163MO - Single-cell T cell dynamics induced by neoadjuvant nivolumab +/- ipilimumab in early triple negative breast cancer with tumor-infiltrating lymphocytes (BELLINI trial)

Background

Anti-PD1 added to chemotherapy improves outcome for patients with early-stage triple negative breast cancer (TNBC). However, it is unknown which patients benefit from anti-PD1. It is also largely unknown how anti-PD1 remodels the TNBC tumor microenvironment and whether anti-CTLA4 could enhance antitumor T cell response. In this work, we analyze the role of tumor-associated T cell populations in response to anti-PD1 ± anti-CTLA4 in early TNBC.

Methods

In the BELLINI trial (NCT03815890), we investigated whether a short course (4 weeks before standard of care) of neoadjuvant nivolumab (anti-PD1) ± ipilimumab (anti-CTLA4) can induce immune activation in TNBC with ≥ 5% tumor-infiltrating lymphocytes (TIL). Each cohort included 15 patients stratified by TIL levels. Response (secondary endpoint) was defined as ≥ 30% tumor decrease by MRI, significant tumor downstaging at surgery or tumor absence in the post-treatment biopsy.

Results

Higher baseline TIL levels were correlated with response, with all responders (n=12/31) having TIL ≥ 30%. HALO spatial analyses based on immunohistochemistry revealed that shorter distances from tumor cells to nearest CD8 T cell were strongly correlated with response. Bulk and single-cell RNA-Seq revealed a strong pre-existing immune activity in responding patients, including upregulation of IFNy, IFNa and IL2 signaling and higher fractions of tumor-reactive CD8 T cells (as previously functionally defined by Rosenberg and Wu laboratories) and follicular helper T cells. After anti-PD1 ± anti-CTLA4, responders demonstrated higher degree of T cell activation, cytokine production and antigen presentation pathway activity. Moreover, they were characterized by higher effector CD8 and memory CD4 T cell fraction after treatment, while in non-responders a higher fraction of regulatory T cells (Treg) was observed.

Conclusions

Single-cell RNA-Seq data revealed that TNBC patients responding to neoadjuvant anti-PD1 ± anti-CTLA4 have a pre-existing tumor-reactive CD8 T cell population and are enriched in follicular helper T cells. TNBC patients not responding to neoadjuvant anti-PD1 ± anti-CTLA4 harbor a higher fraction of Treg after treatment.

Clinical trial identification

NCT03815890, January 24, 2019.

Legal entity responsible for the study

The Netherlands Cancer Institute.

Funding

Netherlands Organization for Scientific Research; Victoria’s Secret Global Fund for Women’s Cancers Rising Innovator Research Grant, in partnership with Pelotonia & AACR; Bristol Myers Squibb.

Disclosure

G.S. Sonke: Financial Interests, Institutional, Research Funding: Merck, Agendia, AstraZeneca, Roche; Financial Interests, Personal and Institutional, Research Funding: Novartis; Financial Interests, Personal, Speaker, Consultant, Advisor: Seattle Genetics, Biovica. S.C. Linn: Financial Interests, Institutional, Research Funding: Roche, Genentech, Bristol Myers Squibb, AstraZeneca, Tesaro, Merck, Immunomedics, Eurocept Pharmaceuticals, Agendia, Novartis; Financial Interests, Personal, Other, Travel grant: Daiichi Sankyo. C.U. Blank: Financial Interests, Institutional, Advisory Board: BMS, MSD, Roche, Novartis, GSK, AZ, Pfizer, Lilly, GenMab, Pierre Fabre; Financial Interests, Personal, Advisory Board: Third Rock Ventures; Financial Interests, Personal, Stocks/Shares: Immagene; Financial Interests, Personal, Stocks/Shares, intention to develop IFN signature algorithm: Signature Oncology; Financial Interests, Institutional, Coordinating PI: NanoString, BMS, Novartis, 4SC; Other, Personal, Other, pending patent: WO 2021/177822 A1. K.E. de Visser: Financial Interests, Personal, Speaker, Consultant, Advisor: Macomics; Financial Interests, Institutional, Research Funding: Roche. R.F. Salgado: Financial Interests, Personal and Institutional, Research Funding: Merck, Roche; Financial Interests, Personal, Advisory Board: Bristol Myers Squibb, Exact Sciences; Financial Interests, Institutional, Research Funding: Puma Biotechnology. L.F.A. Wessels: Financial Interests, Institutional, Research Funding: Genmab. T.N. Schumacher: Financial Interests, Personal, Speaker, Consultant, Advisor: Third Rock Ventures; Financial Interests, Personal, Stocks/Shares: Allogene Therapeutics, Asher Bio, Celsius, Merus, Scenic Biotech, Neogene Therapeutics. H.M. Horlings: Financial Interests, Personal, Speaker, Consultant, Advisor: Roche Diagnostics; Financial Interests, Personal, Advisory Role: SlideScore, Ellogon. M. Kok: Financial Interests, Institutional, Advisory Board, Adboard, invited speaker: Roche, BMS; Financial Interests, Institutional, Advisory Board: Daiichi, MSd, Alderaan; Financial Interests, Institutional, Invited Speaker: Gilead; Financial Interests, Institutional, Research Grant: BMS, Roche, AZ; Financial Interests, Personal, Steering Committee Member: BMS. All other authors have declared no conflicts of interest.