We report a multicentre retrospective study that analysed clinical characteristics and outcomes in 117 patients with primary plasma cell leukaemia (pPCL) treated at the participating institutions between January 2006 and December 2016. The median age at the time of pPCL diagnosis was 61 years. Ninety-eight patients were treated with novel agents, with an overall response rate of 78%. Fifty-five patients (64%) patients underwent upfront autologous stem cell transplantation (ASCT). The median follow-up time was 50 months (95% confidence interval [CI] 33; 76), with a median overall survival (OS) for the entire group of 23 months (95% CI 15; 34). The median OS time in patients who underwent upfront ASCT was 35 months (95% CI 24·3; 46) as compared to 13 months (95% CI 6·3; 35·8) in patients who did not receive ASCT (P = 0·001). Multivariate analyses identified age ≥60 years, platelet count ≤100 × 10 /l and peripheral blood plasma cell count ≥20 × 10 /l as independent predictors of worse survival. The median OS in patients with 0, 1 or 2-3 of these risk factors was 46, 27 and 12 months, respectively (P < 0·001). Our findings support the use of novel agents and ASCT as frontline treatment in patients with pPCL. The constructed prognostic score should be independently validated.

The role of c-myc in multiple myeloma (MM) is controversial. We conducted a retrospective study of 117 patients with MM diagnosed between 2004 and 2010 at Herlev Hospital. Immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) were performed on tissue microarrays (TMAs) made from diagnostic bone marrow aspirates. Clinical data were obtained from the Danish Multiple Myeloma Database (DMMD). Overexpression of c-myc was found in 40% of patients. MYC translocation was found in 10% of patients. Overexpression of c-myc was not associated with MYC translocation. Overexpression of c-myc was associated with hypercalcemia (p = 0.02) and extramedullary myeloma (p < 0.01). Overexpression of c-myc was associated with shorter overall survival (OS) by multivariable analysis of the entire patient cohort [HR 1.92 (1.06-3.45), p = 0.03] and univariable analysis of high-dose-therapy (HDT)-ineligible patients [HR 2.01 (1.05-3.86), p = 0.04]. Further studies of c-myc overexpression in larger cohorts of patients with MM are warranted.

This multicenter retrospective study included 101 patients (median age 62 years) with secondary plasma cell leukemia (sPCL). The median time from initial multiple myeloma diagnosis to sPCL was 31 months. Fifty-five out of 72 patients (75%) who received any therapy were treated with immunomodulators (IMiDs) and/or proteasome inhibitors (PIs), and 14/72 (19%) underwent salvage autologous stem cell transplantation (ASCT). The overall response rate in patients who received ASCT or PI (either alone or in combination) was higher than in those who did not (93% vs. 36% and 60% vs. 30%, respectively). The median overall survival (OS) in patients who received therapy was 4.2 months (95% CI: 1.3; 8.0) with a 1-year OS of 19%. Platelet count ≤100 × 10/L at sPCL diagnosis was the only independent predictor of a poorer OS in treated patients (HR = 3.98, p = .0001). These findings suggest that patients with sPCL may benefit from salvage ASCT- and PI-based regimens.

In 2019 the UK Myeloma Research Alliance introduced the Myeloma Risk Profile (MRP) for prediction of outcome in patients with newly diagnosed multiple myeloma (MM), ineligible for autologous stem cell transplantation. To validate the MRP in a population-based setting we performed a study of the entire cohort of transplant ineligible MM patients above 65 years in the Danish National MM Registry. Our data confirmed the value of the MRP. In a cohort of 1,377 patients, the MRP score separated patients into three distinct risk-groups with an observed hazard ratio of 2.91 for early death in high-risk versus low-risk patients.