Double hit diffuse large B-cell lymphomas: diagnostic and therapeutic challenges

Although diffuse large B-cell lymphoma (DLBCL) is curable with standard chemoimmunotherapy, over 30% of patients with advanced stage disease experience refractory disease or progression. Recent studies suggest that rearrangement of the myc oncogene occurs in approximately 10% of patients with DLBCL, and confers a very poor prognosis, particularly when there is concomitant rearrangement of bcl-2, a condition referred to as "double hit DLBCL". Using immunohistochemistry, up to 30% of patients have evidence of increased expression of myc, which occurs in both activated B-cell and germinal center type DLBCL. When bcl-2 is also positive by immunohistochemistry, prognosis is also poor. There are no randomized studies guiding treatment for patients with double hit DLBCL, but new datasets are emerging suggesting a possible role for dose-adjusted EPOCH infusional chemotherapy with rituximab. This review will conclude with a survey of novel agents which may be rationally incorporated into chemotherapy platforms for this high risk subset of DLBCL.