Immunocytokines targeting immune checkpoints have shown great potential in overcoming resistance to immune checkpoint blockade (ICB), making them a major focus of development in recent years. However, severe dose-limiting toxicity hindered their clinical application. Therefore, it is vital to develop versatile strategies to improve safety and elucidate the underlying mechanisms of resistance reversal for advancing immunocytokine therapy.
A general prodrug platform was established to construct interleukin (IL)-15 and IL-12-based immunocytokine prodrugs (P-T, P-Y, and P-Y-IL12). The efficacy of the masking strategy was validated by in vitro activity assays and in vivo safety evaluations. Antitumor efficacy of P-T was assessed in two murine cold tumor models. A comprehensive immune correlate analysis was conducted in the tumor and tumor-draining lymph node (TDLN) to identify key effector cells responsible for overcoming resistance, followed by further confirmation with egression of T cell blockade, surgical excision of TDLN, and adoptive transfer experiments. Finally, the synergistic antitumor effects of P-T with other ICB or HPK1 inhibitors were investigated.
P-T or P-Y using steric hindrance from antibody moiety Fab and Fc shields IL-15 activity in circulation, and reactivates it on cleavage by tumor-specific proteases. The universality of this masking strategy is also applicable to IL-12. Compared with prior constructs, P-T and P-Y exhibit prolonged half-life and tumor retention, facilitating sustained intratumoral immune response. P-T demonstrates reduced systemic toxicity but better control of established tumors over the unmasked counterpart. CD44+ CD8+ T cells in TDLNs are identified as critical mediators of P-T's efficacy: blockade of CD44+ CD8+ T cell trafficking into the tumor microenvironment (TME) markedly diminishes its antitumor effects. On P-T treatment, CD44+ CD8+ T cells exhibit enhanced proliferation in TDLNs and improved antitumor activity. Furthermore, P-T combined with other immunotherapies enhances antitumor effects by increasing CD44+ CD8+ T cells in TDLNs or promoting their infiltration into the TME.
The Fab and Fc-masked prodrug serves as a universal strategy for next-generation immunocytokines design, effectively addressing their dose-limiting toxicity. Additionally, leveraging immunocytokines to mobilize T cells in TDLNs offers a promising therapy option to overcome resistance to ICB and HPK1 inhibitors.
© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.

Personalized cancer vaccines (PCVs) largely leverage neoantigens arising from somatic mutations, limiting their application to patients with relatively high tumor mutational burden (TMB). This underscores the need for alternative antigens to design PCVs for low TMB cancers. To this end, we substantiate endogenous retroviral elements (EVEs) as tumor antigens through large-scale genomic analyses of healthy tissues and solid cancers. These analyses revealed that the breadth of EVE expression in tumors stratify checkpoint inhibitor-treated melanoma patients into groups with differential overall and progression-free survival. To enable the design of PCVs containing EVE-derived epitopes with therapeutic potential, we developed a computational pipeline, ObsERV. We show that EVE-derived peptides are presented as epitopes on tumors and can be predicted by ObsERV. Preclinical testing of ObsERV demonstrates induction of sustained poly-functional CD4+ and CD8+ T-cell responses as well as long-term tumor protection. As such, EVEs may facilitate and improve PCVs, especially for low-TMB patients.
© 2025. The Author(s).

Blockade of immune checkpoints PD-1 and TIGIT has demonstrated activity in mouse tumor models and human patients with cancer. Although these coinhibitory receptors can restrict signaling in CD8+ T cells by regulating their associated co-stimulatory receptors CD28 and CD226, the functional consequences of combining PD-1 and TIGIT blockade remain poorly characterized. In mouse tumor models, we show that combination blockade elicited CD226-driven clonal expansion of tumor antigen-specific CD8+ T cells. The expanded clones emerged from a population of stem-like cells in draining lymph nodes, entering the blood as a previously unidentified single-phenotype, multiclonal population. Upon reaching the tumor, these transiting cells expanded further and differentiated into effector or exhausted T cells, with combination blockade restricting entry into the exhaustion pathway by favoring co-stimulation. Thus, PD-1 and TIGIT inhibition helps shape the repertoire of tumor-reactive CD8+ T cells in draining lymph nodes and determines their immunological fate in the tumor to enhance therapeutic benefit. Analysis of clinical trial samples suggests a similar mechanism may also occur in patients with cancer.
© 2024. The Author(s).

Evidence from clinical trials suggests that CXCR4 antagonists enhance immunotherapy effectiveness in several cancers. However, the specific mechanisms through which CXCR4 contributes to immune cell phenotypes are not fully understood. Here, we employed single-cell transcriptomic analysis and identified CXCR4 as a marker gene in T cells, with CD8+PD-1high exhausted T (Tex) cells exhibiting high CXCR4 expression. By blocking CXCR4, the Tex phenotype was attenuated in vivo. Mechanistically, CXCR4-blocking T cells mitigated the Tex phenotype by regulating the JAK2-STAT3 pathway. Single-cell RNA/TCR/ATAC-seq confirmed that Cxcr4-deficient CD8+ T cells epigenetically mitigated the transition from functional to exhausted phenotypes. Notably, clinical sample analysis revealed that CXCR4+CD8+ T cells showed higher expression in patients with a non-complete pathological response. Collectively, these findings demonstrate the mechanism by which CXCR4 orchestrates CD8+ Tex cells and provide a rationale for combining CXCR4 antagonists with immunotherapy in clinical trials.
Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.

Background: Alzheimer's Disease (AD) is a neuropathological condition marked by cognitive deterioration and chronic neuroinflammation. Previous investigations have unveiled a strong correlation between the gut microbiota and the progression of AD. In this study, our objective is to probe the effects of Parabacteroides distasonis ( P.distasonis ), previously found to be conspicuously diminished in AD patients, on the APP/PS1 mice model. Methods: : To assess the impact of orally administered P.distasonis on gut microbiota and metabolites, we utilized 16s rDNA sequencing and GC-MS to analyze gut composition and short-chain fatty acids in APP/PS1 mice after one month of P.distasonis gavage. To investigate the effects of P.distasonis administration over a six-month period on APP/PS1 mice, we evaluated cognitive function using novel object recognition and Y-maze tests, assessed intestinal barrier integrity and AD-related pathological features with immunofluorescence, and analyzed immune cell subpopulations in intestine, blood, spleen, and brain tissues via flow cytometry. The Luminex assay was employed to detect inflammatory cytokine secretion in the same regions. Results: : One-month oral administration of P.distasonis modulated the gut microbiota, elevated butyrate levels. Six-month oral administration of P.distasonis improved cognitive function in APP/PS1 mice, reducing Aβ deposition and inhibiting glial cell proliferation. It also amplified Treg cells within the gut, concomitant with the decreased Th1 proliferation and intestinal inflammation. Additionally, we observed the migration of peripheral CD4 + T cells to the brain through chemotaxis, accompanied by an increase in Treg cells and higher levels of anti-inflammatory factors such as IL-10 and TGF-β in the brain. Collectively, these multifaceted effects contributed to the alleviation of neuroinflammation. Conclusion: These findings underscore the potential of transplanting P.distasonis in alleviating AD-related pathology, suggesting a role for gut microbiota in neuroinflammation attenuation.