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Colorectal Cancer, PIK3CA, Q546E (c.1636C>G)

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Expand Collapse Colorectal Cancer  - General Description A cancer that begins in the colon is often called colon cancer and a cancer that begins in the rectum is often called rectal cancer, but sometimes the term colorectal cancer is used for a cancer that begins in either place. This year about 132,700 people in the U.S. will be diagnosed with cancer of the colon or rectum. However, nearly 1.1 million remain alive today after having been diagnosed with colorectal cancer.

The colon and rectum are parts of the large intestine. In the colon, which accounts for most of the length of the large intestine, water and nutrients are extracted from partly-digested food before the food is turned into waste. The waste then enters the rectum before being pushed out of the body, leaving via the short anal canal and the anus (cancers also develop in the anus and anal canal, but they aren't classified as colorectal cancers). Most colon cancers and rectal cancers are adenocarcinomas, tumors that begin in gland-like cells lining the colon or rectum. Other types of cancerous tissues account for only 2% to 5% of colorectal cancers.

Colorectal cancer (and other tumors) can spread (metastasize) from the place where it started (the primary tumor) in 3 ways. First, it can invade the normal tissue surrounding it. Second, cancer cells can enter the lymph system and travel through lymph vessels to distant parts of the body. Third, the cancer cells can get into the bloodstream and go to other places in the body. In these distant places, the colon/rectal cancer cells cause secondary tumors to grow. The main sites to which colorectal cancer spreads are the liver, lungs and peritoneum. To find out whether the cancer has entered the lymph system, a surgeon removes all or part of a node near the primary tumor and a pathologist examines it to see if cancer cells are present. Several kinds of imaging also can be performed to determine if the cancer has spread. These include chest x-rays, MRI, CT scans and PET scans.

The FDA has approved several targeted therapies for treatment of patients with metastatic colorectal cancer. These include bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix) and ziv-afibercept (Zaltrap).

Despite significant improvements in the treatment of colorectal cancers, novel therapies and treatment strategies are needed.

Source: National Cancer Institute, 2015
The prognosis of patients with colon cancer is clearly related to the degree of tumor penetration through the bowel wall, the presence or absence of nodal involvement, and the presence or absence of distant metastases. These three characteristics form the basis for all staging systems developed for this disease. Bowel obstruction and bowel perforation are indicators of poor prognosis. Elevated pretreatment serum levels of carcinoembryonic antigen (CEA) have a negative prognostic significance. The American Joint Committee on Cancer and a National Cancer Institute-sponsored panel recommended that at least 12 lymph nodes be examined in patients with colon and rectal cancer to confirm the absence of nodal involvement by tumor. This recommendation takes into consideration that the number of lymph nodes examined is a reflection of the aggressiveness of lymphovascular mesenteric dissection at the time of surgical resection and the pathologic identification of nodes in the specimen. Retrospective studies demonstrated that the number of lymph nodes examined in colon and rectal surgery may be associated with patient outcome.

Many other prognostic markers have been evaluated retrospectively for patients with colon cancer, though most have not been prospectively validated (including allelic loss of chromosome 18q or thymidylate synthase expression). Microsatellite instability, also associated with hereditary nonpolyposis colon cancer (HNPCC), has been associated with improved survival (independent of tumor stage) in a population-based series of 607 patients younger than 50 years of age with colorectal cancer. Treatment decisions generally depend on factors such as physician/patient preferences and the stage of the disease, rather than the age of the patient. Racial differences in overall survival after adjuvant therapy have been observed (although not in disease-free survival), suggesting that comorbid conditions play a role in survival outcome in different patient populations.

Source: National Cancer Institute, 2012
A cancer that begins in the colon is often called colon cancer and a cancer that begins in the rectum is often called rectal cancer, but sometimes the term colorectal cancer is used for a cancer that begins in either place. This year about 132,700 people in the U.S. will be diagnosed with cancer of the colon or rectum. However, nearly 1.1 million remain alive today after having been diagnosed with colorectal cancer.

The colon and rectum are parts of the large intestine. In the colon, which accounts for most of the length of the large intestine, water and nutrients are extracted from partly-digested food before the food is turned into waste. The waste then enters the rectum before being pushed out of the body, leaving via the short anal canal and the anus (cancers also develop in the anus and anal canal, but they aren't classified as colorectal cancers). Most colon cancers and rectal cancers are adenocarcinomas, tumors that begin in gland-like cells lining the colon or rectum. Other types of cancerous tissues account for only 2% to 5% of colorectal cancers.

Colorectal cancer (and other tumors) can spread (metastasize) from the place where it started (the primary tumor) in 3 ways. First, it can invade the normal tissue surrounding it. Second, cancer cells can enter the lymph system and travel through lymph vessels to distant parts of the body. Third, the cancer cells can get into the bloodstream and go to other places in the body. In these distant places, the colon/rectal cancer cells cause secondary tumors to grow. The main sites to which colorectal cancer spreads are the liver, lungs and peritoneum. To find out whether the cancer has entered the lymph system, a surgeon removes all or part of a node near the primary tumor and a pathologist examines it to see if cancer cells are present. Several kinds of imaging also can be performed to determine if the cancer has spread. These include chest x-rays, MRI, CT scans and PET scans.

The FDA has approved several targeted therapies for treatment of patients with metastatic colorectal cancer. These include bevacizumab (Avastin), cetuximab (Erbitux), panitumumab (Vectibix) and ziv-afibercept (Zaltrap).

Despite significant improvements in the treatment of colorectal cancers, novel therapies and treatment strategies are needed.

Source: National Cancer Institute, 2015
The prognosis of patients with colon cancer is clearly related to the degree of tumor penetration through the bowel wall, the presence or absence of nodal involvement, and the presence or absence of distant metastases. These three characteristics form the basis for all staging systems developed for this disease. Bowel obstruction and bowel perforation are indicators of poor prognosis. Elevated pretreatment serum levels of carcinoembryonic antigen (CEA) have a negative prognostic significance. The American Joint Committee on Cancer and a National Cancer Institute-sponsored panel recommended that at least 12 lymph nodes be examined in patients with colon and rectal cancer to confirm the absence of nodal involvement by tumor. This recommendation takes into consideration that the number of lymph nodes examined is a reflection of the aggressiveness of lymphovascular mesenteric dissection at the time of surgical resection and the pathologic identification of nodes in the specimen. Retrospective studies demonstrated that the number of lymph nodes examined in colon and rectal surgery may be associated with patient outcome.

Many other prognostic markers have been evaluated retrospectively for patients with colon cancer, though most have not been prospectively validated (including allelic loss of chromosome 18q or thymidylate synthase expression). Microsatellite instability, also associated with hereditary nonpolyposis colon cancer (HNPCC), has been associated with improved survival (independent of tumor stage) in a population-based series of 607 patients younger than 50 years of age with colorectal cancer. Treatment decisions generally depend on factors such as physician/patient preferences and the stage of the disease, rather than the age of the patient. Racial differences in overall survival after adjuvant therapy have been observed (although not in disease-free survival), suggesting that comorbid conditions play a role in survival outcome in different patient populations.

Source: National Cancer Institute, 2012
Expand Collapse PIK3CA  - General Description
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PIK3CA is a gene that provides the code for making one piece of the phosphatidylinositol 3-kinase (PI3K) protein, which is an enzyme that is part of an important signaling pathway (PI3K/AKT) involved in controlling the growth, division, survival, nutrient utilization, movement and structure of cells. PIK3CA encodes the catalytic subunit of PI3K, which is the part of the protein that lets it function as an enzyme. PI3K function is tightly maintained in normal cells. The enzymatic activity is activated by specific signals from growth factor receptor tyrosine kinases (RTKs) or from activated RAS proteins. PI3K then generates molecules that attract another enzyme (particularly AKT) to the cell membrane, where it is activated. The activated AKT acts on other proteins that regulate various cell processes that promotes cell growth and survival.

Mutations in PIK3CA lead to enhanced activation of its signaling function, thereby driving the tumorigenic process. These activating mutations are commonly associated with breast and colon cancer, and more rarely with melanoma of the skin. Defects in this gene have also been associated with ovarian cancer, endometrial cancer, and liver cancer.

Tumor mutation profiling performed clinically at the MGH Cancer Center has identified PIK3CA mutations across a broad-spectrum of cancer types. The highest incidence of PIK3CA mutations have been found in endometrial cancer (25%), breast cancer (20%), colon cancer (25%) and cancers of the head and neck (10%). In the other major tumor types, PIK3CA mutations have been found in less than 10% of cases that have been tested.

Sources: Genetics Home Reference
The PIK3CA gene encodes the p110 alpha catalytic subunit of the phosphoinositol 3-kinase (PI3K) complex. PI3K receives upstream activation signals from growth factor receptor tyrosine kinases (e.g. EGFR family members), and in turn signals through AKT and mTOR in order to promote cell survival, cell growth and cellular proliferation. PIK3CA mutations lead to increased activation of PI3K/AKT/mTOR signaling. PI3K function is opposed by PTEN, a lipid phosphatase that is often inactivated by mutations or silenced by methylation in many cancers.

Tumor mutation profiling performed clinically at the MGH Cancer Center has identified PIK3CA mutations across a broad-spectrum of cancer types. The highest incidence of PIK3CA mutations have been found in endometrial cancer (25%), breast cancer (20%), colon cancer (25%) and cancers of the head and neck (10%). In the other major tumor types, PIK3CA mutations have been found in less than 10% of cases that have been tested.

Sources: Genetics Home Reference
Expand Collapse Q546E (c.1636C>G)  in PIK3CA
The PIK3CA Q546E mutation arises from a single nucleotide change (c.1636C>G) and results in an amino acid substitution of the glutamine (Q) at position 546 by a glutamic acid (E).
The PIK3CA Q546E mutation arises from a single nucleotide change (c.1636C>G) and results in an amino acid substitution of the glutamine (Q) at position 546 by a glutamic acid (E).

The diagnostic relevance of PIK3CA mutations in colorectal adenocarcinoma has largely been limited to a single, large population-based study, which determined that PIK3CA mutations were more frequent in well-differentiated and mucinous colorectal tumors and tended to co-exist with KRAS mutations.

Results from the multi-institutional Dutch TME trial identified the presence of a PIK3CA mutation is associated with increased local recurrence in rectal cancer patients. Furthermore, a large population-based study has reported that the presence of an activating PIK3CA mutation is independently associated with shorter survival in patients with stage I to III resectable colorectal cancer, but only in the absence of a concurrent KRAS mutation. Interestingly, a recent retrospective study showed that regular aspirin use after diagnosis of early-stage colorectal cancer was associated with longer survival, but only among patients with PIK3CA-mutated tumors.

The therapeutic implications of PIK3CA mutations in colorectal cancer are the focus of ongoing investigations. Preliminary studies have implicated PIK3CA mutations as a mechanism of resistance to the anti-EGFR agent cetuximab or panitumumab in colorectal cancer. However, clinical follow-up is required to validate these findings. Preclinical studies have also demonstrated that PIK3CA mutations confer greater sensitivity to PI3K/AKT/mTOR inhibitors and early phase clinical trials are being conducted to evaluate their efficacy in the treatment of metastatic colorectal cancer. As PIK3CA mutations frequently coexist with KRAS mutations in colorectal cancer, trials with combination of PI3K pathway inhibitors and MEK inhibitors are underway.

The diagnostic relevance of PIK3CA mutations in colorectal adenocarcinoma has largely been limited to a single, large population-based study, which determined that PIK3CA mutations were more frequent in well-differentiated and mucinous colorectal tumors and tended to co-exist with KRAS mutations.

Results from the multi-institutional Dutch TME trial identified the presence of a PIK3CA mutation is associated with increased local recurrence in rectal cancer patients. Furthermore, a large population-based study has reported that the presence of an activating PIK3CA mutation is independently associated with shorter survival in patients with stage I to III resectable colorectal cancer, but only in the absence of a concurrent KRAS mutation. Interestingly, a recent retrospective study showed that regular aspirin use after diagnosis of early-stage colorectal cancer was associated with longer survival, but only among patients with PIK3CA-mutated tumors.

The therapeutic implications of PIK3CA mutations in colorectal cancer are the focus of ongoing investigations. Preliminary studies have implicated PIK3CA mutations as a mechanism of resistance to the anti-EGFR agent cetuximab or panitumumab in colorectal cancer. However, clinical follow-up is required to validate these findings. Preclinical studies have also demonstrated that PIK3CA mutations confer greater sensitivity to PI3K/AKT/mTOR inhibitors and early phase clinical trials are being conducted to evaluate their efficacy in the treatment of metastatic colorectal cancer. As PIK3CA mutations frequently coexist with KRAS mutations in colorectal cancer, trials with combination of PI3K pathway inhibitors and MEK inhibitors are underway.

PubMed ID's
20619739, 19237633, 18516290, 19223544, 15950905, 19401449, 19903786
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Your Matched Clinical Trials

Trial Matches: (D) - Disease, (G) - Gene, (M) - Mutation
Trial Status: Showing Results: 1-10 of 28 Per Page:
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Protocol # Title Location Status Match
NCT02279433 A First-in-human Study to Evaluate the Safety, Tolerability and Pharmacokinetics of DS-6051b A First-in-human Study to Evaluate the Safety, Tolerability and Pharmacokinetics of DS-6051b MGH Open D
NCT02099058 A Phase 1/1b Study With ABBV-399, an Antibody Drug Conjugate, in Subjects With Advanced Solid Cancer Tumors A Phase 1/1b Study With ABBV-399, an Antibody Drug Conjugate, in Subjects With Advanced Solid Cancer Tumors MGH Open D
NCT02327169 A Phase 1B Study of MLN2480 in Combination With MLN0128 or Alisertib, or Paclitaxel, or Cetuximab, or Irinotecan in Adult Patients With Advanced Nonhematologic Malignancies A Phase 1B Study of MLN2480 in Combination With MLN0128 or Alisertib, or Paclitaxel, or Cetuximab, or Irinotecan in Adult Patients With Advanced Nonhematologic Malignancies MGH Open D
NCT02219724 A Phase I, Open-Label Study of MOXR0916 in Patients With Locally Advanced or Metastatic Solid Tumors A Phase I, Open-Label Study of MOXR0916 in Patients With Locally Advanced or Metastatic Solid Tumors MGH Open D
NCT02365662 A Study Evaluating Safety and Pharmacokinetics of ABBV-221 in Subjects With Advanced Solid Tumor Types Likely to Exhibit Elevated Levels of Epidermal Growth Factor Receptor A Study Evaluating Safety and Pharmacokinetics of ABBV-221 in Subjects With Advanced Solid Tumor Types Likely to Exhibit Elevated Levels of Epidermal Growth Factor Receptor MGH Open D
NCT01714739 A Study of an Anti-KIR Antibody in Combination With an Anti-PD1 Antibody in Patients With Advanced Solid Tumors A Study of an Anti-KIR Antibody in Combination With an Anti-PD1 Antibody in Patients With Advanced Solid Tumors MGH Open D
NCT01633970 A Study of Atezolizumab Administered in Combination With Bevacizumab and/or With Chemotherapy in Participants With Locally Advanced or Metastatic Solid Tumors A Study of Atezolizumab Administered in Combination With Bevacizumab and/or With Chemotherapy in Participants With Locally Advanced or Metastatic Solid Tumors MGH Open D
NCT02467361 A Study of BBI608 Administered in Combination With Immune Checkpoint Inhibitors in Adult Patients With Advanced Cancers A Study of BBI608 Administered in Combination With Immune Checkpoint Inhibitors in Adult Patients With Advanced Cancers MGH Open D
NCT02228811 A Study of DCC-2701 in Participants With Advanced Solid Tumors A Study of DCC-2701 in Participants With Advanced Solid Tumors MGH Open D
NCT02082210 A Study of LY2875358 in Combination With Ramucirumab (LY3009806) in Participants With Advanced Cancer A Study of LY2875358 in Combination With Ramucirumab (LY3009806) in Participants With Advanced Cancer MGH Open D
Trial Status: Showing Results: 1-10 of 28 Per Page:
123Next »
Our Colorectal Cancer Team

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