ICOS agonism by JTX-2011 (vopratelimab) requires initial T cell priming and Fc cross-linking for optimal T cell activation and anti-tumor immunity in preclinical models

Immunotherapy checkpoint inhibitors, such as antibodies targeting PD-1 and CTLA-4, have demonstrated the potential of harnessing the immune system to treat cancer. However, despite encouraging results particularly with respect to survival, only a minority of patients benefit from these therapies. In clinical studies aimed at understanding changes in the immune system following immunotherapy treatment, ICOS (Inducible T cell CO-Stimulator) was shown to be significantly up-regulated on CD4+ T cells and this was associated with clinical activity, indicating that ICOS stimulatory activity may be beneficial in the treatment of solid tumors. In this report, we describe the generation of specific, species cross-reactive, agonist antibodies to ICOS, including the humanized clinical candidate, JTX-2011 (vopratelimab). Preclinical studies suggest that the ICOS stimulating antibodies require Fc receptor cross-linking for optimal agonistic activity. Notably, the ICOS antibodies do not exhibit superagonist properties but rather require T cell receptor (TCR)-mediated upregulation of ICOS for agonist activity. Treatment with the ICOS antibodies results in robust anti-tumor benefit and long-term protection in preclinical syngeneic mouse tumor models. Additional benefit is observed when the ICOS antibodies are administered in combination with anti-PD-1 and anti-CTLA-4 therapies. Based on the preclinical data, JTX-2011 is currently being developed in the clinical setting for the treatment of solid tumors.

Abstract SY03-02: Preclinical assessment of JTX-2011, an agonist antibody targeting ICOS, supports evaluation in ICONIC clinical trial

ICOS (the inducible T-cell co-stimulator) is a co-stimulatory molecule expressed on the surface of T cells and a member of the CD28 family, which includes clinically validated targets of cancer immunotherapies, such as PD-1 and CTLA-4. Clinical data identified ICOS as a potentially key molecule in providing optimal antitumor benefit following anti-CTLA-4 therapy. We have developed a species cross-reactive humanized IgG1 agonist antibody, JTX-2011, that binds ICOS and is designed to induce an antitumor immune response. Our preclinical data suggest that JTX-2011 functions through a dual mechanism of action, by stimulating T effector cells (Teff) and depleting intratumoral T regulatory cells (Tregs). The ICOS antibody is efficacious as a single agent in mouse syngeneic tumor models and demonstrates enhanced activity when administered in combination with anti-PD-1. Single-agent activity in the preclinical models appears to correlate with ICOS expression, with greater efficacy observed in tumor models that exhibit a higher percentage of ICOS-expressing immune cell infiltrate. An integrated expression analysis of human tumors identified non-small cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSCC) as indications with higher percentages of ICOS-expressing cell infiltrate. Preclinical studies performed in rodent and monkeys evaluated safety, pharmacokinetics, and pharmacodynamics of JTX-2011 to inform the first in-human study. The ICONIC phase I/II clinical trial is currently ongoing for evaluation of JTX-2011 alone or in combination with the anti-PD-1 antibody Nivolumab in patients with advanced solid tumors and incorporates a patient enrichment strategy design based on the preclinical and translational findings.

Citation Format: Jennifer S. Michaelson, Christopher Harvey, Kutlu Elpek, Ellen Duong, Lindsey Shallberg, Matthew Wallace, Robert Mabry, Jenny Shu, Amit Deshpande, Tong Zi, Stephen Sazinsky, Joshua Apgar, Barbara Mounho-Zamora, Michael Briskin, Elizabeth Trehu, Jason Reeves, Heather Hirsch, Sriram Sathyanarayanan, Deborah Law. Preclinical assessment of JTX-2011, an agonist antibody targeting ICOS, supports evaluation in ICONIC clinical trial [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 SY03-02. doi:10.1158/1538-7445.AM2017-SY03-02