Technology
Frameshift mutation is characteristically present in sporadic and hereditary cancers associated with genetic microsatellite instability (MSI). Our technology platform based on proprietary designed PCR-primers provides novel diagnostic tests for detection of early occurring cancer specific frameshift mutations as biomarkers of MSI-cancer in liquid biopsies.
Frameshift mutations are caused by defects in the DNA mismatch repair machinery (MMR). It occurs in genes with stretches of short tandem DNA repeats (microsatellites) and is constituted by nucleotide deletion and/or insertion in the micro satellite. The frameshift mutation creates a shift of codons for protein expression, resulting in a truncated non-functional protein, in some cases causing malignant transformation and cancer progression.
Short DNA fragments, cell free DNA (cfDNA), are present in peripheral blood. Presence of frameshift cfDNA in the blood constitute biomarkers of MSI-cancer (Eriksen H & Eriksen JA, 2022, Song Y. et al. 2024). Our tests provide simple methods for surveillance of risk of MSI cancer in individuals of risk populations (E.G. Lynch Syndrome, risk of cancer recurrence after surgery), and thus, allowing early treatment with potentially improved outcome.
Detection of cancer biomarkers in liquid biopsies enabling early identification and monitoring of pre-cancerous and cancerous lesions both new and recurrence, thus allowing early treatment to improve prognosis and the quality of the lives of at-risk individuals and families.
MSI is observed across a range of cancers and is particularly prominent in colorectal cancer, stomach cancer and endometrial cancers with a frequency of 15-28% (Cortes-Ciriano I et al 2017; NATURE COMMUNICATIONS|8:15180| (2017)).
The frameshift mutation profile can vary between indications and patients. Therefore, a panel of four DNA frameshifts that is anticipated to provide biomarker coverage of up to 100% of MSI cases has been selected: TGFbR2, ACVR, TAF1B and ASTE1 frameshifts. The selected frameshifts occur early, sometimes before (Staffa L et al 2015), malignant cell transformation.
| Indication (MSI-cancer) | Target frameshifts and prevalence | |||
| ACVR2A | TGFbR2 | ASTE1 | TAF1b | |
| Colorectal | 92% | 77% | 86% | 84% |
| Endometrial | - | 5% | 92% | 50% |
| Gastric | 93% | 80% | - | 87% |
The test-assays are based on proprietary designed primers for use in standard polymerase chain reaction (PCR) assays. By introducing selective repulsion between PCR primer and cfDNA template, the primers are designed to anneal directly to the frameshift (mutated) DNA sequence and not to the wild type (wildtype) DNA sequence (Eriksen H & Eriksen JA). Since the frameshift DNA can be selectively detected there is no need for sequencing of the PCR product which is a significant cost and time reducing feature of the new tests compared to the standard PCR methodology.
Frameshift mutant TGFβR2 is present in 44% of MSI related cancers and particularly in more than 77% of MSI-H colorectal cancer (Maby P. et al. Cancer Res; 75(17) September 1, 2015 (3446 – 3455)) and 80% of MSI-H stomach cancer (Cortes-Ciriano I et al 2017; NATURE COMMUNICATIONS|8:15180| (2017)). Over 90% of patients with familial hereditary colorectal cancer (Lynch Syndrome) have TGFβR2 frameshift mutation (Pinheiro M et al, British Journal of Cancer (2015) 113, 686–692).
The annual incidence of MSI in CRC, EC and SC in Europe, North America and Asia is more than 500 000.
| Cancer | MSI | Annual incidence (MSI) | |
| Europe + N. America | Asia | ||
| Colorectal (CRC) | 15-20% | ≈100 000 | ≈140 000 |
| Endometrial (EC) | 28% | ≈50 000 | ≈40 000 |
| Stomach (SC) | 22% | ≈35 000 | ≈170 000 |
Lynch Syndrome constitutes a lifetime risk of hereditary cancers
Lynch syndrome is a genetic condition with a lifetime high risk of developing frameshift mutations and MSI cancers. Cancer caused by Lynch Syndrome affects a number of organs but especially the colon and endometrium. Lynch Syndrome is inherited from one or both parents and cannot be cured. It is estimated that Lynch Syndrome affects about 0.4% of the general population. Monitoring and early detection MSI-cancer biomarkers in liquid biopsies will potentially allow earlier treatment and improved clinical outcome for individuals with Lynch Syndrome that develop cancer.
In Lynch Syndrome a deficient mismatch DNA repair machinery (dMMR) is inherited from parents. dMMR is the underlying cause of frameshift mutation (that is left unrepaired) and progression of MSI cancers.
Detection of cancer biomarkers in liquid biopsies enabling early identification and monitoring of pre-cancerous and cancerous lesions both new and recurrence, thus allowing early treatment to improve prognosis and the quality of the lives of at-risk individuals and families.
| Cancer | Population risk | MLH1 and MSH2 | MSH6 | PMS2 | |||
| Risk | Mean age of onset | Risk | Mean age of onset | Risk | Mean age of onset | ||
| Colon | 5.5% | 55-80% | 44-61 | 10-20% | 54 | 15-20% | 61-66 |
| Endometrial | 2.7% | 25-60% | 48-62 | 16-26% | 55 | 15% | 49 |
| Stomach | <1% | 1-13% | 56 | <3% | 63 | 70-78 | |
| Ovary | 1.6% | 4-24% | 42.5 | 1-11% | 46 | 42 | |