Germline variants associated with toxicity to immune checkpoint blockade.

Immune checkpoint inhibitors (ICIs) have yielded remarkable responses but often lead to immune-related adverse events (irAEs). Although germline causes for irAEs have been hypothesized, no individual variant associated with developing irAEs has been identified. We carried out a genome-wide association study of 1,751 patients on ICIs across 12 cancer types. We investigated two irAE phenotypes: (1) high-grade (3-5) and (2) all-grade events. We identified 3 genome-wide significant associations (P < 5 × 10-8) in the discovery cohort associated with all-grade irAEs: rs16906115 near IL7 (combined P = 3.6 × 10-11; hazard ratio (HR) = 2.1); rs75824728 near IL22RA1 (combined P = 3.5 × 10-8; HR = 1.8); and rs113861051 on 4p15 (combined P = 1.2 × 10-8, HR = 2.0); rs16906115 was replicated in 3 independent studies. The association near IL7 colocalized with the gain of a new cryptic exon for IL7, a critical regulator of lymphocyte homeostasis. Patients carrying the IL7 germline variant exhibited significantly increased lymphocyte stability after ICI initiation, which was itself predictive of downstream irAEs and improved survival.

Phase Ib study of pembrolizumab in combination with trastuzumab emtansine for metastatic HER2-positive breast cancer.

BACKGROUND: Preclinical and clinical data support potential synergy between anti-HER2 therapy plus immune checkpoint blockade. The safety and tolerability of trastuzumab emtansine (T-DM1) combined with pembrolizumab is unknown. METHODS: This was a single-arm phase Ib trial (registration date January 26, 2017) of T-DM1 plus pembrolizumab in metastatic, human epidermal growth factor receptor 2 (HER2)-positive breast cancer. Eligible patients had HER2-positive, metastatic breast cancer previously treated with taxane, trastuzumab, and pertuzumab, and were T-DM1-naïve. A dose de-escalation design was used, with a dose-finding cohort followed by an expansion cohort at the recommended phase 2 dose (RP2D), with mandatory baseline biopsies. The primary endpoint was safety and tolerability. Secondary endpoints included objective response rate (ORR) and progression-free survival (PFS). Immune biomarkers were assessed using histology, protein/RNA expression, and whole exome sequencing. Associations between immune biomarkers and treatment response, and biomarker changes before and during treatment, were explored. RESULTS: 20 patients received protocol therapy. There were no dose-limiting toxicities. The RP2D was 3.6 mg/kg T-DM1 every 21 days plus 200 mg pembrolizumab every 21 days. 85% of patients experienced treatment-related adverse events (AEs) ≥grade 2, 20% of patients experienced grade 3 AEs, and no patients experienced grade >4 AEs. Four patients (20%) experienced pneumonitis (three grade 2 events; one grade 3 event). ORR was 20% (95% CI 5.7% to 43.7%), and median PFS was 9.6 months (95% CI 2.8 to 16.0 months). Programmed cell death ligand-1 and tumor infiltrating lymphocytes did not correlate with response in this small cohort. CONCLUSIONS: T-DM1 plus pembrolizumab was a safe and tolerable regimen. Ongoing trials will define if there is a role for checkpoint inhibition in the management of HER2-positive metastatic breast cancer. TRIAL REGISTRATION NUMBER: NCT03032107.

Insights into Immune Escape During Tumor Evolution and Response to Immunotherapy Using a Rat Model of Breast Cancer.

Animal models are critical for the preclinical validation of cancer immunotherapies. Unfortunately, mouse breast cancer models do not faithfully reproduce the molecular subtypes and immune environment of the human disease. In particular, there are no good murine models of estrogen receptor-positive (ER+) breast cancer, the predominant subtype in patients. Here, we show that Nitroso-N-methylurea-induced mammary tumors in outbred Sprague-Dawley rats recapitulate the heterogeneity for mutational profiles, ER expression, and immune evasive mechanisms observed in human breast cancer. We demonstrate the utility of this model for preclinical studies by dissecting mechanisms of response to immunotherapy using combination TGFBR inhibition and PD-L1 blockade. Short-term treatment of early-stage tumors induced durable responses. Gene expression profiling and spatial mapping classified tumors as inflammatory and noninflammatory, and identified IFNγ, T-cell receptor (TCR), and B-cell receptor (BCR) signaling, CD74/MHC II, and epithelium-interacting CD8+ T cells as markers of response, whereas the complement system, M2 macrophage phenotype, and translation in mitochondria were associated with resistance. We found that the expression of CD74 correlated with leukocyte fraction and TCR diversity in human breast cancer. We identified a subset of rat ER+ tumors marked by expression of antigen-processing genes that had an active immune environment and responded to treatment. A gene signature characteristic of these tumors predicted disease-free survival in patients with ER+ Luminal A breast cancer and overall survival in patients with metastatic breast cancer receiving anti-PD-L1 therapy. We demonstrate the usefulness of this preclinical model for immunotherapy and suggest examination to expand immunotherapy to a subset of patients with ER+ disease. See related Spotlight by Roussos Torres, p. 672.

Molecular correlates of response to eribulin and pembrolizumab in hormone receptor-positive metastatic breast cancer.

Immune checkpoint inhibitors (ICIs) have minimal therapeutic effect in hormone receptor-positive (HR+ ) breast cancer. We present final overall survival (OS) results (n = 88) from a randomized phase 2 trial of eribulin ± pembrolizumab for patients with metastatic HR+ breast cancer, computationally dissect genomic and/or transcriptomic data from pre-treatment tumors (n = 52) for molecular associations with efficacy, and identify cytokine changes differentiating response and ICI-related toxicity (n = 58). Despite no improvement in OS with combination therapy (hazard ratio 0.95, 95% CI 0.59-1.55, p = 0.84), immune infiltration and antigen presentation distinguished responding tumors, while tumor heterogeneity and estrogen signaling independently associated with resistance. Moreover, patients with ICI-related toxicity had lower levels of immunoregulatory cytokines. Broadly, we establish a framework for ICI response in HR+ breast cancer that warrants diagnostic and therapeutic validation. ClinicalTrials.gov Registration: NCT03051659.

Phase II trial of veliparib and temozolomide in metastatic breast cancer patients with and without BRCA1/2 mutations.

PURPOSE: We evaluated the efficacy and safety of poly-(adenosine diphosphate-ribose) polymerase (PARP) 1 and 2 inhibitor veliparib and temozolomide in metastatic breast cancer patients with and without germline BRCA1/2 mutations. METHODS: In this single-arm phase II trial, patients with metastatic breast cancer received veliparib 30 to 40 mg twice daily on days 1 to 7 with concurrent temozolomide 150 mg/m2 on days 1 to 5 of a 28-day cycle. The primary cohort was unselected for BRCA mutation status, and an expansion cohort enrolled only BRCA1/2 carriers. The primary endpoint was objective response rate (ORR) in each cohort. Secondary endpoints included progression-free survival (PFS), clinical benefit rate (CBR), and evaluation of safety and tolerability. RESULTS: In the primary cohort of 41 unselected patients, which included 9 BRCA mutation carriers, the ORR was 10% and clinical benefit rate at 4 months (CBR) was 27%. In the expansion cohort of 21 BRCA1/2 carriers, the ORR was 14% and CBR was 43%. Among all 30 BRCA1/2 carriers, the ORR was 23% versus 0% among non-carriers. In the subset of BRCA1/2 carriers, the ORR was 32% among platinum-naïve patients versus 9% among platinum-exposed patients. The median PFS was 3.3 months among BRCA1/2 carriers compared to 1.8 months among non-carriers (HR: 0.48, p = 0.006). A longer median PFS of 6.2 months was observed among BRCA1/2 carriers who had no prior platinum therapy. The most common grade 3 and 4 toxicities were thrombocytopenia (32%) and neutropenia (21%) that generally improved with dose modifications. CONCLUSION: Veliparib and temozolomide demonstrated clinical activity in platinum-naïve BRCA-associated metastatic breast cancer with manageable toxicity at doses of veliparib well below the single-agent active dose. Although the study did not meet its primary endpoint in unselected nor BRCA-associated breast cancer, this regimen was further evaluated in the BROCADE 2 study. TRIAL REGISTRATION: NCT01009788 (ClinicalTrials.gov), November 9, 2009.

Nivolumab in combination with cabozantinib for metastatic triple-negative breast cancer: a phase II and biomarker study.

This single-arm phase II study investigated the efficacy and safety of cabozantinib combined with nivolumab in metastatic triple-negative breast cancer (mTNBC). The primary endpoint was objective response rate (ORR) by RECIST 1.1. Biopsies at baseline and after cycle 1 were analyzed for tumor-infiltrating lymphocytes (TILs), PD-L1, and whole-exome and transcriptome sequencing. Only 1/18 patients achieved a partial response (ORR 6%), and the trial was stopped early. Toxicity led to cabozantinib dose reduction in 50% of patients. One patient had a PD-L1-positive tumor, and three patients had TILs > 10%. The responding patient had a PD-L1-negative tumor with low tumor mutational burden but high TILs and enriched immune gene expression. High pretreatment levels of plasma immunosuppressive cytokines, chemokines, and immune checkpoint molecules were associated with rapid progression. Although this study did not meet its primary endpoint, immunostaining, genomic, and proteomic studies indicated a high degree of tumor immunosuppression in this mTNBC cohort.

Clinical Efficacy and Molecular Response Correlates of the WEE1 Inhibitor Adavosertib Combined with Cisplatin in Patients with Metastatic Triple-Negative Breast Cancer.

PURPOSE: We report results from a phase II study assessing the efficacy of the WEE1 inhibitor adavosertib with cisplatin in metastatic triple-negative breast cancer (mTNBC). PATIENTS AND METHODS: Patients with mTNBC treated with 0-1 prior lines of chemotherapy received cisplatin 75 mg/m2 i.v. followed 21 days later by cisplatin plus adavosertib 200 mg oral twice daily for five doses every 21 days. The study had 90% power to detect the difference between null (20%) and alternative (40%) objective response rates (ORR) with a one-sided type I error of 0.1: an ORR >30% was predefined as making the regimen worthy of further study. RNA sequencing and multiplex cyclic immunofluorescence on pre- and post-adavosertib tumor biopsies, as well as targeted next-generation sequencing on archival tissue, were correlated with clinical benefit, defined as stable disease ≥6 months or complete or partial response. RESULTS: A total of 34 patients initiated protocol therapy; median age was 56 years, 2 patients (6%) had BRCA2 mutations, and 14 (41%) had one prior chemotherapy. ORR was 26% [95% confidence interval (CI), 13-44], and median progression-free survival was 4.9 months (95% CI, 2.3-5.7). Treatment-related grade 3-5 adverse events occurred in 53% of patients, most commonly diarrhea in 21%. One death occurred because of sepsis, possibly related to study therapy. Tumors from patients with clinical benefit demonstrated enriched immune gene expression and T-cell infiltration. CONCLUSIONS: Among patients with mTNBC treated with 0-1 prior lines, adavosertib combined with cisplatin missed the prespecified ORR cutoff of >30%. The finding of immune-infiltrated tumors in patients with clinical benefit warrants validation.

Role of Immunotherapy in Triple-Negative Breast Cancer.

Immune checkpoint inhibitors (ICIs) have led to durable clinical remissions in many metastatic cancers. However, the single-agent efficacy of ICIs in breast cancer is low, including in triple-negative breast cancer (TNBC), which has several key characteristics that enhance ICI responses. Strategies to improve anticancer immune responses in TNBC are urgently needed to extend survival for patients with metastatic disease. This review presents ICI monotherapy response rates and discusses combination strategies with chemotherapy, targeted therapies, and novel immunotherapies. It concludes with a summary of immunotherapy biomarkers in TNBC and a call to action for future directions of research critical to advancing the efficacy of immunotherapy for patients with TNBC.

Tumor Mutational Burden and PTEN Alterations as Molecular Correlates of Response to PD-1/L1 Blockade in Metastatic Triple-Negative Breast Cancer.

PURPOSE: Few patients with metastatic triple-negative breast cancer (mTNBC) benefit from immune checkpoint inhibitors (ICI). On the basis of immunotherapy response correlates in other cancers, we evaluated whether high tumor mutational burden (TMB) ≥10 nonsynonymous mutations/megabase and PTEN alterations, defined as nonsynonymous mutations or 1 or 2 copy deletions, were associated with clinical benefit to anti-PD-1/L1 therapy in mTNBC. EXPERIMENTAL DESIGN: We identified patients with mTNBC, who consented to targeted DNA sequencing and were treated with ICIs on clinical trials between April 2014 and January 2019 at Dana-Farber Cancer Institute (Boston, MA). Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were correlated with tumor genomic features. RESULTS: Sixty-two women received anti-PD-1/L1 inhibitors alone (23%) or combined with targeted therapy (19%) or chemotherapy (58%). High TMB (18%) was associated with significantly longer PFS (12.5 vs. 3.7 months; P = 0.04), while PTEN alterations (29%) were associated with significantly lower ORR (6% vs. 48%; P = 0.01), shorter PFS (2.3 vs. 6.1 months; P = 0.01), and shorter OS (9.7 vs. 20.5 months; P = 0.02). Multivariate analyses confirmed that these associations were independent of performance status, prior lines of therapy, therapy regimen, and visceral metastases. The survival associations were additionally independent of PD-L1 in patients with known PD-L1 and were not found in mTNBC cohorts treated with chemotherapy (n = 90) and non-ICI regimens (n = 169). CONCLUSIONS: Among patients with mTNBC treated with anti-PD-1/L1 therapies, high TMB and PTEN alterations were associated with longer and shorter survival, respectively. These observations warrant validation in larger datasets.

Genomic correlates of response to immune checkpoint blockade.

Despite impressive durable responses, immune checkpoint inhibitors do not provide a long-term benefit to the majority of patients with cancer. Understanding genomic correlates of response and resistance to checkpoint blockade may enhance benefits for patients with cancer by elucidating biomarkers for patient stratification and resistance mechanisms for therapeutic targeting. Here we review emerging genomic markers of checkpoint blockade response, including those related to neoantigens, antigen presentation, DNA repair, and oncogenic pathways. Compelling evidence also points to a role for T cell functionality, checkpoint regulators, chromatin modifiers, and copy-number alterations in mediating selective response to immune checkpoint blockade. Ultimately, efforts to contextualize genomic correlates of response into the larger understanding of tumor immune biology will build a foundation for the development of novel biomarkers and therapies to overcome resistance to checkpoint blockade.

Personalizing Aspirin Use for Targeted Breast Cancer Chemoprevention in Postmenopausal Women.

OBJECTIVE: To evaluate the association of aspirin and other nonsteroidal anti-inflammatory drugs with the incidence of postmenopausal breast cancer for risk subgroups defined by selected nonmodifiable or difficult to modify breast cancer risk factors in order to better understand the potential risk-benefit ratio for targeted chemoprevention. PATIENTS AND METHODS: Postmenopausal women with no history of cancer on July 1, 1992 (N=26,580), were prospectively followed up through December 31, 2005, for breast cancer incidence (N=1581). Risk subgroups were defined on the basis of family history of breast cancer, age at menarche, age at menopause, parity/age at first live birth, personal history of benign breast disease, and body mass index. Hazard ratios (HRs) and 95% CIs adjusted for other breast cancer risk factors were estimated using Cox models. RESULTS: Aspirin use was associated with a lower incidence of breast cancer for women with a family history of breast cancer (HR, 0.62 for 6 or more times per week vs never use; 95% CI, 0.41-0.93) and those with a personal history of benign breast disease (HR, 0.69; 95% CI, 0.50-0.95) but not for women in higher-risk subgroups for age at menarche, age at menopause, parity/age at first live birth, or body mass index. In contrast, inverse associations with aspirin use were observed in all lower-risk subgroups. Nonsteroidal anti-inflammatory drug use had no association with breast cancer incidence. CONCLUSION: On the basis of their increased risk of breast cancer, postmenopausal women with a family history of breast cancer or a personal history of benign breast disease could potentially be targeted for aspirin chemoprevention studies. Future studies are needed to confirm these findings.

Relation between self-reported physical activity level, fitness, and cardiometabolic risk.

Physical activity and cardiorespiratory fitness are associated with improved cardiovascular health and reduced all-cause mortality. The relation between self-reported physical activity, objective physical fitness, and the association of each with cardiometabolic risk has not been fully described. We studied 2,800 healthy Brazilian subjects referred for an employer-sponsored health screening. Physical activity level was determined as "low," "moderate," or "high" with the International Physical Activity Questionnaire: Short Form (IPAQ-SF). Fitness was measured as METs achieved on a maximal, symptom-limited, treadmill stress test. Using multivariate linear regression analysis, we calculated age, gender, and smoking-adjusted correlation coefficients among IPAQ-SF, fitness, and cardiometabolic risk factors. Mean age of study participants was 43 ± 9 years; 81% were men, and 43% were highly active. Mean METs achieved was 12 ± 2. IPAQ-SF category and fitness were moderately correlated (r = 0.377). Compared with IPAQ-SF category, fitness was better correlated with cardiometabolic risk factors including anthropomorphic measurements, blood pressure, fasting blood glucose, dyslipidemia, high-sensitivity C-reactive protein, and hepatic steatosis (all p <0.01). Among these, anthropomorphic measurements, blood pressure, high-sensitivity C-reactive protein, and hepatic steatosis had the largest discrepancies in correlation, whereas lipid factors had the least discrepant correlation. When IPAQ-SF and fitness were discordant, poor fitness drove associations with elevated cardiometabolic risk. In conclusion, self-reported physical activity level and directly measured fitness are moderately correlated, and the latter is more strongly associated with a protective cardiovascular risk profile.

Racial patterns of cardiovascular disease risk factors in serious mental illness and the overall U.S. population.

BACKGROUND: Serious mental illness (SMI) and minority race are each associated with elevated cardiovascular disease (CVD) mortality. However, little is known about racial variation in CVD risk factors in individuals with SMI. This study aimed to determine racial patterns of CVD risk factors in individuals with SMI and to compare these patterns to those of the general population. METHODS: Overweight/obese adults with SMI (163 whites; 111 African Americans) examined from 2008 to 2011 during a weight loss trial were compared at study baseline to overweight/obese adults (1103 whites; 550 African Americans) of similar age, sex, and race in the 2007 to 2010 National Health and Nutrition Examination Survey. RESULTS: All CVD risk factors except cholesterol were higher in SMI than the overall U.S. population. After adjusting for age and sex, both racial groups with SMI had similarly high risks of smoking, obesity, diabetes, and hypertension, while African Americans with SMI had lower risks of high cholesterol (RR 0.73; 95% CI 0.57-0.94) and metabolic syndrome (RR 0.75; 95% CI 0.63-0.91) than whites with SMI. In the U.S. population sample, African Americans compared to whites had higher risks of obesity (RR 1.23; 95% CI 1.14-1.34), diabetes (RR 1.68; 95% CI 1.21-2.34), and hypertension (RR 1.44; 95% CI 1.31-1.60) but no significant difference in smoking, high cholesterol, and metabolic syndrome. CONCLUSIONS: Compared to the general population, the greater burden and dissimilar racial pattern of CVD risk factors in SMI underscore the need for CVD prevention programs targeting the SMI population.

Genetics of lipid traits and relationship to coronary artery disease.

Despite the critical importance of plasma lipoproteins in the development of atherosclerosis, varying degrees of evidence surround the causal associations of lipoproteins with coronary artery disease (CAD). These causal contributions can be assessed by employing genetic variants as unbiased proxies for lipid levels. A relatively large number of low-density lipoprotein cholesterol (LDL-C) variants strongly associate with CAD, confirming the causal impact of this lipoprotein on atherosclerosis. Although not as firmly established, genetic evidence supporting a causal role of triglycerides (TG) in CAD is growing. Conversely, high-density lipoprotein cholesterol (HDL-C) variants not associated with LDL-C or TG have not yet been shown to be convincingly associated with CAD, raising questions about the causality of HDL-C in atherosclerosis. Finally, genetic variants at the LPA locus associated with lipoprotein(a) [Lp(a)] are decisively linked to CAD, indicating a causal role for Lp(a). Translational investigation of CAD-associated lipid variants may identify novel regulatory pathways with therapeutic potential to alter CAD risk.