Synthetic IL9R signaling to rewire T cells for adoptive cell therapy of cancer

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PROJECT SUMMARY Adoptive cell therapy (ACT) using engineered T cells – such as chimeric antigen receptor (CAR) or T cell receptor (TCR) modified T cells – is an effective immunotherapy for hematologic malignancies. Success with ACT has been elusive for solid tumors, which present unique challenges to T cells. ACT also requires conditioning chemotherapy to deplete a patient’s endogenous T cells, which results in significant toxicity. Our goal is to engineer T cells with synthetic functions to overcome hurdles of ACT for solid tumors including the need for conditioning chemotherapy, which would dramatically improve the feasibility and safety of this therapy. In this proposal we use the orthogonal IL2 cytokine-receptor pair developed by our collaborator Dr. Garcia at Stanford. Orthogonal IL2Rβ (o2R) is only activated by the orthogonal IL2 (oIL2) cytokine, and not by wildtype IL2. When activated, o2R signals through the intracellular domain (ICD) of IL2Rβ, which involves cooperation with the native common gamma chain (γc). Leveraging this cooperation, we studied chimeric orthogonal receptors in which the IL2Rβ ICD of o2R is replaced with ICDs of receptors for other γc cytokines, such that oIL2 elicits the corresponding γc signal. Of these chimeras, signaling through the IL9R ICD (o9R) generated a unique STAT phosphorylation profile and differentiation trajectory, prompting further exploration in vivo. Despite a weaker proliferative signal than o2R signaling, o9R signaling resulted in T cells with superior anti-tumor efficacy, an effect pronounced in the absence of lymphodepletion. To translate this finding into a viable treatment for patients with advanced solid tumors will require an understanding of the functional features of o9R signaling T cells that permit their anti-tumor efficacy, especially in the absence of conditioning chemotherapy. Our preliminary data led us to focus on two of these features, which we tackle in Aims 1 and 2. In Aim 1, we focus on the peripheral in vivo effects of o9R signaling that rely on interaction with the host, especially lymph node homing and priming. We hypothesize that the o9R signaling reprograms T cells in the periphery for efficient lymph node homing and spatial positioning that promotes priming that is critical for their anti-tumor effects in vivo. Aim 1 will use both TCR- and CAR- based syngeneic mouse solid tumor models of ACT. In Aim 2, we turn to the cell-intrinsic effects of o9R signaling on effector capacity in the face of chronic antigen stimulation. We hypothesize that o9R signaling interferes with the epigenetic changes that drive T cell dysfunction in the context of chronic antigen stimulation, resulting in superior effector capacity. Aim 2 will primarily use human T cells engineered with a TCR specific for the NY-ESO-1 antigen along with the pmel model. Our complementary aims outline an approach to define the effects of IL9R signaling in T cells that underlie their anti-tumor functions in solid tumors without conditioning chemotherapy. Our findings will set the stage for the therapeutic translation of T cells endowed with IL9R signaling.