Distinguishing between the major types of lymphomas is important in order for physicians to accurately match a targeted therapy for adequate treatment. With more and more targeted therapies being launched, it becomes very important to differentiate between the major types of Diffuse Large B Cell Lymphomas (DLBCL) — namely, Germinal Centre B Cell like (GCB) and Activated B Cell like (ABC), as their management strategies are different and affect treatment outcomes.
The main challenge faced by scientists while diagnosing cases of B cell lymphoma is its morphological similarity, which makes the application of targeted therapy difficult. The gold standard for distinguishing between different kinds of lymphomas is array-based Gene Expression Profiling (GEP), followed by Immunohistochemistry (IHC), both of which have their shortcomings in terms of efficacy and reliability.
A group of researchers led by lead investigator Philippe Ruminy, PhD, of the Centre Henri Becquerel, Institute for Research and Innovation in Biomedicine, University of Rouen (France), examined 259 lymph node biopsies from patients including 195 patients from the Centre Henri Becquerel and 64 from an external group (the Lymphoma Study Association) with different forms of DLBCL. The team used a technique called reverse transcriptase multiplex ligation-dependent probe amplification (RT-MLPA) assay to distinguish between different lymphoma subtypes. This method proved effective in identifying and distinguishing tumor subtypes, up to 90% and 93% in two sets of tests with randomly selected samples.
In addition, the assay was useful in detecting subtypes from low-concentration samples like frozen and archived formalin-fixed, paraffin-embedded (FFPE) tissues. When tested among 28 such samples, it gave accurate results in 89.3% of cases. According to Dr. Rumini, “Because RT-MLPA requires only short cDNA fragments for the correct binding and ligation of the gene-specific oligonucleotide probes, it is less affected by the use of low RNA concentrations and RNA degradation. It could thus be used for the retrospective analysis of archival collections and for the inclusion of patients in prospective clinical trials, because only a few institutions routinely collect frozen biopsy material.”
RT-MLPA was also beneficial in determining the prognostic value of patients with different forms of the tumor. For instance, while evaluating the chances of survival of 135 patients diagnosed and treated between 2001 and 2011, patients with the ABC subtype were found to have a significantly worse progression free survival and overall survival when compared to their GCB counterparts. Gene expression of several genes identified through this assay (high LMO2, high BCL6, and low TNFRSF13B expression) also proved helpful to detect the exact genotype of this condition.
Dr. Ruminy concluded, saying, “The robust and cost-effective RT-MLPA assay can yield results within one day and requires reagents costing less than $5 per sample. Since RT-MLPA utilizes materials and equipment that are standard in many laboratories, the process can easily be implemented for routine use.”