TCR- and BsAb-induced interaction drives avidity-based cellular immunotherapy efficacy

The success of chimeric antigen receptor (CAR) T cell therapy for hematological malignancies has not yet translated into long-term elimination of solid tumors, indicating the need for adequate tuning of CAR T cell functionality. The CAR binding moiety is the critical trigger for CAR T cell signaling. CAR binding affinity alone does not determine T cell effector functions. In a panel of anti-Her2 CARs covering a 4-log affinity range, we observed that rather high affinity and cell avidity above the minimum threshold, combined with elevated tonic signaling, produce adequate T cell capacity for expansion and tumor control. The same scFv mutations increased both antigen-specific affinity, cell avidity, and antigen-independent tonic signaling; above a minimum threshold, raise in affinity translated into cell avidity in a non-linear fashion. In this case, replacement by amino acids of higher hydrophobicity within the scFv coincidentally augmented affinity, non-specific binding, spontaneous CAR clustering, and tonic signaling, all together relating to T cell functionality in an integrated fashion. Data highlight the mechanistic complexity of CAR signaling and suggest inclusion of additional variables, for example, hydrophobic interactions, into the equation when determining the CAR’s antigen-specific and tonic signaling capacities.

Translocations involving FGFR2 gene fusions are common in cholangiocarcinoma and gastric carcinoma and predict response to FGFR kinase inhibitors. However, response rates and durability are limited due to the emergence of resistance, typically involving FGFR2 kinase domain mutations, and to sub-optimal dosing, relating to adverse drug effects.

This webcast will present new work showing that the vast majority of such alterations retain the extracellular domain (ECD), potentially enabling highly selective targeting of the FGFR2 ECD using biotherapeutics.

To improve on the activity of traditional bivalent monotopic antibodies, the Sellers lab systematically generated biparatopic antibodies targeting distinct epitope pairs in FGFR2 ECD, and identified antibodies that effectively block signaling and malignant growth driven by FGFR2-fusions.

These antibodies robustly blocked proliferation and colony formation in FGFR2-fusion driven cholangiocarcinoma and demonstrated robust in vivo anti-tumour activity. In vivo activity was marked by significant antibody-mediated downregulation of FGFR2 and in turn this was associated with robust lysosomal internalization enacted by the two biparatopics. In vitro, the biparatopic antibodies demonstrated activity against FGFR inhibitor resistant alleles of FGFR2. The internalization properties of the antibodies also make them suitable for exploration as antibody-drug conjugates

Commercial CAR-T therapies still suffer from severe limitations, as majority of patients fail to achieve complete response and ultimately relapse.

Watch this Webinar to discover Prof. Marco Ruella’s team have adopted a novel CAR-T avidity screening method to improve safety and exhaustion profile, leading to 100% clinical response in a phase I trial.

Acute myeloid leukemia (AML) continues to be an unmet clinical need for both adult and pediatric patients. Although CAR-T cell therapy has demonstrated substantial therapeutic potential, further advancements are necessary to achieve safe and lasting disease remission. In this webinar, CAR-CIK cell pioneer Dr. Sarah Tettamanti, from the Tettamnti foundation in Milan, Italy (alongside our Lead Product Manager, Shira Segal, at LUMICKS) discuss how Cell avidity was used to generate an additional layer of information to understand the mechanism of action and enhance decision-making on identifying the most efficacious candidates whilst limiting toxicity to healthy cells.

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