Young High Risk Patients with MYC/BCL2 Double Hit Lymphoma, BCL2+ and/or Germinal Centre B-Cell like Diffuse Large B-Cell Lymphoma Benefit from Dose-Dense Chemoimmunotherapy Including Early CNS Prophylaxis: Analysis of Data from the Nordic Lymphoma Group CRY-04 and Chic Trials

Background. Survival of patients with high-risk diffuse large B-cell lymphoma (DLBCL) is suboptimal, and the risk of central nervous system (CNS) progression is relatively high. We investigated the efficacy of dose-dense chemoimmunotherapy and systemic CNS prophylaxis in two Nordic trials including patients less than 65 years with high-risk DLBCL. We combined individual patient data from these trials to compare clinical outcome and biological prognostic factors in patients treated with CNS prophylaxis given in the beginning (CHIC) versus at the end (CRY-04) of therapy.

Patients and methods. In CRY-04 study, patients were treated with six courses of R-CHOEP14 followed by HD-Mtx and HD-Ara-C. In CHIC trial, treatment started with two courses of HD-Mtx in combination with R-CHOP14, followed by four courses of R-CHOEP-14 and one course of R-HD-AraC. In addition, liposomal AraC was administered intrathecally at courses 1, 3 and 5. For the correlative studies, formalin fixed paraffin embedded pretreatment tumor samples were analyzed by fluorescent in situ hybridization for BCL2 and c-MYC breakpoints and by immunochemistry for CD10, BCL6, MUM1, MYC and BCL2 expression. Germinal center B-cell-like (GCB)/non-GCB) subclassification was performed according to Hans algorithm.

Results. Among 303 patients enrolled in the trials (CRY-04, n=160 and CHIC, n=143), 295 (CRY-04, n=154 and CHIC, n=139) were evaluable for baseline characteristics and outcome. Median age (54 and 56 years, p=0.222), male/female ratio, stage, and aaIPI scores were comparable in the two cohorts. CHIC regimen improved outcome over CRY-04; the findings included 4-year estimates of PFS (81% vs 66%, p=0.003), OS (83% and 79%, p=ns) and cumulative incidence rates of CNS progression (2.4% and 5.0%, p=ns). Treatment with the CHIC regimen reduced the risk of systemic progression (aaIPI adjusted RR=0.489, 95%CI 0.308-0.777, p=0.002). PFS benefit with CHIC over CRY-04 was observed across pre-specified subgroups, and particularly in patients less than 60 years old (p=0.008).

In the entire study population, dual protein expression (DPE) of BCL2 and MYC was the only parameter to be significantly correlated with a worse PFS (4-y PFS 77% vs 50%, p=0.024; RR=2.300, 95% CI 1.088-4.860, p=0.029). Neither any single immunohistochemical marker nor the GCB/non-GCB subtype or MYC/BCL2-translocations significantly affected outcome. However, when treatment interaction was tested, MYC/BCL2 double hit status (DHL; 13%) predicted poor outcome among patients treated with CRY-04 regimen compared with patients who received CHIC regimen (4-y PFS; 38% vs 78%, p=0.086). GCB subtype and BCL2 positivity were also associated with better outcome in the CHIC cohort (4 y PFS; 63% vs 84%, p=0.011 and 61% vs 80%, p=0.007, respectively), whereas there were no significant survival differences between these regimens among the patients with non-GCB subtype, BCL2 negative DLBCL or DPE lymphomas.

Conclusions. Our results derived from trial data with homogenous treatment support the use of HD-Mtx in the beginning rather than at the end of therapy. The survival benefit related to CHIC regimen over CRY-04 is due to better systemic control of the disease, and at least partly linked to improved survival among patients with GCB subtype, BCL2 positivity and DHL.