DNA mismatch repair in cancer Baretti, Marina; Le, Dung T.
Pharmacology & therapeutics (Oxford),
September 2018, 2018-09-00, 20180901, Letnik:
189
Journal Article
Recenzirano
Microsatellite instability (MSI) refers to the hypermutator phenotype secondary to frequent polymorphism in short repetitive DNA sequences and single nucleotide substitution, as consequence of DNA ...mismatch repair (MMR) deficiency. MSI secondary to germline mutation in DNA MMR proteins is the molecular fingerprint of Lynch syndrome (LS), while epigenetic inactivation of these genes is more commonly found in sporadic MSI tumors. MSI occurs at different frequencies across malignancies, although original methods to assess MSI or MMR deficiency have been developed mostly in LS related cancers. Here we will discuss the current methods to detect MSI/MMR deficiency with a focus of new tools which are emerging as highly sensitive detector for MSI across multiple tumor types.
Due to high frequencies of non-synonymous mutations, the presence of frameshift-mutated neoantigens, which can trigger a more robust and long-lasting immune response and strong TIL infiltration with tumor eradication, MSI has emerged as an important predictor of sensitivity for immunotherapy-based strategies, as showed by the recent FDA's first histology agnostic-accelerated approval to immune checkpoint inhibitors for refractory, adult and pediatric, MMR deficient (dMMR) or MSI high (MSI-H) tumors. Moreover, it is known that MSI status may predict cancer response/resistance to certain chemotherapies.
Here we will describe the complex interplay between the genetic and clinical-pathological features of MSI/dMMR tumors and the cancer immunotherapy, with a focus on the predictive and prognostic role of MMR status for immune checkpoint inhibitors (ICIs) and providing some suggestions on how to conceive better predictive markers for immunotherapy in the next future.
Initial results by Le and colleagues, which were published in the June 25, 2015 issue of the New England Journal of Medicine, report significant responses of cancers with microsatellite instability ...(MSI) to anti-PD-1 inhibitors in patients who failed conventional therapy. This finding fits into a broader body of research associating somatic hypermutation and neoepitope formation with response to immunotherapy, with the added benefit of relying on a simple, widely used diagnostic test. This review surveys the pathogenesis and prognostic value of MSI, diagnostic guidelines for detecting it, and the frequency of MSI across tumors, with the goal of providing a reference for its use as a biomarker for PD-1 blockade. MSI usually arises from either germline mutations in components of the mismatch repair (MMR) machinery (MSH2, MSH6, MLH1, PMS2) in patients with Lynch syndrome or somatic hypermethylation of the MLH1 promoter. The result is a cancer with a 10- to 100-fold increase in mutations, associated in the colon with poor differentiation, an intense lymphocytic infiltrate, and a superior prognosis. Diagnostic approaches have evolved since the early 1990s, from relying exclusively on clinical criteria to incorporating pathologic features, PCR-based MSI testing, and immunohistochemistry for loss of MMR component expression. Tumor types can be grouped into categories based on the frequency of MSI, from colorectal (20%) and endometrial (22%-33%) to cervical (8%) and esophageal (7%) to skin and breast cancers (0%-2%). If initial results are validated, MSI testing could have an expanded role as a tool in the armamentarium of precision medicine.
Antibiotic resistance (ABR) is an increasing burden for global health. The prevalence of ABR in Southeast Asia is among the highest worldwide, especially in relation to hospital-acquired infections ...(HAI) in intensive care units (ICU). However, little is known about morbidity and mortality attributable to ABR in neonates.
This study aimed to assess mortality and the length of hospitalization attributable to ABR in gram-negative bacteria (GNB) causing HAI in a Vietnamese neonatal ICU (NICU).
We conducted a prospective cohort study (n = 296) in a NICU in Hanoi, Vietnam, from March 2016 to October 2017. Patients isolated with HAI caused by GNB were included. The exposure was resistance to multiple antibiotic classes, the two outcomes were mortality and length of hospital stay (LOS). Data were analysed using two regression models, controlling for confounders and effect modifiers such as co-morbidities, time at risk, severity of illness, sex, age, and birthweight.
The overall case fatality rate was 44.3% and the 30 days mortality rate after infection was 31.8%. For every additional resistance to an antibiotic class, the odds of a fatal outcome increased by 27% and LOS increased by 2.1 days. These results were statistically significant (p < 0.05).
ABR was identified as a significant risk factor for adverse outcomes in neonates with HAI. These findings are generally in line with previous research in children and adults. However, heterogeneous study designs, the neglect of important confounders and varying definitions of ABR impair the validity, reliability, and comparability of results.
Mesothelin is a tumor antigen that is highly expressed in many human cancers, including malignant mesothelioma and pancreatic, ovarian, and lung adenocarcinomas. It is an attractive target for cancer ...immunotherapy because its normal expression is limited to mesothelial cells, which are dispensable. Several antibody-based therapeutic agents as well as vaccine and T-cell therapies directed at mesothelin are undergoing clinical evaluation. These include antimesothelin immunotoxins (SS1P, RG7787/LMB-100), chimeric antimesothelin antibody (amatuximab), mesothelin-directed antibody drug conjugates (anetumab ravtansine, DMOT4039A, BMS-986148), live attenuated Listeria monocytogenes-expressing mesothelin (CRS-207, JNJ-64041757), and chimeric antigen receptor T-cell therapies. Two antimesothelin agents are currently in multicenter clinical registration trials for malignant mesothelioma: amatuximab in the first-line setting and anetumab ravtansine as second-line therapy. Phase II randomized clinical trials of CRS-207 as a boosting agent and in combination with immune checkpoint inhibition for pancreatic cancer are nearing completion. These ongoing studies will define the utility of mesothelin immunotherapy for treating cancer.
Summary Background Few effective treatments exist for patients with advanced urothelial carcinoma that has progressed after platinum-based chemotherapy. We assessed the activity and safety of ...nivolumab in patients with locally advanced or metastatic urothelial carcinoma whose disease progressed after previous platinum-based chemotherapy. Methods In this phase 1/2, multicentre, open-label study, we enrolled patients (age ≥18 years) with urothelial carcinoma of the renal pelvis, ureter, bladder, or urethra at 16 sites in Finland, Germany, Spain, the UK, and the USA. Patients were not selected by PD-L1 expression, but tumour PD-L1 membrane expression was assessed retrospectively. Patients received nivolumab 3 mg/kg intravenously every 2 weeks until disease progression or treatment discontinuation because of unacceptable toxicity or other protocol-defined reasons, whichever occurred later. The primary endpoint was objective response by investigator assessment. All patients who received at least one dose of the study drug were included in the analyses. We report an interim analysis of this ongoing trial. CheckMate 032 is registered with ClinicalTrials.gov , NCT01928394. Findings Between June 5, 2014, and April 24, 2015, 86 patients with metastatic urothelial carcinoma were enrolled in the nivolumab monotherapy group and 78 received at least one dose of treatment. At data cutoff (March 24, 2016), the minimum follow-up was 9 months (median 15·2 months, IQR 12·9–16·8). A confirmed investigator-assessed objective response was achieved in 19 (24·4%, 95% CI 15·3–35·4) of 78 patients. Grade 3–4 treatment-related adverse events occurred in 17 (22%) of 78 patients; the most common were elevated lipase (four 5%), elevated amylase (three 4%), and fatigue, maculopapular rash, dyspnoea, decreased lymphocyte count, and decreased neutrophil count (two 3% each). Serious adverse events were reported in 36 (46%) of 78 patients and eight (10%) had a serious adverse event judged to be treatment related. Two (3%) of 78 patients discontinued because of treatment-related adverse events (grade 4 pneumonitis and grade 4 thrombocytopenia) and subsequently died. Interpretation Nivolumab monotherapy was associated with a substantial and durable clinical response and a manageable safety profile in previously treated patients with locally advanced or metastatic urothelial carcinoma. These data support further investigation of nivolumab monotherapy in advanced urothelial carcinoma. Funding Bristol-Myers Squibb.
A complex DNA repair machinery has evolved to protect genomic integrity in the face of a myriad of DNA damage sources. When DNA repair fails, this damage can lead to carcinogenesis and tumor genomic ...instability. Indeed, many heritable cancer predisposition syndromes are attributable to germline defects in DNA repair pathways. On the other hand, these defects may also portend particular vulnerabilities of the cancer and may be exploited therapeutically. Most recently this has been demonstrated in the case of mismatch repair-deficient cancers, in which the immune checkpoint inhibitors have been demonstrated to be highly active. This observation has paved the way for further research investigating other sources of genomic instability that may serve as biomarkers to select patients for immunotherapy.
More than 1.6 million new cases of cancer will be diagnosed in the U.S. in 2016, resulting in more than 500,000 deaths. Although chemotherapy has been the mainstay of treatment in advanced cancers, ...immunotherapy development, particularly with PD‐1 inhibitors, has changed the face of treatment for a number of tumor types. One example is the subset of tumors characterized by mismatch repair deficiency and microsatellite instability that are highly sensitive to PD‐1 blockade. Hereditary forms of cancer have been noted for more than a century, but the molecular changes underlying mismatch repair‐deficient tumors and subsequent microsatellite unstable tumors was not known until the early 1990s. In this review article, we discuss the history and pathophysiology of mismatch repair, the process of testing for mismatch repair deficiency and microsatellite instability, and the role of immunotherapy in this subset of cancers.
Implications for Practice:
Mismatch repair deficiency has contributed to our understanding of carcinogenesis for the past 2 decades and now identifies a subgroup of traditionally chemotherapy‐insensitive solid tumors as sensitive to PD‐1 blockade. This article seeks to educate oncologists regarding the nature of mismatch repair deficiency, its impact in multiple tumor types, and its implications for predicting the responsiveness of solid tumors to immune checkpoint blockade.
摘要
2016年美国共确诊160万余例新发肿瘤, 这些肿瘤造成50万余例死亡。尽管化疗已成为晚期癌症治疗的支柱, 但免疫治疗特别是PD‐1抑制剂的发展, 已改变了多个瘤种治疗的面貌。其中一个范例是, 以错配修复缺陷和微卫星不稳定性为特点的肿瘤亚型对PD‐1阻滞高度敏感。肿瘤的遗传类型在一个多世纪前已为人所知, 但错配修复缺陷性肿瘤及随后的微卫星不稳定性肿瘤之下隐含的分子学改变直到1990年代早期才被人熟知。本篇综述讨论了错配修复的历史和病理生理学、错配修复缺陷检查的流程及免疫治疗在该亚型肿瘤中的作用。The Oncologist 2016; 21: 1200–1211
对临床实践的提示:在过去20年间, 错配修复缺陷加深了我们对致癌机制的理解, 并鉴定出了一类对传统化疗不敏感但对PD‐1阻滞高度敏感的实体瘤亚型。本文旨在帮助肿瘤科医生学习有关错配修复缺陷的性质、其对众多类型肿瘤的影响, 及其在预测实体瘤对免疫检查点阻滞治疗反应上的临床意义。
In this review article, the history and pathophysiology of mismatch repair, the process of testing for mismatch repair deficiency and microsatellite instability, and the role of immunotherapy in a number of tumor types, including those that are highly sensitive to PD‐1 blockade, are discussed.
KEYNOTE-164 (NCT02460198) evaluated the antitumor activity of pembrolizumab in previously treated, metastatic, microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) colorectal cancer ...(CRC).
This phase II open-label study involved 128 centers worldwide. Eligible patients were age ≥ 18 years and had metastatic MSI-H/dMMR CRC treated with ≥ 2 prior lines of standard therapy, including fluoropyrimidine, oxaliplatin, and irinotecan with or without anti-vascular endothelial growth factor/epidermal growth factor receptor monoclonal antibody (cohort A) or ≥ 1 prior line of therapy (cohort B). MSI-H/dMMR status was assessed locally. Patients received pembrolizumab 200 mg every 3 weeks for up to 2 years until progression, unacceptable toxicity, or withdrawal. The primary end point was objective response rate by RECIST version 1.1 by independent central review. Secondary end points were duration of response, progression-free survival (PFS), overall survival, safety, and tolerability.
A total of 124 patients with MSI-H/dMMR CRC (61 in cohort A, 63 in cohort B) enrolled. At data cutoff, median follow-up was 31.3 months (range, 0.2-35.6 months) for cohort A and 24.2 months (range, 0.1-27.1 months) for cohort B. Objective response rate was 33% (95% CI, 21% to 46%) and 33% (95% CI, 22% to 46%), respectively, with median duration of response not reached in either cohort. Median PFS was 2.3 months (95% CI, 2.1 to 8.1 months) and 4.1 months (95% CI, 2.1 to 18.9 months). Median overall survival was 31.4 months (95% CI, 21.4 months to not reached) and not reached (95% CI, 19.2 months to not reached). Treatment-related grade 3-4 adverse events occurred in 10 patients (16%) in cohort A and 8 (13%) in cohort B, with the most common occurring in ≥ 2 patients being pancreatitis, fatigue, increased alanine aminotransferase, and increased lipase (2 patients each; 3%) in cohort A.
Pembrolizumab is effective with a manageable safety profile in patients with MSI-H/dMMR CRC.
Summary Background Expression of PD-L1 has been shown to be upregulated in some patients with gastric cancer. As part of the phase 1b KEYNOTE-012 study, we aimed to assess the safety and activity of ...the anti-PD-1 antibody pembrolizumab in patients with PD-L1-positive recurrent or metastatic adenocarcinoma of the stomach or gastro-oesophageal junction. Methods This study was a multicentre, open-label, phase 1b trial done at 13 cancer research centres in the USA, Israel, Japan, South Korea, and Taiwan. We enrolled patients with PD-L1-positive recurrent or metastatic adenocarcinoma of the stomach or gastro-oesophageal junction. Patients received intravenous pembrolizumab at 10 mg/kg once every 2 weeks for 24 months or until progression or unacceptable toxic effects occurred. Response was assessed every 8 weeks in accordance with Response Evaluation Criteria in Solid Tumors version 1.1. The primary objectives were safety in patients who received at least one dose of pembrolizumab and the proportion of patients achieving overall responses in patients who received at least one pembrolizumab dose and who either had a post-baseline scan or who discontinued therapy because of clinical disease progression or a treatment-related adverse event before the first post-baseline scan. The study is registered with ClinicalTrials.gov , number NCT01848834 , and is ongoing but no longer enrolling patients. Findings From Oct 23, 2013, to May 5, 2014, 39 patients were enrolled. 36 were evaluable for response by central assessment. Eight (22%, 95% CI 10–39) patients were judged to have had an overall response at central review; all responses were partial. All 39 patients were included in the safety analyses. Five (13%) patients had a total of six grade 3 or 4 treatment-related adverse events, consisting of two cases of grade 3 fatigue, one case each of grade 3 pemphigoid, grade 3 hypothyroidism, and grade 3 peripheral sensory neuropathy, and one case of grade 4 pneumonitis. No treatment-related deaths occurred. Interpretation In this population of patients with recurrent or metastatic PD-L1-positive gastric cancer, pembrolizumab had a manageable toxicity profile and promising antitumour activity, warranting further study in phase 2 and 3 trials. Funding Merck & Co.
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