No abstract

Natural killer (NK) cells are useful for cancer immunotherapy and have proven clinically effective against hematologic malignancies. However, immunotherapies for poor prognosis solid malignancies, including ovarian cancer, have not been as successful due to immunosuppression by solid tumors. Although rearming patients' own NK cells to treat cancer is an attractive option, success of that strategy is limited by the impaired function of NK cells from cancer patients and by inhibition by self-MHC. In this study, we show that expansion converts healthy donor and immunosuppressed ovarian cancer patient NK cells to a cytotoxic CD56CD16 subset with activation state and antitumor functions that increase with CD56 brightness. We investigated whether these expanded NK cells may overcome the limitations of autologous NK cell therapy against solid tumors. Peripheral blood- and ascites-derived NK cells from ovarian cancer patients were expanded and then adoptively transferred into cell-line and autologous patient-derived xenograft models of human ovarian cancer. Expanded ovarian cancer patient NK cells reduced the burden of established tumors and prolonged survival. These results suggest that CD56 NK cells harbor superior antitumor function compared with CD56 cells. Thus, NK cell expansion may overcome limitations on autologous NK cell therapy by converting the patient's NK cells to a cytotoxic subset that exerts a therapeutic effect against autologous tumor. These findings suggest that the value of expanded autologous NK cell therapy for ovarian cancer and other solid malignancies should be clinically assessed. .

Ovarian cancer (OC) is the leading cause of gynecological cancer-related death in North America. Most ovarian cancer patients (OCPs) experience disease recurrence after first-line surgery and chemotherapy; thus, there is a need for novel second-line treatments to improve the prognosis of OC. Although peripheral blood-derived NK cells are known for their ability to spontaneously lyse tumour cells without prior sensitization, ascites-derived NK cells (ascites-NK cells) isolated from OCPs exhibit inhibitory phenotypes, impaired cytotoxicity and may play a pro-tumourigenic role in cancer progression. Therefore, it is of interest to improve the cytotoxic effector function of impaired OCP ascites-NK cells at the tumour environment. We investigated the efficacy of using an artificial APC-based ex vivo expansion technique to generate cytotoxic, expanded NK cells from previously impaired OCP ascites-NK cells, for use in an autologous model of NK cell immunotherapy. We are the first to obtain a log-scale expansion of OCP ascites-NK cells that upregulate the surface expression of activating receptors NKG2D, NKp30, NKp44, produce robust amounts of anti-tumour cytokines in the presence of OC cells and mediate direct tumour cytotoxicity against ascites-derived, primary OC cells obtained from autologous patients. Our findings demonstrate that it is possible to generate cytotoxic OCP ascites-NK cells from previously impaired OCP ascites-NK cells, which presents a promising immunotherapeutic target for the second-line treatment of OC. Future work should focus on evaluating the in vivo efficacy of autologous NK cell immunotherapy through the intraperitoneal delivery of NK cell expansion factors to a preclinical xenograft mouse model of human OC.

With over 600,000 units of umbilical cord blood (CB) stored on a global scale, it is important to elucidate the therapeutic abilities of this cryopreserved reservoir. In the advancing field of natural killer (NK) cell cancer immunotherapy, CB has proven to be a promising and noninvasive source of therapeutic NK cells. Although studies have proven the clinical efficacy of using long-term cryopreserved CB in the context of hematopoietic stem cell transplantations, little is known about its use for the ex vivo expansion of effector immune cells. Therefore, our group sought to derive ex vivo-expanded NK cells from long-term cryopreserved CB, using an artificial antigen presenting cell-mediated expansion technique. We compared the expansion potential and antitumor effector function of CB-derived NK (CB-NK) cells expanded from fresh (n=4), short-term cryopreserved (<1-year old, n=5), and long-term cryopreserved (1-10-year old, n=5) CB. Here, we demonstrated it is possible to obtain an exponential amount of expanded CB-NK cells from long-term cryopreserved CB. Ex vivo-expanded CB-NK cells had an increased surface expression of activating markers and showed potent antitumor function by producing robust levels of proinflammatory cytokines, interferon-γ, and tumor necrosis factor-α. Moreover, expanded CB-NK cells (n=3-5) demonstrated cytotoxicity towards primary breast cancer cells (n=2) derived from a triple-negative breast cancer and an estrogen receptor-positive/progesterone receptor-positive breast cancer patient. Long-term cryopreservation had no effect on the expansion potential or effector function of expanded CB-NK cells. Therefore, we propose that long-term cryopreserved CB remains clinically useful for the ex vivo expansion of therapeutic NK cells.

High intensity interval training (HIIT) boosts natural killer (NK) cell number and activity in normal weight breast cancer patients; however, whether this occurs in obese individuals is not well established. The goal of this study was to determine whether HIIT effectively boosts NK cells as a therapeutic strategy against breast cancer in an obese mouse model and in overweight/obese women. Diet induced female C57Bl/6 obese mice were assigned to undergo HIIT for four weeks or remain sedentary. Female participants were subjected to a six weeks HIIT protocol. HIIT mice acclimatized to treadmill running were subsequently injected with 5 × 105 polyoma middle T (MT) breast cancer cells intravenously. NK cell number and activation were monitored using flow cytometry, and tumor burden or lipid content evaluated from histological lung and liver tissues, respectively. In both mice and humans, circulating NK cell number and activation (CD3−NK1.1+CD27+ and CD3−CD56+, respectively) markedly increased immediately after HIIT. HIIT obese mice had reduced lung tumor burden compared to controls following MT challenge, and had diminished hepatic lipid deposition despite minimal body weight loss. Our findings demonstrate that HIIT can benefit obese individuals by enhancing NK cell number and activity, reducing tumor burden, and enhancing metabolic health.

Lung cancer remains the leading cause of cancer death worldwide despite the significant progress made by immune checkpoint inhibitors, including programmed death receptor-1 (PD1)/PD ligand 1 (PDL1)-blockade therapy. PD1/PDL1−blockade has achieved unprecedented tumor regression in some patients with advanced lung cancer. However, the majority of patients fail to respond to PD1/PDL1 inhibitors. The high rate of therapy non-response results from insufficient PDL1 expression on most patients’ tumors and the presence of further immunosuppressive mechanisms in the tumor microenvironment. Here, we sensitize non-responding tumors from patients with lung cancer to PD1-blockade therapy using highly cytotoxic expanded natural killer (NK) cells. We uncover that NK cells expanded from patients with lung cancer dismantle the immunosuppressive tumor microenvironment by maintaining strong antitumor activity against both PDL1+ and PDL1− patient tumors. In the process, through a contact-independent mechanism involving interferon γ, expanded NK cells rescued tumor killing by exhausted endogenous TILs and upregulated the tumor proportion score of PDL1 across patient tumors. In contrast, unexpanded NK cells, which are susceptible to tumor-induced immunosuppression, had no effect on tumor PDL1. As a result, combined treatment of expanded NK cells and PD1-blockade resulted in robust synergistic tumor destruction of initially non-responding patient tumors. Thus, expanded NK cells may overcome the critical roadblocks to extending the prodigious benefits of PD1-blockade therapy to more patients with lung cancer and other tumor types.

No abstract

<div>Abstract<p>Natural killer (NK) cells are useful for cancer immunotherapy and have proven clinically effective against hematologic malignancies. However, immunotherapies for poor prognosis solid malignancies, including ovarian cancer, have not been as successful due to immunosuppression by solid tumors. Although rearming patients' own NK cells to treat cancer is an attractive option, success of that strategy is limited by the impaired function of NK cells from cancer patients and by inhibition by self-MHC. In this study, we show that expansion converts healthy donor and immunosuppressed ovarian cancer patient NK cells to a cytotoxic CD56^superbrightCD16⁺ subset with activation state and antitumor functions that increase with CD56 brightness. We investigated whether these expanded NK cells may overcome the limitations of autologous NK cell therapy against solid tumors. Peripheral blood- and ascites-derived NK cells from ovarian cancer patients were expanded and then adoptively transferred into cell-line and autologous patient-derived xenograft models of human ovarian cancer. Expanded ovarian cancer patient NK cells reduced the burden of established tumors and prolonged survival. These results suggest that CD56^bright NK cells harbor superior antitumor function compared with CD56^dim cells. Thus, NK cell expansion may overcome limitations on autologous NK cell therapy by converting the patient's NK cells to a cytotoxic subset that exerts a therapeutic effect against autologous tumor. These findings suggest that the value of expanded autologous NK cell therapy for ovarian cancer and other solid malignancies should be clinically assessed. <i>Cancer Immunol Res; 6(10); 1174–85. ©2018 AACR</i>.</p></div>