Beyond checkpoint inhibition: PD-1 cis-targeting of an IL-2Rβγ-biased interleukin-2 variant as a novel approach to build on checkpoint inhibition

The immunocytokine PD1-IL2v was designed to overcome liabilities and improve efficacy of IL-2 therapies. PD1-IL2v preferentially targets PD-1⁺ T-cells and acts on antigen-specific stem-like PD-1⁺ TCF-1⁺ CD8⁺ T-cells expanding and differentiating them towards better effectors resulting in superior efficacy in LCMV chronic infection and tumor models compared to checkpoint inhibition.

Selective targeting of IL2Rβγ combined with radiotherapy triggers CD8- and NK-mediated immunity, abrogating metastasis in HNSCC

The implementation of cancer immunotherapies has seen limited clinical success in head and neck squamous cell carcinoma (HNSCC). Interleukin-2 (IL-2), which modulates the survival and functionality of lymphocytes, is an attractive target for new immunotherapies but one that is limited by presence of regulatory T cells (Tregs) expressing the high-affinity IL-2Rα. The bispecific immunocytokine PD1-IL2v preferentially delivers IL-2 signaling through IL-2Rβγ on PD-1-expressing cells. Selectively targeting the intermediate-affinity IL-2Rβγ can be leveraged to induce anti-tumor immune responses in effector T cells and natural killer (NK) cells while limiting the negative regulation of IL-2Rα activation on Tregs. Using radiation therapy (RT) in combination with PD1-IL2v improves local tumor control and survival, and controls metastatic spread in orthotopic HNSCC tumor models. PD1-IL2v drives systemic activation and expansion of circulating and tumor-infiltrating cytotoxic T cells and NK cells while limiting Treg-mediated immunosuppression. These data show that PD1-L2v induces durable systemic tumor control in HNSCC.

Simultaneous targeting of PD-1 and IL-2Rβγ with radiation therapy inhibits pancreatic cancer growth and metastasis

In pancreatic ductal adenocarcinoma (PDAC) patients, we show that response to radiation therapy (RT) is characterized by increased IL-2Rβ and IL-2Rγ along with decreased IL-2Rα expression. The bispecific PD1-IL2v is a PD-1-targeted IL-2 variant (IL-2v) immunocytokine with engineered IL-2 cis targeted to PD-1 and abolished IL-2Rα binding, which enhances tumor-antigen-specific T cell activation while reducing regulatory T cell (Treg) suppression. Using PD1-IL2v in orthotopic PDAC KPC-driven tumor models, we show marked improvement in local and metastatic survival, along with a profound increase in tumor-infiltrating CD8+ T cell subsets with a transcriptionally and metabolically active phenotype and preferential activation of antigen-specific CD8+ T cells. In combination with single-dose RT, PD1-IL2v treatment results in a robust, durable expansion of polyfunctional CD8+ T cells, T cell stemness, tumor-specific memory immune response, natural killer (NK) cell activation, and decreased Tregs. These data show that PD1-IL2v leads to profound local and distant response in PDAC.

Abstract 5747: A novel combination therapy of arenavirus vectors and PD1-IL2v strongly potentiates tumor specific T cell responses resulting in synergistic anti-tumor efficacy

It is undisputed that CD8 T cells play a critical role in controlling tumor growth and killing tumor cells, and that tumor specific T cells are essential for clinical responses to immune checkpoint inhibitors. Yet, the induction and maintenance of functional tumor antigen specific T cell responses represent still one of the greatest challenges in cancer immunotherapy.

Therapeutic cancer vaccines based on engineered arenavirus vectors have been shown preclinically to overcome self-tolerance to tumor associated antigens (TAA) and mount unprecedented T cell responses, both, in preclinical tumor models as well as HPV16+ cancer patients in an ongoing Phase 1/2 trial. The novel PD-1 targeted IL-2 variant (PD1-IL2v) was created to maximize the potency of IL-2R activation of effector T cells while overcoming the toxicities of wildtype IL-2. Cis binding of PD1-IL2v to PD-1 and IL-2Rβγ on the same cell was recently shown to promote differentiation of stem-like CD8 T cells into better effectors and was therefore identified as an ideal compound for combination therapies with arenavirus vectors. Combination of vectors encoding tumor associated foreign or self-antigens with PD1-IL2v lead to a massive, up to 60-fold, increase of peripheral tumor specific CD8 T cell numbers compared to vector treatment alone. Notably, frequency of peripheral regulatory T cells was not enhanced by this combination. The massive increase of TAA specific CD8 T cells was associated with synergistic anti-tumor efficacy in two independent tumor models, resulting in longer survival times and up to 60% complete responders. Complete tumor clearance resulted in a stable memory T cell population and protection against tumor re-challenge. Ongoing studies will address modifications of the tumor microenvironment and further characterization of tumor infiltrating T cells upon combination therapy.

These preclinical data establish the combination of arenavirus vectors and PD1-IL2v as a promising next generation cancer immunotherapy.

Citation Format: Judith Strauss, Diana Reckendorfer, Kimberly Pojar, Laura Codarri Deak, Valeria Nicolini, Roger Sutmuller, Christian Klein, Pablo Umaña, Klaus K. Orlinger, Henning Lauterbach. A novel combination therapy of arenavirus vectors and PD1-IL2v strongly potentiates tumor specific T cell responses resulting in synergistic anti-tumor efficacy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5747.

Bispecific PD1-IL2v and anti-PD-L1 break tumor immunity resistance by enhancing stem-like tumor-reactive CD8+ T cells and reprogramming macrophages

Immunotherapies have shown remarkable, albeit tumor-selective, therapeutic benefits in the clinic. Most patients respond transiently at best, highlighting the importance of understanding mechanisms underlying resistance. Herein, we evaluated the effects of the engineered immunocytokine PD1-IL2v in a mouse model of de novo pancreatic neuroendocrine cancer that is resistant to checkpoint and other immunotherapies. PD1-IL2v utilizes anti-PD-1 as a targeting moiety fused to an immuno-stimulatory IL-2 cytokine variant (IL2v) to precisely deliver IL2v to PD-1⁺ T cells in the tumor microenvironment. PD1-IL2v elicited substantial infiltration by stem-like CD8⁺ T cells, resulting in tumor regression and enhanced survival in mice. Combining anti-PD-L1 with PD1-IL2v sustained the response phase, improving therapeutic efficacy both by reprogramming immunosuppressive tumor-associated macrophages and enhancing T cell receptor (TCR) immune repertoire diversity. These data provide a rationale for clinical trials to evaluate the combination therapy of PD1-IL2v and anti-PD-L1, particularly in immunotherapy-resistant tumors infiltrated with PD-1⁺ stem-like T cells.

Abstract 2070: Differentiating PD-1+TCF-1+ stem-like resource CD8 T cells towards a distinct effector Tcell population with enhanced anti-tumor potential by delivering an engineered IL-2 variant to PD-1 via cis-targeting

PD1-IL2v is a novel immunocytokine constituted by a high affinity bivalent blocking PD-1 antibody and a heterodimeric silent Fc-part fused to a monomeric IL-2 variant (IL2v). In contrast to wildtype IL2, IL2v does not bind to CD25 (IL2Ra) and, therefore, the preferential targeting of T regulatory cells (Tregs) and endothelial cells through CD25 is abolished. The PD-1 antibody, having ca. 50-fold higher affinity than IL2v, dictates the preferential cis-delivery of IL2v to PD-1 positive T cells, such as antigen-experienced tumor-reactive T cells. In addition, due to the reduced expression levels of PD-1 on Tregs compared to CD8 and conventional T cells, PD1-IL2v preferentially binds to the latter in vitro and ex vivo, rescuing them from Treg-mediated suppression. To assess the effects of the cis-delivery of IL2v to PD-1+ T cells in vivo, we applied subcutaneous B16F10-OVA and Panc02-H7-Fluc tumor models in syngeneic mice. PD1-IL2v lead to significantly improved survival of the B16F10-OVA tumor bearing and tumor regression in the Panc02-H7-Fluc tumor bearing mice. The OVA-specific CD8 T cells expressed the highest amount of PD-1 in the tumor microenvironment, and PD1-IL2v not only increased the total number of CD8 tumor infiltrating lymphocytes (TILs), but, more importantly, it expanded the OVA-specific T cells. The recently discovered PD-1+ TCF1+ stem-like or resource T cells responsible for the proliferative burst following anti-PD-1 therapy, correlate with clinical responses and better prognosis. However, stem-like T cells ultimately differentiate into terminally exhausted T cells resulting in relapses and tumor growth. Here, we show that PD1-IL2v targets OVA-specific stem-like T cells, and leads to their expansion and differentiation into a unique population of effector CD8 T cells, so-called “fresh and better effectors”. These cells have a distinct phenotypic and molecular signature in addition to diverse TCR clonality in comparison to the terminally exhausted CD8 TILs generated by anti-PD1 therapy alone or in combination with a non-cis targeted FAP-IL2v immunocytokine. Thus, PD1-IL2v is a differentiated immune cell-targeted IL2v, which promotes an effective and long-term anti-tumor immune-response by delivering IL-2v to PD-1+ tumor-specific T cells, like stem-like T cells, and by generating a distinct effector T cell population.

Citation Format: Maria Karagianni, Eleni Maria Varypataki, Valeria Nicolini, Christian Münz, Pablo Umana, Christian Klein, Laura Codarri Deak. Differentiating PD-1+TCF-1+ stem-like resource CD8 T cells towards a distinct effector Tcell population with enhanced anti-tumor potential by delivering an engineered IL-2 variant to PD-1 via cis-targeting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2070.