Genetic prognostic markers in LymphGen-unclassifiable diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL), the most common subtype of non-Hodgkin lymphoma, has variable treatment responses and distinct molecular subtypes. Despite therapeutic advances, a significant number of patients experience treatment failure or relapse. Recent genetic subtyping methods, such as the LymphGen algorithm, classify DLBCL into molecular subtypes. However, a subset of cases remains categorized as "LymphGen-unclassifiable" ("Other" group in the LymphGen classification). These cases lack distinctive genetic features and present challenges for risk assessment. In this study, we aimed to identify prognostic genetic markers specific to LymphGen-unclassifiable DLBCL. Using a discovery cohort from the National Cancer Institute, we identified genetic alterations in CDKN2A and PIM1 that were significantly associated with overall survival in this patient group. We then validated the model in a separate cohort from Komagome Hospital in Tokyo. Our model, combined with the International Prognostic Index (IPI), identified high-risk LymphGen-unclassifiable DLBCL patients within the high-risk IPI group, showing a 2-year overall survival rate of 38% versus 72%. This approach could support the development of more targeted therapies by improving prognostic accuracy and advancing understanding of LymphGen-unclassifiable DLBCL.