Tumor Regression and Delayed Onset Toxicity Following B7-H4 CAR T Cell Therapy.

B7-H4 protein is frequently overexpressed in ovarian cancer. Here, we engineered T cells with novel B7-H4-specific chimeric antigen receptors (CARs) that recognized both human and murine B7-H4 to test the hypothesis that B7-H4 CAR T cell therapy can be applied safely in preclinical models. B7-H4 CAR T cells specifically secreted IFN-γ and lysed B7-H4(+) targets. In vivo, B7-H4 CAR T cells displayed antitumor reactivity against B7-H4(+) human ovarian tumor xenografts. Unexpectedly, B7-H4 CAR T cell treatment reproducibly showed delayed, lethal toxicity 6-8 weeks after therapy. Comprehensive assessment of murine B7-H4 protein distribution uncovered expression in ductal and mucosal epithelial cells in normal tissues. Postmortem analysis revealed the presence of widespread histologic lesions that correlated with B7-H4(+) expression, and were inconsistent with graft versus host disease. Lastly, expression patterns of B7-H4 protein in normal human tissue were comparable to distribution in mice, advancing our understanding of B7-H4. We conclude that B7-H4 CAR therapy mediates control of cancer outgrowth. However, long-term engraftment of B7-H4 CAR T cells mediates lethal, off-tumor toxicity that is likely due to wide expression of B7-H4 in healthy mouse organs. This model system provides a unique opportunity for preclinical evaluation of safety approaches that limit CAR-mediated toxicity after tumor destruction in vivo.

Race-based disparities in loss of functional independence after hysterectomy for uterine cancer.

PURPOSE: Racial disparities in uterine cancer-related outcomes have been reported. The goal of this study was to determine if race, pre-operative body mass index (BMI), and medical comorbidities are predictors of loss of functional independence after hysterectomy for uterine cancer. METHODS: Loss of independence was defined as a change from pre-operative functional independence, to a post-operative requirement of discharge to a post-care facility, or death within the first 30 days following uterine cancer surgery. Demographic factors, comorbidities, BMI, intra-operative and post-operative outcomes, and discharge status were abstracted from the 2011 and 2012 American College of Surgeons National Surgical Quality Improvement Program (NSQIP). Statistical analyses included multivariable logistic regression and Wald tests for interaction. RESULTS: A total of 4005 patients had uterine cancer and were functionally independent pre-operatively. After adjusting for clinical features and comorbidities, Black women were not significantly more likely to lose functional independence than non-Black women. However, a significant interaction (OR = 1.17, p < 0.001) was found between race and BMI for loss of functional independence. Interaction plots revealed worsening functional outcomes for Black women with BMI >40 but not in non-Blacks. CONCLUSIONS: The interaction suggests a 17 % increased odds of losing independence for each unit of BMI difference for Black uterine cancer patients, or 170 % increased odds of losing independence for a 10-point increase in BMI, given a linear association. To reduce the likelihood of losing post-operative functional independence, Black, high-BMI patients with or at risk for uterine cancer may especially benefit from weight loss or interventions to optimize physical function.

Targeted cancer immunotherapy via combination of designer bispecific antibody and novel gene-engineered T cells.

BACKGROUND: Redirection of T lymphocytes against tumor antigens can induce dramatic regression of advanced stage malignancy. The use of bispecific antibodies (BsAbs) that bind both the T-cell receptor (TCR) and a target antigen is one promising approach to T-cell redirection. However, BsAbs indiscriminately bind all CD3+ T-cells and trigger TCR activation in the absence of parallel costimulatory signals required to overcome T-cell unresponsiveness or anergy. METHODS: To address these limitations, a combination platform was designed wherein a unique BsAb referred to as frBsAb exclusively engages T-cells engineered to express a novel chimeric receptor comprised of extracellular folate receptor fused to intracellular TCR and CD28 costimulatory signaling domains in tandem; a BsAb-binding immune receptor (BsAb-IR). As a surrogate TCR, the BsAb-IR allows for concomitant TCR and costimulatory signaling exclusively in transduced T-cells upon engagement with specific frBsAbs, and can therefore redirect T-cells on command to desired antigen. Human primary T-cells were transduced with lentiviral vector and expanded for 14-18 days. BsAb-IRs were harvested and armed with frBsAbs to test for redirected cytotoxicity against CD20 positive cancer cell lines. RESULTS: Using frBsAbs specific for CD20 or HER2, the lytic activity of primary human T-cells expressing the BsAb-IR was specifically redirected against CD20+ leukemic cells or HER2+ epithelial cancer cells, respectively, while non-engineered T-cells were not activated. Notably, elimination of the CD28 costimulatory domain from the BsAb-IR construct significantly reduced frBsAb-redirected antitumor responses, confirming that frBsAbs are capable of delivering simultaneous TCR activation and costimulatory signals to BsAb-IR T-cells. CONCLUSION: In summary, our results establish the proof of concept that the combination of BsAbs with optimized gene-engineered T-cells provides the opportunity to specify and augment tumor antigen-specific T-cell activation and may improve upon the early success of conventional BsAbs in cancer immunotherapy.

B7-H4 as a potential target for immunotherapy for gynecologic cancers: a closer look.

B7-H4 is a transmembrane protein that binds an unknown receptor on activated T cells resulting in inhibition of T-cell effector function via cell cycle arrest, decreased proliferation, and reduced IL-2 production. B7-H4 is up-regulated on the surface of cancer cells and immunosuppressive tumor-associated macrophages (TAMs) in a variety of human cancers. Notably, B7-H4 expression levels inversely correlate with patient survival in ovarian cancer, making B7-H4 an attractive candidate for therapeutic intervention. Here, we summarize the experimental data and methodologies that have revealed B7-H4's mRNA and protein expression and function in both mice and humans since its discovery in 2003, with a specific focus on B7-H4's role in ovarian cancer. We also underscore the discrepancies in published data due to high variability in methodology and use of different antibodies, most of which are not commercially available. Finally, since B7-H4 is expressed on tumor cells and TAMs in various cancer types, directing therapeutics against B7-H4 could have tremendous synergistic outcomes in favorably altering the tumor micro-environment and eliminating cancer cells. We highlight the therapeutic potential of targeting B7-H4, both by comparing other negative immune modulators such as PD-1 and CTLA-4 and by identifying novel methods to target B7-H4 directly or indirectly to overcome B7-H4-mediated T-cell inhibition.

Surgical risk score predicts suboptimal debulking or a major perioperative complication in patients with advanced epithelial ovarian, fallopian tube, or primary peritoneal cancer.

BACKGROUND: Patients who present with an advanced ovarian cancer are typically treated with primary debulking surgery (PDS) or neoadjuvant chemotherapy (NAC) followed by interval debulking surgery. The accurate pretreatment identification of patients best suited for PDS versus NAC is challenging. A paradigm for selecting one approach over the other could improve patient outcomes. In this study, we developed a prediction model for "successful surgery" (defined as optimal residual disease and no major perioperative complication) in patients who underwent PDS. PATIENTS: Preoperative clinical characteristics, laboratory values, computed tomography findings, and surgical outcomes of 106 consecutive medically fit patients with advanced ovarian, tubal, or peritoneal cancer were reviewed. Preoperative predictors of suboptimal residual disease and major perioperative complications were determined using regression analysis. A surgical risk score (SRS) that minimized the false-negative rate (ie, likelihood of incorrectly predicting successful surgery) was constructed. RESULTS: Sixty (57%) of the 106 patients were optimally cytoreduced. Fifty-six "radical procedures" were performed, and there were a total of 24 major perioperative complications. Diffuse peritoneal studding (P < 0.0001), para-aortic lymphadenopathy (P < 0.0001), and mesenteric involvement (Mes, P = 0.006) were associated with suboptimal (>1 cm) residual disease. Low albumin (P = 0.04) and splenic disease (spleen, P = 0.02) were the only 2 parameters associated with a higher risk of a major perioperative complication. The median SRSs of patients who had successful and "unsuccessful surgery" were 1 (0-4) and 3 (0-6), respectively. The false-negative rate of the SRS was only 7%. CONCLUSIONS: We developed a model that incorporated complications, in addition to residual disease status, into predicting surgical outcome for medically fit patients with advanced ovarian cancer. The SRS might be useful in determining the initial treatment strategy (ie, PDS vs NAC) for these patients. The accuracy of the SRS needs to be validated in a prospective manner.

Overcoming barriers of car T-cell therapy in patients with mesothelin-expressing cancers.

One obstacle to the application of immunotherapy to solid malignancies is to overcome the existing tolerance to self-antigens. Vaccine strategies aimed at harnessing endogenous antitumor T cells are limited by the T-cell receptor repertoire, which can be detected within the thymus as central tolerance or rendered nonfunctional by post-thymic mechanisms of peripheral tolerance. Adoptive immunotherapy can overcome these obstacles, since therapeutically effective T cells can be engineered to recognize tumors. Continued advancements in novel treatments, including immunotherapy, in solid malignancies are imperative. While mesothelin is an attractive target for cancer immunotherapy given its normal expression is limited to mesothelial cells, the breakthrough for chimeric antigen receptor T-cell treatment against this antigen is still forthcoming.

Possible Compartmental Cytokine Release Syndrome in a Patient With Recurrent Ovarian Cancer After Treatment With Mesothelin-targeted CAR-T Cells.

Cytokine release syndrome (CRS) is a potentially severe systemic toxicity seen after adoptive T-cell therapy and caused by T-cell activation and proliferation and is associated with elevated circulating levels of cytokines such as C-reactive protein, interleukin-6 (IL-6), and interferon-γ and has previously been described as a systemic response in hematologic malignancies. A 52-year-old woman with BRCA 1 mutation positive heavily pretreated advanced recurrent serous ovarian cancer was treated under a compassionate use protocol with autologous mesothelin-redirected chimeric antigen receptor T cells (CART-meso). Autologous T cells were transduced to express a receptor composed of an extracellular antimesothelin single-chain variable fragment fused to 4-1BB and TCR-zeta signaling domain. This patient was infused with 3×10 CART-meso T cells/m without lymphodepletion and developed compartmental CRS confined to the pleural cavities. The compartmental CRS was evidenced by an increase in IL-6 and accumulation of CART-meso T cells in pleural fluid compared with peripheral blood and was successfully treated the anti-IL6 receptor antagonist tocilizumab on D21 after the T-cell infusion. This is the first description of a compartmental CRS in a patient with solid malignancy. This response could be due to malignant pleural fluid creating an environment where T cells could interact with tumor cells and suggests localized on-target CAR-T-cell activation.

Mesothelin as a target for chimeric antigen receptor-modified T cells as anticancer therapy.

Mesothelin is a promising target for immune-based therapy, specifically for mesothelioma and pancreatic and ovarian cancers that have high levels of mesothelin expression. Many preclinical and clinical studies that target tumors with high mesothelin expression with antibodies, immunotoxins, antibody-drug conjugates and vaccines have shown the potential of mesothelin as a target. Studies of T cells genetically modified with chimeric antigen receptors (CAR) report significant efficacy in hematologic malignancies, and antimesothelin CAR T cells are currently being investigated in clinical studies. Here we outline the rationale for using mesothelin as a target for immunotherapy, review the clinical and preclinical studies evaluating mesothelin-directed therapies and explore the promise of CAR T cells directed against mesothelin for immunotherapy in the future.

Follicle-Stimulating Hormone Receptor as a Target in the Redirected T-cell Therapy for Cancer.

Adoptive transfer of T cells engineered to express chimeric immunoreceptors is an effective strategy to treat hematologic cancers; however, the use of this type of therapy for solid cancers, such as ovarian cancer, remains challenging because a safe and effective immunotherapeutic target has not yet been identified. Here, we constructed and evaluated a novel redirected T-cell-based immunotherapy targeting human follicle-stimulating hormone receptor (FSHR), a highly conserved molecule in vertebrate animals with expression limited to gonadal tissues, ovarian cancer, and cancer-associated vasculature. Receptor ligand-based anti-FSHR immunoreceptors were constructed that contained small binding fragments from the ligand for FSHR, FSH, fused to T-cell transmembrane and T-cell signaling domains. Human T cells transduced to express anti-FSHR immunoreceptors were specifically immunoreactive against FSHR-expressing human and mouse ovarian cancer cell lines in an MHC-nonrestricted manner and mediated effective lysis of FHSR-expressing tumor cells, but not FSHR-deficient targets, in vitro. Similarly, the outgrowth of human ovarian cancer xenografts in immunodeficient mice was significantly inhibited by the adoptive transfer of FSHR-redirected T cells. Our experimental observations show that FSHR is a promising immunotherapeutic target for ovarian cancer and support further exploration of FSHR-targeted immune therapy approaches for patients with cancer.