🇬🇧 Decoding tumor-reactive T cells to avoid immune evasion and improve immunotherapies

Abstract

Cancer immune evasion is a fundamental challenge in oncology, enabling malignant cells to escape detection and destruction by the
immune system. Tumors exploit various mechanisms to suppress or bypass immune responses, including altering antigen presentation, recruiting immunosuppressive cells, and inducing T-cell dysfunction.

Among these, T-cell exhaustion—a state of progressive
functional decline in T cells due to chronic antigen exposure—is a
key barrier to effective immunotherapy. Exhausted T cells often
express inhibitory receptors such as PD-1, TIM-3, and LAG-3, and
lose their ability to proliferate or kill cancer cells efficiently.

Understanding and reversing T-cell dysfunction is critical to
improving the success of immunotherapies such as checkpoint
inhibitors and chimeric antigen receptor (CAR) T-cell therapy. In
B-cell malignancies like chronic lymphocytic leukemia (CLL), failure
of these treatments is frequently linked to the presence of
dysfunctional or exhausted T cells, particularly within the tumor
microenvironment. In recent studies, we have used advanced
single-cell technologies to map the complex T-cell landscape in CLL,
revealing that the lymph node microenvironment harbors highly
exhausted and regulatory T-cell populations. These insights have
identified new immunosuppressive pathways, such as the
Galectin-9/TIM-3 axis, which may serve as therapeutic targets.

In this context, emerging data on IL-10 challenge its classical role as
an immunosuppressive cytokine. Using the Eμ-TCL1 mouse model
of CLL, we demonstrate that IL-10–Fc treatment preserves CD8⁺
T-cell effector function under chronic antigen stimulation and limits
the development of T-cell exhaustion. In parallel, IL-10–Fc directly
reprograms the myeloid compartment, shifting suppressive
monocytes toward a more inflammatory phenotype, thereby
reshaping the tumor microenvironment. Importantly, these
immunomodulatory effects translate into improved disease control
and strongly enhance the depth and durability of response to
ibrutinib, suggesting a strategy to overcome both immune
dysfunction and therapeutic resistance in CLL.

Moreover, combination approaches remain highly promising. For
example, CD19 CAR T cells combined with CD20-targeting bispecific
antibodies can reinvigorate both endogenous and engineered T
cells, improving tumor clearance and survival in preclinical models.
Together, these findings highlight the importance of targeting both
T-cell exhaustion and the broader immune microenvironment to
develop more effective, multi-layered immunotherapeutic
strategies in CLL.