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BackgroundOX40 is a costimulatory receptor upregulated on antigen-activated T cells and constitutively expressed on regulatory T cells (Tregs). INCAGN01949, a fully human immunoglobulin G1κ anti-OX40 agonist monoclonal antibody, was designed to promote tumor-specific immunity by effector T-cell activation and Fcγ receptor-mediated Treg depletion. This first-in-human study was conducted to determine the safety, tolerability, and preliminary efficacy of INCAGN01949.MethodsPhase I/II, open-label, non-randomized, dose-escalation and dose-expansion study conducted in patients with advanced or metastatic solid tumors. Patients received INCAGN01949 monotherapy (7–1400 mg) in 14-day cycles while deriving benefit. Safety measures, clinical activity, pharmacokinetics, and pharmacodynamic effects were assessed and summarized with descriptive statistics.ResultsEighty-seven patients were enrolled; most common tumor types were colorectal (17.2%), ovarian (8.0%), and non-small cell lung (6.9%) cancers. Patients received a median three (range 1–9) prior therapies, including immunotherapy in 24 patients (27.6%). Maximum tolerated dose was not reached; one patient (1.1%) receiving 350 mg dose reported dose-limiting toxicity of grade 3 colitis. Treatment-related adverse events were reported in 45 patients (51.7%), with fatigue (16 (18.4%)), rash (6 (6.9%)), and diarrhea (6 (6.9%)) being most frequent. One patient (1.1%) with metastatic gallbladder cancer achieved a partial response (duration of 6.3 months), and 23 patients (26.4%) achieved stable disease (lasting >6 months in one patient). OX40 receptor occupancy was maintained over 90% among all patients receiving doses of ≥200 mg, while no treatment-emergent antidrug antibodies were detected across all dose levels. Pharmacodynamic results demonstrated that treatment with INCAGN01949 did not enhance proliferation or activation of T cells in peripheral blood or reduce circulating Tregs, and analyses of tumor biopsies did not demonstrate any consistent increase in effector T-cell infiltration or function, or decrease in infiltrating Tregs.ConclusionNo safety concerns were observed with INCAGN01949 monotherapy in patients with metastatic or advanced solid tumors. However, tumor responses and pharmacodynamic effects on T cells in peripheral blood and post-therapy tumor biopsies were limited. Studies evaluating INCAGN01949 in combination with other therapies are needed to further evaluate the potential of OX40 agonism as a therapeutic approach in patients with advanced solid tumors.Trial registration numberNCT02923349.

BackgroundRetifanlimab (INCMGA00012) is a humanized, hinge-stabilized immunoglobulin G4 kappa (IgG4κ), anti-programmed cell death protein (PD)-1 monoclonal antibody with safety and clinical pharmacology that are characteristic for the class. Evaluation of retifanlimab in solid tumors is under investigation in phase 2 and 3 studies. POD1UM-201 is an open-label, single-arm, multicenter, phase 2 study evaluating the efficacy and safety of retifanlimab in patients with chemotherapy-naïve or chemotherapy-refractory advanced/metastatic Merkel cell carcinoma (MCC). Updated results from the chemotherapy-naïve cohort are reported here.MethodsEligible patients were ≥18 years of age, had metastatic or recurrent unresectable loco-regional MCC, Eastern Cooperative Oncology Group performance status ≤1, measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, and had not received prior systemic treatment for MCC. Retifanlimab 500 mg IV every 4 weeks (Q4W) was administered for up to 2 years. The primary endpoint was overall response rate (ORR) assessed by independent central review per RECIST v1.1. Secondary endpoints included duration of response, disease control rate (DCR; defined as proportion of patients with either an objective response or stable disease lasting at least 6 months), progression-free survival, overall survival, safety, and pharmacokinetics.ResultsAs of April 16, 2021, 87 patients with chemotherapy-naïve advanced/metastatic MCC had received retifanlimab. Per protocol, the primary efficacy analyses are based on the first 65 patients assessed. At the data cutoff, 34 of these 65 patients (52.3%) were on treatment; 4 (6.2%) had completed treatment; and 27 (41.5%) had discontinued treatment for reasons including disease progression (18 [27.7%]), adverse event (AE; 7 [10.8%]), death (1 [1.5%]), and physician decision (1 [1.5%]). The ORR in these patients was 46.2% (n=30: complete response, 8 [12.3%]; partial response, 22 [33.8%]). The DCR was 53.8% (n=35). Other secondary efficacy results are not yet mature. Among all treated patients (n=87), 66 (75.9%) had a treatment-emergent AE (TEAE), 25 (28.7%) had a grade ≥3 TEAE, and 12 (13.8%) had a grade ≥3 treatment-related AE. Twenty-three patients (26.4%) had an immune-related AE (irAE), and 8 (9.2%) had a grade ≥3 irAE. Four patients (4.6%) discontinued treatment due to irAEs (peripheral sensorimotor neuropathy, pancreatitis, eosinophilic fasciitis, and polyarthritis [each n=1]). One patient (1.1%) had a grade 3 infusion reaction.ConclusionsThese data from the POD1UM-201 trial show that retifanlimab monotherapy at 500 mg Q4W continues to demonstrate promising clinical activity and safety in patients with advanced/metastatic chemotherapy-naïve MCC. Updated results will be presented at the meeting.AcknowledgementsThe study is sponsored by Incyte Corporation (Wilmington, DE). Statistical support was provided by Xiaohan Xu of Incyte Corporation. Editorial assistance was provided by Matthew Bidgood of Envision Pharma Group (Philadelphia, PA, USA).Trial RegistrationClinicaltrials.gov NCT03599713; EudraCT 2018-001627-39Ethics ApprovalThe study was approved by institutional review boards or independent ethics committees in Canada (McGill University Health Center-Research Ethics Board [MP-37-2019-5103, MEO-37-2019-1616]; Ontario Cancer Research Ethics Board [1728]; Health Research Ethics Board of Alberta – Cancer Committee [HREBA.CC-19-0004, HREBA.CC-19-0020]); Czech Republic (Eticka komise Fakultni nemocnice Kralovske Vinohrady, Eticka komise IKEM a FTNsP, Eticka komise Nemocnice Na Bulovce, Statni ustav pro kontrolu leciv, Eticka komise FN a LF UP Olomouc [169/18MEK24, LEK/04/07/2018, (L-18-85) 8522/23.3.2021, 22.3.2021/9965/EK-Z]); France (Comité de Protection des Personnes Ile de France X [CNRIPH : 18.11.19.49212/Id. 2043]; Agence Nationale de Sécurité du Médicament et des Produits de Santé); Germany (Ethik-Kommission der Medizinischen Fakultaet der Universitaet Duisburg-Essen [18-8371-AF]; Bundesamt fuer Strahlenschutz; Paul-Ehrlich Institute); Hungary (Egeszsegugyi Tudomanyos Tanacs Klinikai Farmakologiai Etikai Bizottsaga [IV/2407-0/2021-EKL, OGYÉI/11697-2/2021]; Orszagos Gyogyszereszeti es Elelmezes-egeszsegugyi Intezet); Italy (Comitato Etico IRCCS Pascale Napoli [116/21 E - 87/18]; Comitato Etico IRCCS di Candiolo [232/2021]; Istituto Tumori Giovanni Paolo II IRCCS Ospedale Oncologico Bari [736/CE]; Comitato Etico Locale per la Sperim. Clin. dei Medicinali dell’Az. Osp.ra Univ.ria Senese di Siena [14107]; Comitato Etico dell’IRCCS Istituto Nazionale per la Ricerca sul Cancro di Genova [389/2018 - 24/05/2021]; Comitato etico degli IRCCS Istituto Europeo di Oncologia e Centro Cardiologico Monzino [IEO 948 - RE3065/IB Edition 7 dated 10Nov2020 (SA7)]; Comitato Etico, Fondazione IRCCS Istituto Nazionale dei Tumori, .c. Medicina Oncologica 1 – Fondazio [INT 01/19]; Comitato Etico IRCCS Istituto Oncologico Veneto di Padova [EM 109/2021]; Comitato Etico dell’IRCCS Istituto Dermopatico dell’Immacolata Ospedale Generale S. Carlo di Roma [550/7]; AIFA – Agenzia Italiana del Farmaco [0040152-01/04/2021-AIFA-AIFA_USC-P]; Comitatao Etico Policlinico di Modena [1017/2018/FARM/AOUMO - EMENDAMENTO SOSTANZIALE IB EDIZIONE 7 DEL 10/11/20 (201800162739-010) (p. 9869/21)]); Poland (Komisja Bioetyczna przy Centrum Onkologii [no. 55/2019]; Office for Registration of Medicinal Products, Medical Devices and Biocidal Products [UR/DBL/D/328/2019]); Spain (CEIC Hospital General Universitario Gregorio Marañon [280/18]; Agencia Española del Medicamento y Productos Sanitarios); Switzerland (Kantonale Ethikkommission Zürich (KEK-Zürich) [2019-00200]; Swissmedic [2019DR2035]); United Kingdom (North East – York Research Ethics Committee [248465]; Medicines and Healthcare products Regulatory Agency; Health Research Authority); United States (Copernicus Group IRB; Western Institutional Review Board [20181738, Work order number -– IQV1-18-309]; Roswell Park Cancer Institute IRB [STUDY00000802/P 75918]; Inova Institutional Review Board, Human Research Protection Program; Stanford IRB Research Compliance Office [48198]; Rush University Medical Center [18072304-IRB01]; University of Miami IRB; Mayo Clinic IRB – Rochester).

Highlights • Agonistic antibodies against OX40 are in active clinical development. • Pre-clinical studies suggest sequential therapy is superior to combinational. • We report two cases of ovarian cancer treated with OX40 followed by PD-1/CTLA4 Ab. • Both experienced unusually deep and durable responses. • The cases support further investigation of the relevance of sequential immunotherapy., Agonists of the co-stimulatory molecule OX40 (CD134) are in clinical assessment alone and in combination with other immunotherapies. Recent pre-clinical studies have suggested that concurrent administration of OX40 agonists with anti-PD1 therapy is detrimental to the efficacy of such combinations and maximal efficacy may require sequential administration of the OX40 agonist followed by anti-PD1 therapy. In this report, we detail two patients with advanced ovarian carcinoma were treated with INCAGN01949, an agonistic OX40 Ab, as part of a clinical trial until disease progression. Both patients then received the combination of ipilimumab and nivolumab and experienced unusually deep and durable responses. These cases support the hypothesis raised in pre-clinical studies and highlight the potential relevance of sequence in combinational immunotherapy.

Because both phosphatidylinositol 3-kinase δ (PI3Kδ) and Janus kinase (JAK)-signal transducer and activator of transcription pathways contribute to tumor cell proliferation and survival in B-cell malignancies, their simultaneous inhibition may provide synergistic treatment efficacy. This phase 1 dose-escalation/expansion study assessed the safety, efficacy, pharmacokinetics, and pharmacodynamics of INCB040093, a selective PI3Kδ inhibitor, as monotherapy or combined with itacitinib (formerly INCB039110), a selective JAK1 inhibitor, in adult patients with relapsed or refractory (R/R) B-cell lymphomas. Final results are reported. Overall, 114 patients were treated (monotherapy, n = 49; combination therapy, n = 72 [7 patients crossed over from monotherapy to combination]). INCB040093 100 mg twice daily (monotherapy) and INCB040093 100 mg twice daily + itacitinib 300 mg once daily (combination) were the recommended phase 2 doses. One dose-limiting toxicity (gastrointestinal bleed secondary to gastric diffuse large B-cell lymphoma [DLBCL] regression) occurred with monotherapy. The most common serious adverse events with monotherapy were pneumonia (n = 5) and pyrexia (n = 4), and with combination Pneumocystis jiroveci pneumonia (n = 5), pneumonia (unrelated to P jiroveci; n = 5), and pyrexia (n = 4). Grade 3 or higher transaminase elevations were less common with combination. INCB040093 was active across the B-cell lymphomas; 63% of patients (5/8) with follicular lymphoma responded to monotherapy. Adding itacitinib provided promising activity in select subtypes, with responses of 67% (14/21) in classic Hodgkin lymphoma (vs 29% [5/17] with monotherapy) and 31% (4/13) in nongerminal center B-cell-like DLBCL. INCB040093 with/without itacitinib was tolerated and active in this study, and is a promising treatment strategy for patients with select R/R B-cell lymphomas. This trial was registered at www.clinicaltrials.gov as #NCT01905813.

OX40 is a T cell co-stimulatory receptor that can enhance the magnitude and durability of T cell immune responses. Anti-OX40 agonist antibodies have shown significant single agent tumoricidal activity in preclinical models, and can combine effectively with other immunomodulatory antibodies, targeted therapies and vaccines. OX40 agonists are able to counteract the immunosuppressive tumor microenvironment and promote tumor-specific cellular immunity via at least two distinct mechanisms: 1) promoting OX40 forward signaling in tumor-specific T cells; and 2) co-engaging Fcγ receptors expressed by tumor-associated effector cells, and facilitating the selective elimination of OX40high intratumoral regulatory T cells. INCAGN1949, an anti-OX40 human IgG1 antibody, was selected based on its ability to optimally enhance T cell responsiveness under conditions of suboptimal T cell receptor stimulation. INCAGN1949 was shown to mediate effective apical OX40 clustering that is translated into effective downstream activation of the NFκB pathway. Notably, INCAGN1949 was shown to maintain a sigmoidal dose response curve across a broad range of antibody concentrations. This suggests a wide therapeutic window and may be advantageous for dosing considerations. By contrast, evaluation of reference OX40 antibodies indicated an inverted U-shaped dose response curve, leading to impaired T cell responses at high concentrations. INCAGN1949 was selected for clinical development based on its optimal agonist profile, further reinforced by its ability to combine with other co-inhibitory and co-stimulatory antibodies to augment T cell responsiveness. Prior to human testing, the pharmacology and tolerability of INCAGN1949 was evaluated in non-human primates (NHPs). Pharmacokinetic (PK) and pharmacodynamic (PD) parameters were evaluated including longitudinal measurements of serum cytokines, immune cell populations, activation state and T cell-mediated immune responses to reporter vaccine antigens. INCAGN1949 exhibited a linear PK profile and was well tolerated at all doses tested, with no maximum tolerated dose established. Co-administration of INCAGN1949 and vaccines in NHPs showed an immune-based PD signature across a broad exposure range. These studies were in line with in vitro findings and support a wide PD range for INCAGN1949 in patients. An important secondary mechanism of INCAGN1949 is the ability of its IgG1 Fc region to mediate selective depletion of OX40high intratumoral regulatory T cells. Immunohistochemistry and flow cytometry analyses support the validity of this regulatory T cell depletion mechanism in a range of tumors. The functional in vitro and in vivo attributes of INCAGN1949 make it suitable for clinical development. It is currently under evaluation in a Phase 1/2 study in subjects with advanced or metastatic tumors (NCT02923349). Citation Format: Ana M. Gonzalez, Mariana L. Manrique, Lukasz Swiech, Thomas Horn, Ekaterina Breous, Jeremy Waight, David Savitsky, Yuqi Liu, Shiwen Lin, Christopher Clarke, Taha Merghoub, Daniel Hirschhorn-Cymerman, David Schaer, Gerd Ritter, Jennifer Pulini, Kevin Heller, Peggy Scherle, Gregory Hollis, Reid Huber, Marc van Dijk, Jennifer Buell, Robert Stein, Nicholas Wilson. INCAGN1949, an anti-OX40 antibody with an optimal agonistic profile and the ability to selectively deplete intratumoral regulatory T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4703. doi:10.1158/1538-7445.AM2017-4703

Background: PI3Kδ inhibitors have demonstrated efficacy in the treatment of B-cell malignancies, but off-target toxicity and/or the inability to achieve near-complete inhibition of the PI3Kδ pathway may affect the depth and duration of response. INCB050465 is a novel, potent, and selective PI3Kδ inhibitor (Shin et al. AACR 2015. Abstract 2671), with a differentiated profile for potency (whole blood IC50 = 10 nM), dose (10-fold). An open-label phase 1 study was initiated to evaluate INCB050465 alone or in combination with other agents in patients with previously treated B-cell malignancies; preliminary results of the dose escalation of INCB050465 monotherapy are reported. Methods: Adult patients with B-cell malignancies who were refractory to or for whom available treatments had failed were eligible. Dose escalation was conducted with a 3 + 3 design after an initial single patient cohort. Patients were observed for 21 days before enrollment of the next cohort. Results: As of the data cutoff, 15 patients were enrolled and treated with INCB050465 at doses ranging from 5 to 30 mg once daily. The median age was 64 years and 47% were men. Patients received a median of 2 prior treatment regimens and the median time since initial diagnosis was 4.9 years. Disease subtypes included DLBCL (n = 6), CLL (n = 3), FL (n = 2), MZL (n = 2), MCL (n = 1), and HL (n = 1). Median exposure to INCB050465 was 15.4 weeks (range, 6.9 to 36.4+ weeks) and no patients required dose reduction. INCB050465 was well tolerated with no DLTs observed. Five patients discontinued treatment, 4 due to disease progression and 1 due to an adverse event (grade 2 exfoliative dermatitis). Ten grade 3 or greater treatment-emergent adverse events were seen in 6 patients: anemia (n = 2), bacteremia, Escherichia infection, hypotension, neutropenia, pneumonia, sepsis, syncope, and WBC count decreased (n = 1 each). To date, only grade 1 transaminase elevations have been observed. Responses were observed in DLBCL (3/6 patients), CLL (1/3), FL (2/2), MZL (2/2), and MCL (1/1). Clinical benefit was observed early in the course of treatment, and the longest duration of response was 27+ weeks. Terminal half-life and suppression of PI3Kδ signaling at trough support once daily dosing. Conclusions: INCB050465 monotherapy was generally well tolerated at all doses tested. Robust and durable signaling pathway inhibition was achieved at all doses and INCB050465 showed promising efficacy in FL, DLBCL, and other lymphomas, with a potentially favorable toxicity profile vs other PI3Kδ inhibitors. Enrollment in dose-escalation, combination therapy, and disease-specific cohorts is ongoing. Citation Format: Andres Forero-Torres, Michael S. Wertheim, Tycel J. Phillips, Martin E. Gutierrez, William J. Edenfield, Swamy Yeleswaram, Maureen Bleam, Li Zhou, Jennifer H. Pulini, Théa Faivre, Harry Miao, Matt Spear, Rod Ramchandren. Preliminary safety, efficacy, and pharmacodynamics of a highly selective PI3Kδ inhibitor, INCB050465, in patients with previously treated B-cell malignancies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT056.

8558 Background: Efficacy of treatment options for pts with r/r cHL is limited. Evidence suggests blocking the PI3K or JAK-STAT pathways may be efficacious in cHL directly and through modulation of...

TPS8607 Background: In vitro data suggest that both the PI3K and JAK-STAT pathways contribute to tumor growth and survival in HL. Therapies that block both pathways may prove more beneficial in pts...