Clinical and genetic characterization of de novo double-hit B cell precursor leukemia/lymphoma.

The 2016 revised World Health Organization (WHO) classification of lymphoid neoplasms included the category of high-grade B cell lymphomas (HGBLs) with combined MYC and BCL2 and/or BCL6 rearrangements (double-hit, DH). However, the clinical features of B cell precursor leukemia (BCP-ALL) that harbor DH genetics remain widely unknown. We performed a retrospective analysis of the German Multicenter Study Group for Adult ALL registry and a literature search for de novo DH-BCP-ALLs. We identified 6 patients in the GMALL registry and 11 patients published in the literature between 1983 and June 2018. Patients of all ages (range, 15-86 years) are affected. There is a high incidence of meningeal disease and other extramedullary disease manifestations. Current treatment approaches are mainly ALL-based and are sufficient to induce first complete remissions, but progression-free survival is only 4.0 months (95% CI, 1.5-6.5 months) and all patients succumb to their disease, once relapsed, with a median survival of 5.0 months (95% CI, 3.1-6.9 months), despite intensive salvage and targeted therapy approaches. Of all patients, only two that attained an initial complete remission were alive at data cutoff. In all cases, the BCL2 gene was rearranged to be in proximity to the IGH locus, whereas MYC had various translocation partners juxtaposed. There was no significant survival difference between IG and non-IG translocation partners (HR, 1.03; 95% CI, 0.33-3.2; p = 0.89). In conclusion, de novo DH-BCP-ALL is an aggressive B cell malignancy with deleterious outcome. Physicians have to be aware of this rare disease subset due to the atypical clinical behavior and especially because latest classification systems do not cover this sub-entity.