.001), and overall survival (OS;P < 0.001) for pembrolizumab, but not chemotherapy (all, P > 0.05). Chemotherapy induced larger ctDNA decreases from baseline to treatment cycle 2 than pembrolizumab; however, change with pembrolizumab (n = 87) were more associated with BOR (P = 4.39 × 10-5) and OS (P = 7.07 × 10-5) versus chemotherapy (n = 102; BOR: P = 1.01 × 10-4; OS: P = 0.018). Tumor tissue-informed versions of ctDNA change metrics were most associated with clinical outcomes but did not show statistically significant independent value for explaining OS beyond radiographic change by RECIST v1.1 when jointly modeled (pembrolizumab P = 0.364; chemotherapy P = 0.823). These results suggest distinct patterns in early ctDNA changes with immunotherapy and chemotherapy and differences in their association with long-term outcomes, which provide preliminary insights on the utility of liquid biopsies for treatment monitoring in metastatic urothelial cancer. Clinical trial registration: NCT02853305.

Concordance between an FDA-approved companion diagnostic and an alternative assay kit for assessing homologous recombination deficiency in ovarian cancer.

OBJECTIVE: Authors evaluated the performance of a commercially available next-generation sequencing assay kit; this was based on genomic content from Illumina's TruSight™ Oncology 500 research assay that identifies BRCA variants and proprietary algorithms licensed from Myriad and, with additional genomic content, measures the homologous recombination deficiency (HRD) genomic instability score (GIS) in tumor tissue (TSO 500 HRD assay). METHODS: Data from the TSO 500 HRD assay were compared with data from the Myriad MyChoice®CDx PLUS assay (Myriad assay). Prevalence rates for overall HRD status and BRCA mutations (a deleterious or suspected deleterious BRCA1 or BRCA2 mutation or both) and assay agreement rates for HRD GIS and BRCA analysis were assessed in ovarian tumor samples. Pearson correlations of the continuous HRD GIS and analytic sensitivity and specificity were evaluated. RESULTS: The prevalence of overall HRD positivity was 51.2% (TSO 500 HRD assay) versus 49.2% (Myriad assay) and the prevalence of BRCA mutations was 27.6% (TSO 500 HRD assay) versus 25.5% (Myriad assay). After post-processing optimization, concordance of the HRD GIS was 0.980 in all samples and 0.976 in the non-BRCA mutation cohort; the area under the receiver operating characteristic curve was 0.995 and 0.992, respectively. CONCLUSIONS: Comparison between the Illumina and Myriad assays showed that overall HRD status, the individual components of BRCA analysis, and HRD GIS detection results were highly concordant (>93%), suggesting the TSO 500 HRD assay will approach the analytical accuracy of the FDA-approved Myriad assay.

Association Between Biomarkers and Clinical Outcomes of Pembrolizumab Monotherapy in Patients With Metastatic Triple-Negative Breast Cancer: KEYNOTE-086 Exploratory Analysis.

PURPOSE: In the two-cohort phase II KEYNOTE-086 study (ClinicalTrials.gov identifier: NCT02447003), first-line and second-line or later pembrolizumab monotherapy demonstrated antitumor activity in metastatic triple-negative breast cancer (mTNBC; N = 254). This exploratory analysis evaluates the association between prespecified molecular biomarkers and clinical outcomes. METHODS: Cohort A enrolled patients with disease progression after one or more systemic therapies for metastatic disease irrespective of PD-L1 status; Cohort B enrolled patients with previously untreated PD-L1-positive (combined positive score [CPS] ≥ 1) metastatic disease. The association between the following biomarkers as continuous variables and clinical outcomes (objective response rate [ORR], progression-free survival [PFS], and overall survival [OS]) was evaluated: PD-L1 CPS (immunohistochemistry), cluster of differentiation 8 (CD8; immunohistochemistry), stromal tumor-infiltrating lymphocyte (sTIL; hematoxylin and eosin staining), tumor mutational burden (TMB; whole-exome sequencing [WES]), homologous recombination deficiency-loss of heterozygosity, mutational signature 3 (WES), mutational signature 2 (apolipoprotein B mRNA editing catalytic polypeptide-like; WES), T-cell-inflamed gene expression profile (TcellinfGEP; RNA sequencing), and 10 non-TcellinfGEP signatures (RNA sequencing); Wald test P values were calculated, and significance was prespecified at α = 0.05. RESULTS: In the combined cohorts (A and B), PD-L1 (P = .040), CD8 (P < .001), sTILs (P = .012), TMB (P = .007), and TcellinfGEP (P = .011) were significantly associated with ORR; CD8 (P < .001), TMB (P = .034), Signature 3 (P = .009), and TcellinfGEP (P = .002) with PFS; and CD8 (P < .001), sTILs (P = .004), TMB (P = .025), and TcellinfGEP (P = .001) with OS. None of the non-TcellinfGEP signatures were associated with outcomes of pembrolizumab after adjusting for the TcellinfGEP. CONCLUSION: In this exploratory biomarker analysis from KEYNOTE-086, baseline tumor PD-L1, CD8, sTILs, TMB, and TcellinfGEP were associated with improved clinical outcomes of pembrolizumab and may help identify patients with mTNBC who are most likely to respond to pembrolizumab monotherapy.

Associations of Tissue Tumor Mutational Burden and Mutational Status With Clinical Outcomes With Pembrolizumab Plus Chemotherapy Versus Chemotherapy For Metastatic NSCLC.

Introduction: We evaluated tissue tumor mutational burden (tTMB) and mutations in STK11, KEAP1, and KRAS as biomarkers for outcomes with pembrolizumab plus platinum-based chemotherapy (pembrolizumab-combination) for NSCLC among patients in the phase 3 KEYNOTE-189 (ClinicalTrials.gov, NCT02578680; nonsquamous) and KEYNOTE-407 (ClinicalTrials.gov, NCT02775435; squamous) trials. Methods: This retrospective exploratory analysis evaluated prevalence of high tTMB and STK11, KEAP1, and KRAS mutations in patients enrolled in KEYNOTE-189 and KEYNOTE-407 and the relationship between these potential biomarkers and clinical outcomes. tTMB and STK11, KEAP1, and KRAS mutation status was assessed using whole-exome sequencing in patients with available tumor and matched normal DNA. The clinical utility of tTMB was assessed using a prespecified cutpoint of 175 mutations/exome. Results: Among patients with evaluable data from whole-exome sequencing for evaluation of tTMB (KEYNOTE-189, n = 293; KEYNOTE-407, n = 312) and matched normal DNA, no association was found between continuous tTMB score and overall survival (OS) or progression-free survival for pembrolizumab-combination (Wald test, one-sided p > 0.05) or placebo-combination (Wald test, two-sided p > 0.05) in patients with squamous or nonsquamous histology. Pembrolizumab-combination improved outcomes for patients with tTMB greater than or equal to 175 compared with tTMB less than 175 mutations/exome in KEYNOTE-189 (OS, hazard ratio = 0.64 [95% confidence interval (CI): 0.38‒1.07] and 0.64 [95% CI: 0.42‒0.97], respectively) and KEYNOTE-407 (OS, hazard ratio = 0.74 [95% CI: 0.50‒1.08 and 0.86 [95% CI: 0.57‒1.28], respectively) versus placebo-combination. Treatment outcomes were similar regardless of KEAP1, STK11, or KRAS mutation status. Conclusions: These findings support pembrolizumab-combination as first-line treatment in patients with metastatic NSCLC and do not suggest the utility of tTMB, STK11, KEAP1, or KRAS mutation status as a biomarker for this regimen.

Biomarkers predictive of response to pembrolizumab in head and neck cancer.

BACKGROUND: We performed an integrated biomarker evaluation in pembrolizumab-treated patients with R/M HNSCC enrolled in KEYNOTE-012 or KEYNOTE-055. The relationship between biomarkers and HPV status was explored. METHODS: We evaluated PD-L1 (combined positive score [CPS]), TMB, T-cell-inflamed gene expression profile (Tcellinf GEP), and HPV status. Associations between biomarkers were evaluated by logistic regression (ORR) and Cox regression (PFS, OS). RESULTS: Two hundred and fifty-seven patients (KEYNOTE-012, n = 106; KEYNOTE-055, n = 151) had TMB data available; of these, 254 had PD-L1 and 236 had Tcellinf GEP. TMB, PD-L1, and Tcellinf GEP were each significantly associated with ORR (p < 0.01). Kaplan-Meier curves at prespecified cutoffs generally showed PFS and OS separation in the anticipated direction for these biomarkers, except for OS and TMB. TMB did not correlate with PD-L1 or Tcellinf GEP (Spearman ρ = -0.03 and ρ = -0.13, respectively); PD-L1 and Tcellinf GEP were moderately correlated (Spearman ρ = 0.47). In multivariate models, TMB, PD-L1, and Tcellinf GEP were each independently predictive for ORR (p < 0.001). ORR was higher in patients with high versus low levels of biomarkers when dichotomized using prespecified cutoffs; patients with higher versus lower levels of TMB and PD-L1 or TMB and Tcellinf GEP had the highest ORRs. Within HPV subgroups, higher versus lower distributions of biomarkers (PD-L1, TMB, and Tcellinf GEP) were associated with response. HPV detection by p16-immunohistochemistry and WES showed good concordance (81%); results were generally similar by HPV status, regardless of the detection method. CONCLUSIONS: TMB and the inflammatory biomarkers PD-L1 and Tcellinf GEP, assessed alone or together, may be useful for characterizing clinical response to pembrolizumab in R/M HNSCC.

T cell-inflamed gene expression profile and PD-L1 expression and pembrolizumab efficacy in advanced esophageal cancer.

Aim: Investigate the relationship between response to pembrolizumab and expression of the 18-gene T cell-inflamed gene expression profile (TcellinfGEP) or PD-L1 combined positive score (CPS) in esophageal cancer. Materials & methods: This analysis included heavily pretreated patients with advanced/metastatic esophageal/gastroesophageal junction adenocarcinoma or squamous cell carcinoma who received pembrolizumab in the single-arm, phase II study KEYNOTE-180. PD-L1 CPS was evaluated with PD-L1 IHC 22C3 pharmDx. Results: In patients with squamous cell carcinoma, trends toward enrichment for responders were observed for patients with PD-L1 CPS ≥10 tumors. In patients with adenocarcinoma, a trend was observed for TcellinfGEP but not for PD-L1. Conclusion: TcellinfGEP and PD-L1 CPS may enrich for responders to pembrolizumab in patients with esophageal cancer. Clinical trial registration: NCT02559687 (ClinicalTrials.gov).

Putative Biomarkers of Clinical Benefit With Pembrolizumab in Advanced Urothelial Cancer: Results from the KEYNOTE-045 and KEYNOTE-052 Landmark Trials.

PURPOSE: In an exploratory analysis, we investigated the association between programmed death ligand 1 (PD-L1), tumor mutational burden (TMB), T-cell-inflamed gene expression profile (TcellinfGEP), and stromal signature with outcomes of pembrolizumab in urothelial carcinoma (UC). PATIENTS AND METHODS: Patients with advanced UC received first-line pembrolizumab 200 mg every 3 weeks in the single-arm phase II KEYNOTE-052 trial (NCT02335424) and salvage pembrolizumab 200 mg every 3 weeks or chemotherapy (paclitaxel/docetaxel/vinflunine) in the randomized phase III KEYNOTE-045 trial (NCT02256436). The association of each biomarker (continuous variable) with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) was evaluated using logistic regression (ORR) and Cox PH (PFS, OS), adjusted for ECOG PS; nominal P values were calculated without multiplicity adjustment (one-sided, pembrolizumab; two-sided, chemotherapy). Significance was prespecified at α = 0.05. RESULTS: In KEYNOTE-052, PD-L1, TMB, and TcellinfGEP were significantly associated with improved outcomes; stromal signature was significantly associated with worse outcomes. In KEYNOTE-045, although findings for TMB and TcellinfGEP with pembrolizumab were consistent with those of KEYNOTE-052, PD-L1 was not significantly associated with improved outcomes, nor was stromal signature associated with worse outcomes with pembrolizumab; chemotherapy was not associated with outcomes in a consistent manner for any of the biomarkers. Hazard ratio (HR) estimates at prespecified cutoffs showed an advantage for pembrolizumab versus chemotherapy regardless of PD-L1 or TMB, with a trend toward lower HRs in the combined positive score ≥10 and the TMB ≥175 mutation/exome subgroup. For TcellinfGEP, PFS and OS HRs were lower in the TcellinfGEP-nonlow subgroup regardless of treatment. CONCLUSIONS: Multiple biomarkers characterizing the tumor microenvironment may help predict response to pembrolizumab monotherapy in UC, and potential clinical utility of these biomarkers may be context-dependent.

Influence of tumor mutational burden, inflammatory gene expression profile, and PD-L1 expression on response to pembrolizumab in head and neck squamous cell carcinoma.

BACKGROUND: To characterize genomic determinants of response to pembrolizumab in recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) in the KEYNOTE-012 study. METHODS: Associations between biomarkers (tumor mutational burden (TMB), neoantigen load (NL), 18-gene T-cell-inflamed gene expression profile (TcellinfGEP), and PD-L1 combined positive score (CPS)) and clinical outcomes with pembrolizumab were assessed in patients with R/M HNSCC (n=192). Tumor human papillomavirus (HPV) status was also evaluated with the use of p16 immunohistochemistry and whole exome sequencing (WES; HPV+, mapping >20 HPV reads) in pretreatment tumor samples (n=106). RESULTS: TMB, clonality-weighted TMB, and TcellinfGEP were significantly associated with objective response (p=0.0276, p=0.0201, and p=0.006, respectively), and a positive trend was observed between NL and PD-L1 CPS and clinical response (p=0.0550 and p=0.0682, respectively). No correlation was observed between TMB and TcellinfGEP (Spearman ρ=-0.026) or TMB and PD-L1 (Spearman ρ=0.009); a correlation was observed between TcellinfGEP and PD-L1 (Spearman ρ=0.511). HPV status by WES and p16 immunohistochemistry showed concordance (84% Ò¡=0.573) among patients whose HPV results were available using both methods. CONCLUSIONS: TMB and inflammatory biomarkers (TcellinfGEP and PD-L1) may represent distinct and complementary biomarkers predicting response to anti-programmed death 1 therapies in HNSCC; further study of these relationships in randomized clinical trials is needed. TRIAL REGISTRATION NUMBER: NCT01848834.

Tumor mutational burden predicts the efficacy of pembrolizumab monotherapy: a pan-tumor retrospective analysis of participants with advanced solid tumors.

BACKGROUND: Several studies have evaluated the relationship between tumor mutational burden (TMB) and outcomes of immune checkpoint inhibitors. In the phase II KEYNOTE-158 study of pembrolizumab monotherapy for previously treated recurrent or metastatic cancer, high TMB as assessed by the FoundationOne CDx was associated with an improved objective response rate (ORR). METHODS: We retrospectively assessed the relationship between TMB and efficacy in participants with previously treated advanced solid tumors enrolled in 12 trials that evaluated pembrolizumab monotherapy, including 3 randomized trials that compared pembrolizumab with chemotherapy. TMB was assessed in formalin-fixed, paraffin-embedded pretreatment tumor samples by whole-exome sequencing. High TMB was defined as ≥175 mutations/exome. Microsatellite instability (MSI) phenotype was based on whole-exome sequencing results. Programmed death ligand 1 (PD-L1) expression was assessed by immunohistochemistry. The primary end point was ORR assessed per RECIST V.1.1 by independent central review. Other end points included progression-free survival (PFS) assessed per RECIST V.1.1 by independent central review and overall survival (OS). RESULTS: Of the 2234 participants in the analysis, 1772 received pembrolizumab monotherapy and 462 received chemotherapy. Among the pembrolizumab-treated participants, ORR was 31.4% (95% CI 27.1 to 36.0) in the 433 participants with TMB ≥175 mutations/exome and 9.5% (95% CI 8.0 to 11.2) in the 1339 participants with TMB <175 mutations/exome. The association of TMB with ORR was observed regardless of PD-L1 expression and not driven by specific tumor types or participants with very high TMB or high MSI. In the 3 randomized controlled trials, TMB was associated with ORR (p≤0.016), PFS (p≤0.005), and OS (p≤0.029) of pembrolizumab but not of chemotherapy (p≥0.340, p≥0.643, and p≥0.174, respectively), and pembrolizumab improved efficacy versus chemotherapy in participants with TMB ≥175 mutations/exome. CONCLUSIONS: TMB ≥175 mutations/exome is associated with clinically meaningful improvement in the efficacy of pembrolizumab monotherapy and improved outcomes for pembrolizumab versus chemotherapy across a wide range of previously treated advanced solid tumor types. These data suggest TMB has broad clinical utility irrespective of tumor type, PD-L1 expression, or MSI status and support its use as a predictive biomarker for pembrolizumab monotherapy in participants with previously treated advanced solid tumors.

Transcriptomic Determinants of Response to Pembrolizumab Monotherapy across Solid Tumor Types.

PURPOSE: To explore relationships between biological gene expression signatures and pembrolizumab response. EXPERIMENTAL DESIGN: RNA-sequencing data on baseline tumor tissue from 1,188 patients across seven tumor types treated with pembrolizumab monotherapy in nine clinical trials were used. A total of 11 prespecified gene expression signatures [18-gene T-cell-inflamed gene expression profile (TcellinfGEP), angiogenesis, hypoxia, glycolysis, proliferation, MYC, RAS, granulocytic myeloid-derived suppressor cell (gMDSC), monocytic myeloid-derived suppressor cell (mMDSC), stroma/epithelial-to-mesenchymal transition (EMT)/TGFß, and WNT] were evaluated for their relationship to objective response rate (per RECIST, version 1.1). Logistic regression analysis of response for consensus signatures was adjusted for tumor type, Eastern Cooperative Oncology Group performance status, and TcellinfGEP, an approach equivalent to evaluating the association between response and the residuals of consensus signatures after detrending them for their relationship with the TcellinfGEP (previously identified as a determinant of pembrolizumab response) and tumor type. Testing of the 10 prespecified non-TcellinfGEP consensus signatures for negative association [except proliferation (hypothesized positive association)] with response was adjusted for multiplicity. RESULTS: Covariance patterns of the 11 signatures (including TcellinfGEP) identified in Merck-Moffitt and The Cancer Genome Atlas datasets showed highly concordant coexpression patterns in the RNA-sequencing data from pembrolizumab trials. TcellinfGEP was positively associated with response; signatures for angiogenesis, mMDSC, and stroma/EMT/TGFß were negatively associated with response to pembrolizumab monotherapy. CONCLUSIONS: These findings suggest that features beyond IFNγ-related T-cell inflammation may be relevant to anti-programmed death 1 monotherapy response and may define other axes of tumor biology as candidates for pembrolizumab combinations. See related commentary by Cho et al., p. 1479.

First-in-Class Anti-immunoglobulin-like Transcript 4 Myeloid-Specific Antibody MK-4830 Abrogates a PD-1 Resistance Mechanism in Patients with Advanced Solid Tumors.

PURPOSE: In this first-in-human study (NCT03564691) in advanced solid tumors, we investigated a novel first-in-class human IgG4 monoclonal antibody targeting the immunoglobulin-like transcript 4 (ILT4) receptor, MK-4830, as monotherapy and in combination with pembrolizumab. PATIENTS AND METHODS: Patients with histologically/cytologically confirmed advanced solid tumors, measurable disease by RECIST v1.1, and evaluable baseline tumor sample received escalating doses of intravenous MK-4830 every 3 weeks as monotherapy (parts A and B) and in combination with pembrolizumab (part C). Safety and tolerability were the primary objectives. Pharmacokinetics, objective response rate per RECIST v1.1, and molecular biomarkers were also evaluated. RESULTS: Of 84 patients, 50 received monotherapy and 34 received combination therapy. No dose-limiting toxicities were observed; maximum tolerated dose was not reached. MK-4830 showed dose-related target engagement. Eleven of 34 patients in the dose-escalation phase who received combination therapy achieved objective responses; 5 previously had progressive disease on anti-PD-1/PD-L1 therapies. Exploratory evaluation of the association between response and pretreatment gene expression related to interferon-gamma signaling in tumors suggested higher sensitivity to T-cell inflammation with combination therapy than historically expected with pembrolizumab monotherapy, with greater response at more moderate levels of inflammation. CONCLUSIONS: This first-in-class MK-4830 antibody dosed as monotherapy and in combination with pembrolizumab was well tolerated with no unexpected toxicities, and demonstrated dose-related evidence of target engagement and antitumor activity. Inflammation intrinsic to the ILT4 mechanism may be facilitated by alleviating the myeloid-suppressive components of the tumor microenvironment, supporting the target of ILT4 as a potential novel immunotherapy in combination with an anti-PD-1/PD-L1 agent.

Clinical Utility of the Combined Positive Score for Programmed Death Ligand-1 Expression and the Approval of Pembrolizumab for Treatment of Gastric Cancer.

CONTEXT.­: Regulatory approval of pembrolizumab for treatment of gastric and gastroesophageal junction (G/GEJ) adenocarcinoma required a reproducible scoring method for use of programmed death ligand-1 (PD-L1) protein expression as a companion diagnostic to identify likely responders to therapy. OBJECTIVE.­: To develop an immunohistochemical scoring algorithm that includes PD-L1 expression for tumor and immune cells, that is, the combined positive score. DESIGN.­: Four previously treated tumor types in the KEYNOTE-012 and KEYNOTE-028 studies were analyzed descriptively with a version of the PD-L1 immunohistochemical 22C3 pharmDx assay labeled for investigational use only to determine the relative importance of PD-L1 expression in tumor versus immune cells as a biomarker for pembrolizumab response. A combined positive score was developed as a novel scoring method and was compared with the tumor proportion score in cohort 1 from the KEYNOTE-059 study (G/GEJ cancer). External reproducibility was assessed. RESULTS.­: Per combined positive score cutoff of 1 or more, the prevalence of PD-L1 expression in patients with G/GEJ cancer was 57.6% (148 of 257 patients), with reasonable enrichment of responses (odds ratio, 2.8). Per tumor proportion score cutoff of 1% or more, prevalence was 12.5% (32 of 257 patients), with minimal enrichment (odds ratio, 1.4). External reproducibility assessments demonstrated interpathologist overall agreement of 96.6% (591 of 612; 95% CI, 94.0%-98.7%) and intrapathologist overall agreement of 97.2% (595 of 612; 95% CI, 95.3%-98.9%). CONCLUSIONS.­: Combined positive score is a robust, reproducible PD-L1 scoring method that predicts response to pembrolizumab in patients with G/GEJ cancer. This novel scoring method supported US Food and Drug Administration approval of pembrolizumab as third-line therapy for G/GEJ cancer and has facilitated investigation in other indications.

T-Cell-Inflamed Gene-Expression Profile, Programmed Death Ligand 1 Expression, and Tumor Mutational Burden Predict Efficacy in Patients Treated With Pembrolizumab Across 20 Cancers: KEYNOTE-028.

PURPOSE: Biomarkers that can predict response to anti-programmed cell death 1 (PD-1) therapy across multiple tumor types include a T-cell-inflamed gene-expression profile (GEP), programmed death ligand 1 (PD-L1) expression, and tumor mutational burden (TMB). Associations between these biomarkers and the clinical efficacy of pembrolizumab were evaluated in a clinical trial that encompassed 20 cohorts of patients with advanced solid tumors. METHODS: KEYNOTE-028 ( ClinicalTrials.gov identifier: NCT02054806) is a nonrandomized, phase Ib trial that enrolled 475 patients with PD-L1-positive advanced solid tumors who were treated with pembrolizumab 10 mg/kg every 2 weeks for 2 years or until confirmed disease progression or unacceptable toxicity occurred. The primary end point was objective response rate (ORR; by RECIST v1.1, investigator review). Secondary end points included safety, progression-free survival (PFS), and overall survival (OS). Relationships between T-cell-inflamed GEP, PD-L1 expression, and TMB and antitumor activity were exploratory end points. RESULTS: ORRs (with 95% CIs) ranged from 0% (0.0% to 14.2%) in pancreatic cancer to 33% (15.6% to 55.3%) in small-cell lung cancer. Across cohorts, median (95% CI) PFS ranged from 1.7 months (1.5 to 2.9 months) to 6.8 months (1.9 to 14.1 months) in pancreatic and thyroid cancers, respectively, and median OS from 3.9 months (2.8 to 5.5 months) to 21.1 months (9.1 to 22.4 months) in vulvar and carcinoid tumors, respectively. Higher response rates and longer PFS were demonstrated in tumors with higher T-cell-inflamed GEP, PD-L1 expression, and/or TMB. Correlations of TMB with GEP and PD-L1 were low. Response patterns indicate that patients with tumors that had high levels of both TMB and inflammatory markers (GEP or PD-L1) represent a population with the highest likelihood of response. Safety was similar and consistent with prior pembrolizumab reports. CONCLUSION: A T-cell--inflamed GEP, PD-L1 expression, and TMB predicted response to pembrolizumab in multiple tumor types. These biomarkers (alone/in combination) may help identify patients who have a higher likelihood of response to anti-PD-1 therapies across a broad spectrum of cancers.

Efficacy and Safety of Pembrolizumab for Heavily Pretreated Patients With Advanced, Metastatic Adenocarcinoma or Squamous Cell Carcinoma of the Esophagus: The Phase 2 KEYNOTE-180 Study.

IMPORTANCE: Effective treatment options are limited for patients with advanced, metastatic esophageal cancer progressing after 2 or more lines of systemic therapy. OBJECTIVE: To evaluate the efficacy and safety of pembrolizumab for patients with advanced, metastatic esophageal squamous cell carcinoma (ESCC) or advanced, metastatic adenocarcinoma of the esophagus and gastroesophageal junction that progressed after 2 or more lines of systemic therapy. DESIGN, SETTING, AND PARTICIPANTS: This phase 2, open-label, interventional, single-arm study, KEYNOTE-180, enrolled 121 patients from January 12, 2016, to March 21, 2017, from 57 sites in 10 countries. Patients had advanced, metastatic esophageal cancer that progressed after 2 or more lines of therapy and had evaluable tumor samples for biomarkers. INTERVENTIONS: Pembrolizumab, 200 mg, was administered intravenously every 3 weeks until disease progression, unacceptable toxic effects, or study withdrawal, for up to 2 years. MAIN OUTCOMES AND MEASURES: Primary end point was objective response rate per the Response Evaluation Criteria in Solid Tumors by central imaging review for all patients. RESULTS: As of September 18, 2017, of 121 enrolled patients (100 men and 21 women; median age, 65 years [range, 33-87 years]), 18 (14.9%) had undergone 3 or more prior therapies, 63 (52.1%) had ESCC, and 58 (47.9%) had tumors positive for programmed death ligand-1 (PD-L1), defined as a combined positive score of 10 or higher assessed by immunohistochemistry. Median duration of follow-up was 5.8 months (range, 0.2-18.3 months). Objective response rate was 9.9% (95% CI, 5.2%-16.7%) among all patients (12 of 121), and median duration of response was not reached (range, 1.9-14.4 months). Objective response rate was 14.3% (95% CI, 6.7%-25.4%) among patients with ESCC (9 of 63), 5.2% (95% CI, 1.1%-14.4%) among patients with adenocarcinoma (3 of 58), 13.8% (95% CI, 6.1%-25.4%) among patients with PD-L1-positive tumors (8 of 58), and 6.3% (95% CI, 1.8%-15.5%) among patients with PD-L1-negative tumors (4 of 63). Overall, 15 patients (12.4%) had treatment-related grade 3 to 5 adverse events. Only 5 patients (4.1%) discontinued treatment because of adverse events. There was 1 treatment-related death from pneumonitis. CONCLUSIONS AND RELEVANCE: Where effective treatment options are an unmet need, pembrolizumab provided durable antitumor activity with manageable safety in patients with heavily pretreated esophageal cancer. Phase 3 studies evaluating pembrolizumab vs standard therapy for patients with esophageal cancer progressing after first-line therapy or in combination with chemotherapy as first-line therapy for patients with locally advanced unresectable or metastatic esophageal cancer are ongoing. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02559687.

Pan-tumor genomic biomarkers for PD-1 checkpoint blockade-based immunotherapy.

Programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) checkpoint blockade immunotherapy elicits durable antitumor effects in multiple cancers, yet not all patients respond. We report the evaluation of >300 patient samples across 22 tumor types from four KEYNOTE clinical trials. Tumor mutational burden (TMB) and a T cell-inflamed gene expression profile (GEP) exhibited joint predictive utility in identifying responders and nonresponders to the PD-1 antibody pembrolizumab. TMB and GEP were independently predictive of response and demonstrated low correlation, suggesting that they capture distinct features of neoantigenicity and T cell activation. Analysis of The Cancer Genome Atlas database showed TMB and GEP to have a low correlation, and analysis by joint stratification revealed biomarker-defined patterns of targetable-resistance biology. These biomarkers may have utility in clinical trial design by guiding rational selection of anti-PD-1 monotherapy and combination immunotherapy regimens.

Safety and Antitumor Activity of the Anti-Programmed Death-1 Antibody Pembrolizumab in Patients With Advanced Esophageal Carcinoma.

Purpose The anti-programmed death-1 antibody pembrolizumab was evaluated in KEYNOTE-028, a multicohort, phase IB study of patients with programmed death ligand-1 (PD-L1)-positive advanced solid tumors. Results from the esophageal carcinoma cohort are reported herein. Patients and Methods Eligible patients with squamous cell carcinoma or adenocarcinoma of the esophagus or gastroesophageal junction in whom standard therapy failed and who had PD-L1-positive tumors received pembrolizumab 10 mg/kg every 2 weeks for up to 2 years or until confirmed disease progression or intolerable toxicity. Response was assessed every 8 weeks up to 6 months and every 12 weeks thereafter. Primary end points were safety and overall response rate, determined by investigator review per Response Evaluation Criteria in Solid Tumors (version 1.1). Results Among 83 patients with esophageal carcinoma and samples evaluable for PD-L1 expression, 37 (45%) had PD-L1-positive tumors, and 23 were enrolled. Median age was 65 years; 78% had squamous histology; and 87% received ≥ two prior therapies for advanced/metastatic disease. As of the data cutoff (February 20, 2017), median follow-up was 7 months (range, 1 to 33 months). Nine patients (39%) experienced treatment-related adverse events, most commonly decreased appetite, decreased lymphocyte count, generalized rash, and rash (two patients [9%] each). No grade 4 adverse events or deaths were attributed to pembrolizumab. Overall response rate was 30% (95% CI, 13% to 53%); median duration of response was 15 months (range, 6 to 26 months). A six-gene interferon-γ gene expression signature analysis suggested that delayed progression and increased response occur among pembrolizumab-treated patients with higher interferon-γ composite scores. Conclusion Pembrolizumab demonstrated manageable toxicity and durable antitumor activity in patients with heavily pretreated, PD-L1-positive advanced esophageal carcinoma.

PD-L2 Expression in Human Tumors: Relevance to Anti-PD-1 Therapy in Cancer.

Purpose: Tumor-associated PD-L1 expression is predictive of clinical response to PD-1-directed immunotherapy. However, PD-L1-negative patients may also respond to PD-1 checkpoint blockade, suggesting that other PD-1 ligands may be relevant to the clinical activity of these therapies. The prevalence of PD-L2, the other known ligand of PD-1, and its relationship to response to anti-PD-1 therapy were evaluated.Experimental Design: PD-L2 expression was assessed in archival tumor tissue from seven indications using a novel immunohistochemical assay. In addition, relationships between clinical response and PD-L2 status were evaluated in tumor tissues from patients with head and neck squamous cell carcinoma (HNSCC) with recurrent or metastatic disease, treated with pembrolizumab.Results: PD-L2 expression was observed in all tumor types and present in stromal, tumor, and endothelial cells. The prevalence and distribution of PD-L2 correlated significantly with PD-L1 (P = 0.0012-<0.0001); however, PD-L2 was detected in the absence of PD-L1 in some tumor types. Both PD-L1 and PD-L2 positivity significantly predicted clinical response to pembrolizumab on combined tumor, stromal and immune cells, with PD-L2 predictive independent of PD-L1. Response was greater in patients positive for both PD-L1 and PD-L2 (27.5%) than those positive only for PD-L1 (11.4%). PD-L2 status was also a significant predictor of progression-free survival (PFS) with pembrolizumab independent of PD-L1 status. Longer median times for PFS and overall survival were observed for PD-L2-positive than PD-L2-negative patients.Conclusions: Clinical response to pembrolizumab in patients with HNSCC may be related partly to blockade of PD-1/PD-L2 interactions. Therapy targeting both PD-1 ligands may provide clinical benefit in these patients. Clin Cancer Res; 23(12); 3158-67. ©2017 AACR.

IFN-γ-related mRNA profile predicts clinical response to PD-1 blockade.

Programmed death-1-directed (PD-1-directed) immune checkpoint blockade results in durable antitumor activity in many advanced malignancies. Recent studies suggest that IFN-γ is a critical driver of programmed death ligand-1 (PD-L1) expression in cancer and host cells, and baseline intratumoral T cell infiltration may improve response likelihood to anti-PD-1 therapies, including pembrolizumab. However, whether quantifying T cell-inflamed microenvironment is a useful pan-tumor determinant of PD-1-directed therapy response has not been rigorously evaluated. Here, we analyzed gene expression profiles (GEPs) using RNA from baseline tumor samples of pembrolizumab-treated patients. We identified immune-related signatures correlating with clinical benefit using a learn-and-confirm paradigm based on data from different clinical studies of pembrolizumab, starting with a small pilot of 19 melanoma patients and eventually defining a pan-tumor T cell-inflamed GEP in 220 patients with 9 cancers. Predictive value was independently confirmed and compared with that of PD-L1 immunohistochemistry in 96 patients with head and neck squamous cell carcinoma. The T cell-inflamed GEP contained IFN-γ-responsive genes related to antigen presentation, chemokine expression, cytotoxic activity, and adaptive immune resistance, and these features were necessary, but not always sufficient, for clinical benefit. The T cell-inflamed GEP has been developed into a clinical-grade assay that is currently being evaluated in ongoing pembrolizumab trials.