A bispecific anti-PD-1 and PD-L1 antibody induces PD-1 cleavage and provides enhanced anti-tumor activity.

Combinatorial strategies, such as targeting different immune checkpoint receptors, hold promise to increase the breadth and duration of the response to cancer therapy. Here we describe the preclinical evaluation of CTX-8371, a protein construct which combines PD-1 and PD-L1 targeting in one bispecific, tetravalent antibody. CTX-8371 matched or surpassed the activity of anti-PD-1 and PD-L1 benchmark antibodies in several in vitro T cell activation assays and outperformed clinically approved benchmarks in the subcutaneous MC38 colon and the B16F10 lung metastasis mouse tumor models. Investigation into the mechanism of action revealed that CTX-8371 co-engagement of PD-1 and PD-L1 induced the proteolytic cleavage and loss of cell surface PD-1, which is a novel and non-redundant mechanism that adds to the PD-1/PD-L1 signaling axis blockade. The combination of CTX-8371 and an agonistic anti-CD137 antibody further increased the anti-tumor efficacy with long-lasting curative therapeutic effect. In summary, CTX-8371 is a novel checkpoint inhibitor that might provide greater clinical benefit compared to current anti-PD-1 and PD-L1 antibodies, especially when combined with agents with orthogonal mechanisms of action, such as agonistic anti-CD137 antibodies.

Targeting the DLL/Notch Signaling Pathway in Cancer: Challenges and Advances in Clinical Development.

The DLL/Notch signaling pathway plays an important role in cancer as a key driver in maintaining cancer stemness and inducing tumor angiogenesis. Many different types of DLL/Notch inhibitors have been developed and explored in clinical trials for cancer treatment, including small-molecule compounds to inhibit gamma-secretase and antibodies targeting Notch ligands or receptors. Despite promising efficacy of these inhibitors in preclinical studies, the overall clinical outcomes have been insufficient to advance to the next stage of clinical development primarily due to safety concerns or modest efficacy. To overcome the narrow therapeutic window of DLL/Notch inhibitors, diverse strategies for improving the balance between the safety and efficacy are currently being explored. Here, we review the clinical perspective and potential of DLL/Notch inhibitors as anticancer agents based on recent results from multiple clinical studies. An antibody specifically targeting Notch ligands or receptors may offer a better approach to reduce concerns about toxicity derived from broad-spectrum DLL/Notch blockers. In addition, combination therapy with an angiogenesis inhibitor targeting VEGF could be a better option for increasing anticancer efficacy. Taken together, the results of clinical trials suggest a bispecific antibody blocking the DLL/Notch and VEGF/VEGFR signaling pathways as a promising approach for effective anticancer treatment.

Differentiated agonistic antibody targeting CD137 eradicates large tumors without hepatotoxicity.

CD137 (4-1BB) is a member of the TNFR superfamily that represents a promising target for cancer immunotherapy. Recent insights into the function of TNFR agonist antibodies implicate epitope, affinity, and IgG subclass as critical features, and these observations help explain the limited activity and toxicity seen with clinically tested CD137 agonists. Here, we describe the preclinical characterization of CTX-471, a fully human IgG4 agonist of CD137 that engages a unique epitope that is shared by human, cynomolgus monkey, and mouse and is associated with a differentiated pharmacology and toxicology profile. In vitro, CTX-471 increased IFN-γ production by human T cells in an Fcγ receptor-dependent (FcγR-dependent) manner, displaying an intermediate level of activity between 2 clinical-stage anti-CD137 antibodies. In mice, CTX-471 exhibited curative monotherapy activity in various syngeneic tumor models and showed a unique ability to cure mice of very large (~500 mm3) tumors compared with validated antibodies against checkpoints and TNFR superfamily members. Extremely high doses of CTX-471 were well tolerated, with no signs of hepatic toxicity. Collectively, these data demonstrate that CTX-471 is a unique CD137 agonist that displays an excellent safety profile and an unprecedented level of monotherapy efficacy against very large tumors.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of the CGRP Binding Monoclonal Antibody LY2951742 (Galcanezumab) in Healthy Volunteers.

Background: Calcitonin gene-related peptide (CGRP) is pivotal in the pathophysiology of migraine headaches and represents a promising target for migraine treatment. The humanized monoclonal antibody galcanezumab (LY2951742) binds to CGRP and may be effective in migraine prophylaxis. Objectives: The primary objective was to evaluate the safety and tolerability of single and multiple doses of galcanezumab in humans. Secondary objectives included assessing the pharmacokinetics and evaluating target engagement. Methods: A double-blind, randomized, placebo-controlled study (NCT 01337596) with single escalating and multiple subcutaneous (SC) doses of galcanezumab was performed in healthy male volunteers. Single doses of 1, 5, 25, 75, 200, and 600 mg of galcanezumab (n = 7/dose) or placebo (n = 2/dose) were injected SC in six consecutive cohorts of nine subjects each. One cohort of nine subjects received multiple (4) 150 mg doses of galcanezumab or placebo every other week. Target engagement was evaluated by measuring inhibition of capsaicin-induced increase in dermal blood flow (DBF). Findings: Sixty-three subjects were randomized and included in the safety analyses. Galcanezumab was well tolerated in single doses (1-600 mg SC) and consecutive doses (150 mg SC). There was no dose-dependent difference in type or frequency of treatment-emergent adverse events, and no clinically meaningful difference when compared with placebo. Pharmacokinetics were linear. Galcanezumab induced a robust, dose-dependent, and durable inhibition of capsaicin-induced increase in DBF, supporting the continued clinical development of galcanezumab for prophylaxis in migraine patients.

Overall survival analysis of a phase II randomized controlled trial of a Poxviral-based PSA-targeted immunotherapy in metastatic castration-resistant prostate cancer.

PURPOSE: Therapeutic prostate-specific antigen (PSA) -targeted poxviral vaccines for prostate cancer have been well tolerated. PROSTVAC-VF treatment was evaluated for safety and for prolongation of progression-free survival (PFS) and overall survival (OS) in a randomized, controlled, and blinded phase II study. PATIENTS AND METHODS: In total, 125 patients were randomly assigned in a multicenter trial of vaccination series. Eligible patients had minimally symptomatic castration-resistant metastatic prostate cancer (mCRPC). PROSTVAC-VF comprises two recombinant viral vectors, each encoding transgenes for PSA, and three immune costimulatory molecules (B7.1, ICAM-1, and LFA-3). Vaccinia-based vector was used for priming followed by six planned fowlpox-based vector boosts. Patients were allocated (2:1) to PROSTVAC-VF plus granulocyte-macrophage colony-stimulating factor or to control empty vectors plus saline injections. RESULTS: Eighty-two patients received PROSTVAC-VF and 40 received control vectors. Patient characteristics were similar in both groups. The primary end point was PFS, which was similar in the two groups (P = .6). However, at 3 years post study, PROSTVAC-VF patients had a better OS with 25 (30%) of 82 alive versus 7 (17%) of 40 controls, longer median survival by 8.5 months (25.1 v 16.6 months for controls), an estimated hazard ratio of 0.56 (95% CI, 0.37 to 0.85), and stratified log-rank P = .0061. CONCLUSION: PROSTVAC-VF immunotherapy was well tolerated and associated with a 44% reduction in the death rate and an 8.5-month improvement in median OS in men with mCRPC. These provocative data provide preliminary evidence of clinically meaningful benefit but need to be confirmed in a larger phase III study.

A phase I/II clinical trial of enzyme replacement therapy in mucopolysaccharidosis II (Hunter syndrome).

OBJECTIVE: To evaluate the safety and explore the efficacy of idursulfase (recombinant human iduronate-2-sulfatase) treatment for mucopolysaccharidosis II (MPS II). STUDY DESIGN: Twelve patients were enrolled into a randomized, double-blind, placebo-controlled trial for 24 weeks followed by an open-label extension study. Three groups of 4 patients were enrolled sequentially, with 3 patients in each group receiving idursulfase and 1 patient receiving placebo. The first group received idursulfase at 0.15 mg/kg infused every other week with the 2nd and 3rd groups receiving 0.5 and 1.5 mg/kg, respectively. After 24 weeks the placebo-treated patients were changed to idursulfase at the dose of their group. The primary endpoint was a change from baseline in urinary excretion of glycosaminoglycans. Results were pooled for analysis by ANOVA and compared to baseline. RESULTS: Urinary glycosaminoglycans were reduced within 2 weeks of initiating idursulfase and were decreased 49% after 48 weeks of treatment (P<0.0001). Both liver and spleen volume were decreased at 24 weeks (P<0.01) and 48 weeks (P<0.001). The 6-minute walk test distance increased an average of 48 meters after 48 weeks (P=0.013). Six patients in the higher dose groups developed IgG antibodies that did not influence the clinical effects of idursulfase. CONCLUSIONS: This study describes the first experience with enzyme replacement therapy for the treatment of patients with MPS II. Idursulfase was generally well tolerated and was associated with reductions in urine glycosaminoglycans levels and organ size, as well as an increased 6-minute walk test distance.