Neoadjuvant immune checkpoint blockade triggers persistent and systemic T_reg activation which blunts therapeutic efficacy against metastatic spread of breast tumors

ABSTRACT

The clinical successes of immune checkpoint blockade (ICB) in advanced cancer patients have recently spurred the clinical implementation of ICB in the neoadjuvant and perioperative setting. However, how neoadjuvant ICB therapy affects the systemic immune landscape and metastatic spread remains to be established. Tumors promote both local and systemic expansion of regulatory T cells (T_regs), which are key orchestrators of tumor-induced immunosuppression, contributing to immune evasion, tumor progression and metastasis. T_regs express inhibitory immune checkpoint molecules and thus may be unintended targets for ICB therapy counteracting its efficacy. Using ICB-refractory models of spontaneous primary and metastatic breast cancer that recapitulate the poor ICB response of breast cancer patients, we observed that combined anti-PD-1 and anti-CTLA-4 therapy inadvertently promotes proliferation and activation of T_regs in the tumor, tumor-draining lymph node and circulation. Also in breast cancer patients, T_reg levels were elevated upon ICB. Depletion of T_regs during neoadjuvant ICB in tumor-bearing mice not only reshaped the intratumoral immune landscape into a state favorable for ICB response but also induced profound and persistent alterations in systemic immunity, characterized by elevated CD8+ T cells and NK cells and durable T cell activation that was maintained after treatment cessation. While depletion of T_regs in combination with neoadjuvant ICB did not inhibit primary tumor growth, it prolonged metastasis-related survival driven predominantly by CD8+ T cells. This study demonstrates that neoadjuvant ICB therapy of breast cancer can be empowered by simultaneous targeting of T_regs, extending metastasis-related survival, independent of a primary tumor response.

KEYWORDS:

• Breast cancer metastasis
• myeloid cells
• neoadjuvant immune checkpoint blockade
• regulatory T cells
• resistance mechanisms

Acknowledgments

We thank the members of the Tumor Biology & Immunology Department at the Netherlands Cancer Institute for their insightful input. We thank the flow cytometry facility, animal laboratory facility, transgenesis facility and animal pathology facility of the Netherlands Cancer Institute for technical assistance.

Disclosure statement

K.E.d.V. reports research funding from Roche and is consultant for Macomics, outside the scope of this work. M.K. reports funding to the institute from BMS, Roche/Genentech, AZ and an advisory role for BMS, Roche, MSD and Daiichi Sankyo, outside the submitted work.

Data availability statement

Data are available from the authors on reasonable request. The RNAseq data of the GELATO trial is available as previously described. Voorwerk L, Isaeva OI, Horlings HM, Balduzzi S, Chelushkin M, Bakker NAM, Champanhet E, Garner H, Sikorska K, Loo CE, Kemper I, Mandjes IAM, de Maaker M, van Geel JJL, Boers J, de Boer M, Salgado R, van Dongen MGJ, Sonke GS, de Visser KE, Schumacher TN, Blank CU, Wessels LFA, Jager A, Tjan-Heijnen VCG, Schröder CP, Linn SC, Kok M. PD-L1 blockade in combination with carboplatin as immune induction in metastatic lobular breast cancer: the GELATO trial. Nat Cancer. 2023 Apr 10. doi: 10.1038/s43018-023-00542-x. Epub ahead of print. PMID: 37038006.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/2162402X.2023.2201147

Authors’ contributions

O.S.B., K.Ko., L.S., and K.E.d.V. conceived the ideas and designed the experiments. O.S.B., K.Ko., L.S., M.D.W., D.E.M.D., and K.Ke. performed experiments and data analysis. C-S.H., D.K., E.A.M.R., and K.V. performed animal experiments. S.K. did the pathological assessments. Clinical data acquisition and analysis was done by O.I.I., H.G., and N.B. M.K. is the principal investigator of the TONIC and GELATO trials. K.E.d.V. supervised the study. K.E.d.V, K.Ko., and L.S. acquired funding. O.S.B., K.Ko, L.S., and K.E.d.V. wrote the paper and prepared the figures with input from all authors.

Additional information

Funding

Research in the De Visser lab is funded by the Netherlands Organization for Scientific Research (NWO-VICI91819616), Dutch Cancer Society (KWF10083; KWF10623; KWF13191), Oncode Institute, and the KWF/Oncode consortium grant 14339. Additional funding was granted by NWO Oncology Graduate School Amsterdam Diamond Program to K.Ko. and by the Swiss National Science Foundation (P2FRP3_171794 and P400PM_18318/1) to L.S. The Dutch Cancer Society (10653ALPE) and A Sister’s Hope contributed to the blood immunophenotyping of the TNBC patients. The TONIC study was funded by BMS-International Immuno-Oncology Network (BMS/II-ON) and the Dutch Cancer Society (NKI2015-7710). The GELATO study was funded by F. Hoffmann-La Roche Ltd, Basel, Switzerland. This research was further supported by an institutional grant to the NKI of the Dutch Cancer Society and of the Dutch Ministry of Health, Welfare and Sport.