Leslie R. DeMars

HPV vaccines – A review of the first decade

Pre-adolescent girls (9-15years) have the option of receiving a two dose HPV vaccine series at either a six month or one year interval to provide protection from HPV 16, the most prevalent type associated with cervical cancers, as well as several other less prevalent types. This series of vaccinations is highly likely to protect her from HPV infection until she enters the routine screening program, whether that be primary HPV testing or a combination of HPV testing and cytology. The two dose program has been recommended by the World Health Organization (WHO) since 2015. For women 15years and older, the three dose vaccine schedule is still recommended. The past ten years of Gardasil use has provided evidence of reduced HPV 16/18 infections in countries where there has been high coverage. Gardasil9 has replaced Gardasil. Gardasil9 has the same rapid anti-HPV 18 and HPV45 titer loss as Gardasil did. Cervarix remains equivalent to Gardasil9 in the prevention of HPV infections and precancers of any HPV type; Cervarix also has demonstrated sustained high antibody titers for at least 10years. One dose of Cervarix provides protection against HPV 16/18 infection with robust antibody titers well above natural infection titers. This may offer the easiest and most cost effective vaccination program over time, especially in low and lower middle income countries. Cervical cancer screening must continue to control cancer incidence over the upcoming decades. Future studies of prophylactic HPV vaccines, as defined by the WHO, must demonstrate protection against six month type specific persistent infections, not actual cervical cancer precursor disease endpoints, such as cervical intraepithelial neoplasia grade 3 (CIN 3) or adenocarcinoma in situ (AIS). This simplifies and makes less expensive future comparative studies between existing and new generic vaccines.

Human Immunodeficiency Virus–Specific and CD3-Redirected Cytotoxic T Lymphocyte Activity in the Human Female Reproductive Tract: Lack of Correlation between Mucosa and Peripheral Blood

CD8(+) T cell phenotype and function were assessed in the female reproductive tracts (FRTs) of 3 human immunodeficiency virus (HIV)-positive patients who had undergone hysterectomy. FRT cytotoxic T lymphocyte (CTL) lytic activity from 1 patient (patient 872) was detected by using CD3-dependent redirected-lysis assay and HIV-specific assay, concomitant with the presence of CD8(+) cells. In contrast, samples from the 2 other HIV-positive patients (patients 1356 and 1364), who also were asymptomatic for HIV-associated illnesses, demonstrated no CTL activity in any solid tissue tested by either assay, despite activity by autologous peripheral blood mononuclear cells (PBMC). This absence of CTL activity was correlated with a relative absence of CD8(+) cells in the FRT, whereas CD8(+) cells were present in PBMC. Thus, CTL activity in PBMC may fail to correlate with mucosal activity. The finding of CTL activity in the FRT of patient 872 represents the first description of CTL in upper and lower FRT tissues of an HIV-positive woman.

B7H6-specific chimeric antigen receptors lead to tumor elimination and host antitumor immunity

Chimeric antigen receptor (CAR) T-cell therapies have demonstrated durable and potentially curative therapeutic efficacy against B-cell leukemia in clinical trials. A CAR strategy can target any tumor surface antigens as long as an antigen-binding receptor can be generated. New CARs that target solid tumors and have the potential to target multiple tumor types are needed. In this study, B7H6, a ligand for the NK cell activating receptor NKp30, was targeted to create a CAR that targets multiple tumor types. B7H6 is expressed on various primary human tumors, including leukemia, lymphoma and gastrointestinal stromal tumors, but it is not constitutively expressed on normal tissues. B7H6-specific CAR T cells have robust cellular cytotoxicity and interferon-γ secretion when co-cultured with B7H6+ tumor cells, and they exhibit little self-reactivity to immature dendritic cells or pro-inflammatory monocytes. In vivo, B7H6-specific CAR T cells greatly enhanced the survival of RMA/B7H6 lymphoma-bearing mice. The long-term survivor mice were protected against a B7H6-deficient tumor re-challenge. This CAR therapy also decreased tumor burden in a murine ovarian cancer model. In conclusion, B7H6-specific CARs have the potential to treat B7H6+ hematologic and solid tumors.

Catumaxomab for the treatment of malignant ascites in patients with chemotherapy-refractory ovarian cancer a phase II study

Objective The aim of this study was to investigate the efficacy and safety of intraperitoneal catumaxomab in heavily pretreated patients with chemotherapy-refractory ovarian cancer and recurrent symptomatic malignant ascites. Methods The study is a single-arm open-label multicenter US phase II study. Patients received 4 three-hour intraperitoneal catumaxomab infusions (10, 20, 50, and 150 &mgr;g within 10 days). The primary end point was the percentage of patients with at least a 4-fold increase in the puncture-free interval (PuFI) relative to the pretreatment interval. The main secondary end points were puncture-free survival, overall survival, ascites symptoms, and safety. Time to first therapeutic puncture (TTPu) was analyzed post hoc. Results Forty patients were screened, and 32 patients (80%) were treated. Seven patients (23%) achieved the primary end point. The median PuFI was prolonged 2-fold from 12 to 27.5 days. The median TTPu was prolonged 4-fold from 12 to 52 days. The median puncture-free survival and overall survival were 29.5 and 111 days, respectively. Nineteen patients (59%) required puncture after catumaxomab treatment. Ascites symptoms improved in most of the 13 predefined categories. At study end, most symptoms were still improved compared with screening. The most frequent treatment-related adverse events were related to cytokine release (vomiting, nausea, pyrexia, fatigue, and chills) or intraperitoneal administration (abdominal pain). Transient increases in liver parameters and transient decreases in blood lymphocytes were regularly observed but were generally without clinical relevance. Conclusions Catumaxomab prolonged PuFI and TTPu had a beneficial effect on quality of life, as shown by the improvement in ascites symptoms, and had an acceptable safety profile, which is consistent with its mode of action.

Primary strategies for HPV infection and cervical cancer prevention.

Counseling messages for tobacco cessation, condom use, circumcision, and selective choice in the number of sexual partners can help reduce the risk of cervical cancer. Other sexual behavioral and reproductive risk factors for cervical cancer are a younger age at first intercourse and at first full-term pregnancy as well as increasing duration of combined hormonal oral contraceptive use. Micronutrients and supplements can reduce the risk of human papillomavirus infection, persistence, progression, and regression. Some human papillomavirus infections can be prevented by vaccination. Cervical cancer is best prevented by screening.

B7H6-Specific Bispecific T Cell Engagers Lead to Tumor Elimination and Host Antitumor Immunity

Substantial evidence showed that T cells are the key effectors in immune-mediated tumor eradication; however, most T cells do not exhibit antitumor specificity. In this study, a bispecific T cell engager (BiTE) approach was used to direct T cells to recognize B7H6+ tumor cells. B7H6 is a specific ligand for the NK cell–activating receptor NKp30. B7H6 is expressed on various types of primary human tumors, including leukemia, lymphoma, and gastrointestinal stromal tumors, but it is not constitutively expressed on normal tissues. Data from this study showed that B7H6-specific BiTEs direct T cells to mediate cellular cytotoxicity and IFN-γ secretion upon coculturing with B7H6+ tumors. Furthermore, B7H6-specific BiTE exhibited no self-reactivity to proinflammatory monocytes. In vivo, B7H6-specific BiTE greatly enhanced the survival benefit of RMA/B7H6 lymphoma-bearing mice through perforin and IFN-γ effector mechanisms. In addition, long-term survivor mice were protected against an RMA lymphoma tumor rechallenge. The B7H6-specific BiTE therapy also decreased tumor burden in murine melanoma and ovarian cancer models. In conclusion, B7H6-specific BiTE activates host T cells and has the potential to treat various B7H6+ hematological and solid tumors.

Universal screening for Lynch syndrome in endometrial cancers: frequency of germline mutations and identification of patients with Lynch-like syndrome

Lynch syndrome (LS) is an inherited clinical syndrome characterized by a high risk of colorectal, endometrial (lifetime risk of up to 60%), ovarian, and urinary tract cancers. The diagnosis is confirmed by identification of germline mutations in the DNA mismatch repair genes MLH1, PMS2, MSH2, MSH6, or EPCAM. In 2015, our institution implemented universal screening of endometrial cancer (EC) hysterectomy specimens by mismatch repair immunohistochemistry (IHC) with reflex MLH1 promoter hypermethylation analysis for tumors with loss of MLH1/PMS2 expression. Patients with tumors negative for MLH1 methylation and those with a loss of the heterodimer pair MSH2 and MSH6, or isolated loss of either PMS2 or MSH6 were referred to the Familial Cancer Program for genetic counseling and consideration of germline testing. Between May 2015 to Dec 2016, 233 EC patients were screened by IHC for LS with a median age of 63 years. Sixty tumors (27%) had abnormal IHC staining results. Fifty-one (22%) harbored heterodimeric loss of MLH1 and PMS2, 49 of which showed MLH1 promoter methylation (1 failure, 1 negative). One showed loss of MLH1/PMS2 and MSH6, 2 showed loss of MSH2/MSH6, and 6 had isolated loss of MSH6 only. Ten patients underwent genetic counseling, and germline testing was performed in 8; LS was confirmed in 5 patients (2.1%). In addition, 3 patients with negative germline testing and presumed Lynch-like syndrome were identified and offered additional somatic testing. Universal screening for LS in EC patients has yielded positive results for identification of patients at risk for this inherited syndrome.

Phase II study of Vigil® DNA engineered immunotherapy as maintenance in advanced stage ovarian cancer

OBJECTIVES The majority of women with Stage III/IV ovarian cancer who achieve clinical complete response with frontline standard of care will relapse within 2years. Vigil immunotherapy, a GMCSF/bi-shRNA furin DNA engineered autologous tumor cell (EATC) product, demonstrated safety and induction of circulating activated T-cells against autologous tumor in Phase I trial Senzer et al. (2012, 2013) . Our objectives for this study include evaluation of safety, immune response and recurrence free survival (RFS). METHODS This is a Phase II crossover trial of Vigil (1.0×107 cells/intradermal injection/month for 4 to 12 doses) in Stage III/IV ovarian cancer patients achieving cCR (normal imaging, CA-125≤35units/ml, physical exam, and no symptoms suggestive of the presence of active disease) following primary surgical debulking and carboplatin/paclitaxel adjuvant or neoadjuvant chemotherapy. Patients received Vigil or standard of care during the maintenance period. RESULTS Forty-two patients were entered into trial, 31 received Vigil and 11 received standard of care. No≥Grade 3 toxicity related to product was observed. A marked induction of circulating activated T-cell population was observed against individual, pre-processed autologous tumor in the Vigil arm as compared to pre-Vigil baseline using IFNγ ELISPOT response (30/31 negative ELISPOT pre Vigil to 31/31 positive ELISPOT post Vigil, median 134 spots). Moreover, in correlation with ELISPOT response, RFS from time of procurement was improved (mean 826days/median 604days in the Vigil arm from mean 481days/median 377days in the control arm, p=0.033). CONCLUSION In conjunction with the demonstrated safety, the high rate of induction of T-cell activation and correlation with improvement in RFS justify further Phase II/III assessment of Vigil.