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Resistance to therapies targeting the epidermal growth factor receptor (EGFR), such as cetuximab, remains a major roadblock in the search for effective therapeutic strategies in head and neck squamous cell carcinoma (HNSCC). Due to its close interaction with the EGFR pathway, redundant or compensatory activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway has been proposed as a major driver of resistance to EGFR inhibitors. Understanding the role of each of the main proteins involved in this pathway is utterly important to develop rational combination strategies able to circumvent resistance. Therefore, the current work reviewed the role of PI3K/Akt pathway proteins, including Ras, PI3K, tumor suppressor phosphatase and tensing homolog, Akt and mammalian target of rapamycin in resistance to anti-EGFR treatment in HNSCC. In addition, we summarize PI3K/Akt pathway inhibitors that are currently under (pre)clinical investigation with focus on overcoming resistance to EGFR inhibitors. In conclusion, genomic alterations in and/or overexpression of one or more of these proteins are common in both human papillomavirus (HPV)-positive and HPV-negative HNSCC tumors. Therefore, downstream effectors of the PI3K/Akt pathway serve as promising drug targets in the search for novel therapeutic strategies that are able to overcome resistance to anti-EGFR treatment. Co-targeting EGFR and the PI3K/Akt pathway can lead to synergistic drug interactions, possibly restoring sensitivity to EGFR inhibitors and hereby improving clinical efficacy. Better understanding of the predictive value of PI3K/Akt pathway alterations is needed to allow the identification of patient populations that might benefit most from these combination strategies., (© 2021 Wiley Periodicals LLC.)

Several retrospective studies have shown that a high level of microsatellite instability (MSI-H) is an important prognostic factor of a more favorable outcome in stage II and III colorectal cancer (CRC) patients. In this study, three commonly used polymerase chain reaction (PCR)-based MSI analysis techniques were compared (polyacrylamide gel electrophoresis followed by silver-staining [SSPAGE], fluorescence capillary electrophoresis [FCE], and denaturing high-performance liquid chromatography [DHPLC]) on a limited group of CRC patients, to identify the most optimal detection technique. Pathology blocks of 26 CRC patients were subjected to microdissection and the Bethesda reference panel was used for MSI analysis. Considering the samples analyzed by both SSPAGE and FCE, 8.7% were MSI-H, 8.7% were MSI-L, and 82.6% were MSS using SSPAGE. FCE resulted in 16% MSI-H, 4% MSI-L, and 80% MSS. Due to difficulties in analyzing the dinucleotide markers on DHPLC, we only analyzed the mononucleotide markers with this technique. The results were 100% concordant to those obtained by FCE. SSPAGE is time consuming, subjective, and less user-friendly and interpretable. DHPLC was not feasible due to interpretation difficulties for the dinucleotide markers. We recommend the use of FCE to analyze MSI status. This technique is sensitive, reproducible, user-friendly and leads to easy interpretation and high-throughput., ((c) 2006 Wiley-Liss, Inc.)