Tag: Colon Cancer

SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 140,250 new cases of CRC will be diagnosed in the United States in 2018 and about 50,630 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 21 (4.7%).

Even though the incidence of Colorectal cancer (CRC) in the United States has been rapidly declining overall, primarily driven by screening, the incidence however has been increasing among adults younger than age 50 years. Currently, genetic testing is recommended in patients with polyposis phenotypes, strong family histories, and those whose tumors demonstrate MicroSatellite Instability (MSI) or fail to stain for MisMatch Repair (MMR) gene proteins by immunohistochemistry. Whether patients younger than 50 years of age with CRC, should be tested with a broad multigene panel to detect additional genetic abnormalities, has remained unclear.

The authors conducted this study to ascertain the proportion of young CRC cases associated with genetic predisposition. In this retrospective study, 430 individuals diagnosed with CRC at an age younger than 50 years were evaluated by the clinical genetics service at a single tertiary care cancer center from 1998 through 2015. Data collection included patient histories, tumor phenotypes, and results of germline DNA sequencing. If information was uninformative, germline DNA samples were resequenced using a research-based Next-Generation Sequencing multigene panel. The primary outcome was identification of a pathogenic germline mutation associated with cancer predisposition.

The researchers noted that 26% of young CRC cases had a first-degree relative with CRC and 10% had tumors with histologic evidence for MisMatch Repair (MMR) deficiency and 6% had polyposis phenotype. Germline mutations associated with a hereditary cancer syndrome were identified in 79 patients (18%) following clinically driven germline sequencing, and Next-Generation Sequence analysis using a multigene panel detected actionable germline variants in 6 patients (5%) with uninformative clinical evaluations. Lynch syndrome was identified in 56 patients (14%) of the entire cohort, Familial Adenomatous Polyposis in 2%, MUTYH in 2%, and SMAD4 was mutated in 2 patients, BRCA1 in one, TP53 in one, and CHEK2 in one. Only 51% of the patients with germline mutations associated with a hereditary cancer syndrome gave a family history of CRC diagnosis in a first-degree relative.

The authors concluded that 20% of patients diagnosed with CRC at age younger than 50 years carry a germline mutation associated with cancer, and half of these patients do not have clinical histories typically associated with the identified syndrome. Germline testing with Next-Generation Sequencing multigene cancer panels should therefore be considered for all young patients with CRC. Germline Genetic Features of Young Individuals with Colorectal Cancer. Stoffel EM, Koeppe E, Everett J, et al. Gastroenterology 2017 Nov 13; [e-pub]. (http://dx.doi.org/10.1053/j.gastro.2017.11.004)

SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 135,430 new cases of ColoRectal Cancer will be diagnosed in the United States in 2017 and over 50,260 patients are expected to die of the disease. The lifetime risk of developing ColoRectal Cancer (CRC) is about 1 in 20 (5%). The Mitogen-Activated Protein Kinase pathway (MAPK pathway) is an important signaling pathway which enables the cell to respond to external stimuli. This pathway plays a dual role, regulating cytokine production and participating in cytokine dependent signaling cascade. The MAPK pathway of interest is the RAS-RAF-MEK-ERK pathway. The RAF family of kinases includes ARAF, BRAF and CRAF signaling molecules. BRAF is a very important intermediary of the RAS-RAF-MEK-ERK pathway. The BRAF V600 mutations results in constitutive activation of the MAP kinase pathway. Inhibiting BRAF can transiently reduce MAP kinase signaling. However, this can result in feedback upregulation of EGFR signaling pathway, which can then reactivate the MAP kinase pathway. This aberrant signaling can be blocked by dual inhibition of both BRAF and EGFR.

The initial evaluation of patients with metastatic ColoRectal Cancer (CRC) includes Molecular diagnostic testing including testing for extended RAS (RAt Sarcoma) and RAF (Rapid Accelerated Fibrosarcoma) mutations. Next-Generation Sequencing (NGS) allows expanded mutational testing for RAS which includes KRAS, NRAS and HRAS. RAS mutations are predictive of resistance to EGFR targeted therapy. NGS is able to detect approximately 20% of the patients who were originally classified as having KRAS Wild-Type (WT) metastatic CRC but were subsequently found to have KRAS or NRAS mutations, thus predicting resistance to EGFR targeted therapy.

Approximately 10% of CRCs detected by NGS harbor BRAF V600E mutation and the detection of BRAF V600E mutation is recognized as a marker of poor prognosis in patients with metastatic CRC. RAS and BRAF V600E mutations occur in a mutually exclusive fashion. Patients with this molecular subtype of CRC are older than age 60 years, more frequently female, have a right-sided tumor with high-grade histology, and often have MicroSatellite Instability (MSI-H). These patients often have peritoneal metastasis and despite chemotherapeutic intervention have a shortened overall survival. These tumors have limited response to EGFR targeted therapy and current guidelines recommend against the use of anti-EGFR antibodies in BRAF V600E-mutated mCRC.

The significance of non-V600 BRAF mutations detected by NGS however has remained unclear. The authors in this multicenter, retrospective cohort study, pooled NGS data from three large US reference laboratories and attempted to establish the clinical characteristics of patients with non-V600 BRAF mutations. Using NGS databases from the Mayo Clinic (MC), The University of Texas MD Anderson Cancer Center (MDACC), and Foundation Medicine (FM) from 2013-2016, patients with non-V600 BRAF mutations from these three institutions were identified and pooled for the primary analysis. Out of a total of 9,643 patients with metastatic CRC who underwent NGS testing, 208 patients with non-V600 BRAF mutations and 133 patients with V600E BRAF mutations, were identified. This study also included 249 patients with Wild-Type BRAF metastatic CRC, for comparative analysis , identified from the same NGS database, from the Mayo Clinic.

It was noted that the prevalence rate of any BRAF mutation was 10%, non-V600 BRAF mutations occurred in 2.2% of all patients tested and accounted for 22% of all BRAF mutations identified. Of particular clinical interest, compared with those with V600E BRAF mutations, patients harboring a non-V600 BRAF mutation were significantly younger, more frequently male, and presented with left-sided MicroSatellite-Stable (MSS) tumors. Additionally, non-V600 BRAF-mutated tumors were mostly low grade and did not often metastasize to the peritoneum. The median Overall Survival was significantly longer in patients with non-V600 BRAF-mutant metastatic CRC compared with those with both V600E BRAF-mutant and Wild-Type BRAF metastatic CRC (60.7 vs 11.4 vs 43.0 months, respectively; P<0.001) and in multivariable analysis, non-V600 BRAF mutation was independently associated with improved Overall Survival (HR=0.18; P<0.001).

This study concluded that Non-V600 BRAF mutations in metastatic ColoRectal Cancer (CRC), which accounted for 22% of all BRAF mutations identified by NGS, is a clinically distinct subtype of CRC, with an excellent prognosis and aggressive chemotherapeutic intervention could be avoided for this group of patients. Non-V600 BRAF Mutations Define a Clinically Distinct Molecular Subtype of Metastatic Colorectal Cancer. Jones JC, Renfro LA, Al-Shamsi HO, et al. J Clin Oncol 2017;35: 2624-2630

SUMMARY: ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 135,430 new cases of ColoRectal Cancer will be diagnosed in the United States in 2017 and over 50,260 patients are expected to die of the disease. The lifetime risk of developing ColoRectal Cancer is about 1 in 20 (5%).

Even though the incidence of Colorectal cancer (CRC) in the United States has been rapidly declining overall, primarily driven by screening, the incidence however has been increasing among adults younger than age 50 years. To understand this trend, the authors in this publication conducted a retrospective cohort study among 490,305 patients aged 20 years and older, who were diagnosed with colorectal cancer between 1974 and 2013, using data from nine oldest Surveillance, Epidemiology, and End Results (SEER) registries. The SEER program is considered the gold standard for cancer registration worldwide because of the high quality of data and is the only source for historical population-based cancer incidence in the United States. This study included people born in 1890 thru 1990. Colorectal cancer incidence trends were analyzed by 5-year age group and birth cohorts.

The authors noted variations in CRC incidence patterns by age, tumor location in the colon, calendar period, and birth cohort. The study found that in adults aged 20-39 years, after a decrease in the previous decade, colon cancer incidence rates increased by 1.0-2.4% per year since the mid-1980s thru 2013. For adults aged 40-54 years during the same period, colon cancer incidence rates increased by 0.5-1.3%. Conversely, from the mid-1980s thru 2013, colon cancer rates declined in adults aged 55 years and older. In adults younger than age 50 years, there was an increasing trend for tumors to be confined to the distal colon, with the exception of adults aged 40-49 years, among whom there was an also an increasing trend for proximal tumors.

The incidence of rectal cancer has been increasing even longer and faster than colon cancer, rising about 3.2% per year from 1974-2013 in adults aged 20-29 years and from 1980-2013 in adults aged 30-39 years. In adults aged 40 to 54, rectal cancer rates increased by 2.3% per year from the 1990s to 2013. Again, rectal cancer rates declined, in adults aged 55 years and older, from 1974-2013.

Compared with adults born around 1950, those born around 1990 had double the risk of colon cancer and quadruple the risk of rectal cancer. The increase in the incidence of CRC in young adults has been attributed to western style, high carbohydrate, high fat, low fiber diet which can initiate inflammation and proliferation in the colonic mucosa within two weeks. Other lifestyle factors associated with CRC include obesity, high consumption of processed meat and alcohol, low levels of physical activity and cigarette smoking. Further, young patients are 58% more likely than older patients to be diagnosed with advanced versus localized stage CRC, due to delayed follow-up of symptoms, sometimes for years and these young adults are less likely to be screened for colon cancer, despite their symptoms.

The authors concluded that there is an increasing rate of colon and rectal cancer among young and middle-aged adults in the US and compared with adults born around 1950 when the risk was at the lowest, those born around 1990 have double the risk of colon cancer and quadruple the risk of rectal cancer. They added that as nearly a third of rectal cancer patients are younger than age 55 years, screening initiation before age 50 years should be considered. Colorectal Cancer Incidence Patterns in the United States, 1974-2013. Siegel RL, Fedewa SA, Anderson WF, et al. J Natl Cancer Inst. 2017 Aug 1;109(8). doi: 10.1093/jnci/djw322.

SUMMARY: The FDA on July 31, 2017, granted accelerated approval to OPDIVO® (Nivolumab) for the treatment of patients 12 years and older with MisMatch Repair deficient (dMMR) and MicroSatellite Instability-High (MSI-H) metastatic ColoRectal Cancer, that has progressed following treatment with a Fluoropyrimidine, Oxaliplatin, and Irinotecan. ColoRectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 135,430 new cases of ColoRectal Cancer will be diagnosed in the United States in 2017 and over 50,260 patients are expected to die of the disease. The lifetime risk of developing ColoRectal Cancer is about 1 in 20 (5%).

The DNA MisMatchRepair (MMR) system is responsible for molecular surveillance and works as an editing tool that identifies errors within the microsatellite regions of DNA and removes them. Defective MMR system leads to MSI (Micro Satellite Instability) and hypermutation, triggering an enhanced antitumor immune response. MSI (Micro Satellite Instability) is therefore a hallmark of defective/deficient DNA MisMatchRepair (MMR) system and occurs in 15% of all colorectal cancers. Defective MisMatchRepair can be a sporadic or heritable event. Approximately 65% of the MSI tumors are sporadic and when sporadic, the DNA MisMatchRepair gene is MLH1. Defective MisMatchRepair can also manifest as a germline mutation occurring in 1 of the 4 MisMatchRepair genes which include MLH1, MSH2, MSH6, PMS2. This produces Lynch Syndrome (Hereditary Nonpolyposis Colorectal Carcinoma – HNPCC), an Autosomal Dominant disorder and is the most common form of hereditary colon cancer, accounting for 35% of the MSI colorectal cancers. MSI tumors tend to have better outcomes and this has been attributed to the abundance of tumor infiltrating lymphocytes in these tumors from increase immunogenicity. These tumors therefore are susceptible to PD-1 blockade with immune checkpoint inhibitors.

MSI (Micro Satellite Instability) testing is performed using a PCR based assay and MSI-High refers to instability at 2 or more of the 5 mononucleotide repeat markers and MSI-Low refers to instability at 1 of the 5 markers. Patients are considered Micro Satellite Stable (MSS) if no instability occurs. MSI-L and MSS are grouped together because MSI-L tumors are uncommon and behave similar to MSS tumors. Tumors considered MSI-H have deficiency of one or more of the DNA MisMatchRepair genes. MMR gene deficiency can be detected by ImmunoHistoChemistry (IHC). MLH1 gene is often lost in association with PMS2. NCCN Guidelines recommend MMR or MSI testing for all patients with a history of Colon or Rectal cancer.

This latest approval for OPDIVO® was based on results from the phase II CheckMate-142 trial, which is a multicenter, open label, single arm study, involving 53 patients with dMMR or MSI-H metastatic ColoRectal Cancer, who had disease progression during, after, or were intolerant to prior treatment with Fluoropyrimidine, Oxaliplatin, and Irinotecan-based chemotherapy. These 53 patients were a subset of the 74 patients who received at least one prior treatment regimen containing a Fluoropyrimidine with Oxaliplatin or Irinotecan for metastatic disease. All patients received OPDIVO® 3 mg/kg by intravenous infusion every 2 weeks until unacceptable toxicity or radiographic progression. The median age was 53 years. The Primary endpoint was Objective Response Rate (ORR) and exploratory endpoints included Safety, Progression Free Survival, Overall Survival and efficacy in biomarker-defined populations.

The Objective Response Rate as assessed by independent radiographic review committee, was 28% in the 53 patients who received prior Fluoropyrimidine, Oxaliplatin, and Irinotecan and responses lasted 6 months or more for the 67% of the responding patients. There was 1 complete response and 14 partial responses. The ORR was 32% among the 74 patients in the overall population. These responses and Clinical Benefit was seen regardless of PD-L1 expression, BRAF mutation status, KRAS mutation status, and clinical history of Lynch Syndrome. The most common adverse reactions related to OPDIVO® included fatigue, asthenia, rash, fever, nausea, diarrhea, musculoskeletal pain, cough and dyspnea.

The authors concluded that patients with metastatic ColoRectal Cancer who have dMMR or MSI-H tumors are less likely to respond to conventional chemotherapy and OPDIVO® demonstrated durable responses and disease control in this heavily pretreated patient group. Nivolumab in patients with DNA mismatch repair deficient/microsatellite instability high metastatic colorectal cancer: Update from CheckMate 142. Overman MJ, Lonardi S, Leone F, et al. J Clin Oncol 35, 2017 (suppl 4S; abstract 519).