Efficacy and safety of pembrolizumab for the treatment of advanced biliary cancer: Results from the KEYNOTE-158 and KEYNOTE-028 studies.

We present data from patients with advanced biliary tract cancer (BTC) receiving pembrolizumab in the KEYNOTE-158 (NCT02628067; phase 2) and KEYNOTE-028 (NCT02054806; phase 1b) studies. Eligible patients aged ≥18 years from both studies had histologically/cytologically confirmed incurable BTC that progressed after standard treatment regimen(s), measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, Eastern Cooperative Oncology Group performance status 0/1, and no prior immunotherapy. Programmed death ligand 1 (PD-L1)-positive tumors were required for eligibility in KEYNOTE-028 only. Patients received pembrolizumab 200 mg every three weeks (KEYNOTE-158) or 10 mg/kg every two weeks (KEYNOTE-028) for ≤2 years. Primary efficacy endpoint was objective response rate (ORR) by RECIST v1.1. Response assessed by independent central review is reported. KEYNOTE-158 enrolled 104 patients and KEYNOTE-028 enrolled 24 patients. Median (range) follow-up was 7.5 months (0.6-34.3) in KEYNOTE-158 and 5.7 months (0.6-55.4) in KEYNOTE-028. In KEYNOTE-158, ORR was 5.8% (6/104; 95% CI, 2.1%-12.1%); median duration of response (DOR) was not reached (NR) (range, 6.2-26.6+ months). Median (95% CI) OS and PFS were 7.4 (5.5-9.6) and 2.0 (1.9-2.1) months. Among PD-L1-expressers (n = 61) and PD-L1-nonexpressers (n = 34), respectively, ORR was 6.6% (4/61) and 2.9% (1/34). In KEYNOTE-028, ORR was 13.0% (3/23; 95% CI, 2.8%-33.6%); median DOR was NR (range, 21.5-53.2+ months). Median (95% CI) OS and PFS were 5.7 (3.1-9.8) and 1.8 (1.4-3.1) months. Grade 3 to 5 treatment-related adverse events occurred in 13.5% of patients in KEYNOTE-158 (no grade 4; grade 5 renal failure, n = 1) and 16.7% in KEYNOTE-028 (no grade 4/5). In summary, pembrolizumab provides durable antitumor activity in 6% to 13% of patients with advanced BTC, regardless of PD-L1 expression, and has manageable toxicity.

Multiparameter Flow Cytometry Assay for Quantification of Immune Cell Subsets, PD-1 Expression Levels and PD-1 Receptor Occupancy by Nivolumab and Pembrolizumab.

We report the development and validation of a 12 parameter immunofluorescence flow cytometry method for the sensitive determination of cell concentrations, their expression of PD-1, and PD-1 receptor occupancy. Cell subsets include CD4+ and CD8+ -T-cells, B-cells, natural killer cells, classical-, intermediate- and non-classical monocytes, and myeloid- and plasmacytoid dendritic cells. Cells were isolated from peripheral blood by density gradient centrifugation. The validation parameters included specificity, linearity, limit of quantification, precision, biological within- and between subject variations. The lower limit of quantification was 5.0% of PD-1+ cells. Samples were stable for at least 153 days of storage at -80°C. The clinical applicability of the method was demonstrated in 11 advanced cancer patients by the successful determination of immune cell concentrations, relative number of PD-1+ immune cells, and number of PD-1 molecules per immune cell. Shortly after infusion of nivolumab, receptor occupancy on CD8+ -T-cells was 98%. Similar values were found predose cycle 2, suggesting receptor occupancy remained high throughout the entire cycle. © 2019 International Society for Advancement of Cytometry.

Antidrug Antibody Formation in Oncology: Clinical Relevance and Challenges.

: In oncology, an increasing number of targeted anticancer agents and immunotherapies are of biological origin. These biological drugs may trigger immune responses that lead to the formation of antidrug antibodies (ADAs). ADAs are directed against immunogenic parts of the drug and may affect efficacy and safety. In other medical fields, such as rheumatology and hematology, the relevance of ADA formation is well established. However, the relevance of ADAs in oncology is just starting to be recognized, and literature on this topic is scarce. In an attempt to fill this gap in the literature, we provide an up-to-date status of ADA formation in oncology. In this focused review, data on ADAs was extracted from 81 clinical trials with biological anticancer agents. We found that most biological anticancer drugs in these trials are immunogenic and induce ADAs (63%). However, it is difficult to establish the clinical relevance of these ADAs. In order to determine this relevance, the possible effects of ADAs on pharmacokinetics, efficacy, and safety parameters need to be investigated. Our data show that this was done in fewer than 50% of the trials. In addition, we describe the incidence and consequences of ADAs for registered agents. We highlight the challenges in ADA detection and argue for the importance of validating, standardizing, and describing well the used assays. Finally, we discuss prevention strategies such as immunosuppression and regimen adaptations. We encourage the launch of clinical trials that explore these strategies in oncology. IMPLICATIONS FOR PRACTICE: Because of the increasing use of biologicals in oncology, many patients are at risk of developing antidrug antibodies (ADAs) during therapy. Although clinical consequences are uncertain, ADAs may affect pharmacokinetics, patient safety, and treatment efficacy. ADA detection and reporting is currently highly inconsistent, which makes it difficult to evaluate the clinical consequences. Standardized reporting of ADA investigations in the context of the aforementioned parameters is critical to understanding the relevance of ADA formation for each drug. Furthermore, the development of trials that specifically aim to investigate clinical prevention strategies in oncology is needed.

First-in-human phase I study of the OX40 agonist GSK3174998 with or without pembrolizumab in patients with selected advanced solid tumors (ENGAGE-1).

BACKGROUND: The phase I first-in-human study ENGAGE-1 evaluated the humanized IgG1 OX40 agonistic monoclonal antibody GSK3174998 alone (Part 1 (P1)) or in combination with pembrolizumab (Part 2 (P2)) in patients with advanced solid tumors. METHODS: GSK3174998 (0.003-10 mg/kg) ± pembrolizumab (200 mg) was administered intravenously every 3 weeks using a continuous reassessment method for dose escalation. Primary objectives were safety and tolerability; secondary objectives included pharmacokinetics, immunogenicity, pharmacodynamics, and clinical activity. RESULTS: 138 patients were enrolled (45 (P1) and 96 (P2, including 3 crossovers)). Treatment-related adverse events occurred in 51% (P1) and 64% (P2) of patients, fatigue being the most common (11% and 24%, respectively). No dose-toxicity relationship was observed, and maximum-tolerated dose was not reached. Dose-limiting toxicities (P2) included Grade 3 (G3) pleural effusion and G1 myocarditis with G3 increased troponin. GSK3174998 ≥0.3 mg/kg demonstrated pharmacokinetic linearity and >80% receptor occupancy on circulating T cells; 0.3 mg/kg was selected for further evaluation. Limited clinical activity was observed for GSK3174998 (P1: disease control rate (DCR) ≥24 weeks 9%) and was not greater than that expected for pembrolizumab alone (P2: overall response rate 8%, DCR ≥24 weeks 28%). Multiplexed immunofluorescence data from paired biopsies suggested that increased infiltration of natural killer (NK)/natural killer T (NKT) cells and decreased regulatory T cells (Tregs) in the tumor microenvironment may contribute to clinical responses: CD16+CD56-CD134+ NK /NKT cells and CD3+CD4+FOXP3+CD134+ Tregs exhibited the largest magnitude of change on treatment, whereas CD3+CD8+granzyme B+PD-1+CD134+ cytotoxic T cells were the least variable. Tumor gene expression profiling revealed an upregulation of inflammatory responses, T-cell proliferation, and NK cell function on treatment with some inflammatory cytokines upregulated in peripheral blood. However, target engagement, evidenced by pharmacologic activity in peripheral blood and tumor tissue, did not correlate with clinical efficacy. The low number of responses precluded identifying a robust biomarker signature predictive of response. CONCLUSIONS: GSK3174998±pembrolizumab was well tolerated over the dose range tested and demonstrated target engagement. Limited clinical activity does not support further development of GSK3174998±pembrolizumab in advanced cancers. TRIAL REGISTRATION NUMBER: NCT02528357.

A Phase I, Open-Label, Dose-Escalation Study of the OX40 Agonist Ivuxolimab in Patients with Locally Advanced or Metastatic Cancers.

PURPOSE: Stimulation of effector T cells is an appealing immunotherapeutic approach in oncology. OX40 (CD134) is a costimulatory receptor expressed on activated CD4+ and CD8+ T cells. Induction of OX40 following antigen recognition results in enhanced T-cell activation, proliferation, and survival, and OX40 targeting shows therapeutic efficacy in preclinical studies. We report the monotherapy dose-escalation portion of a multicenter, phase I trial (NCT02315066) of ivuxolimab (PF-04518600), a fully human immunoglobulin G2 agonistic monoclonal antibody specific for human OX40. PATIENTS AND METHODS: Adult patients (N = 52) with selected locally advanced or metastatic cancers received ivuxolimab 0.01 to 10 mg/kg. Primary endpoints were safety and tolerability. Secondary/exploratory endpoints included preliminary assessment of antitumor activity and biomarker analyses. RESULTS: The most common all-causality adverse events were fatigue (46.2%), nausea (28.8%), and decreased appetite (25.0%). Of 31 treatment-related adverse events, 30 (96.8%) were grade ≤2. No dose-limiting toxicities occurred. Ivuxolimab exposure increased in a dose-proportionate manner from 0.3 to 10 mg/kg. Full peripheral blood target engagement occurred at ≥0.3 mg/kg. Three (5.8%) patients achieved a partial response, and disease control was achieved in 56% of patients. Increased CD4+ central memory T-cell proliferation and activation, and clonal expansion of CD4+ and CD8+ T cells in peripheral blood were observed at 0.1 to 3.0 mg/kg. Increased immune cell infiltrate and OX40 expression were evident in on-treatment tumor biopsies. CONCLUSIONS: Ivuxolimab was generally well tolerated with on-target immune activation at clinically relevant doses, showed preliminary antitumor activity, and may serve as a partner for combination studies.

First-in-human study of an OX40 (ivuxolimab) and 4-1BB (utomilumab) agonistic antibody combination in patients with advanced solid tumors.

BACKGROUND: Ivuxolimab (PF-04518600) and utomilumab (PF-05082566) are humanized agonistic IgG2 monoclonal antibodies against OX40 and 4-1BB, respectively. This first-in-human, multicenter, open-label, phase I, dose-escalation/dose-expansion study explored safety, tolerability, pharmacokinetics, pharmacodynamics, and antitumor activity of ivuxolimab+utomilumab in patients with advanced solid tumors. METHODS: Dose-escalation: patients with advanced bladder, gastric, or cervical cancer, melanoma, head and neck squamous cell carcinoma, or non-small cell lung cancer (NSCLC) who were unresponsive to available therapies, had no standard therapy available or declined standard therapy were enrolled into five dose cohorts: ivuxolimab (0.1-3 mg/kg every 2 weeks (Q2W)) intravenously plus utomilumab (20 or 100 mg every 4 weeks (Q4W)) intravenously. Dose-expansion: patients with melanoma (n=10) and NSCLC (n=20) who progressed on prior anti-programmed death receptor 1/programmed death ligand-1 and/or anti-cytotoxic T-lymphocyte-associated antigen 4 (melanoma) received ivuxolimab 30 mg Q2W intravenously plus utomilumab 20 mg Q4W intravenously. Adverse events (AEs) were graded per National Cancer Institute Common Terminology Criteria for Adverse Events V.4.03 and efficacy was assessed using Response Evaluation Criteria in Solid Tumors (RECIST) V.1.1 and immune-related RECIST (irRECIST). Paired tumor biopsies and whole blood were collected to assess pharmacodynamic effects and immunophenotyping. Whole blood samples were collected longitudinally for immunophenotyping. RESULTS: Dose-escalation: 57 patients were enrolled; 2 (3.5%) patients with melanoma (0.3 mg/kg+20 mg and 0.3 mg/kg+100 mg) achieved partial response (PR), 18 (31.6%) patients achieved stable disease (SD); the disease control rate (DCR) was 35.1% across all dose levels. Dose-expansion: 30 patients were enrolled; 1 patient with NSCLC achieved PR lasting >77 weeks. Seven of 10 patients with melanoma (70%) and 7 of 20 patients with NSCLC (35%) achieved SD: median (range) duration of SD was 18.9 (13.9-49.0) weeks for the melanoma cohort versus 24.1 (14.3-77.9+) weeks for the NSCLC cohort; DCR (NSCLC) was 40%. Grade 3-4 treatment-emergent AEs were reported in 28 (49.1%) patients versus 11 (36.7%) patients in dose-escalation and dose-expansion, respectively. There were no grade 5 AEs deemed attributable to treatment. Ivuxolimab area under the concentration-time curve increased in a dose-dependent manner at 0.3-3 mg/kg doses. CONCLUSIONS: Ivuxolimab+utomilumab was found to be well tolerated and demonstrated preliminary antitumor activity in selected groups of patients. TRIAL REGISTRATION NUMBER: NCT02315066.

Enzyme linked immunosorbent assay for the quantification of nivolumab and pembrolizumab in human serum and cerebrospinal fluid.

Immunotherapy with monoclonal antibodies targeting the programmed-death-1 (PD-1) receptor has become standard of care for an increasing number of tumor types. Pharmacokinetic studies may help to optimize anti-PD-1 therapy. Therefore, accurate and sensitive determination of antibody concentrations is essential. Here we report an enzyme linked immunosorbent assay (ELISA) capable of measuring nivolumab and pembrolizumab concentrations in serum and cerebrospinal fluid (CSF) with high sensitivity and specificity. The assay was developed and validated based on the specific capture of nivolumab and pembrolizumab by immobilized PD-1, with subsequent enzymatic chemiluminescent detection by anti-IgG4 coupled with horse radish peroxidase (HRP). The lower limit of quantification for serum and CSF was 2 ng/mL for both anti-PD-1 agents. The ELISA method was validated and showed long term sample stability of >1 year. This method is reliable, relatively inexpensive and can be used in serum and CSF from pembrolizumab and nivolumab treated patients.

Efficacy and Safety of Pembrolizumab in Previously Treated Advanced Cervical Cancer: Results From the Phase II KEYNOTE-158 Study.

PURPOSE: KEYNOTE-158 ( ClinicalTrials.gov identifier: NCT02628067) is a phase II basket study investigating the antitumor activity and safety of pembrolizumab in multiple cancer types. We present interim results from patients with previously treated advanced cervical cancer. PATIENTS AND METHODS: Patients received pembrolizumab 200 mg every 3 weeks for 2 years or until progression, intolerable toxicity, or physician or patient decision. Tumor imaging was performed every 9 weeks for the first 12 months and every 12 weeks thereafter. The primary end point was objective response rate (ORR), assessed per Response Evaluation Criteria in Solid Tumors (version 1.1) by independent central radiologic review. Safety was a secondary end point. RESULTS: Ninety-eight patients were treated. Median age was 46.0 years (range, 24 to 75 years), and 65.3% of patients had Eastern Cooperative Oncology Group performance status of 1. Eighty-two patients (83.7%) had programmed death-ligand 1 (PD-L1)-positive tumors (combined positive score ≥ 1), 77 having previously received one or more lines of chemotherapy for recurrent or metastatic disease. Median follow-up was 10.2 months (range, 0.6 to 22.7 months). ORR was 12.2% (95% CI, 6.5% to 20.4%), with three complete and nine partial responses. All 12 responses were in patients with PD-L1-positive tumors, for an ORR of 14.6% (95% CI, 7.8% to 24.2%); 14.3% (95% CI, 7.4% to 24.1%) of these responses were in those who had received one or more lines of chemotherapy for recurrent or metastatic disease. Median duration of response was not reached (range, ≥ 3.7 to ≥ 18.6 months). Treatment-related adverse events occurred in 65.3% of patients, and the most common were hypothyroidism (10.2%), decreased appetite (9.2%), and fatigue (9.2%). Treatment-related grade 3 to 4 adverse events occurred in 12.2% of patients. CONCLUSION: Pembrolizumab monotherapy demonstrated durable antitumor activity and manageable safety in patients with advanced cervical cancer. On the basis of these results, the US Food and Drug Administration granted accelerated approval of pembrolizumab for patients with advanced PD-L1-positive cervical cancer who experienced progression during or after chemotherapy.