Direct mutational analysis in a family with hereditary non-polyposis colorectal cancer

The Cancer Immunotherapy Biomarker Testing Landscape

CONTEXT.—

Cancer immunotherapy provides unprecedented rates of durable clinical benefit to late-stage cancer patients across many tumor types, but there remains a critical need for biomarkers to accurately predict clinical response. Although some cancer immunotherapy tests are associated with approved therapies and considered validated, other biomarkers are still emerging and at various states of clinical and translational exploration.

OBJECTIVE.—

To provide pathologists with a current and practical update on the evolving field of cancer immunotherapy testing. The scientific background, clinical data, and testing methodology for the following cancer immunotherapy biomarkers are reviewed: programmed death ligand-1 (PD-L1), mismatch repair, microsatellite instability, tumor mutational burden, polymerase δ and ε mutations, cancer neoantigens, tumor-infiltrating lymphocytes, transcriptional signatures of immune responsiveness, cancer immunotherapy resistance biomarkers, and the microbiome.

DATA SOURCES.—

Selected scientific publications and clinical trial data representing the current field of cancer immunotherapy.

CONCLUSIONS.—

The cancer immunotherapy field, including the use of biomarker testing to predict patient response, is still in evolution. PD-L1, mismatch repair, and microsatellite instability testing are helping to guide the use of US Food and Drug Administration-approved therapies, but there remains a need for better predictors of response and resistance. Several categories of tumor and patient characteristics underlying immune responsiveness are emerging and may represent the next generation of cancer immunotherapy predictive biomarkers. Pathologists have important roles and responsibilities as the field of cancer immunotherapy continues to develop, including leadership of translational studies, exploration of novel biomarkers, and the accurate and timely implementation of newly approved and validated companion diagnostics.

The impact of predictive genetic testing for hereditary nonpolyposis colorectal cancer: three years after testing

BACKGROUND

To fully assess predictive genetic testing programs, it is important to assess outcomes over periods of time longer than the 1-year follow-up reported in the literature.

METHODS

We conducted a 3-year study of individuals who received predictive genetic test results for previously identified familial mutations in Australian Familial Cancer Clinics. Questionnaires were sent before attendance at the familial cancer clinic and 2 weeks, 4 months, 1 year, and 3 years after receiving test results. Psychological measures were included each time, and preventive behaviors were assessed at baseline and 1 and 3 years. Psychological measures were adjusted for age, gender, and baseline score.

RESULTS

The study included 19 carriers and 54 non-carriers. We previously reported an increase in mean cancer-specific distress in carriers at 2 weeks with a return to baseline levels by 12 months. This level was maintained until 3 years. Non-carriers showed sustained decreases after testing with a significantly lower level at 3 years compared with baseline (P < 0.001). These scores tended to be lower than those for carriers at 3 years (P = 0.09). Mean depression and anxiety scores did not differ between carriers and non-carriers and, at 3 years, were similar to baseline. All carriers and 7% of non-carriers had had a colonoscopy by 3 years, and 69% of 13 female carriers had undergone gynecological screening in the previous 2 years. Prophylactic surgery was rare.

CONCLUSION

This report of long-term data indicates appropriate screening and improved psychological measures for non-carriers with no evidence of undue psychological distress in carriers of hereditary nonpolyposis colorectal cancer mutations.

The molecular and genetic basis of colon cancer

Remarkable progress has been accomplished in understanding the molecular basis of genetic colon cancer syndromes including FAP and HNPCC, and their variants; of sporadic colon cancer; and of the rare hamartomatous polyp syndromes. This molecular progress now has to be translated into clinical progress in molecular diagnosis, and in pharmacologic therapy for colonic polyps and cancers. It is hoped that such progress will impact on the frequency and mortality of this very common and frequently fatal cancer.

Hereditary non-polyposis colorectal cancer syndrome

Hereditary non-polyposis colorectal cancer (HNPCC) syndrome may account for up to 4% of the total colorectal cancer burden in our community. It is assuming an increasingly important role, both as a clinical management issue and as a model for the application of laboratory and clinical genetic services in cancer detection and prevention. Recent developments in the understanding of the molecular biology of the condition have underpinned recommendations for consideration of genetic testing for DNA mismatch repair gene mutation, recommendations that may have far-reaching implications in terms of the numbers of patients offered genetic testing and for associated costs (both financial and psychological). The aim of this review is to highlight the clinical, pathologic and molecular biologic features of HNPCC that underlie the clinical management of affected index patients and their at-risk family members.

Familial and hereditary non-polyposis colorectal cancer: issues relevant for surgical practice

About 15% of patients with colorectal cancer report a family history of this disease. An estimated 1%-5% of patients have hereditary non-polyposis colorectal cancer (HNPCC). Recently, DNA mismatch repair genes associated with this syndrome were identified. For about 50% of families in which HNPCC occurs, DNA-based diagnosis and presymptomatic DNA testing are now feasible. Diagnosis of a hereditary tumour syndrome is relevant for both the patient with cancer and his or her close relatives. The complexities of family studies warrant the forming of a multidisciplinary team which may choose to work within a specialized cancer family clinic.

Growth control mechanisms in normal and transformed intestinal cells

The cells populating the intestinal crypts are part of a dynamic tissue system which involves the self-renewal of stem cells, a commitment to proliferation, lineage-specific differentiation, movement and cell death. Our knowledge of these processes is limited, but even now there are important clues to the nature of the regulatory systems, and these clues are leading to a better understanding of intestinal cancers. Few intestinal-specific markers have been described; however, homeobox genes such as cdx-2 appear to be important for morphogenic events in the intestine. There are several intestinal cell surface proteins such as the A33 antigen which have been used as targets for immunotherapy. Many regulatory cytokines (lymphokines or growth factors) influence intestinal development: enteroglucagon, IL-2, FGF, EGF family members. In conjunction with cell-cell contact and/or ECM, these cytokines lead to specific differentiation signals. Although the tissue distribution of mitogens such as EGF, TGF alpha, amphiregulin, betacellulin, HB-EGF and cripto have been studied in detail, the physiological roles of these proteins have been difficult to determine. Clearly, these mitogens and the corresponding receptors are involved in the maintenance and progression of the tumorigenic state. The interactions between mitogenic, tumour suppressor and oncogenic systems are complex, but the tumorigenic effects of multiple lesions in intestinal carcinomas involve synergistic actions from lesions in these different systems. Together, the truncation of apc and activation of the ras oncogene are sufficient to induce colon tumorigenesis. If we are to improve cancer therapy, it is imperative that we discover the biological significance of these interactions, in particular the effects on cell division, movement and survival.

Diagnosis of hereditary non-polyposis colorectal cancer

The term hereditary non-polyposis colorectal cancer (HNPCC) was introduced initially to encompass autosomal dominant syndromes predisposing to colorectal cancer other than the polyposes. The term is a poor descriptor and is often applied to families on the basis of inadequate information. It is suggested that 'hereditary mismatch repair deficiency syndrome' (HMRDS) should replace the term HNPCC for describing the specific autosomal dominant condition which predisposes to cancer displaying the mutator phenotype. Population-based studies have shown that HMRDS probably accounts for no more than 2% of bowel cancer. A working diagnosis of HMRDS can be made on the basis of clinical, pathological and molecular characteristics. The histopathologist has an important role to play in the recognition and diagnosis of HMRDS. The characteristic morphology of colorectal cancer in HMRDS is reviewed and the diagnostic utility of 'field changes' and adenomas is discussed critically.

Incidence of hereditary nonpolyposis colorectal cancer and the feasibility of molecular screening for the disease

BACKGROUND

Genetic disorders that predispose people to colorectal cancer include the polyposis syndromes and hereditary nonpolyposis colorectal cancer. In contrast to the polyposis syndromes, hereditary nonpolyposis colorectal cancer lacks distinctive clinical features. However, a germ-line mutation of DNA mismatch-repair genes is a characteristic molecular feature of the disease. Since clinical screening of carriers of such mutations can help prevent cancer, it is important to devise strategies applicable to molecular screening for this disease.

METHODS

We prospectively screened tumor specimens obtained from 509 consecutive patients with colorectal adenocarcinomas for DNA replication errors, which are characteristic of hereditary colorectal cancers. These replication errors were detected through microsatellite-marker analyses of tumor DNA. DNA from normal tissue from the patients with replication errors was screened for germ-line mutations of the mismatch-repair genes MLH1 and MSH2.

RESULTS

Among the 509 patients, 63 (12 percent) had replication errors. Specimens of normal tissue from 10 of these 63 patients had a germ-line mutation of MLH1 or MSH2. Of these 10 patients (2 percent of the 509 patients), 9 had a first-degree relative with endometrial or colorectal cancer, 7 were under 50 years of age, and 4 had had colorectal or endometrial cancer previously.

CONCLUSIONS

In this series of patients with colorectal cancer in Finland, at least 2 percent had hereditary nonpolyposis colorectal cancer. We recommend testing for replication errors in all patients with colorectal cancer who meet one or more of the following criteria: a family history of colorectal or endometrial cancer, an age of less than 50 years, and a history of multiple colorectal or endometrial cancers. Patients found to have replication errors should undergo further analysis for germ-line mutations in DNA mismatch-repair genes.

The genetics of colorectal cancer

This article reviews the genetic alterations that are thought to play a role in the development of sporadic and hereditary forms of colorectal cancer. It also highlights their potential utility in clinical practice, especially in the field of presymptomatic diagnostic testing for hereditary forms of colorectal cancer.

Mutations predisposing to hereditary nonpolyposis colorectal cancer

Since 1993 four genes have been identified that, when mutated, confer predisposition to a form of hereditary colon cancer (hereditary nonpolyposis colorectal cancer [HNPCC]). These genes belong to the Mut-related family of DNA mismatch repair genes whose protein products are responsible for the recognition and correction of errors that arise during DNA replication. Mutational inactivation of both copies of a DNA mismatch repair gene results in a profound repair defect demonstrable by biochemical assays, and in vivo this defect is presumed to lead to progressive accumulation of secondary mutations throughout the genome, some of which affect important growth-regulatory genes and, hence, give rise to cancer. To date, more than 70 different germline mutations have been detected in DNA mismatch repair genes and shown to be associated with HNPCC. Current evidence suggests that two genes, MSH2 and MLH1, account for roughly equal proportions of HNPCC kindreds, together being responsible for a majority of these families, but striking interethnic differences occur. Most mutations lead to truncated protein products. Mutation screening is quite demanding in HNPCC since, with a few exceptions, the predisposing mutations typically vary from kindred to kindred and individual mutations are scattered throughout the genes. Knowledge of the predisposing mutations allows genotype-phenotype correlations and forms the basis for further studies clarifying the pathogenesis of this disorder. In at-risk individuals, it allows predictive testing for cancer susceptibility and, consequently, appropriate clinical management of mutation carriers and noncarriers.

Hereditary nonpolyposis colorectal cancer (Lynch syndrome). An updated review

BACKGROUND

Hereditary nonpolyposis colorectal cancer (HNPCC) dates to Aldred Warthin's description of Family G a century ago. The phenotype features an excess of early onset colorectal carcinoma (CRC) with a propensity to involve the proximal colon, and a variety of extracolonic cancers, particularly carcinoma of the endometrium, ovary, stomach, small bowel, ureter, and renal pelvis. The recent discovery that HNPCC patients carry germline mutations in DNA mismatch repair genes has engendered great interest in the syndrome.

METHODS

This is a description of HNPCC based on the authors' experience with more than 170 families and a review of the world literature.

RESULTS

This review describes the genotypic and phenotypic features of HNPCC. The distinctive natural history of the syndrome is discussed in light of the recent discovery that ineffective DNA mismatch repair is the principal abnormality in affected individuals.

CONCLUSIONS

Clinical and molecular genetic knowledge about HNPCC is now available to physicians, and should enable them to provide highly targeted surveillance and management for patients with a high cancer risk. Genetic counseling can prove lifesaving. The study of HNPCC will likely contribute to knowledge about the causes and control of common forms of cancer in the general population.

Familial giant hyperplastic polyposis predisposing to colorectal cancer: a new hereditary bowel cancer syndrome

A mother and five of her ten offspring developed colonic cancers, the mother and one of the offspring being younger than 50 years of age at diagnosis. Despite fulfilling the Amsterdam criteria for hereditary non-polyposis colorectal cancer (HNPCC), several features pointed towards the possibility that this represented a different syndrome of familial cancer. Most notable was the presence of large, multiple hyperplastic polyps and mixed polyps in four of the subjects whose pathology was available for review. In addition, three of the four subjects had cancers that were negative for DNA replication errors (RER-). The subject with an RER+ cancer had a second RER+ cancer and three adenomas, one in contiguity with the second cancer. This subject also had multiple, large hyperplastic polyps, thereby combining hyperplastic polyposis and a proneness to multiple RER+ tumours. One of the hyperplastic polyps was also RER+. Two of five young asymptomatic descendants have been found to harbour multiple colorectal polyps. It is suggested that giant hyperplastic polyposis is a new familial syndrome predisposing to colorectal cancer.