NK cell-triggered CCL5/IFNγ-CXCL9/10 axis underlies the clinical efficacy of neoadjuvant anti-HER2 antibodies in breast cancer.

BACKGROUND: The variability in responses to neoadjuvant treatment with anti-HER2 antibodies prompts to personalized clinical management and the development of innovative treatment strategies. Tumor-infiltrating Natural Killer (TI-NK) cells can predict the efficacy of HER2-targeted antibodies independently from clinicopathological factors in primary HER2-positive breast cancer patients. Understanding the mechanism/s underlying this association would contribute to optimizing patient stratification and provide the rationale for combinatorial approaches with immunotherapy. METHODS: We sought to uncover processes enriched in NK cell-infiltrated tumors as compared to NK cell-desert tumors by microarray analysis. Findings were validated in clinical trial-derived transcriptomic data. In vitro and in vivo preclinical models were used for mechanistic studies. Findings were analysed in clinical samples (tumor and serum) from breast cancer patients. RESULTS: NK cell-infiltrated tumors were enriched in CCL5/IFNG-CXCL9/10 transcripts. In multivariate logistic regression analysis, IFNG levels underlie the association between TI-NK cells and pathological complete response to neoadjuvant treatment with trastuzumab. Mechanistically, the production of IFN-É£ by CD16+ NK cells triggered the secretion of CXCL9/10 from cancer cells. This effect was associated to tumor growth control and the conversion of CD16 into CD16-CD103+ NK cells in humanized in vivo models. In human breast tumors, the CD16 and CD103 markers identified lineage-related NK cell subpopulations capable of producing CCL5 and IFN-É£, which correlated with tissue-resident CD8+ T cells. Finally, an early increase in serum CCL5/CXCL9 levels identified patients with NK cell-rich tumors showing good responses to anti-HER2 antibody-based neoadjuvant treatment. CONCLUSIONS: This study identifies specialized NK cell subsets as the source of IFN-É£ influencing the clinical efficacy of anti-HER2 antibodies. It also reveals the potential of serum CCL5/CXCL9 as biomarkers for identifying patients with NK cell-rich tumors and favorable responses to anti-HER2 antibody-based neoadjuvant treatment.

CD137 Costimulation Counteracts TGFß Inhibition of NK-cell Antitumor Function.

Enhancing natural killer (NK) cell-based cancer immunotherapy by overcoming immunosuppression is an area of intensive research. Here, we have demonstrated that the anti-CD137 agonist urelumab can overcome TGFß-mediated inhibition of human NK-cell proliferation and antitumor function. Transcriptomic, immunophenotypic, and functional analyses showed that CD137 costimulation modified the transcriptional program induced by TGFß on human NK cells by rescuing their proliferation in response to IL2, preserving their expression of activating receptors (NKG2D) and effector molecules (granzyme B, IFNγ) while allowing the acquisition of tumor-homing/retention features (CXCR3, CD103). Activated NK cells cultured in the presence of TGFß1 and CD137 agonist recovered CCL5 and IFNγ secretion and showed enhanced direct and antibody-dependent cytotoxicity upon restimulation with cancer cells. Trastuzumab treatment of fresh breast carcinoma-derived multicellular cultures induced CD137 expression on tumor-infiltrating CD16+ NK cells, enabling the action of urelumab, which fostered tumor-infiltrating NK cells and recapitulated the enhancement of CCL5 and IFNγ production. Bioinformatic analysis pointed to IFNG as the driver of the association between NK cells and clinical response to trastuzumab in patients with HER2-positive primary breast cancer, highlighting the translational relevance of the CD137 costimulatory axis for enhancing IFNγ production. Our data reveals CD137 as a targetable checkpoint for overturning TGFß constraints on NK-cell antitumor responses.

High Numbers of Circulating CD57+ NK Cells Associate with Resistance to HER2-Specific Therapeutic Antibodies in HER2+ Primary Breast Cancer.

Natural killer (NK) cells can orchestrate effective antitumor immunity. The presence of tumor-infiltrating NK cells in diagnostic biopsies predicts pathologic complete response (pCR) to HER2-specific therapeutic antibodies in patients with primary breast cancer. Here, we analyzed whether diversity in circulating NK cells might influence tumor infiltration and HER2-specific therapeutic antibody efficacy. We found that numbers of circulating CD57+ NK cells inversely correlated with pCR to HER2-specific antibody treatment in patients with primary breast cancer independently of age, traditional clinicopathologic factors, and CD16A 158F/V genotype. This association was uncoupled from the expression of other NK-cell receptors, the presence of adaptive NK cells, or changes in major T-cell subsets, reminiscent of cytomegalovirus-induced immunomodulation. NK-cell activation against trastuzumab-coated HER2+ breast cancer cells was comparable in patients with high and low proportions of CD57+ NK cells. However, circulating CD57+ NK cells displayed decreased CXCR3 expression and CD16A-induced IL2-dependent proliferation in vitro Presence of CD57+ NK cells was reduced in breast tumor-associated infiltrates as compared with paired peripheral blood samples, suggesting deficient homing, proliferation, and/or survival of NK cells in the tumor niche. Indeed, numbers of circulating CD57+ were inversely related to tumor-infiltrating NK-cell numbers. Our data reveal that NK-cell differentiation influences their antitumor potential and that CD57+ NK cells may be a biomarker useful for tailoring HER2 antibody-based therapeutic strategies in breast cancer.