A Genetic Mouse Model Recapitulates Immune Checkpoint Inhibitor-Associated Myocarditis and Supports a Mechanism-Based Therapeutic Intervention

Immune checkpoint inhibitors (ICI) targeting CTLA4 or PD-1/PD-L1 have transformed cancer therapy but are associated with immune-related adverse events, including myocarditis. Here, we report a robust preclinical mouse model of ICI-associated myocarditis in which monoallelic loss of Ctla4 in the context of complete genetic absence of Pdcd1 leads to premature death in approximately half of mice. Premature death results from myocardial infiltration by T cells and macrophages and severe ECG abnormalities, closely recapitulating the clinical and pathologic hallmarks of ICI-associated myocarditis observed in patients. Using this model, we show that Ctla4 and Pdcd1 functionally interact in a gene dosage-dependent manner, providing a mechanism by which myocarditis arises with increased frequency in the setting of combination ICI therapy. We demonstrate that intervention with CTLA4-Ig (abatacept) is sufficient to ameliorate disease progression and additionally provide a case series of patients in which abatacept mitigates the fulminant course of ICI myocarditis. SIGNIFICANCE: We provide a preclinical model of ICI-associated myocarditis which recapitulates this clinical syndrome. Using this model, we demonstrate that CTLA4 and PD-1 (ICI targets) functionally interact for myocarditis development and that intervention with CTLA4-Ig (abatacept) attenuates myocarditis, providing mechanistic rationale and preclinical support for therapeutic clinical studies.See related commentary by Young and Bluestone, p. 537.This article is highlighted in the In This Issue feature, p. 521.

Abstract PR008: Identifying mechanisms of immune evasion in microsatellite instable endometrial cancer mouse models

Introduction: Microsatellite instability (MSI), caused by defects in DNA mismatch repair genes, including MLH1 and MSH2, occur in 30% of endometrial cancers (EC). High mutational loads associated with MSI have been associated with greater immunogenicity, and an increase in immune inhibitory factors such as PD-1 and PD-L1. While immunotherapy with anti-PD-L1 has shown promising results in MSI ECs, up to 40% did not respond, suggesting there are alternate immunosuppressive mechanisms. To improve understanding of response/resistance to immunotherapy, we evaluated immune activation and evasion using a novel immunocompetent mouse model of MSI EC.

Methods: Endometrial lesions were evaluated in mice with MSH2 loss targeted to the endometrium (PRCre+MSH2flox/flox). When aged to 12-16 months, 22% develop hyperplasia and 18% develop spontaneous EC. MSI status was confirmed by PCR. Immune infiltration and function were assessed by immunohistochemistry (IHC) and Nanostring digital spatial profiling. Tumors were evaluated for tumor infiltrating lymphocytes (TIL) based on CD8a expression and found to separate into TILHIGH and TILLOW groups and further characterized to determine immune activation/resistance mechanisms using transcriptome analysis with Affymetrix Clariom D assay and validation by RT-PCR. A gene signature score approach was used to quantify immune-related expression changes for tumors from PRCre+MSH2flox/flox mice and MSI EC patient data from TCGA. Cell lines were generated from tumors and used to evaluate a syngeneic orthotopic mouse model for immunotherapy studies, where immune infiltration was characterized.

Results: All endometrial tumors were MSI and included endometrioid, serous, and mixed histologies. Tumors showed varying degrees of CD8+ T cell infiltration, irrespective of histology. TILHIGH tumors had increased infiltration of dendritic cells and Type I interferon response, including genes IFI203 (fold-change, FC=18.5), IFI204 (FC=11.1) and CXCL9 (FC=5.7). There was no significant difference in type II interferon response. TILLOW tumors had low expression of IFN-associated genes. TILHIGH tumors also exhibited increased immune exhaustion markers such as TIM3 (FC=2.4) and LAG3 (FC=3.2). Tumoral PD-L1 expression was negative (<1% of positive cells). Similar to our mouse model, TILHIGH MSI uterine cancer patients from TCGA also showed activation of type I interferon, increased dendritic cell infiltration, and increased T cell exhaustion markers. Primary cell lines used in an orthotopic mouse model retained the immune profile of the original tumor.

Conclusions: Elucidating immune activation and evasion mechanisms is critical for improving immunotherapies. The PRCre+MSH2flox/flox mouse model reflects the spectrum of immunogenicity observed in patients. A panel of primary cell lines generated from this model are an important tool that enable studies of immunotherapy efficacy and resistance mechanisms, in both immunogenic and non-immunogenic tumors.

Citation Format: Brenda Melendez, Emily Hinchcliff, Nisha Gokul, Xiaoping Su, Daniel McGrail, Elizabeth Whitley, Russell Broaddus, Rosemarie Schmandt, Karen Lu, Melinda Yates. Identifying mechanisms of immune evasion in microsatellite instable endometrial cancer mouse models [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr PR008.

Abstract 3421: Identifying mechanisms of immune evasion in microsatellite instable endometrial cancers

Inherited or sporadic defects in mismatch repair genes (MLH1, MSH2, MSH6, and PSM2) can lead to microsatellite instable (MSI) tumors, most commonly colon, endometrial or gastric tumors. High mutation rates in MSI tumors have been associated with greater immunogenicity, but these tumors can evade immune response. Recently developed mouse models of MSI endometrial cancer (EC) were used to evaluate immune surveillance mechanisms.

Uterine-targeted MSH2 knockout (PR-Cre+MSH2flox/flox) mice were characterized and determined that 22% of mice develop spontaneous EC by 12-16 months of age. Microsatellite instability was evaluated by PCR. Immune infiltration was quantified by immunohistochemistry (IHC) using FoxP3 (Tregs), CD11b (myeloid cells) and CD8 (tumor infiltrating lymphocytes, TILs) antibodies. Tumors were divided into TILHigh and TILLow (<5 TIL/mm2). Comprehensive transcriptome analysis of tumor and normal controls was performed using the Affymetrix Clariom D assay. A subset of candidate gene changes were validated by RT-PCR and at the protein level by IHC. Cell lines were generated from spontaneous tumors and used for orthotopic syngeneic tumor studies of advanced EC. Immune infiltration in orthotopic tumors was characterized using flow cytometry.

All endometrial tumors from PR-Cre+MSH2flox/flox mice were MSI and included endometrioid, serous, and mixed histologies. Tumors showed varying degrees of immune infiltrate, irrespective of histology. Of 7 tumors, 4 (57%) were TILHigh and 3 (43%) were TILLow. Transcriptome analysis showed TILHigh tumors upregulated innate immunity related pathways including, pattern recognition-associated factors, Type I IFN signaling molecules and CXCL5. Activation of adaptive immunity was observed by an increase in T cell chemoattractants, CXCL9 and CCL21. TILHigh tumors displayed at least a 2-fold increase in MHC class I molecules and CD86 needed for T cell activation. IL1A, CSF1, and TGFB2 (cytokines involved in immunosuppressive cell recruitment and induction) were also highly expressed. IHC confirmed co-localization of TILs with myeloid cells and Tregs in TILHigh tumors. TILLow tumors had decreased expression of several members in the IFN family responsible for initiating innate responses. Primary cell lines from TILHigh and TILLow tumors used in an orthotopic syngeneic mouse model retained the immune profile of the original tumor.

Understanding mechanisms of immune evasion is critical for improving immunotherapy. This model of MSI EC reflects the spectrum of immunogenicity observed in clinical studies. TILHigh tumors express a wide range of factors involved in innate and adaptive anti-tumor responses, while TILLow tumors lack key mediators needed for immune activation. These new models for MSI EC will be essential to test the efficacy of immunotherapies and study mechanisms of resistance.

Citation Format: Brenda Melendez, Emily Hinchcliff, Nisha Gokul, Elizabeth Whitley, Russell R. Broaddus, Rosemarie E. Schmandt, Karen H. Lu, Melinda S. Yates. Identifying mechanisms of immune evasion in microsatellite instable endometrial cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3421.

The Relation Between Cognitive Performance and Symptom Factors Following Concussion

Purpose

The purpose of this study was to explore if symptom factors are related to cognitive outcomes. Prior studies have examined the relationship of individual symptoms to cognition. However, the relation between empirically-derived symptom factors and cognitive outcomes has yet to be explored.

Methods

Data were extracted via retrospective chart review of 691 patients (aged 10–24, mean: 14.99±2.63). Participants completed ImPACT and the PCSS within 14 days of injury (mean: 9.27±3.37). Predictors were PCSS factor scores of Cognitive-Fatigue-Migraine (CFM), Affective (AFF), Somatic (SOM), and Sleep (SLP) (Kontos et al., 2012). Outcomes examined were ImPACT composite scores. Univariate analyses were performed and values with p < 0.10 were entered into stepwise linear regression (LR) models. Retained predictors in each LR model had p values <.05.

Results

Verbal memory was predicted by CFM, SOM, age, and gender. Visual memory was predicted by CFM and SOM. Visual motor speed was predicted by age, gender, CFM, SOM, and AFF. Reaction time was best predicted by SOM, CFM, and age. The variance explained was fairly small (0.08 to 0.21). SLP was not a significant predictor in any LR.

Conclusion

CFM and SOM factors were most predictive of lower cognitive performance, similar to prior studies linking dizziness to longer recovery and post-traumatic migraine to worse cognitive performance. These findings underscore the clinical importance of diverse symptom assessment and injury education. Higher CFM and SOM scores may also serve as proxy for injury severity, which we would expect to be associated with worse cognitive performance.

Acute hydrogen sulfide-induced neuropathology and neurological sequelae: challenges for translational neuroprotective research

Hydrogen sulfide (H2 S), the gas with the odor of rotten eggs, was formally discovered in 1777, over 239 years ago. For many years, it was considered an environmental pollutant and a health concern only in occupational settings. Recently, however, it was discovered that H2 S is produced endogenously and plays critical physiological roles as a gasotransmitter. Although at low physiological concentrations it is physiologically beneficial, exposure to high concentrations of H2 S is known to cause brain damage, leading to neurodegeneration and long-term neurological sequelae or death. Neurological sequelae include motor, behavioral, and cognitive deficits, which are incapacitating. Currently, there are concerns about accidental or malicious acute mass civilian exposure to H2 S. There is a major unmet need for an ideal neuroprotective treatment, for use in the field, in the event of mass civilian exposure to high H2 S concentrations. This review focuses on the neuropathology of high acute H2 S exposure, knowledge gaps, and the challenges associated with development of effective neuroprotective therapy to counteract H2 S-induced neurodegeneration.

The Public Health Framework of Legalized Marijuana in Colorado

On January 1, 2014, Colorado became the first state in the nation to sell legal recreational marijuana for adult use. As a result, Colorado has had to carefully examine potential population health and safety impacts as well as the role of public health in response to legalization. We have discussed an emerging public health framework for legalized recreational marijuana. We have outlined this framework according to the core public health functions of assessment, policy development, and assurance. In addition, we have discussed challenges to implementing this framework that other states considering legalization may face.

A patient navigation intervention for drug-involved former prison inmates

BACKGROUND

Former prison inmates experience high rates of hospitalizations and death during the transition from prison to the community, particularly from drug-related causes and early after release. The authors designed a randomized controlled trial (RCT) of patient navigation to reduce barriers to health care and hospitalizations for former prison inmates.

METHODS

Forty former prison inmates with a history of drug involvement were recruited and randomized within 15 days after prison release. Participants were randomized to receive 3 months of patient navigation (PN) with facilitated enrollment into an indigent care discount program (intervention) or facilitated enrollment into an indigent care discount program alone (control). Structured interviews were conducted at baseline, 3 months, and 6 months. Outcomes were measured as a change in self-reported barriers to care and as the rate of health service use per 100 person-days.

RESULTS

The mean number of reported barriers to care was reduced at 3 and 6 months in both groups. At 6 months, the rate of emergency department/urgent care visits per 100 person-days since baseline was 1.1 among intervention participants and 0.5 among control participants (P = .04), whereas the rate of hospitalizations per 100 person-days was 0.2 in intervention participants and 0.6 in control participants (P = .04).

CONCLUSIONS

Recruitment of former inmates into an RCT of patient navigation was highly feasible, but follow-up was limited by rearrests. Results suggest a significantly lower rate of hospitalizations among navigation participants, although the rate of emergency department/urgent care visits was not improved. Patient navigation is a promising, pragmatic intervention that may be effective at reducing high-cost health care utilization in former prison inmates.

Costs and outcomes evaluation of patient navigation after abnormal cancer screening: evidence from the Patient Navigation Research Program

BACKGROUND

Navigators can facilitate timely access to cancer services, but to the authors' knowledge there are little data available regarding their economic impact.

METHODS

The authors conducted a cost-consequence analysis of navigation versus usual care among 10,521 individuals with abnormal breast, cervical, colorectal, or prostate cancer screening results who enrolled in the Patient Navigation Research Program study from January 1, 2006 to March 31, 2010. Navigation costs included diagnostic evaluation, patient and staff time, materials, and overhead. Consequences or outcomes were time to diagnostic resolution and probability of resolution. Differences in costs and outcomes were evaluated using multilevel, mixed-effects regression modeling adjusting for age, race/ethnicity, language, marital status, insurance status, cancer, and site clustering.

RESULTS

The majority of individuals were members of a minority (70.7%) and uninsured or publically insured (72.7%). Diagnostic resolution was higher for navigation versus usual care at 180 days (56.2% vs 53.8%; P = .008) and 270 days (70.0% vs 68.2%; P < .001). Although there were no differences in the average number of days to resolution between the 2 groups (110 days vs 109 days; P = .63), the probability of ever having diagnostic resolution was higher for the navigation group versus the usual-care group (84.5% vs 79.6%; P < .001). The added cost of navigation versus usual care was $275 per patient (95% confidence interval, $260-$290; P < .001). There was no significant difference in stage distribution among the 12.4% of patients in the navigation group vs 11% of the usual-care patients diagnosed with cancer.

CONCLUSIONS

Navigation adds costs and modestly increases the probability of diagnostic resolution among patients with abnormal screening test results. Navigation is only likely to be cost-effective if improved resolution translates into an earlier cancer stage at the time of diagnosis.

Patient navigation for breast and colorectal cancer treatment: a randomized trial

BACKGROUND

There is limited high-quality evidence about the impact of patient navigation (PN) on outcomes for patients with diagnosed cancer.

METHODS

We pooled data from two sites from the national Patient Navigation Research Program. Patients (n = 438) with newly diagnosed breast (n = 353) or colorectal cancer (n = 85) were randomized to PN or usual care. Trained lay navigators met with patients randomized to PN to help them assess treatment barriers and identify resources to overcome barriers. We used intent-to-treat analysis to assess time to completion of primary treatment, psychologic distress (impact of events scale), and satisfaction (patient satisfaction with cancer-related care) within 3 months after initiation of cancer treatment.

RESULTS

The sample was predominantly middle-aged (mean age = 57) and female (90%); 44% were race-ethnic minorities (44%), 46% reported lower education levels, 18% were uninsured, and 9% reported a non-English primary language. The randomized groups were comparable in baseline characteristics. Primary analysis showed no statistically significant group differences in time to completion of primary cancer treatment, satisfaction with cancer-related care, or psychologic distress. Subgroup analysis showed that socially disadvantaged patients (i.e., uninsured, low English proficiency, and non-English primary language) who received PN reported higher satisfaction than those receiving usual care (all P < 0.05). Navigated patients living alone reported greater distress than those receiving usual care.

CONCLUSIONS

Although the primary analysis showed no overall benefit, the subgroup analysis suggests that PN may improve satisfaction with care for certain disadvantaged individuals.

IMPACT

PN for cancer patients may not necessarily reduce treatment time nor distress.

The impact of patient navigation on receipt of quality breast cancer treatment in the national patient navigation research program

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Background: The discrepancy in breast cancer outcomes for underserved populations has been linked to lack of receipt of quality treatment. Patient navigation programs are being rapidly adopted as a model to improve cancer outcomes for these vulnerable populations, yet the effect of navigation on their quality of cancer care is unknown. Methods: We conducted a secondary analysis of the National Patient Navigation Research Program (PNRP) data to assess the impact of navigation on receipt of quality care among women diagnosed with breast cancer. Data pooled from 7 PRNP sites were used to determine the proportion of newly diagnosed cancer patients whose care met National Comprehensive Cancer Network (NCCN) quality metrics: 1) hormonal therapy for HR+ patients 2) post-lumpectomy radiation therapy; and 3) chemotherapy for hormone negative, >1cm tumors, in patients <70 years of age. Chi-square tests were performed to compare probability of receiving recommended care among navigated and control patients. Results: A total of 1,006 breast cancer patients eligible for treatment were enrolled across all sites: 491 (49%) in the intervention arm, 515 (51%) in the control arm (mean age: 56 years; 38% African American, 23% Hispanic; 13% uninsured and 38% Medicaid). Among those eligible for hormone therapy, 283/357 (79%) navigated patients received hormonal therapy compared to 237/371 (64%) of controls (p < 0.001). Among those eligible for radiation therapy post lumpectomy, 235/277 (85%) of navigated patients received radiation compared to 270/324 (83%) of controls (p=0.62). Among those eligible for chemotherapy, 79/122 (65%) of navigated patients received chemotherapy compared to 81/100 (81%) of controls (p < 0.007). Logistic regression models to determine the odds of receiving recommended care for navigated and non-navigated patients, adjusting for patient demographics, will be conducted. Conclusions: Navigation had a positive effect for receipt of hormonal therapy, but not for radiation therapy and chemotherapy. Future studies are needed to assess the role navigation may play in ensuring quality care for the most vulnerable.

Influence of maternal and paternal IQ on offspring health and health behaviours: evidence for some trans-generational associations using the 1958 British birth cohort study

PURPOSE

Individuals scoring poorly on tests of intelligence (IQ) have been reported as having increased risk of morbidity, premature mortality, and risk factors such as obesity, high blood pressure, poor diet, alcohol and cigarette consumption. Very little is known about the impact of parental IQ on the health and health behaviours of their offspring.

METHODS

We explored associations of maternal and paternal IQ scores with offspring television viewing, injuries, hospitalisations, long standing illness, height and BMI at ages 4 to 18 using data from the National Child Development Study (1958 birth cohort).

RESULTS

Data were available for 1446 mother-offspring and 822 father-offspring pairs. After adjusting for potential confounding/mediating factors, the children of higher IQ parents were less likely to watch TV (odds ratio (95% confidence interval) for watching 3+ vs. less than 3hours per week associated with a standard deviation increase in maternal or paternal IQ: 0.75 (0.64, 0.88) or 0.78 (0.64, 0.95) respectively) and less likely to have one or more injuries requiring hospitalisation (0.77 (0.66, 0.90) or 0.72 (0.56, 0.91) respectively for maternal or paternal IQ).

CONCLUSIONS

Children whose parents have low IQ scores may have poorer selected health and health behaviours. Health education might usefully be targeted at these families.

Early lesion formation in colorectal carcinogenesis is associated with adiponectin status whereas neoplastic lesions are associated with diet and sex in C57BL/6J mice

Adiponectin is an antiinflammatory and insulin-sensitizing hormone that is decreased in obesity. Although controversial, it has been suggested that decreased adiponectin contributes to colorectal cancer risk in obesity. To further investigate the role of adiponectin in obesity-linked colorectal carcinogenesis, we used male and female adiponectin knockout (KO) and wild-type (Wt) C57BL/6J mice. Tumorigenesis was induced in all mice with the combined treatment of azoxymethane (AOM) and dextran sodium sulfate (DSS). Following AOM/DSS treatment, mice were fed a low-fat control (LFC), or high-fat lard (HFL) diet for 7 1/2 wk. KO mice developed fewer total lesions than Wt mice, males developed fewer lesions than females, and mice fed the HFL diet developed fewer lesions than those fed the LFC diet. Early lesion multiplicity was influenced by genotype, whereas advanced lesion development was influenced by sex and diet. Moreover, lesion types were differentially correlated with serum adipokines and colon gene expression of adiponectin receptors, insulin receptor, and toll-like receptor 4. These data suggest that in the AOM/DSS model of carcinogenesis, adiponectin functions to promote early lesion development whereas sex and diet are important regulators of advanced lesion development through pathways involved in inflammation and insulin signaling.

Establishing common cost measures to evaluate the economic value of patient navigation programs

BACKGROUND

Patient navigation is an intervention aimed at reducing barriers to health care for underserved populations as a means to reduce cancer health disparities. Despite the proliferation of patient navigation programs across the United States, information related to the economic impact and sustainability of these programs is lacking.

METHODS

After a review of the relevant literature, the Health Services Research (HSR)-Cost workgroup of the American Cancer Society National Patient Navigator Leadership Summit met to examine cost data relevant to assessing the economic impact of patient navigation and to propose common cost metrics.

RESULTS

Recognizing that resources available for data collection, management, and analysis vary, 5 categories of core and optional cost measures were identified related to patient navigator programs, including program costs, human capital costs, direct medical costs, direct non-medical costs, and indirect costs.

CONCLUSIONS

Information demonstrating economic as well as clinical value is necessary to make decisions about sustainability of patient navigation programs. Adoption of these common cost metrics are recommended to promote understanding of the economic impact of patient navigation and comparability across diverse patient navigation programs.

Stems to GEMs: impact of stem cell technology on engineered animal models

Collectively, these presentations introduced the audience to the roles of ES cells in generating phenotypes of transgenic animals,and they provided examples where the GEMs were used to define molecular mechanisms of disease or where ES cells were used as a therapeutic modality. Points of discussion among audience members reinforced the importance of strain-associated background lesions in animal models, technological advances in imaging functional biology, opportunities for stem cell therapies, and ubiquitination in regulation of cell proliferation. The 2012 American College of Veterinary Pathologists symposium ‘‘Evolutionary Aspects of Animal Models’’ will focus on the proper selection of a relevant animal model in biomedical research as critical to investigative success. Recent work characterizing rapid evolutionary changes and differences in physiology between species questions the validity of some comparative models. Dr. Robert Hamlin will be speaking on cardiovascular disease in ‘‘Animals as Models of Human Cardiovascular Disease: Or the Search to Overcome Outdated Evolutionary Homeostatic Mechanisms.’’ Dr. Stefan Niewiesk will discuss evolutionary factors that affect modeling the human immune system in ‘‘Of Mice and Men: Evolutionarily, What Are the Best Rodent Models of the Human Immune System for Infectious Disease Research?’’ Dr. Steven Austad will consider evolution in ‘‘Evolutionary Aspects of Animal Models of Aging.’’Finally, Dr. Elizabeth Uhl will conclude the session with ‘‘Modeling Disease Phenotypes: How an Evolutionary Perspective Enhances the Questions.’’