Published in Journal for Immunotherapy of Cancer: Using Single-Cell Analysis to Assess the Effects of an Anti-OX40 Monoclonal Antibody in Its First-in-Human Phase I/II Study for Advanced Solid Cancer

Immunotherapies that harness the immune system to attack malignant cells have been successfully used to treat a number of cancers. As researchers have gained a better understanding of how immune cells function and signal, these findings have been applied to immunotherapies with the goal of improving clinical outcomes. IsoPlexis' technology helps to provide critical information about the efficacy of and response to novel therapies by rendering critical immune cell functional data at single-cell resolution.

While immune checkpoint inhibitors have been used to prevent the loss of T cell activity, T cell costimulatory receptors can also be activated to increase immunity against tumor cells. OX40 is a receptor that regulates T cell activity, proliferation, and apoptosis, and has been detected on activated CD4⁺ and CD8⁺ T cells. In addition, OX40 is constitutively expressed on regulatory T cells (Tregs). By using a monoclonal antibody, called INCAGN01949, that acts as an agonist, thereby activating OX40, researchers sought to increase expansion and survival of tumor-specific T cells while also decreasing Tregs, which can suppress immune responses.

Single-Cell Functionality Helps to Characterize Immune Response

INCAGN01949, an anti-OX40 monoclonal antibody agonist, was tested in a first-in-human phase I/II trial to treat advanced solid tumors, the results of which were recently published in theJournal for Immunotherapy of Cancer. The primary endpoints were safety and tolerability, but researchers also assessed clinical response, pharmacokinetic and pharmacodynamic characteristics, and T cell function.

At the end of the trial, the researchers concluded that the therapy was generally well tolerated, with a safety profile in line with other OX40 agonist antibodies. Neither the maximum tolerated dose nor pharmacologically active dose was reached as the authors wanted to avoid overstimulation and exhaustion of T cells, which have been reported in other studies using OX40 agonists. INCAGN01949 had no significant clinical response, and further characterization of immune response showed no increase in effector T cell infiltration or change in the frequency of Tregs in the tumor microenvironment.

The researchers used IsoPlexis' IsoCode single-cell functional analysis platform to determine how individual immune cells functioned in response to INCAGN01949 treatment. Analyses that rely on average across many cells may miss key individual differences, but IsoPlexis' single-cell analysis has been used to reveal key subsets of immune cell populations that drive immune response. However, in line with the other results from this trial, the authors found no consistent changes across timepoints or doses in the frequency of polyfunctional cells-cells that can secrete 2 or more cytokines and are associated with immune response-in the blood or polyfunctional strength index (PSI), a combination of the polyfunctionality metric with the strength of cytokine secretions.

Because of these results, the authors concluded that INCAGN01949 alone may not be an effective treatment but could instead be combined with other types of immune modulators, such as a toll-like receptor 9 agonist. Alternatively, the dosing strategy could be re-evaluated or the therapy could be individualized for specific types of tumors that could most benefit from OX40 agonism.

Using Single-Cell Analysis to Inform Therapeutic Strategy

Assessing polyfunctionality and PSI of immune cells in response to INCAGN01949 therapy helped the researchers to determine that they needed to revise their treatment strategy. By performing single-cell functional analysis, researchers can gain insightful data into how novel therapies affect immune cell function and identify crucial drivers of immune response, when present. IsoPlexis makes it easy for labs to get actionable functional data at the single-cell level, helping to drive development of more effective cancer therapies.

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