Tumor M2-PK is a synonym for the dimeric form of the pyruvate kinase isoenzyme type M2 (PKM2), a key enzyme within tumor metabolism. Tumor M2-PK can be elevated in many tumor types, rather than being an organ-specific tumor marker such as PSA. Increased stool (fecal) levels are being investigated as a method of screening for colorectal tumors, and EDTA plasma levels are undergoing testing for possible application in the follow-up of various cancers.
Sandwich ELISAs based on two monoclonal antibodies which specifically recognize Tumor M2-PK (the dimeric form of M2-PK) are available for the quantification of Tumor M2-PK in stool and EDTA-plasma samples respectively. As a biomarker, the amount of Tumor M2-PK in stool and EDTA-plasma reflects the specific metabolic status of the tumors
M2-PK, as measured in feces, is a potential tumor marker for colorectal cancer. When measured in feces with a cutoff value of 4 U/ml, its sensitivity has been estimated to be 85% (with a 95% confidence interval of 65 to 96%) for colon cancer and 56% (confidence interval 41–74%) for rectal cancer.[1] Its specificity is 95%.]
The M2-PK test is not dependent on occult blood (ELISA method), so it can detect bleeding or non-bleeding bowel cancer and also polyps with high sensitivity and high specificity with no false negative, but false positives may occur
Most people are more willing to accept non-invasive preventive medical check-ups. Therefore, the measurement of tumor M2-PK in stool samples, with follow-up by colonoscopy to clarify the tumor M2-PK positive results, may prove to be an advance in the early detection of colorectal carcinomas. The CE marked M2-PK Test is available in form of an ELISA test for quantitative results or as point of care test to receive results within minutes.
Tumor M2-PK is also useful to diagnose lung cancer and better than SCC and NSE tumor markers. With renal cell carcinoma (RCC), the M2PK test has sensitivity of 66.7 percent for metastatic RCC and 27.5 percent for nonmetastatic RCC, but M2PK test cannot detect transitional cell carcinoma of the bladder, prostate cancer and benign prostatic hyperplasia
Highly sensitive and specific metabolic biomarker for colorectal cancer screening which is independent of “Faecal Occult Blood” (FOB).
Colorectal (bowel) cancer is one of the most common cancers in the western world, affecting around 160 000 people annually in the USA and 370 000 in Europe and resulting in about 55 000 and 200 000 deaths per annum respectively. If diagnosed early, the chances of a cure are very high (nearly 100%).
The most reliable investigation for diagnosis of colorectal cancer is total colonoscopy. However, the acceptance of this costly and invasive method is low. For a successful colorectal cancer screening program it is therefore necessary to use the next best screening tools, which should be easy, economical and most of all be well accepted by patients. Patients identified by these tools should be investigated further by colonoscopy.
The currently most commonly used test for bowel cancer screening is the Fecal Occult Blood Test (FOBT). As it simply recognizes blood in the stool the test is non-specific for colorectal cancer. In addition, only bleeding colorectal tumors – if any – are recognized. The largest study conducted so far on this subject is the American Veterans Association study in which a total of 2885 participants underwent total colonoscopy. The result was that only 23,9% of those participants with advanced neoplasia had a positive fecal occult blood test.
The ScheBo® • M2-PK™ Stool Test is a totally new approach for bowel cancer screening tests. Previously, only non-specific tests for blood in the stool could be used to give an indication of an existing bowel cancer or its precursors. With the new ELISA method for M2-PK in the stool it′s now possible to detect bleeding or non-bleeding bowel cancers, as well as polyps, with high sensitivity and specificity. The test is more accurate because it is not dependent on occult blood.
The majority of human tumors strongly overexpress an isoform of the glycolytic enzyme pyruvate kinase, the type M2. This isoenzyme is released from tumor cells and is quantitatively detectable in body fluids. The concentration of the type M2 isoenzyme indicates a metabolic switch turning normal cells into tumor cells. It highly correlates with the malignancy of cancer (staging) and it is independent from the histological grading.
This novel type of marker for malignancies is called M2-PK and is the only metabolic marker so far. ScheBo® • Biotech AG developed a highly sensitive enzyme-linked immunosorbent assay (ELISA) which allows the quantitative measurement of M2-PK in EDTA plasma. The test is based on two monoclonal antibodies which specifically react with M2-PK and do not cross react with the other isoforms of pyruvate kinase (Typ L, R, M1 and M2). As M2-PK is a highly tumor specific protein and shows no organ specificity it may be the marker of choice for a variety of tumors.
M2-PK gives additional information that is generally not provided by classical tumor markers which reflect tumor burden.
Urological centers have shown the suitability of M2-PK as a marker for renal cell carcinoma. Since M2-PK is a highly tumor specific protein and has not shown any organ specificity, the test is also suitable for the diagnosis of non-urogenital tumors.
