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.

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.

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.

Abstract CT150: A first-in-human phase I study of the OX40 agonist GSK3174998 (GSK998) +/- pembrolizumab in patients (Pts) with selected advanced solid tumors (ENGAGE-1)

Background: OX40 is a costimulatory receptor transiently expressed on the surface of activated T cells and some innate immune cells (e.g. NK cells). OX40 agonists have been shown to increase antitumor immunity and improve tumor-free survival in preclinical models, demonstrating increased efficacy when given in combination with a PD-1 inhibitor. GSK998 is a humanized IgG1 agonistic OX40 monoclonal antibody. Methods: ENGAGE-1 (NCT02528357) is a Phase 1 dose escalation study evaluating safety, PK, PD, and clinical activity of GSK998 (0.003-10 mg/kg IV Q3W) alone (Part 1) and in combination with pembrolizumab 200 mg IV Q3W (Part 2) in pts with previously treated advanced solid tumors: non-small cell lung cancer (NSCLC), squamous cell carcinoma of the head and neck, renal cell carcinoma, melanoma (MEL), bladder cancer, soft tissue sarcoma (STS), triple-negative breast cancer, and MSI-high colorectal carcinoma. Dose escalation used a continuous reassessment method and 4-week DLT period. Results: A total of 138 pts were enrolled (45 Part 1, 96 Part 2; 3 crossed over from Part 1). Two DLTs occurred in Part 2 only (G3 non-malignant pleural effusion 0.03 mg/kg; G1 myocarditis 10 mg/kg); MTD was not established. Most common (≥10%) treatment-related AEs (mostly G1-2) were diarrhea, fatigue (Part 1) and fatigue, nausea (Part 2). GSK998 demonstrated target engagement in the periphery as evidenced by PK and receptor occupancy (RO); a dose of 0.3 mg/kg was the threshold for linear PK & peripheral RO saturation over the 3-wk dose interval and was selected for further clinical evaluation in MEL, STS, and NSCLC in Part 2 expansion. Clinical responses and SD ≥24 weeks were observed in both PD-1/L1 naïve and experienced pts: Part 1 (1 PR, 1 SD; both 0.3 mg/kg) and Part 2 (2 CR, 7 PR, 9 SD; 0.01-3 mg/kg); Part 2 clinical responses were not correlated with baseline tumor PD-L1 expression levels; including one MEL pt with PD-L1 TPS=0 who progressed on prior CTLA-4/PD-1 treatment and had a CR (>18mo). Overall, peripheral and tumor expression of OX40 was low (<2% total cells in tumor were OX40 +ve). MultiOmyxTM data from tumor biopsies suggested increased NK/decreased Treg involvement in some responders. Conclusions: GSK998 +/- pembrolizumab was well tolerated, with evidence of target engagement; monotherapy clinical activity was limited. While combination responses may not be significantly greater than expected for pembrolizumab alone, responses were observed in some PD-1/L1 experienced pts and some with low PD-L1 expression. Given the low OX40 expression observed and preclinical evidence that increased expression improves activity of OX40 agonism, ongoing clinical evaluation of GSK998 will assess whether concurrent immune-stimulation or immunogenic cell death impacts OX40 expression and increases the efficacy of this agent. Combinations with TLR4 and ICOS agonists and an anti-BCMA antibody-drug conjugate are ongoing.

Citation Format: Sophie Postel-Vinay, Vincent K. Lam, Willeke Ros, Todd M. Bauer, Aaron R. Hansen, Daniel C. Cho, F. Stephen Hodi, Jan H.M. Schellens, Jennifer K. Litton, Sandrine Aspeslagh, Karen A. Autio, Frans L. Opdam, Meredith McKean, Neeta Somaiah, Stephane Champiat, Mehmet Altan, Anna Spreafico, Osama Rahma, Elaine M. Paul, Christoph M. Ahlers, Helen Zhou, Herbert Struemper, Shelby A. Gorman, Maura Watmuff, Kaitlin M. Yablonski, Niranjan Yanamandra, Michael J. Chisamore, Emmett V. Schmidt, Axel Hoos, Aurélien Marabelle, Jeffrey S. Weber, John V. Heymach. A first-in-human phase I study of the OX40 agonist GSK3174998 (GSK998) +/- pembrolizumab in patients (Pts) with selected advanced solid tumors (ENGAGE-1) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT150.

P860 Results from a combination of OX40 (PF-04518600) and 4–1BB (utomilumab) agonistic antibodies in melanoma and non-small cell lung cancer in a phase 1 dose expansion cohort

Background

PF-04518600 (PF-8600) and utomilumab (uto) are humanized agonist IgG2 monoclonal antibodies for the tumor necrosis factor superfamily receptors OX40 and 4-1BB, respectively. In a phase I dose escalation study (NCT02315066), this antibody combination was tolerable at all dose levels and induced responses in patients with melanoma resistant to immune checkpoint inhibitors. We report results from a dose expansion cohort of this study of patients with melanoma and non-small cell lung cancer (NSCLC) treated with PF-8600 (OX40 antibody) in combination with uto. Efficacy, safety, and the association of baseline and pharmacodynamic biomarkers with efficacy were examined.

Methods

In this expansion cohort, patients with locally advanced/metastatic melanoma (n=10) and NSCLC (n=20) who progressed on prior anti-PD1/PD-L1 treatment and/or anti CTLA4 treatment (melanoma only) were enrolled. Patients received OX40 antibody 30 mg IV every 2wks in combination with uto 20 mg IV every 28d. Tumor assessments were performed every 8wks using RECIST1.1. Paired biopsy samples collected at baseline and 6wks were analyzed by immunohistochemistry and RNA sequencing to evaluate the pharmacodynamic effects of the OX40 antibody in combination with uto. Whole blood samples were collected longitudinally, from which DNA was extracted and submitted for high-throughput sequencing of the T cell receptor β-chain.

Results

One patient with NSCLC achieved a confirmed and ongoing partial response lasting at least 6 months; Based on analyses of a subset of baseline biopsies, this patient’s tumor had the lowest FOXP3 expression. A total of 7 (70%) melanoma patients and 7 (35%) NSCLC patients achieved a best overall response of stable disease (SD). The median duration of SD was 16.3 weeks (melanoma: 16.0 weeks; NSCLC: 24.1 weeks), for a disease control rate of 50%. Among patients with a defined response, paired biopsy analyses showed that the greatest increase in CD8 occurred in the NSCLC patient with the longest duration of stable disease. The most frequent treatment related adverse events (TRAEs) reported in ≥10% of patients were pruritis, anemia, fatigue, decreased appetite, and rash. Grade 3 TRAEs, rash and lymphocyte count decreased, were reported in 5 patients and a grade 4 TRAE of lipase increased (asymptomatic) was reported in 1 patient.

Conclusions

The combination of PF-8600 and uto had a tolerable safety profile and demonstrated clinical benefit, including in an NSCLC patient who had progressed on anti-PD1 therapy and achieved a durable partial response. Further combinations with one or both of these immune costimulatory receptor agonist antibodies might enhance their efficacy.

Acknowledgements

This study was funded by Pfizer Inc. Editorial support was provided by Chu Kong Liew, PhD, of Engage Scientific Solutions and was funded by Pfizer Inc.

Trial Registration

ClinicalTrials. gov: NCT02315066

Ethics Approval

The study was approved by the institutional review board at each study center and conducted in accordance with the ethical principles of the Declaration of Helsinki.

Pembrolizumab (pembro) for advanced biliary adenocarcinoma: Results from the KEYNOTE-028 (KN028) and KEYNOTE-158 (KN158) basket studies

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Background: Antitumor activity with pembro, an anti–PD-1 antibody, has been observed in patients (pts) with advanced/metastatic biliary tract cancers (BTC), who have limited treatment options. We present follow-up data from pts with advanced BTC treated with pembro in the KN158 (NCT02628067; phase 2) and KN028 (NCT02054806; phase 1) studies. Methods: Eligible pts ≥18 y in the KN158/KN028 BTC cohorts had histologically/cytologically confirmed incurable advanced BTC that progressed after/failed any number of prior standard treatment regimens, measurable disease per RECIST v1.1, ECOG PS of 0/1, and no prior immunotherapy. PD-L1–positivity (membranous PD-L1 expression in ≥1% of tumor and associated inflammatory cells or positive staining in stroma) was required for eligibility in KN028, but not KN158. Pts received pembro 200 mg Q3W (KN158) or 10 mg/kg Q2W (KN028) for up to 2 y. Radiographic imaging occurred Q9W for 12 mo (KN158) or Q8W for 6 mo (KN028) and Q12W thereafter. Primary efficacy endpoint in both studies was ORR by RECIST 1.1. Response assessed by independent central review is reported. Results: Median (range) follow-up was 7.5 (0.6–29.5) mo in the 104 pts from KN158 and 6.5 (0.6–33.1) mo in the 24 pts from KN028 with BTC. All pts in KN028 and 61 in KN158 had PD-L1–positive tumors. No pt had MSI-H tumors (not assessed in KN028). In KN158, ORR was 5.8% (6/104, all PR [including 1 pt with PD-L1–negative tumor]; 95% CI, 2.1%–12.1%) and median duration of response (DOR) was not reached (NR; range, 6.2 to 23.2+ mo). Median OS and PFS were 7.4 mo (95% CI, 5.5–9.6) and 2.0 mo (95% CI, 1.9–2.1). 12-mo OS rate was 32.7%. In KN028, ORR was 13.0% (3/23, all PR; 95% CI, 2.8%‒33.6%) and median DOR was NR (range, 21.5 to 29.4+ mo). Median OS and PFS were 6.2 mo (95% CI, 3.8‒10.3) and 1.8 mo (95% CI, 1.4‒3.7), respectively. 12-mo OS rate was 27.6%. Grade 3–5 treatment-related AEs occurred in 13.5% in KN158 (1 pt had grade 5 renal failure) and 16.7% of pts in KN028 (no grade 5). 18.3% in KN158 and 20.8% of pts in KN028 had an immune-mediated AE or infusion reaction. Conclusions: Pembro provides durable antitumor activity, regardless of PD-L1 expression, and manageable toxicity in a subset of pts with advanced BTC. Clinical trial information: NCT02054806 and NCT02628067.

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.

Enhancing antitumor response by combining immune checkpoint inhibitors with chemotherapy in solid tumors

BACKGROUND

Cancer immunotherapy has changed the standard of care for a subgroup of patients with advanced disease. Immune checkpoint blockade (ICB) in particular has shown improved survival compared with previous standards of care for several tumor types. Although proven to be successful in more immunogenic tumors, ICB is still largely ineffective in patients with tumors that are not infiltrated by immune cells, the so-called cold tumors.

PATIENTS AND METHODS

This review describes the effects of different chemotherapeutic agents on the immune system and the potential value of these different types of chemotherapy as combination partners with ICB in patients with solid tumors. Both preclinical data and currently ongoing clinical trials were evaluated. In addition, we reviewed findings regarding different dosing schedules, including the effects of an induction phase and applying metronomic doses of chemotherapy.

RESULTS

Combining ICB with other treatment modalities may lead to improved immunological conditions in the tumor microenvironment and could thereby enhance the antitumor immune response, even in tumor types that are so far unresponsive to ICB monotherapy. Chemotherapy, that was originally thought to be solely immunosuppressive, can exert immunomodulatory effects which may be beneficial in combination with immunotherapy. Each chemotherapeutic drug impacts the tumor microenvironment differently, and in order to determine the most suitable combination partners for ICB it is crucial to understand these mechanisms.

CONCLUSION

Preclinical studies demonstrate that the majority of chemotherapeutic drugs has been shown to exert immunostimulatory effects, either by inhibiting immunosuppressive cells and/or activating effector cells, or by increasing immunogenicity and increasing T-cell infiltration. However, for certain chemotherapeutic agents timing, dose and sequence of administration of chemotherapeutic agents and ICB is important. Further studies should focus on determining the optimal drug combinations, sequence effects and optimal concentration-time profiles in representative preclinical models.

Abstract CT010: Pharmacodynamic (PD) changes in tumor RNA expression and the peripheral blood T cell receptor (TCR) repertoire in a phase I study of OX40 agonistic monoclonal antibody (mAb) PF-04518600 (PF-8600)

Introduction: PF-8600 is a fully human IgG2 agonistic mAb against the tumor necrosis factor superfamily receptor OX40. OX40 improves T cell survival, proliferation, and activation and may enhance anti-tumor immunity. In an ongoing phase I study (NCT02315066) of 52 patients (pts) with melanoma, hepatocellular carcinoma, head and neck carcinoma, or renal cell carcinoma treated with PF-8600 monotherapy in dose escalation, 2 pts had best overall response of partial response (PR) and 27 of stable disease. PF-8600 was well-tolerated at all doses. Peripheral blood flow cytometry had previously shown increased proliferation and activation of CD4 central memory T cells at certain dose levels, suggesting a PD effect. RNAseq analysis of tumor biopsy samples and TCR sequencing of peripheral blood were used to further support proof of mechanism.

Methods: Biopsy samples at baseline and wk 6 were collected from 5 dose cohorts [0.1 (4), 0.3 (3), 1.5 (4), 3.0 (3) and 10.0 (2), dose in mg/kg (n)]. Biopsy tissue was analyzed by RNAseq and gene ranking-based gene set enrichment analysis (FGSEA) to identify immune pathways potentially up-regulated by OX40. CD4/CD8 cells were isolated from peripheral blood samples from 4 dose cohorts (0.1, 0.3, 1.5, and 3.0 mg/kg). DNA was extracted for sequencing of the TCR-β chain complementarity-determining region 3 (CDR3).

Results: In a combined analysis of samples from pts dosed with ≥1.5 mg/kg, the top 3 gene sets showing enrichment at wk 6 of therapy were associated with inflammatory response, interferon-γ response and allograft rejection. These gene sets were identical to the top 3 most enriched in tumor from a syngeneic mouse tumor model exposed to a murine OX40 agonist. This pattern of enrichment was not observed if samples from lower doses were included in the analysis. TCR sequencing revealed clonal expansion of CD4/CD8 T cells at all dose levels at wk 6 [CD4: mean = 8 expanded clones per 100,000 clones (range = 1 - 80), CD8: mean = 56 (range = 1 - 500)]. The 2 patients with PR had among the lowest numbers of expanded CD4 and CD8 clones (CD4: 4 and 2; CD8: 7 and 4).

Conclusion: Enrichment of gene sets associated with immune activation in tumor tissue from patients dosed with PF-8600 provides evidence supporting an active, immunomodulatory mechanism. Peripheral CD4/CD8 T cell populations exhibited clonal expansion in response to dosing with PF-8600 at all dose levels further suggesting a PD effect. However, clinical response did not necessarily correlate with a high number of expanded T cell clones, suggesting that clinical response to OX-40 agonism may be driven by the expansion of select anti-tumor T cell clones rather than a broad expansion of T cell clones in the peripheral blood. The phase I study will continue to evaluate PD changes in the tumor and peripheral blood in dose-expansion cohorts of PF-8600 ± utomilumab.

Citation Format: Adi Diab, Omid Hamid, John A. Thompson, Willeke Ros, Fredericus A. L. M. Eskens, Toshihiko Doi, Siwen Hu-Lieskovan, Hua Long, Tenshang Joh, Shoba Potluri, Xiao Wang, Catherine Fleener, Carrie Turich Taylor, Bishu J. Ganguli, Jeffrey Chou, Anthony B. El-Khoueiry. Pharmacodynamic (PD) changes in tumor RNA expression and the peripheral blood T cell receptor (TCR) repertoire in a phase I study of OX40 agonistic monoclonal antibody (mAb) PF-04518600 (PF-8600) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT010.

Phase Ia and Ib studies of the novel carcinoembryonic antigen (CEA) T-cell bispecific (CEA CD3 TCB) antibody as a single agent and in combination with atezolizumab: Preliminary efficacy and safety in patients with metastatic colorectal cancer (mCRC)

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Background: CEA CD3 TCB (RG7802, RO6958688) is a novel T-cell bispecific antibody targeting CEA on tumor cells and CD3 on T cells. In preclinical models, CEA CD3 TCB displays potent anti-tumor activity, leads to increased intra-tumoral T cell infiltration and activation and upregulates PD-1/PD-L1. Methods: Intwo ongoing dose-escalation phase I studies, RO6958688 is given as monotherapy (S1) i.v. QW or in combination (QW) with atezolizumab 1200 mg Q3W (S2) in adult patients (pts) with advanced CEA+ solid tumors. In S1, 80 pts (mCRC: 68) were treated at dose levels from 0.05 mg to 600 mg; in S2, 38 pts (mCRC: 28) from 5 mg to 160 mg. In S1, a Bayesian logistic regression model with overdose control guided dose escalation. Data cutoff 25.01.17. Results: At doses ≥60mg (36 pts in S1; 10 in S2), CT scans revealed tumor inflammation within days of first dose, consistent with the mode of action of RO6958688. 2 (5%) pts in S1 (both microsatellite stable (MSS) and 2 (20%; 1 MSS) in S2 had a partial response (RECIST v1.1). Preliminary tumor size reduction ( > -10% and < -30% [stable disease]) was observed in 4 (11%) additional pts in S1 and 5 (50%) in S2. At week 4-6 FDG PET scan assessment, 10 (28%) pts with mCRC in S1 and 6 (60%) in S2 had a metabolic partial response (EORTC criteria). At all doses in S1, the most common related AEs were pyrexia (56.3%), infusion related reaction (IRR, 50%) and diarrhea (40%). The most common grade ≥ 3 (G3) related AEs were IRR (16.3%) and diarrhea (5%). 5 patients experienced DLTs: G3 dyspnea, G3 diarrhea, G3 hypoxia, G4 colitis and G5 respiratory failure (G4-5 at 600mg). DLT events were likely associated with tumor lesion inflammation. In S2, there was no evidence of new or additive toxicities, with 1 DLT at 160 mg (G3 transient increase of ALT in a patient with liver metastases). PK/PD data are reported separately. Conclusions: Evidence of antitumor activity was observed with RO6958688 monotherapy in ongoing dose escalation. Activity appeared to be enhanced with doses in combination with atezolizumab, with a manageable safety profile. Updated data will be presented. Clinical trial information: NCT02324257 and NCT02650713.

The relationship of pharmacodynamics (PD) and pharmacokinetics (PK) to clinical outcomes in a phase I study of OX40 agonistic monoclonal antibody (mAb) PF-04518600 (PF-8600)

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Background: PF-8600 is a novel fully human IgG2 agonistic mAb against human OX40, a TNF receptor superfamily member expressed primarily on activated T cells. This ongoing phase 1 study (NCT02315066) is investigating the safety, efficacy, PK and PD of PF-8600 in patients (pts) with solid tumors. Methods: PF-8600 (0.01–10 mg/kg) was given IV every 14d. Expression of free/total OX40 receptor, proliferation marker ki67 and activation markers HLA-DR/CD38 were measured in T cell subsets in peripheral blood by flow cytometry in all pts. CD4, CD8, OX40 and FOXP3 were evaluated in paired tumor biopsies (bx), collected from a subset of pts (≥0.1 mg/kg) at baseline (BL) and Wk6, by immunohistochemistry. Results: As of 21Sep2016, 48 pts with melanoma (n = 14), hepatocellular carcinoma (HCC, n = 19), head and neck squamous cell (n = 6) or renal cell carcinoma (n = 9) enrolled in the dose-escalation cohorts (0.01-3 mg/kg). No immune related adverse events (AE) were reported. The most frequent treatment related AEs in > 3 pts were fatigue (27.1%) and nausea and vomiting (8.3% each); all Gr 1-2. 2 pts had a partial response: melanoma at 0.1 (Pt1) and HCC at 0.3 (Pt2) mg/kg. 25 pts had best ORR (BOR) of stable disease (SD; 3 pts ≥24 wks). A majority of pts at 0.1, 0.3, and 3 mg/kg, including Pt1 and Pt2, had increases in ki67 and HLA-DR/CD38 expression in peripheral CD4+ central memory T cells. Pt1, Pt2 and all pts at ≥0.3 mg/kg had full receptor occupancy. Paired bx were only available from pts with BOR of SD or progressive disease. In 10 pts with available paired tumor bx and defined date of radiographic progression (rPD), longer time to rPD correlated with increases in %OX40+ in bx from BL to Wk6, regardless of dose level, tumor type or prior immunotherapy (R2= 0.52, p = 0.0188); no correlation between rPD and CD4+, CD8+ or FOXP3+ expression changes was observed. Updated efficacy, safety, PK and PD data will be presented. Conclusions: PF-8600 is well tolerated with evidence of single agent efficacy. Initial observations of PD markers that change with treatment and correlate with rPD support efforts to confirm these findings as more clinical outcomes and larger sample sizes become available. Clinical trial information: NCT02315066.

Pharmacokinetics (PK) and pharmacodynamics (PD) of a novel carcinoembryonic antigen (CEA) T-cell bispecific antibody (CEA CD3 TCB) for the treatment of CEA-expressing solid tumors

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Background: CEA CD3 TCB (RO6958688) targets CEA on tumor cells and is agonistic for CD3e on T cells. In mouse models, CEA CD3 TCB displays potent anti-tumor activity, leads to increased intra-tumoral T cell infiltration and activation and up-regulates the PD-1/PD-L1 pathway. Methods: Biodistribution was assessed in mice using SPECT/CT. Patient (pts) samples correspond to 2 dose-escalation studies in CEA+ solid tumors. Study 1 (S1): single agent weekly (qW) (0.052 to 600 mg, iv, n = 80), and Study 2 (S2): combination of RO6958688 qW (5 to 160 mg, iv) with 1200mg atezolizumab q3W (n = 38). Analytical methods: PK - population modeling approach; anti-drug antibodies (ADA) - ELISA; immunophenotyping in peripheral blood (PB) by flow cytometry (FCM), in pre- (BSL) and on-treatment (OT) biopsies by immunohistochemistry (IHC) and FCM; plasma cytokines - multiplex assays; PD-L1 - SP142 assay. Results: In mice, RO6958688 preferentially accumulated in CEA+ tumors. In pts with no ADAs tested thus far in both studies (S1 29; S2 21), RO6958688 showed near linear PK and exposure. In S1, OT biopsies demonstrated a statistically significant increase in density and activation profile of T cells (CD3: 2.6-fold, n = 21; CD3/CD8: 3.7 fold, n = 17; CD3/Ki67: 4-fold, n = 20; CD8/PD1: 1.7-fold, n = 15) without dose-dependence. In S2, preliminary data of T cell density (5-80mg) were similar to S1 (2-fold). In S1, a significant correlation was observed between treatment-induced tumor lesion reduction and increases of OT CD8/CD25 fluorescence intensity from BSL (p = 0.028). PD-L1 expression increased in OT biopsies in both studies. In S1, from week 4, a moderate expansion of activated CD8 T cells (HLA-DR/Ki67) but not of CD4, was detected in PB at doses > 60mg ( > 3.3 fold). Transient increases of several cytokines were seen in both studies with levels peaking within 24hrs. Conclusions: PK and PD results consistent with tumor inflammation and mechanism of action support that RO6958688 is the first tumor-targeted T cell bispecific to show intra-tumoral biological activity in pts with CEA+ solid tumors. Updated data will be presented. Clinical data are reported separately.

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.

Replicating reoviruses with a transgene replacing the codons for the head domain of the viral spike

The capacity to modify the reovirus genome facilitates generation of new therapeutic reoviruses. We describe a method for generating replication-competent reoviruses carrying a heterologous transgene. The strategy is based on the expanded-tropism reovirus mutant jin-3, which can infect cells independent of the reovirus receptor junction-adhesion molecule A (JAM-A). Jin-3 harbors a mutation in the S1 segment, resulting in a G196R substitution in the tail of the spike protein σ1. The use of the jin-3 tail-encoding S1 segment allows replacing the codons for the JAM-A-binding head domain by up to 522  nucleotides of foreign sequences, without exceeding the size of the wild-type S1 segment. We inserted the codons for the porcine teschovirus-1 2A element fused with those encoding the fluorescent protein iLOV. Replicating rS1His-2A-iLOV reoviruses were generated by co-transfection of expression plasmids for all reovirus segments. These reoviruses contain the S1His-2A-iLOV segment in the absence of the wild-type S1 segment. Density-gradient centrifugation confirmed the association of the σ1-tail fragment with the capsid. Both JAM-A-positive and -negative cells exposed to the rS1His-2A-iLOV reoviruses exhibited iLOV fluorescence, confirming the jin-3-derived expanded-tropism phenotype. These data demonstrated the feasibility of generating decapitated replication-competent T3D reoviruses carrying a heterologous transgene.

Predictive validity of the BRASS index in screening patients with post-discharge problems. Blaylock Risk Assessment Screening Score

RATIONALE

Discharge planning is a nursing intervention that aims to ensure continuity of care; it consists of several steps of which selecting patients in need of it is the first one. The Blaylock Risk Assessment Screening Score (BRASS) index is a risk screening instrument which can be used early after admission to identify those patients in need of discharge planning.

AIM

To test the predictive validity of the BRASS index in screening patients with post-discharge problems.

DESIGN

Prospective longitudinal design with prediction instrument measured at admission, and outcomes measured at discharge and 7 and 30 days after discharge.

OUTCOME MEASURES

length of stay, discharge destination, status after discharge.

INSTRUMENTS

BRASS index, Problems after discharge Questionnaire, Nottingham Health Profile, COOP/WONCA charts.

RESEARCH METHOD

503 elderly patients were screened at admission with the BRASS index. Length of stay and discharge destination were measured at discharge in these same patients. Outcomes after discharge were gathered only in patients who were discharged home and with length of stay of more than 3 days (n=226); outcomes were measured by postal questionnaires at day 7 and day 30 after discharge.

RESULTS

patients identified by the BRASS index as high risk are frequently not discharged home and have a longer length of stay. The BRASS scores correlate significantly with the outcome scores after discharge: the higher the BRASS score, the higher the difficulty score after discharge on all domains. However, the sensitivity of the BRASS index is rather low.

CONCLUSION

This study demonstrates that the BRASS index is a good predictor instrument for indicating patients who are not discharged home, that the BRASS scores correlate significantly with problems experienced after discharge and that it has high specificity to predict patients with problems after discharge. Clinical use, however, is limited due to the low sensitivity. The BRASS index is a promising case-finding instrument for discharge planning, but needs further development.