Stem cell-like CD8 T cells are at the heart of the anti-tumor response induced by PD-L1/TGFβ dual blockade in immune excluded tumors

In depth analysis of the CD8 T cells infiltrating an immune excluded tumor model revealed the presence of stem cell-like CD8 T cells that expanded in situ upon anti-PD-L1/TGFβ combination therapy fueling an efficient and IFNγ dependent anti-tumor response.
Like

While cancer immunotherapy is a promising strategy for improving patients’ survival and quality of life, currently only a fraction of cancer patients (~25-35%) respond to checkpoint inhibitor therapies (CIT). Patients with inflamed tumors, where CD8 T cells infiltrate the tumor, respond better to CIT compared to those with immune excluded tumors, where CD8 T cells accumulate at the tumor-stroma boundary. 

The excluded immune phenotype is found in more than 50% of all human tumors and is characterized by elevated TGFβ signaling1. Preclinical studies demonstrated that combining CIT with TGFβ inhibition converts immune excluded tumors to inflamed and increases anti-tumor responses2. Unfortunately, this increased anti-tumor efficacy has not been observed in the clinic so far. The lack of efficacy has been accompanied by on target toxicities3. This disconnect between what has been observed in animal models and the clinic warrants additional investigations into the mechanism of action of the CIT/anti-TGFβ combination, with the hope that having a deeper understanding of the biology can help guide future clinical trials. 

Despite the fact that CD8 T cells are the key component of the anti-tumor response, the direct or indirect impact of TGFβ inhibition combined with CIT on CD8 T cells origin and differentiation remains incompletely understood. With this in mind, we aimed to perform an in-depth analysis of the effects of anti-PD-L1/TGFβ combination therapy in a mouse model of T cell exclusion:  the EMT6 breast cancer model. We used a multi-omics approach to analyze how anti-PD-L1/TGFβ combination therapy affects tumor infiltrating CD8 T cells and their interaction with the other main cell types in the tumor microenvironment (TME): tumor cells, myeloid cells and fibroblasts. We show that in immune excluded tumors CD8 T cells are present with three major phenotypes: (1) progenitor-like CD8 T cells (TSCL) with a diverse T cell repertoire, (2) clonally expanded T progenitor exhausted cells (TPEX) characterized by high levels of TGFβ signaling and expression of exhaustion markers like TOX, and (3) different flavors of effector T cells (TEFF) characterized by either high expression of granzymes or IFNγ. Using bioinformatic inferences based both on single-cell RNA sequencing (scRNAseq) and T cell receptor sequencing (scTCRseq) analyses, we show that TSCL are the progenitor cells that can give rise to the different CD8 T cell phenotypes present in the TME. Anti-PD-L1/TGFβ combination therapy expands TSCL within the tumor and pushes CD8 T cell differentiation towards the IFNγhi phenotype, effectively fueling an IFNγ dependent anti-tumor response. IFNγ neutralization or IFNGR1 deletion in EMT6 tumor cells impaired anti-tumor response demonstrating the central role of IFNγ response induced by anti-PD-L1/TGFβ combination therapy. 

Our analysis in an immune excluded mouse model describes how anti-PD-L1 and anti-TGFβ induces a shift towards a more effective CD8 T cell population in the TME and transforms myeloid, stromal, and tumor niches to yield an immune-supportive ecosystem. The data published in this paper improves our understanding of TGFβ biology and might help guide future clinical trials, where the expansion of TSCL could be monitored as a measure of patient’s response to the combination treatment.



  1. Hegde, P. S. & Chen, D. S. Top 10 Challenges in Cancer Immunotherapy. Immunity 52, 17–35 (2020).
  2. Mariathasan, S. et al. TGFβ attenuates tumour response to PD-L1 blockade by contributing to exclusion of T cells. Nature 554, 544–548 (2018).
  3. Robbrecht, D. et al. Safety and efficacy results from the expansion phase of the first-in-human study evaluating TGFβ inhibitor SAR439459 alone and combined with cemiplimab in adults with advanced solid tumors. J. Clin. Oncol. 40, 2524–2524 (2022).

Please sign in or register for FREE

If you are a registered user on Research Communities by Springer Nature, please sign in

Subscribe to the Topic

Cancer Biology
Life Sciences > Biological Sciences > Cancer Biology

Related Collections

With collections, you can get published faster and increase your visibility.

Applied Sciences

This collection highlights research and commentary in applied science. The range of topics is large, spanning all scientific disciplines, with the unifying factor being the goal to turn scientific knowledge into positive benefits for society.

Publishing Model: Open Access

Deadline: Ongoing

Biomedical applications for nanotechnologies

Overall, there are still several challenges on the path to the clinical translation of nanomedicines, and we aim to bridge this gap by inviting submissions of articles that demonstrate the translational potential of nanomedicines with promising pre-clinical data.

Publishing Model: Open Access

Deadline: Mar 31, 2024