Colorectal cancer in adolescents and young adults with Lynch syndrome:A Danish register-based study

OBJECTIVE: To assess clinicopathological predictors and prognosis in early-onset colorectal cancer (CRC) in Lynch syndrome with comparison to patients diagnosed from age 40 and up. DESIGN: National, retrospective register-based case–control study. SETTING: Danish national hereditary CRC register. PARTICIPANTS: Individuals with Lynch syndrome diagnosed with CRC from January 1950 to June 2020. The analysis was based on 215 early-onset CRCs diagnosed between 15 and 39 years of age and 574 CRCs diagnosed at age 40–88 years. MAIN OUTCOME MEASURES: Clinical and histopathological characteristics and survival. Confounding variables were analysed by Cox analysis. RESULTS: 27.2% of the tumours in the Danish Lynch syndrome cohort were diagnosed under age 40. Disease-predisposing alterations in MLH1 and MSH2 were overrepresented in the age 15–39 cohort compared with patients diagnosed over age 40. CRCs diagnosed under age 40 showed an adverse stage distribution with 36.2% stage III–IV tumours compared with 25.8% in the over age 40 group. However, young patients diagnosed with early-stage tumours did have a significantly better prognosis compared with early-stage tumours in the older age group. CONCLUSIONS: Early-onset CRC in Lynch syndrome is primarily linked to alterations in MLH1 and MSH2 and displays an adverse stage distribution. These observations serve as a reminder of surveillance, symptom awareness and rapid diagnostic handling of CRC in young adults with Lynch syndrome

Response to Immune Checkpoint Inhibitors Is Affected by Deregulations in the Antigen Presentation Machinery: A Systematic Review and Meta-Analysis

Immune checkpoint inhibitors (ICI) targeting programmed death 1 (PD-1), its ligand (PD-L1), or cytotoxic T-lymphocyte antigen 4 (CTLA-4) have shown promising results against multiple cancers, where they reactivate exhausted T cells primed to eliminate tumor cells. ICI therapies have been particularly successful in hypermutated cancers infiltrated with lymphocytes. However, resistance may appear in tumors evading the immune system through alternative mechanisms than the PD-1/PD-L1 or CTLA-4 pathways. A systematic pan-cancer literature search was conducted to examine the association between alternative immune evasion mechanisms via the antigen presentation machinery (APM) and resistance towards ICI treatments targeting PD-1 (pembrolizumab and nivolumab), PD-L1 (durvalumab, avelumab, and atezolizumab), and CTLA-4 (ipilimumab). The APM proteins included the human leucocyte antigen (HLA) class I, its subunit beta-2 microglobulin (B2M), the transporter associated with antigen processing (TAP) 1, TAP2, and the NOD-like receptor family CARD domain containing 5 (NLRC5). In total, 18 cohort studies (including 21 original study cohorts) containing 966 eligible patients and 9 case studies including 12 patients were reviewed. Defects in the APM significantly predicted poor clinical benefit with an odds ratio (OR) of 0.39 (95% CI 0.24–0.63, p p = 0.216). In summary, the APM contains important targets for tumorigenic alterations which may explain insensitivity towards ICI therapy