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 1 Dose-Escalation Study of PF-06671008, a Bispecific T-Cell-Engaging Therapy Targeting P-Cadherin in Patients With Advanced Solid Tumors.

P-cadherin is a cell-cell adhesion molecule that is overexpressed in several solid tumors. PF-06671008 is a T-cell-redirecting bispecific antibody that engages both P-cadherin on tumors and CD3ϵ on T cells and induces antitumor activity in preclinical models. We conducted a phase 1, open-label, first-in-human, dose-escalation study to characterize the safety and tolerability of PF-06671008, towards determining the recommended phase 2 dose. Adult patients with treatment-refractory solid tumors received PF-06671008 (1.5-400 ng/kg) as a weekly intravenous (IV) infusion on a 21-day/3-week cycle. Parallel cohorts evaluated dosing via subcutaneous injection (SC) or an IV-prime dose. Of the 27 patients enrolled in the study, 24 received PF-06671008 IV in escalating doses, two received SC, and one IV-prime. A dose-limiting toxicity of cytokine release syndrome (CRS) occurred in the 400-ng/kg IV group, prompting evaluation of SC and IV-prime schedules. In all, 25/27 patients who received PF-06671008 reported at least one treatment-related adverse event (TRAE); the most common were CRS (21/27), decreased lymphocyte count (9/27), and hypophosphatemia (8/27). Seven patients permanently discontinued treatment due to adverse events and no treatment-related deaths occurred. Cytokine peak concentrations and CRS grade appeared to positively correlate with Cmax. Although the study was terminated due to limited antitumor activity, it provides important insights into understanding and managing immune-related adverse events resulting from this class of molecules. Clinical Trial Registration: URL: https://clinicaltrials.gov/ct2/show/NCT02659631, ClinicalTrials.gov Identifier: NCT02659631.

Association of Tumor Mutational Burden and Immune Gene Expression with Response to PD-1 Blockade by Sasanlimab Across Tumor Types and Routes of Administration.

BACKGROUND: Sasanlimab is a monoclonal antibody that binds to the programmed cell death receptor 1 (PD-1). Anti-PD-1 monoclonal antibodies have improved patient clinical outcomes; however, not all treated patients derive clinical benefit. Further insights on potential biomarkers beyond PD-L1 expression levels would help to identify the patients most likely to respond to treatment. OBJECTIVE: This study evaluated tumor biopsies from patients treated with intravenous or subcutaneous sasanlimab to identify biomarkers of response and characterize pharmacodynamic activity. METHODS: Anti-PD-1/PD-ligand 1 (PD-L1)-naive patients with advanced solid tumors received sasanlimab intravenously at 1, 3, or 10 mg/kg every 3 weeks (n = 23) or subcutaneously at 300 mg every 4 weeks (n = 15). Best tumor percentage change from baseline was determined by RECIST. Whole-exome DNA and RNA sequencing were performed in tumor samples collected from treated patients at protocol-defined timepoints. PD-L1 and CD8 protein expression were evaluated in tumor biopsies by immunohistochemistry. Associations with response were assessed by linear regression analysis. RESULTS: Baseline tumor mutational burden (TMB), as well as PD-L1 and CD8 expression, were significantly associated with response to sasanlimab across the multiple dose levels, routes of administration, and range of tumor types evaluated. TMB is an independent biomarker from the various tumor inflammatory genes and signatures evaluated. Gene set enrichment analysis showed that higher baseline expression levels of genes related to the interferon-γ and PD-1 signaling pathways and the cell cycle were significantly associated with response to sasanlimab across tumor types. No differences were observed between routes of administration with regard to response to sasanlimab for the biomarkers of interest (TMB, PD-L1, CD8, and interferon-γ signature). Evaluation of pharmacodynamic changes showed increased tumor expression of genes enriched in adaptive immune response pathways. CONCLUSIONS: Our findings indicate an active, immunomodulatory mechanism for the anti-PD-1 antibody sasanlimab across different tumor types and routes of administration. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT02573259; registered October 2015.

Assessment of Subcutaneous vs Intravenous Administration of Anti-PD-1 Antibody PF-06801591 in Patients With Advanced Solid Tumors: A Phase 1 Dose-Escalation Trial.

IMPORTANCE: We assessed feasibility of monthly subcutaneous administration of PF-06801591, a humanized immunoglobulin G4 monoclonal antibody that binds to the programmed cell death (PD-1) receptor and blocks its interaction with PD-1 ligands. OBJECTIVE: To evaluate the safety, efficacy, and pharmacokinetics of PF-06801591 administered intravenously vs subcutaneously. DESIGN, SETTING, AND PARTICIPANTS: Ongoing phase 1, open-label, multicenter, dose-escalation study of 40 patients, 18 years or older, with locally advanced or metastatic solid tumors, enrolled between March 8, 2016, and March 5, 2018, from 4 US medical centers. INTERVENTIONS: An intravenous dose of 0.5, 1, 3, or 10 mg/kg of PF-06801591 was administered every 3 weeks or a subcutaneous dose of 300 mg was administered every 4 weeks. Dose escalation occurred after 2 to 4 patients were enrolled per dose level, with additional patients enrolled in each cohort for further assessment. MAIN OUTCOMES AND MEASURES: The primary end points were dose-limiting toxic effects and safety. Secondary end points included pharmacokinetics, immunogenicity, PD-1 receptor occupancy, and efficacy. RESULTS: Of 40 enrolled patients (12 men and 28 women; mean [SD] age, 61 [13] years) in this phase 1 dose-escalation trial, 25 received PF-06801591 intravenously at escalating dose levels (0.5, 1, 3, or 10 mg/kg) and 15 patients received the monoclonal antibody subcutaneously at a single dose level. No dose-limiting toxic effects were observed. Grade 3 or higher treatment-related adverse events occurred in 4 (16%) patients treated intravenously and 1 (6.7%) patient treated subcutaneously. Immune-related adverse events occurred in 10 (40%) patients treated intravenously and 3 (20%) treated subcutaneously. No dose-adverse event associations were observed during intravenous dose escalation, and no serious skin toxic effects occurred with subcutaneous delivery. Responses were seen in 5 patients receiving PF-06801591 intravenously and in 2 patients treated subcutaneously for an overall objective response rate of 18.4%. Median overall survival was not reached with intravenous dosing vs 10.7 months with subcutaneous administration. Exposure to PF-06801591 increased in a dose-proportional manner over the range of intravenous doses. Median time to maximum observed serum concentration was 8 days after subcutaneous administration. Full PD-1 receptor occupancy was seen in all dose cohorts. CONCLUSIONS AND RELEVANCE: Anti-PD-1 antibody PF-06801591 was tolerable and showed antitumor activity in a variety of tumor types across all dose levels of intravenous and subcutaneous administration. Monthly subcutaneous administration of PF-06801591 offers a convenient, effective alternative to currently available intravenously administered checkpoint inhibitors. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02573259.

Generation of a high-fidelity antibody against nerve growth factor using library scanning mutagenesis and validation with structures of the initial and optimized Fab-antigen complexes.

Nerve growth factor (NGF) is indispensable during normal embryonic development and critical for the amplification of pain signals in adults. Intervention in NGF signaling holds promise for the alleviation of pain resulting from human diseases such as osteoarthritis, cancer and chronic lower back disorders. We developed a fast, high-fidelity method to convert a hybridoma-derived NGF-targeted mouse antibody into a clinical candidate. This method, termed Library Scanning Mutagenesis (LSM), resulted in the ultra-high affinity antibody tanezumab, a first-in-class anti-hyperalgesic specific for an NGF epitope. Functional and structural comparisons between tanezumab and the mouse 911 precursor antibody using neurotrophin-specific cell survival assays and X-ray crystal structures of both Fab-antigen complexes illustrated high fidelity retention of the NGF epitope. These results suggest the potential for wide applicability of the LSM method for optimization of well-characterized antibodies during humanization.

Proneurotrophins require endocytosis and intracellular proteolysis to induce TrkA activation.

The uncleaved, pro-form of nerve growth factor (proNGF) functions as a pro-apoptotic ligand for the p75 neurotrophin receptor (p75NTR). However, some reports have indicated that proneurotrophins bind and activate Trk receptors. In this study, we have examined proneurotrophin receptor binding and activation properties in an attempt to reconcile these findings. We show that proNGF readily binds p75NTR expressed in HEK293T cells but does not interact with TrkA expressed under similar circumstances. Importantly, proNGF activates TrkA tyrosine phosphorylation, induces Erk and Akt activation, and causes PC12 cell differentiation. We show that inhibiting endocytosis or furin activity reduced TrkA activation induced by proNGF but not that induced by mature NGF and that proNGF123, a mutant form of NGF lacking dibasic cleavage sites in the prodomain, does not induce TrkA phosphorylation in PC12 cells. Therefore, endocytosis and cleavage appear to be prerequisites for proNGF-induced TrkA activity. We also found that proBDNF induces activation of TrkB in cerebellar granule neurons and that proBDNF cleavage by furin and metalloproteases facilitates this effect. Taken together, these data indicate that under physiological conditions, proneurotrophins do not directly bind or activate Trk receptors. However, endocytosis and cleavage of proneurotrophins produce processed forms of neurotrophins that are capable of inducing Trk activation.

Macrophage stimulating protein is a target-derived neurotrophic factor for developing sensory and sympathetic neurons.

Macrophage stimulating protein (MSP) is a pleiotropic growth factor that signals via the Ron receptor tyrosine kinase. We report that Ron mRNA is expressed by NGF-dependent sensory and sympathetic neurons and that these neurons survive and grow with MSP at different stages of development. Whereas NGF-dependent sensory neurons become increasingly responsive to MSP with age, sympathetic neurons exhibit an early response to MSP that is lost by birth. MSP mRNA expression increases with age in sensory neuron targets and decreases in sympathetic targets. After the phase of naturally occurring neuronal death, significant numbers of NGF-dependent sensory neurons, but not sensory neurons, dependent on other neurotrophins, are lost in mice lacking a functional Ron receptor. These results show that MSP is a target-derived neurotrophic factor for subsets of sensory and sympathetic neurons at different times during their development.