Tag: Rectal Cancer

Association between Antibiotic Use and Colorectal Cancer

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SUMMARY: Colorectal Cancer (CRC) is the third leading cause of cancer-related deaths in men and women in the United States. The American Cancer Society estimates that approximately 149,500 new cases of CRC will be diagnosed in the United States in 2021 and about 52,980 patients will die of the disease. The lifetime risk of developing CRC is about 1 in 23.

Colorectal Cancer is a heterogeneous disease classified by its genetics, and even though the overall death rate has continued to drop, deaths from CRC among people younger than 55 years have increased 1% per year from 2008 to 2017, with 12% of CRC cases diagnosed in people under age 50. The proportion of the total number of patients diagnosed with CRC under the age of 50 yrs rose from 10% in 2004 to 12.2% in 2015 (P<0.0001). Younger adults presented with more advanced stage of disease (Stage III/IV) than those 50 yrs or older (51.6% versus 40.0% respectively). Based on these findings, the American Cancer Society in 2018 updated its guidelines to include a “qualified recommendation” to begin CRC screening at the age of 45 yrs. 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.

Preclinical studies have suggested that there is a very complex interplay of the immune system with the host’s microbiome and there may be a relationship between gut bacteria and immune response to cancer. The crosstalk between microbiota in the gut and the immune system allows for the tolerance of commensal bacteria (normal microflora) and oral food antigens and at the same time enables the immune system to recognize and attack opportunistic bacteria. Immune Checkpoint Inhibitors strongly rely on the influence of the host’s microbiome, and the gut microbial diversity enhances mucosal immunity, dendritic cell function, and antigen presentation.

There has been a significant increase in the global antibiotic consumption and colorectal cancer (CRC) rates in individuals aged less than 50 years since the late 1980s. Broad-spectrum antibiotics can potentially alter the bacterial composition and diversity of our gut microbiota, by killing the good bacteria. It has been postulated that this may influence CRC genesis in older patients and negate the benefits of immunotherapy and influence treatment outcomes. Quinolones and Sulfonamides/Trimethoprim antibiotics used to treat a wide range of infections have been associated with these right side colon cancers. It has been postulated that gut flora with more abundant Fusobacteria and Bacteroidetes may contribute to CRC development. The limited effect of Quinolones and Sulfonamides on anaerobic bacteria would therefore favor anaerobic bacteria such as Fusobacteria species and Bacteroidetes species, which may play a role in CRC development. The purpose of this analysis was to investigate antibiotics use in relation to subsequent CRC risk.

The authors conducted a matched case-control study using data from Swedish population from July 2005 to December 2016. Swedish personal Identity numbers enabled multiregister linkage and matching. The CRC cases identified using the Swedish Colorectal Cancer Register, were matched with controls from the Total Population Register. Data on antibiotics use were extracted from the Swedish Prescribed Drug Register, and other variables of interest were taken from the Swedish Inpatient Register and the Longitudinal Integration Database for Health Insurance and Labor Market Studies. All primary CRC cases were classified as proximal colon cancer (cecum, ascending colon, hepatic flexure, transverse colon, splenic flexure), distal colon cancer (descending, sigmoid colon), or rectal cancer (rectosigmoidal junction, rectum). Stages of CRC were categorized as early stage (Stage I-II) and late stage (Stage III-IV) based on TNM Classification. This nationwide, population-based study with a matched case-control design included 40,545 newly diagnosed CRC cases (67% in the colon and 33% in the rectum) and 202720 controls (for each CRC case, 5 controls were selected from the Total Population Register). Approximately 53% were men and 47% were women. Prespecified subgroup analyses (sex, age, and anatomical tumor site) were performed, and those with antibiotic use, within 2 years of CRC diagnosis were excluded. Antibiotics use reported as defined daily doses, was categorized as no use (no reported use of antibiotics during the study period), low (1-10 days), moderate (11-60 days), high (61-180 days), and very high (more than 180 days) use.

It was noted in this analysis that there was a positive dose-response association between antibiotics use and colon cancer. The CRC risk was mostly confined to proximal colon cancer for moderate use and for very high use, versus no use (P<0.001). The association between antibiotics use and risk of proximal colon cancer was more obvious among patients 50 years and older at the time of diagnosis, compared with patients younger than 50 years. There was an inverse association between antibiotics use and rectal cancer, probably reflecting differences in the bacterial flora at those two sites. When stratified by tumor stage, the positive association between antibiotics use and risk of proximal colon cancer was more pronounced in Stage I-II cancer compared with Stage III-IV cancer. In contrast, the inverse association in rectal cancer was limited to Stage III-IV. Quinolones and Sulfonamides and/or Trimethoprims were associated with increased risk of proximal colon cancer whereas Nitrofurantoins, Macrolides and/or Lincosamides, and notably, Metronidazoles and/or Tinidazoles (which exclusively inhibit anaerobic bacteria) were inversely associated with rectal cancer. Antibiotics across all classes generally had an inverse association for rectal cancer in women. There was no association noted between Methenamine hippurate, a urinary tract antiseptic not affecting the gut microbiota, and CRC risk.

It was concluded from this analysis that there was a consistent association between antibiotics use and higher subsequent risk of proximal colon cancer and an inverse association for rectal cancer in women. The authors added that these findings strengthen the evidence from previous investigations and provide new insights into site-specific carcinogenesis, as well as indirect support for the role of gut microbiota. This study provides further reasons to reduce, where possible, frequent and unnecessary antibiotic prescribing.

Antibiotics use and subsequent risk of colorectal cancer: A Swedish nationwide population-based study. Lu SSM, Mohammed Z, Haggstrom C, et al. JNCI: Journal of the National Cancer Institute, djab125, https://doi.org/10.1093/jnci/djab125

Circulating Tumor DNA as a Biomarker in Advanced Colorectal Cancer

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SUMMARY: Colorectal Cancer (CRC) is the third leading cause of cancer-related deaths in men and women in the United States. The American Cancer Society estimates that approximately 149,500 new cases of CRC will be diagnosed in the United States in 2021 and about 52,980 patients will die of the disease. The lifetime risk of developing CRC is about 1 in 23.

Cell-free DNA (cfDNA) refers to DNA molecules that circulate in the bloodstream after cell apoptosis or necrosis. A specific portion of cfDNA that originates from tumor cells is referred to as circulating tumor DNA (ctDNA), which can be detected in the cell-free component of peripheral blood samples in almost all patients with advanced solid tumors, including advanced colorectal cancer. ctDNA is a valuable biomarker and allows early detection of relapse.Liquid-Biopsy

Patients with metastatic colorectal cancer are often treated with chemotherapy and sometimes surgical intervention. Treatment decisions are based on clinical and pathological characteristics such as tumor size and number of metastatic lesions, which is an arbitrary method of treatment stratification. ctDNA can be a potential biomarker of tumor biology and disease trajectory, and can be an important clinical decision tool. The present study was conducted to systematically review ctDNA in Stage IV colorectal cancer, and assess its potential role as a prospective biomarker, to guide treatment decisions.

This meta-analysis included 2823 patients from 28 studies. ctDNA was detectable in 80-90% of patients with metastatic CRC prior to treatment. This analysis found a strong correlation between detectable ctDNA after treatment with surgery or chemotherapy and Overall Survival (HR=2.2; P<0.00001), as well as Progression Free Survival (HR= 3.15; P<0.00001). Further, ctDNA as an early biomarker was able to consistently predict long term prognosis in patients with unresectable disease, with changes after one cycle of systemic therapy demonstrating prognostic value. In patients with surgically resectable disease treated with curative intent, detection of ctDNA offered a lead time of 10 months, over radiological recurrence.

The authors concluded from this analysis that ctDNA is detectable in the majority of resectable and unresectable patients with metastatic colorectal cancer, and the presence of ctDNA is clearly associated with shorter Overall Survival. ctDNA may serve as an early biomarker and dynamic assessment of ctDNA may predict treatment efficacy.

Circulating tumour DNA as a biomarker in resectable and irresectable stage IV colorectal cancer; a systematic review and meta-analysis. Jones RP, Pugh SA, Graham J, et al. Eur J Cancer. 2021 Feb;144:368-381. doi: 10.1016/j.ejca.2020.11.025. Epub 2021 Jan 7.

Antibiotic Use and Early Onset Colon Cancer in Younger Individuals

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SUMMARY: Colorectal Cancer (CRC) is the third leading cause of cancer-related deaths in men and women in the United States. The American Cancer Society estimates that approximately 149,500 new cases of CRC will be diagnosed in the United States in 2021 and about 52,980 patients will die of the disease. The lifetime risk of developing CRC is about 1 in 23.

Colorectal Cancer is a heterogeneous disease classified by its genetics, and even though the overall death rate has continued to drop, deaths from CRC among people younger than 55 years have increased 1% per year from 2008 to 2017, with 12% of CRC cases diagnosed in people under age 50. The proportion of the total number of patients diagnosed with CRC under the age of 50 yrs rose from 10% in 2004 to 12.2% in 2015 (P<0.0001). Younger adults presented with more advanced stage of disease (Stage III/IV) than those 50 yrs or older (51.6% versus 40.0% respectively). Based on these findings, the American Cancer Society in 2018 updated its guidelines to include a “qualified recommendation” to begin CRC screening at the age of 45 yrs. 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.

Preclinical studies have suggested that there is a very complex interplay of the immune system with the host’s microbiome and there may be a relationship between gut bacteria and immune response to cancer. The crosstalk between microbiota in the gut and the immune system allows for the tolerance of commensal bacteria (normal microflora) and oral food antigens and at the same time enables the immune system to recognize and attack opportunistic bacteria. Immune Checkpoint Inhibitors strongly rely on the influence of the host’s microbiome, and the gut microbial diversity enhances mucosal immunity, dendritic cell function, and antigen presentation.

There has been a significant increase in the global antibiotic consumption and colorectal cancer (CRC) rates in individuals aged less than 50 years since the late 1980s. Broad-spectrum antibiotics can potentially alter the bacterial composition and diversity of our gut microbiota, by killing the good bacteria. It has been postulated that this may influence CRC genesis in older patients and negate the benefits of immunotherapy and influence treatment outcomes.

The present study was conducted to investigate the association between exposure to antibiotics and risk of early onset CRC, and also evaluate antibiotic usage in older adults with CRC for comparison. In this case-control study, the authors using a large Scottish primary care database identified 7,903 cases of CRC (5,281 colon, 2,622 rectal) diagnosed between 1999 and 2011, along with 30,418 healthy controls. Analyses were conducted separately for those 50 years or older, diagnosed with early onset CRC. Prescriptions for oral antibiotics (by drug class and by anaerobic/non-anaerobic effect) were extracted and total antibiotic exposure period determined for each matched set. Total exposure time in days was then categorized. The researchers then investigated the associations between each exposure with antibiotics and CRC by tumor location, adjusting for comorbidities.

Antibiotic use was associated with increased risk of colon cancer in both age groups, but the risk was increased by nearly 50% in patients under age 50, compared to 9% in those older than 50 years. Antibiotic use was associated with a significantly increased risk of proximal colon cancer (right colon) among the under those under age 50, but not among the older age group. Quinolones and sulfonamides/trimethoprim antibiotics used to treat a wide range of infections were associated with these right side colon cancers. The researchers noted that this study doesn’t prove that antibiotics cause these cancers, only that there appears to a link.

It was concluded from the findings of this study that antibiotics may play a role in the development of colon cancer, particularly in the proximal colon, in individuals under age 50. The authors added that this is the first study to investigate antibiotic usage in early onset Colorectal Cancer and provides further reasons to reduce, where possible, frequent and unnecessary antibiotic prescribing.

Global rise in early-onset colorectal cancer: An association with antibiotic consumption? Perrott S, McDowell R, Murchie P, et al. DOI:https://doi.org/10.1016/j.annonc.2021.05.049.

AI Derived Molecular Signature Predicts First-line Oxaliplatin-Based Chemotherapy Benefit in Advanced CRC

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SUMMARY: Colorectal Cancer (CRC) is the third leading cause of cancer-related deaths in men and women in the United States. The American Cancer Society estimates that approximately 149,500 new cases of CRC will be diagnosed in the United States in 2021 and about 52,980 patients will die of the disease. The lifetime risk of developing CRC is about 1 in 23. Colorectal Cancer is a heterogeneous disease classified by its genetics, and even though the overall death rate has continued to drop, deaths from CRC among people younger than 55 years have increased 1% per year from 2008 to 2017, with 12% of CRC cases diagnosed in people under age 50. Approximately 15-25% of the patients with CRC present with metastatic disease at the time of diagnosis (synchronous metastases) and 50-60% of the patients with CRC will develop metastatic disease during the course of their illness.

First line treatment of metastatic CRC include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine ( FOLFOX or FOLFIRI), along with a VEGF targeting agent such as Bevacizumab or EGFR targeting agents such as Cetuximab and Panitumumab. However numerous studies have failed to clearly establish that any of these combination regimens would be superior for any given patient based on clinical factors. In the TRIBE2 Phase III study, upfront FOLFOXIRI plus Bevacizumab and reintroduction after progression resulted in significant improvement in median Overall Survival (OS), compared to mFOLFOX6 plus Bevacizumab followed by FOLFIRI plus Bevacizumab, in patients with metastatic CRC. Majority of patients with mCRC receive FOLFOX-based first-line treatment, even though neuropathy almost always limits its use beyond 4 months. Oxaliplatin has also become a first line treatment option as part of FOLFOXIRI in mCRC, as part of FOLFIRINOX in advanced Pancreatic cancer and as a part of FOLFOX for other cancers such as GE Junction and Gastric cancer. A biomarker predicting the relative efficacy of these regimens is presently lacking. However, the availability of large, combined clinical and molecular datasets has enabled the development of a machine-learning approach.

The authors conducted this study to determine a patients’ likelihood of benefit from first-line treatment with FOLFOX followed by FOLFIRI versus FOLFIRI followed by FOLFOX, by taking advantage of an advanced machine-learning approach, to identify a molecular signature (FOLFOXai), predictive of treatment benefit from FOLFOX chemotherapy, by analyzing a combined dataset of comprehensive molecular profiling results and clinical outcomes data.

The researchers leveraged AI algorithms and comprehensive molecular profiling data to develop a machine-learning approach, and identified a 67-gene molecular signature (FOLFOXai), predictive of clinical benefit from FOLFOX chemotherapy, in previously untreated patients with mCRC. The molecular signature included genes involved in mediating WNT signaling (BCL9 and CDX2), epithelial-to-mesenchymal transition (EMT; INHBA, PRRX1, PBX1, and YWHAE), chromatin remodeling (EP300, ARID1A, SMARC4, and NSD3), DNA repair (WRN and BRIP1), NOTCH signaling (MAML2), and cell-cycle regulation (CNTRL and CCNE1). They then validated the putative molecular signature from a large Real World Evidence (RWE) database, a subset of cases from the randomized controlled Phase III TRIBE2 study, as well as RWE data from patients with advanced Esophageal/Gastro Esophageal Junction cancers (EC/GEJ cancers) or Pancreatic Ductal AdenoCarcinoma (PDAC) who received first-line treatments with Oxaliplatin-containing regimens.

The researchers utilized Real World Evidence (RWE) outcomes dataset from the Caris Life Sciences Precision Oncology Alliance registry, and insurance claims data from more than 10,000 physicians. The training cohort or dataset included patients who had a diagnosis of mCRC, received treatment with FOLFOX-based combination therapy, completed at least one full cycle of therapy, and completed Next-Generation DNA analysis of at least one colorectal cancer sample using a 592-gene panel. Patients were excluded if they had prior chemotherapy, including adjuvant therapy.

Two separate RWE validation cohorts were also generated, and patients in these cohorts had a diagnosis of mCRC, received first-line treatment with FOLFOX/Bevacizumab (FOLFOX/Bevacizumab cohort) or FOLFIRI-based treatment (FOLFIRI cohort), completed at least one full cycle of therapy, completed Next-Generation DNA analysis of at least one CRC sample using a 592-gene panel, and switched to an Irinotecan-containing regimen (FOLFOX/bevacizumab cohort) or to FOLFOX (FOLFIRI cohort).

For algorithm training, a TTNT (Time To Next Treatment) of 270 days was chosen to define whether a patient benefitted from receiving first-line FOLFOX. Patients with TTNT of less than 270 days were referred to as having decreased benefit to FOLFOX and others were referred to as having increased benefit. Validation studies used Time To Next Treatment (TTNT), Progression Free Survival (PFS), and Overall Survival (OS) as the primary endpoints.

A total of 105 patients with mCRC from the RWE dataset who had received first-line FOLFOX-based treatment and who had been profiled by Caris Life Sciences, were included in the training cohort. The first validation cohort included 412 patients (with RWE data on treatments and death dates) treated with FOLFOX/Bevacizumab and 55 patients who had received FOLFIRI as first-line treatments. Additional RWE datasets included 333 patients with advanced PDAC and EC/GEJC treated in first line with Oxaliplatin-containing regimens, and blinded retrospective-prospective analysis of samples from patients enrolled in the Phase III TRIBE2 study, with completed Next Generation Sequencing (NGS) analysis.

The researchers noted that
1) A 67-gene signature was cross-validated in a training cohort (N=105) which demonstrated the ability of FOLFOXai to distinguish FOLFOX-treated patients with mCRC with increased benefit from those with decreased benefit.
2) The gene signature was predictive of TTNT and OS in an independent RWE dataset of 412 patients who had received FOLFOX/bevacizumab in first line and inversely predictive of survival in RWE data from 55 patients who had received first-line FOLFIRI.
3) Blinded analysis of TRIBE2 samples confirmed that FOLFOXai was predictive of overall survival in both Oxaliplatin-containing arms (FOLFOX HR=0.629; P=0.04 and FOLFOXIRI HR=0.483; P=0.02).
4) FOLFOXai was also predictive of benefit from Oxaliplatin-containing regimens in advanced Esophageal/Gastro Esophageal Junction cancers, as well as Pancreatic Ductal AdenoCarcinoma.

It was concluded from this analysis that application of FOLFOXai molecular signature could lead to improvements of treatment outcomes for patients with mCRC and other cancers, because patients predicted to have less benefit from Oxaliplatin-containing regimens might benefit from alternative regimens, thus providing critical guidance for the choice of first line therapy. The authors added that this is the first clinically validated, machine-learning powered molecular predictor of chemotherapy efficacy in these diseases, with immediate relevance for the initial therapeutic decision-making process.

Clinical Validation of a Machine-learning–derived Signature Predictive of Outcomes from First-line Oxaliplatin-based Chemotherapy in Advanced Colorectal Cancer. Abraham JP, Magee D, Cremolini C, et al. Clin Cancer Res 2021;27:1174-1183.

Neoadjuvant Chemotherapy in Locally Advanced Rectal Cancer

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SUMMARY: The American Cancer Society estimates that 45,230 new cases of rectal cancer will be diagnosed in the US in 2021. Based on the information from the SEER database, the 5-year relative survival rates for rectal cancer, all SEER stages combined, is 67%. The current standard of care for patients with locally advanced rectal cancer (Stages T3, T4, or N+) consists of Chemoradiation followed by Total Mesorectal Excision (TME), which provides good local disease control, although distant metastases can still occur. Adjuvant chemotherapy after preoperative Chemoradiation remains controversial, as it has not shown an improvement in Overall Survival (OS). This has been attributed in part to poor treatment compliance. Phase II trials of total neoadjuvant therapy have yielded promising results but there is presently no data from Phase III trials.

The Phase III PRODIGE 23 trial sponsored by the French UNICANCER GI group, investigated the role of neoadjuvant modified FOLFIRINOX before standard preoperative chemoradiotherapy, in patients with locally advanced rectal cancer. The aim of the study was to assess whether administering neoadjuvant chemotherapy before preoperative Chemoradiation could reduce the risk of distant recurrences. In this study, 461 patients were randomly assigned 1:1 to either the neoadjuvant chemotherapy group (N=231) or the standard-of-care Chemoradiation group (N=230). Eligible patients had newly diagnosed, biopsy-proven, rectal adenocarcinoma staged cT3 or cT4 M0, with a Performance Status of 0-1. The neoadjuvant chemotherapy group received preoperative chemotherapy with FOLFIRINOX (Oxaliplatin 85 mg/m2 IV, Irinotecan 180 mg/m2 IV, Leucovorin 400 mg/m2 IV, and Fluorouracil 2400 mg/m2 IV as a continuous infusion over 46 hours every 14 days for 6 cycles), followed by Chemoradiation (50 Gy over 5 weeks along with concurrent Capecitabine 800 mg/m2 orally twice daily for 5 days per week), followed by Total Mesorectal Excision, and adjuvant chemotherapy which consisted of modified FOLFOX6 (Oxaliplatin 85 mg/m2 IV and Leucovorin 400 mg/m2 IV, followed by Fluorouracil 400 mg/m2 IV bolus and then Fluorouracil 2400 mg/m2 continuous infusion over 46 hours) every 14 days for six cycles or Capecitabine 1250 mg/m2 orally twice daily on days 1-14 every 21 days.

The Chemoradiotherapy group received preoperative Chemoradiation (50.4 Gy over 5 weeks along with Capecitabine 800 mg/m2 orally twice daily for 5 days per week), followed 7 weeks later by Total Mesorectal Excision and adjuvant chemotherapy, which consisted of 6 months (12 cycles) of modified FOLFOX or 6-8 cycles of Capecitabine. It should be noted that patients received the same schedule of Chemoradiation, the same surgery, and the same total duration of chemotherapy (6 months) in both groups.

The Primary endpoint was Disease Free Survival (DFS) at 3 years. Secondary endpoints included Overall Survival (OS), Metastasis-Free Survival (MFS), and Cancer-Specific Survival (CSS). Safety analyses were performed on treated patients. More than 90% of patients received all planned cycles of FOLFIRINOX.

At a median follow-up of 46.5 months, the 3-year DFS rates were 76% in the neoadjuvant chemotherapy group and 69% in the standard-of-care group (HR=0.69; P=0.034). This represented a 31% reduction in the DFS hazard in the neoadjuvant group. Metastasis-Free-Survival at 3 years was significantly improved in the neoadjuvant group (79% vs 72%, P=0.017) and the pathologic Complete Responses were also significantly higher in the neoadjuvant group (28% versus 12%; P<0.001).
FOLFIRINOX was reported to be well tolerated with 92% compliance rate with this regimen. There were significantly more grade 3 or 4 adverse events in the Chemoradiation group, especially neutropenia and neuropathy. There were significantly more Grade 3 or 4 adverse events associated with adjuvant chemotherapy in the Chemoradiation control group (79% versus 45%, P<0.0001). Grade 3 or 4 neutropenia, thrombocytopenia, lymphopenia and neuropathy, all occurred significantly more often in the patients who received 6 months of adjuvant therapy (Chemoradiation group), suggesting that for the same duration of chemotherapy, the perioperative approach was better tolerated than adjuvant chemotherapy.

The authors concluded that chemotherapy intensification using FOLFIRINOX before preoperative Chemoradiation significantly improved outcomes, with better tolerance and decreased neurotoxicity, compared with standard-of-care preoperative Chemoradiation, among patients with cT3 or cT4 M0 rectal cancer.

Neoadjuvant chemotherapy with FOLFIRINOX and preoperative chemoradiotherapy for patients with locally advanced rectal cancer (UNICANCER-PRODIGE 23): a multicentre, randomised, open-label, phase 3 trial. Conroy T, Bosset J-F, Etienne P-L, et al. Lancet Oncol. 2021;22:702-715.

Role of Aspirin in Colorectal Cancer Prevention and Mortality

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SUMMARY: Colorectal Cancer (CRC) is the third leading cause of cancer-related deaths in men and women in the United States. The American Cancer Society estimates that approximately 149,500 new cases of CRC will be diagnosed in the United States in 2021 and about 52,980 patients will die of the disease. The lifetime risk of developing CRC is about 1 in 23. The majority of CRC cases (about 75 %) are sporadic whereas the remaining 25 % of the patients have family histories of the disease. Only 5-6 % of patients with CRC with a family history background are due to inherited mutations in major CRC genes, while the rest are the result of accumulation of both genetic mutations and epigenetic modifications of several genes. Colorectal Cancer is a heterogeneous disease classified by its genetics, and even though the overall death rate has continued to drop, deaths from CRC among people younger than 55 years have increased 1% per year from 2008 to 2017, with 12% of CRC cases diagnosed in people under age 50.MOA-of-ASPIRIN

Aspirin (AcetylSalicylic Acid) has been studied as a chemopreventive agent for several decades and the temporal relationship between systemic inflammation and cancer has been a topic of ongoing investigation. The US Preventive Services Task Force (USPSTF) found adequate evidence that Aspirin use reduces the incidence of CRC in adults after 5-10 years of use, and recommends initiating low-dose Aspirin use for the primary prevention of CardioVascular Disease (CVD) and CRC, in adults aged 50-69 years, who have a 10% or greater 10-year CVD risk, are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose Aspirin daily for at least 10 years.

The molecular mechanisms underlying Aspirin’s chemoprevention effects as well as the dose, duration, and timing of Aspirin chemoprevention have remained unclear. More recent data suggests that platelets may play a role in tumorigenesis as well, through the release of angiogenic and growth factors due to overexpression of COX-2. Daily low dose Aspirin inhibits COX-1 and COX-2. It is postulated that Aspirin also works by COX-independent mechanisms such as, the inhibition of NF-kB and Wnt/ β-catenin signaling, which may play a role in its chemopreventive properties.Inhibitory-Effect-of-Aspirin-on-Tumorigenesis

Two recently published studies have provided new information on the association between regular aspirin use, and CRC incidence.

In the first study by Zhang and colleagues, the authors addressed the use of aspirin for the primary prevention of CRC and explored the dosing, timing and duration of Aspirin intake, to reduce the incidence of CRC. The authors derived data from two large US cohort studies, The Nurses’ Health Study (January 1980-June 2014) and the Health Professionals Follow-up Study (January 1986-January 2014). These two studies provided data on the use of Aspirin by more than 94,500 participants over a period of 35 years, providing a unique opportunity to evaluate the chemopreventive benefit of Aspirin on CRC. Colorectal cancer incidence was approximately 10% lower amongst individuals reporting regular Aspirin use immediate 10 years or more earlier before follow up started, with the lowest average dose studied (23-70 mg/day) appearing as effective as higher doses. However, when the period of Aspirin use was between 5 and 10 years earlier, a smaller reduction in CRC incidence was noted amongst those taking aspirin, but the greatest reduction was noted among those taking the highest dose. This study suggested that the benefit necessitates at least 6-10 years and most clearly after approximately 10 years since initiation of Aspirin. Both remote use and use within the previous 10 years contributed independently to decreased risk, though a lower dose may be required for a benefit with longer term use.

Figueiredo and colleagues studied whether the use of Aspirin prior to or after a diagnosis of CRC, affects subsequent cancer-related mortality. They utilized data from men and women enrolled in the American Cancer Society’s Cancer Prevention Study-II (CPS-II) Nutrition Cohort who were cancer-free at the baseline (year 1992/1993), and diagnosed with CRC during follow up through 2015. They compared CRC-specific mortality amongst long-term regular Aspirin users (defined as 15 or more times per month) and non-users prior to and after diagnosis. Long-term regular use of Aspirin before diagnosis was associated with lower CRC mortality. Regular use of Aspirin following diagnosis was not statistically significantly associated with risk of CRC-specific mortality overall, although participants who began regular Aspirin use, only after their diagnosis, were at lower risk, than participants who did not use Aspirin at both the pre-and post-diagnosis periods. Further, long-term Aspirin use before diagnosis was also associated with lower risk of distant metastases. This study suggested that long-term Aspirin use before a diagnosis of non-metastatic CRC may be associated with lower CRC-specific mortality after diagnosis, implying possible inhibition of micro-metastases before diagnosis.

Taken together, the study by Zhang et al. suggested that even a relatively small dose of Aspirin taken regularly for 2-5 years during the middle years of life might reduce the risk of colorectal cancer 10 years or so later, whereas the study by Figueiredo and colleagues suggested that Aspirin, taken prior to (or started after) a diagnosis of colorectal cancer, reduced subsequent metastatic spread and cancer related mortality. Even though these two new studies support the anti-cancer effect of Aspirin, additional consistent information may be required before widespread role of Aspirin for primary prevention of cancer is embraced.

Timing of aspirin use in colorectal cancer chemoprevention: a prospective cohort study. Zhang Y, Chan AT, Meyerhardt JA, et al. J Natl Cancer Inst 2021; https://doi.org/10.1093/jnci/djab009

Associations of aspirin and non-aspirin non-steroidal anti-inflammatory drugs with colorectal cancer mortality after diagnosis. Figueiredo JC, Jacobs EJ, Newton CC, et al. J Natl Cancer Inst 2021; https://doi.org/10.1093/jnci/djab008

First Line KEYTRUDA® Superior to Chemotherapy in Metastatic MSI-H/dMMR Colorectal Cancer

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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 147,950 new cases of CRC were diagnosed in the United States in 2020 and about 53,200 patients died of the disease. The lifetime risk of developing CRC is about 1 in 23. The majority of CRC cases (about 75 %) are sporadic whereas the remaining 25 % of the patients have family histories of the disease. Only 5-6 % of patients with CRC with a family history background are due to inherited mutations in major CRC genes, while the rest are the result of accumulation of both genetic mutations and epigenetic modifications of several genes. Colorectal Cancer is a heterogeneous disease classified by its genetics, and even though the diagnosis of Colorectal Cancer in the US is dropping among people 65 years and older, the incidence has been rising in the younger age groups, with 12% of Colorectal Cancer cases diagnosed in people under age 50.

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, with the expression of tumor-specific neoantigens at the surface of cancer cells, triggering an enhanced antitumor immune response. MSI is therefore a hallmark of defective/deficient DNA MisMatchRepair (dMMR) system and occurs in 15% of all colorectal cancers. Defective MMR can be a sporadic or heritable event. Approximately 65% of the MSI high colon tumors are sporadic and when sporadic, the DNA MMR gene is MLH1. Defective MMR can manifest as a germline mutation occurring in MMR genes including MLH1, MSH2, MSH6 and PMS2. This produces Lynch Syndrome often called Hereditary Nonpolyposis Colorectal Carcinoma – HNPCC, an Autosomal Dominant disorder that is often associated with a high risk for Colorectal and Endometrial carcinoma, as well as several other malignancies including Ovary, Stomach, Small bowel, Hepatobiliary tract, Brain and Skin. MSI is a hallmark of Lynch Syndrome-associated cancers. MSI high 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 blockade with immune checkpoint inhibitors.

MSI testing is performed using a PCR or NGS 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 MMR genes. MMR gene deficiency can be detected by ImmunoHistoChemistry (IHC). NCCN Guidelines recommend MMR or MSI testing for all patients with a history of Colon or Rectal cancer. Unlike Colorectal and Endometrial cancer, where MSI-H/dMMR testing is routinely undertaken, the characterization of Lynch Syndrome across heterogeneous MSI-H/dMMR tumors is unknown.

KEYTRUDA® (Pembrolizumab) is a fully humanized, Immunoglobulin G4, anti-PD-1, monoclonal antibody, that binds to the PD-1 receptor and blocks its interaction with ligands PD-L1 and PD-L2, thereby undoing PD-1 pathway-mediated inhibition of the immune response and unleashing the tumor-specific effector T cells. The FDA in 2017 granted accelerated approval to KEYTRUDA® for patients with advanced MSI-High or dMMR solid tumors, that have progressed following prior treatment, and who have no satisfactory alternative treatment options. This has led to routine MSI-H/dMMR testing in advanced solid tumors.

KEYNOTE-177 is an International, multicenter, randomized open-label, Phase III trial conducted, to evaluate the efficacy and safety of KEYTRUDA® versus Standard-of-Care (SOC) chemotherapy, as first-line therapy for dMMR or MSI-H metastatic ColoRectal Cancer (mCRC). In this study, a total of 307 patients with MSI-H/dMMR mCRC as determined locally, and with ECOG PS of 0 or 1 were randomly assigned 1:1 to first-line treatment with KEYTRUDA® 200 mg IV every 3 weeks for up to 2 years (N=153) or investigator’s choice of mFOLFOX-6 or FOLFIRI every 2 weeks, with or without Bevacizumab or Cetuximab (N=154). Chemotherapy regimens were chosen prior to randomization. Treatment was continued until disease progression, unacceptable toxicity or completion of 35 cycles (for KEYTRUDA® only). The median patient age was 63 years and both treatment groups were well balanced. The co-Primary endpoints of the study were Progression Free Survival (PFS) and Overall Survival (OS). Key Secondary endpoints included Overall Response Rate (ORR) and Safety. Patients with confirmed disease progression on chemotherapy were given the option to crossover, to receive treatment with KEYTRUDA®.

At the second interim analysis, after a median follow up of 32.4 months, it was noted that KEYTRUDA® was superior to chemotherapy with a median PFS of 16.5 months versus 8.2 months for chemotherapy (HR=0.60; P=0.00002). The estimated restricted mean survival time after 24 months of follow up was 13.7 months in the KEYTRUDA® group as compared with 10.8 months in the chemotherapy group. Progression Free Survival was consistently longer with KEYTRUDA® than with chemotherapy across prespecified subgroups. The confirmed ORR was 43.8% with KEYTRUDA® versus 33.1% with chemotherapy, with Complete Responses in 11% and 4%, respectively. Among patients with an Overall Response, 83% in the KEYTRUDA® group had ongoing responses, as compared with 35% in the chemotherapy group at 24 months. The median Duration of Response was not reached in the KEYTRUDA® group and was 10.6 months in the chemotherapy group. Following disease progression, 36% of patients assigned to the chemotherapy group crossed over to the KEYTRUDA® group. This study is being continued to evaluate OS. Grade 3-5 treatment related Adverse Event rates were 22% in the KEYTRUDA® arm and 66% in the chemotherapy group.

The authors concluded that when compared to chemotherapy, first-line therapy with KEYTRUDA® provided a clinically meaningful and statistically significant improvement in Progression Free Survival, among patients with MSI-H/dMMR metastatic colorectal cancer, with fewer treatment-related Adverse Events. The authors added that KEYTRUDA® should be the new standard of care for this patient group.

Pembrolizumab in Microsatellite-Instability–High Advanced Colorectal Cancer. Andre T, Shiu K-K, Kim TW, et al. for the KEYNOTE-177 Investigators. N Engl J Med 2020;383:2207-2218.

First Line FOLFOXIRI Plus Bevacizumab May Be a Preferable Strategy for Metastatic Colorectal Cancer

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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 147,950 new cases of CRC will be diagnosed in the United States in 2020 and about 53,200 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 23. Approximately 15-25% of the patients with CRC present with metastatic disease at the time of diagnosis (synchronous metastases) and 50-60% of the patients with CRC will develop metastatic disease during the course of their illness. Patients with metastatic CRC, whose disease has progressed after treatment with standard therapies, have limited therapeutic options available, to treat their disease.

In the TRIBE trial, the triplet combination FOLFOXIRI (Fluorouracil, Leucovorin, Oxaliplatin, and Irinotecan) plus Bevacizumab significantly improved Progression Free Survival compared with the doublet combination FOLFIRI (Fluorouracil, Leucovorin and Irinotecan) plus Bevacizumab in patients with metastatic colorectal cancer. However, the actual benefit of first line treatment with three cytotoxic drugs compared with a preplanned sequential strategy of using doublet therapy, as well as the feasibility or efficacy of these therapies after disease progression has remained unclear. The authors in this study aimed to compare a preplanned strategy of upfront FOLFOXIRI followed by the reintroduction of the same regimen after disease progression versus a sequence of mFOLFOX6 and FOLFIRI doublets, in combination with Bevacizumab. It should be noted that FOLFOXIRI regimen is not FOLFIRINOX. FOLFOXIRI regimen does not require a bolus infusion of Fluorouracil, involves a different infusional dose and schedule, and includes Irinotecan and Leucovorin at lower doses than does FOLFIRINOX.

TRIBE2 is an open-label, randomized, multicenter, Phase III study in which first line FOLFOXIRI followed by reintroduction of the same regimen after disease progression, was compared with a sequence of mFOLFOX6 (Fluorouracil, Leucovorin, and Oxaliplatin) and FOLFIRI (Fluorouracil, Leucovorin, and Irinotecan) doublets, in combination with Bevacizumab, in patients with unresectable, previously untreated metastatic colorectal cancer. A total of 679 patients were randomly assigned 1:1 to the control group (N=340) or experimental group (N=339). Patients in the control group received first-line mFOLFOX6 (Oxaliplatin 85 mg/m2 IV along with Leucovorin 200 mg/m2 IV over 120 min, Fluorouracil 400 mg/m2 IV bolus, followed by Fluorouracil 2400 mg/m2 continuous infusion over 48 hours) plus Bevacizumab 5 mg/kg IV over 30 min starting on day 1. Patients in the experimental group received FOLFOXIRI (Irinotecan 165 mg/m2 IV over 60 min, Oxaliplatin 85 mg/m2 IV along with Leucovorin 200 mg/m2 IV over 120 min, Fluorouracil 3200 mg/m2 continuous infusion over 48 hours) plus Bevacizumab 5 mg/kg IV over 30 min starting on day 1. Treatment was repeated every 14 days for up to 8 cycles. Patients then received maintenance treatment with Fluorouracil and Leucovorin along with Bevacizumab every 14 days until disease progression. After disease progression on maintenance treatment, patients in the control group received FOLFIRI (Irinotecan 180 mg/m2 IV along with Leucovorin 200 mg/m2 IV over 120 min, Fluorouracil 400 mg/m2 IV bolus, followed by Fluorouracil 2400 mg/m2 continuous infusion over 48 hours) plus Bevacizumab 5 mg/kg IV over 30 min starting on day 1 every 2 weeks for 8 cycles. This was followed by Fluorouracil and Leucovorin along with Bevacizumab maintenance. After disease progression on maintenance treatment in the experimental group, FOLFOXIRI was reintroduced for up to 8 cycles, followed by Fluorouracil and Leucovorin along with Bevacizumab maintenance. Patient demographics, clinical and molecular baseline characteristics, were well balanced in both treatment groups. The Primary endpoint was Progression Free Survival 2 (PFS2), defined as the time from randomization to disease progression on any treatment given after first disease progression.

At a median follow up of 35.9 months, the median PFS2 19.2 months in the experimental group versus 16.4 months in the control group (HR=0.74; P=0.0005). The median PFS1 was 12 months versus 9.8 months respectively (HR=0.74, P=0.0002). The Objective Response Rate (ORR) to first line treatment was 62% in the experimental group versus 50% in the control group (P=0.0023). The median Overall Survival was 27.4 months in the experimental group versus 22.5 months in the control group (HR=0.82; P=0.032). The most common Grade 3 or 4 adverse events during first-line treatment in the experimental group were diarrhea and neutropenia. Serious adverse events occurred in 25% of patients in the experimental group versus 17% of patients in the control group. After first disease progression, there were no significant differences in frequency of Grade 3 or 4 adverse events between the control and experimental groups, except for a higher incidence of neurotoxicity in the experimental group (5% versus 0%).

It was concluded that first line treatment with FOLFOXIRI plus Bevacizumab followed by the reintroduction of the same regimen after disease progression is the best first-line treatment option for select group of patients with metastatic colorectal cancer, compared to sequential administration of chemotherapy doublets, in combination with Bevacizumab.

Upfront FOLFOXIRI plus bevacizumab and reintroduction after progression versus mFOLFOX6 plus bevacizumab followed by FOLFIRI plus bevacizumab in the treatment of patients with metastatic colorectal cancer (TRIBE2): a multicentre, open-label, phase 3, randomised, controlled trial. Cremolini C, Antoniotti C, Rossini D, et al. Lancet Oncol 2020;21:497-505

Late Breaking Abstract – ASCO 2020: First Line KEYTRUDA® Superior to Chemotherapy in Metastatic MSI-H/dMMR Colorectal Cancer

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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 147,950 new cases of CRC will be diagnosed in the United States in 2020 and about 53,200 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 23. The majority of CRC cases (about 75 %) are sporadic whereas the remaining 25 % of the patients have family histories of the disease. Only 5-6 % of patients with CRC with a family history background are due to inherited mutations in major CRC genes, while the rest are the result of accumulation of both genetic mutations and epigenetic modifications of several genes.Testing-for-MicroSatellite-Instability-and-MisMatch-Repair-Deficiency

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 is therefore a hallmark of defective/deficient DNA MisMatchRepair (dMMR) system and occurs in 15% of all colorectal cancers. Defective MMR can be a sporadic or heritable event. Approximately 65% of the MSI colon tumors are sporadic and when sporadic, the DNA MMR gene is MLH1. Defective MMR can manifest as a germline mutation occurring in MMR genes including MLH1, MSH2, MSH6 and PMS2. This produces Lynch Syndrome often called Hereditary Nonpolyposis Colorectal Carcinoma – HNPCC, an Autosomal Dominant disorder that is often associated with a high risk for Colorectal and Endometrial carcinoma, as well as several other malignancies including Ovary, Stomach, Small bowel, Hepatobiliary tract, Brain and Skin. MSI is a hallmark of Lynch Syndrome-associated 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 blockade with immune checkpoint inhibitors. MSI 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 MMR genes. MMR gene deficiency can be detected by ImmunoHistoChemistry (IHC). NCCN Guidelines recommend MMR or MSI testing for all patients with a history of Colon or Rectal cancer. Unlike Colorectal and Endometrial cancer, where MSI-H/dMMR testing is routinely undertaken, the characterization of Lynch Syndrome across heterogeneous MSI-H/dMMR tumors is unknown.

KEYTRUDA® (Pembrolizumab) is a fully humanized, Immunoglobulin G4, anti-PD-1, monoclonal antibody, that binds to the PD-1 receptor and blocks its interaction with ligands PD-L1 and PD-L2, thereby undoing PD-1 pathway-mediated inhibition of the immune response and unleashing the tumor-specific effector T cells. The FDA in 2017 granted accelerated approval to KEYTRUDA® for patients with advanced MSI-High or dMMR solid tumors, that have progressed following prior treatment, and who have no satisfactory alternative treatment options. This has led to routine MSI-H/dMMR testing in advanced solid tumors.

KEYNOTE-177 is an International, multicenter, randomized open-label, Phase III trial conducted, to evaluate the efficacy and safety of KEYTRUDA® versus Standard-of-Care (SOC) chemotherapy, as first-line therapy for dMMR or MSI-H metastatic ColoRectal Cancer (mCRC). In this study, a total of 307 patients with MSI-H/dMMR mCRC as determined locally, and with ECOG PS of 0 or 1 were randomly assigned 1:1 to first-line treatment with KEYTRUDA® 200 mg IV every 3 weeks for up to 2 years (N=153) or investigator’s choice of mFOLFOX-6 or FOLFIRI every 2 weeks, with or without Bevacizumab or Cetuximab (N=154). Chemotherapy regimens were chosen prior to randomization. Treatment was continued until disease progression, unacceptable toxicity or completion of 35 cycles (for KEYTRUDA® only). The median patient age was 63 years and both treatment groups were well balanced. The co-Primary endpoints of the study were Progression Free Survival (PFS) and Overall Survival (OS). Key Secondary endpoints included Overall Response Rate (ORR) and Safety. Patients with confirmed disease progression on chemotherapy were given the option to crossover, to receive treatment with KEYTRUDA®. The median follow up was 28 months.

It was noted that KEYTRUDA® was superior to chemotherapy with a median PFS of 16.5 months versus 8.2 months for chemotherapy (HR=0.60; P=0.0002). The 12 and 24-months PFS rates were 55.3% and 48.3% with KEYTRUDA® versus 37.3% and 18.6% with chemotherapy, respectively. The confirmed ORR was 43.8% with KEYTRUDA® versus 33.1% with chemotherapy and the median Duration of Response was not reached in the KEYTRUDA® group and was 10.6 months in the chemotherapy group. Following disease progression, 36% of patients assigned to the chemotherapy group crossed over to the KEYTRUDA® group. This study is being continued to evaluate OS. Grade 3-5 treatment related Adverse Event rates were 22% in the KEYTRUDA® arm and 66% in the chemotherapy group.

The authors concluded that when compared to chemotherapy, first-line therapy with KEYTRUDA® provided a clinically meaningful and statistically significant improvement in Progression Free Survival, among patients with MSI-H/dMMR metastatic colorectal cancer, with fewer treatment-related Adverse Events. The authors added that KEYTRUDA® should be the new standard of care for this patient group.

Pembrolizumab versus chemotherapy for microsatellite instability-high/mismatch repair deficient metastatic colorectal cancer: The phase 3 KEYNOTE-177 study. Andre T, Shiu K-K, Kim TW, et al. J Clin Oncol 38: 2020 (suppl; abstr LBA4)