2011 ASH Annual Meeting, December 10-13, San Diego, USA
New data on aggressive B cell lymphoma
Dr Elaine Jaffe – National Cancer Institute, Bethesda, USA
The WHO classification significantly expands the number of B cell lymphomas, aggressive B cell lymphomas, that are delineated and the classification is based on diversity of cell of origin, differences in clinical features and differences in pathogenesis, including different molecular mechanisms or e-logic (?) causes such as EBV or HHV8. So the number of entities in the 2008 WHO classification is significantly expanded.
What are the implications for diagnosis?
I think for diagnosis it means that we’re moving towards a more molecularly defined classification system and I think this will have relevance as we develop new agents, which a lot of the promising new agents may be more molecularly targeted, leading to attack of specific pathways rather than just broad cytotoxicity. The standard therapy for most aggressive B cell lymphomas is R-CHOP for diffuse large B cell lymphoma, although it’s clear that R-CHOP is suboptimal for some of the entities. In particular one area delineated in the new WHO classification is a category called B cell lymphoma unclassified which really has features that are intermediate between Burkitt lymphoma and diffuse large B cell lymphoma. These cases are mainly characterised by translocations involving the myc oncogene but also multiple other genetic aberrations so we talk about this category as being myc complex rather than myc simple. In Burkitt lymphoma you have a myc translocation occurring as a relatively isolated event with a few other genetic aberrations in the background; in this unclassified group or double hit lymphomas you have myc translocation generally occurring at a late event in tumorigenesis and these tumours, we’re learning and have learned, are resistant to traditional therapies such as R-CHOP so one must come up with newer regimens.
Are there any targeted therapies available?
Not specifically, I think people are starting to develop targeted agents directed against myc directly but I don’t believe any of those are in clinical trials just yet.