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.

NK Cell Infiltrates and HLA Class I Expression in Primary HER2+ Breast Cancer Predict and Uncouple Pathological Response and Disease-free Survival.

PURPOSE: We investigated the value of tumor-infiltrating NK (TI-NK) cells and HLA class I tumor expression as biomarkers of response to neoadjuvant anti-HER2 antibody-based treatment in breast cancer. EXPERIMENTAL DESIGN: TI-NK cells and HLA-I were determined by IHC in pretreatment tumor biopsies from two cohorts of patients with HER2-positive breast cancer [discovery cohort (n = 42) and validation cohort (n = 71)]. Tumor-infiltrating lymphocytes (TIL) were scored according to international guidelines. Biomarker association with pathologic complete response (pCR) and disease-free survival (DFS) was adjusted for prognostic factors. Gene set variation analysis was used for determining immune cell populations concomitant to NK-cell enrichment in HER2-positive tumors from the Cancer Genome Atlas (n = 190). RESULTS: TI-NK cells were significantly associated with pCR in the discovery cohort as well as in the validation cohort (P < 0.0001), independently of clinicopathologic factors. A ≥3 TI-NK cells/50x high-power field (HPF) cutoff predicted pCR in the discovery and validation cohort [OR, 188 (11-3154); OR, 19.5 (5.3-71.8)]. Presence of TI-NK cells associated with prolonged DFS in both patient cohorts [HR, 0.07 (0.01-0.6); P = 0.01; HR, 0.3 (0.08-1.3); P = 0.1]. NK-, activated dendritic- and CD8 T-cell gene expression signatures positively correlated in HER2-positive tumors, supporting the value of NK cells as surrogates of effective antitumor immunity. Stratification of patients by tumor HLA-I expression identified patients with low and high relapse risk independently of pCR. CONCLUSIONS: This study identifies baseline TI-NK cells as an independent biomarker with great predictive value for pCR to anti-HER2 antibody-based treatment and points to the complementary value of tumor HLA-I status for defining patient prognosis independently of pCR.

Trial Watch: Immunostimulatory monoclonal antibodies for oncological indications.

The goal of cancer immunotherapy is to establish new or boost pre-existing anticancer immune responses that eradicate malignant cells while generating immunological memory to prevent disease relapse. Over the past few years, immunomodulatory monoclonal antibodies (mAbs) that block co-inhibitory receptors on immune effectors cells - such as cytotoxic T lymphocyte-associated protein 4 (CTLA4), programmed cell death 1 (PDCD1, best known as PD-1) - or their ligands - such as CD274 (best known as PD-L1) - have proven very successful in this sense. As a consequence, many of such immune checkpoint blockers (ICBs) have already entered the clinical practice for various oncological indications. Considerable attention is currently being attracted by a second group of immunomodulatory mAbs, which are conceived to activate co-stimulatory receptors on immune effector cells. Here, we discuss the mechanisms of action of these immunostimulatory mAbs and summarize recent progress in their preclinical and clinical development.

Interplay between Natural Killer Cells and Anti-HER2 Antibodies: Perspectives for Breast Cancer Immunotherapy.

Overexpression of the human epidermal growth factor receptor 2 (HER2) defines a subgroup of breast tumors with aggressive behavior. The addition of HER2-targeted antibodies (i.e., trastuzumab, pertuzumab) to chemotherapy significantly improves relapse-free and overall survival in patients with early-stage and advanced disease. Nonetheless, considerable proportions of patients develop resistance to treatment, highlighting the need for additional and co-adjuvant therapeutic strategies. HER2-specific antibodies can trigger natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity and indirectly enhance the development of tumor-specific T cell immunity; both mechanisms contributing to their antitumor efficacy in preclinical models. Antibody-dependent NK cell activation results in the release of cytotoxic granules as well as the secretion of pro-inflammatory cytokines (i.e., IFNγ and TNFα) and chemokines. Hence, NK cell tumor suppressive functions include direct cytolytic killing of tumor cells as well as the regulation of subsequent antitumor adaptive immunity. Albeit tumors with gene expression signatures associated to the presence of cytotoxic lymphocyte infiltrates benefit from trastuzumab-based treatment, NK cell-related biomarkers of response/resistance to HER2-specific therapeutic antibodies in breast cancer patients remain elusive. Several variables, including (i) the configuration of the patient NK cell repertoire; (ii) tumor molecular features (i.e., estrogen receptor expression); (iii) concomitant therapeutic regimens (i.e., chemotherapeutic agents, tyrosine kinase inhibitors); and (iv) evasion mechanisms developed by progressive breast tumors, have been shown to quantitatively and qualitatively influence antibody-triggered NK cell responses. In this review, we discuss possible interventions for restoring/enhancing the therapeutic activity of HER2 therapeutic antibodies by harnessing NK cell antitumor potential through combinatorial approaches, including immune checkpoint blocking/stimulatory antibodies, cytokines and toll-like receptor agonists.

Targeting NK-cell checkpoints for cancer immunotherapy.

Natural Killer (NK) cells are cytotoxic lymphocytes specialized in early defense against virus-infected and transformed cells. NK-cell function is regulated by activating and inhibitory surface receptors recognizing their ligands on transformed cells. Modulation of NK numbers and/or function by a variety of agents such as cytokines and monoclonal antibodies may result in enhanced anti-tumor activity. Recombinant cytokines (i.e., IL-15 and IL-2), antibodies blocking inhibitory receptors (i.e., KIR, NKG2A and TIGIT) and agonists delivering signals via CD137, NKG2D and CD16 stand out as the most suitable opportunities. These agents can be used to potentiate NKcell- mediated antibody-dependent cellular cytotoxicity (ADCC) against antibody-coated tumor cells, offering potential for multiple combinatorial immunotherapy strategies against cancer.