Engaging Type 1 and Type 2 Immunity Against Cancer with Combined Immunotherapies

Dec 02, 2024

Cancer immunotherapies are more frequently developed by leveraging and directing type 1 immunity (e.g., adoptive cell transfer) against tumors. By contrast, it remains unclear whether engaging type 2 immunity, as exemplified by various cytokines, such as IL-4, IL-5, IL-9, and IL-13 in immunotherapies would be an effective strategy. This is partly due to the context-dependent outcomes reported so far, where type 2 cytokines may have pro- or anti-tumorigenic functions.¹

However, recent findings support that implementing CAR-T cell immunotherapy strategies that also engage type 2 immunity may be an effective approach leading to durable outcomes.² Therefore, a recent new study has aimed to evaluate and understand the impact of a Type 2 cytokine-based therapy on CAR-T cell responses.³

Leveraging Interleukin-4 (IL4) to improve cellular therapies

Seeking to improve CAR-T efficacy and ensure long-term cancer remission, an international team led by investigators in the US, China, and Switzerland has integrated the use of an engineered form of IL-4 (Feng et al. 2024).³ Because previous studies demonstrated that the type 2 cytokine, IL-4, can effectively extend T cell survival, the team focused on testing its functional effects on CD8+ T cells in various preclinical tumor models. However, for best cytokine performance, the team wanted to improve upon the stability of IL-4. Therefore, they resorted to developing a modified form of IL-4, fused to an IgG2a Fc protein, which proved to retain the activity of the native protein while having desirable longer persistence in vivo.

Throughout this work, Feng et al. 2024, leveraged various mouse tumor models to evaluate the effectiveness of Fc-IL-4 in combination with the adoptive cell transfer (ACT) of tumor-specific activated CD8+ T cells. In this workflow, isolated T-cells must be expanded and activated by cytokines and tumor-specific antigens before being infused. To this end, the investigators relied on several peptides, including “human gp10025–33, OVA257–264 or LCMV gp33–41 peptide (0.5 or 1 μM, GenScript) for PMEL, OT1 and P14 T cells, respectively,” to activate T-cells and enrich for tumor specificity in vitro prior to their infusion.

First, to test the effectiveness of the modified cytokine, Fc-IL-4, the team leveraged melanoma tumor bearing mice, which were first infused with activated T cells enriched for gp100 tumor antigen specificity and subsequently received Fc-IL-4 via peritumoral administration. By following this approach, the team found that Fc-IL-4 efficiently increased infiltration of endogenous and adoptively transferred CD8+ T cells within the tumor microenvironment. Significantly, Fc-IL-4 was very effective promoting the infiltration of T cells with a phenotype corresponding to CD8+ T_TE cells, having high expression of co-inhibitory markers, such as Pdcd1, Ctla4, Lag3 and Nr4a2. Despite the expression of these exhaustion markers, Feng et al. 2024 found that these intratumoral CD8+ T_TE cells had increased cytotoxic function by virtue of their high expression of granzymes and type 1 cytokines.

Next, the team evaluated the effects of combining Fc-IL-4 and ACT on tumor burden. In two different mouse melanoma models, the combined therapy fully eradicated tumors, whereas either monotherapy had limited success. Significantly, a long-lasting cure was achieved as treated animals could remain tumor-free upon rechallenge even 70 days after the initial treatment.

Lastly, the team’s preclinical studies included evaluating the efficacy of combining an anti-HER2 CAR-T cell therapy and Fc-IL-4 in a mouse colon adenocarcinoma model. While the HER2-CAR-T cell therapy alone was not effective, the combined therapy proved effective for tumor eradication, with an over 80% cure rate. They found that a long-lasting protective response could also be induced by the combination of Fc-IL4/anti-HER2-CAR-T immunotherapy against colon tumors in this model as well.

Moving towards the clinic

Encouraged by the preclinical success, Feng et al. initiated studies to evaluate the potential for the clinical application of their combined therapy. In vitro studies showed that human Fc-IL-4 effectively increased the proliferation and cytotoxic properties of anti-CD19 CAR-T cells. Moreover, evaluation in syngeneic and xenograft tumor models matched previous findings. For instance, tumors in a Raji lymphoma immune-deficient mice could be eradicated in a majority of animals by combined anti-CD19 CAR-T cell and Fc-IL-4 immunotherapy, extending survival. Importantly, beyond its potency, administration of Fc-IL-4 showed to be safe.

How does Fc-IL-4 improve immunotherapy efficacy?

Once the effects of Fc-IL-4, increasing CD8+ T_TE cell intratumor frequency and enhancing their effector function, were confirmed, the team confronted the task of pinning down the molecular mechanisms at play. First, Feng and colleagues found that expression of the IL-4 receptor subunit-α (IL-4Rα) was highest in CD8+ T_TE cells and that knocking out this receptor eliminated the benefits of Fc-IL-4. Next, mechanistically they found that IL-4 signaling was critical in promoting the survival of CD8+ T_TE cells, rather than their proliferation. Lastly, they showed that Fc-IL-4 was able to reprogram the metabolic status of CD8+ T_TE cells towards increased glycolysis and thus function. Feng et al. identified various Fc-IL-4 upregulated signaling pathways, including mTOR, eIF4 and p70S6K, PI3K/AKT, and JAK–STAT, with STAT6 and PI3K–AKT–mTOR signaling more significantly underscoring the metabolic reprogramming of CD8+ T_TE cells.