Primary plasma cell leukemia (pPCL) is a rare and aggressive variant of multiple myeloma (MM) with poor long-term survival after cytotoxic chemotherapy. Many novel drugs have revolutionized the treatment algorithms for MM. The impact of targeted therapy, both pre- and post-autologous stem cell transplant (auto-HCT) remains an area of ongoing interest. In this study, we report outcomes post auto-HCT for pPCL and the impact of maintenance therapy posttransplant with novel agents.

The gain/amplification CKS1B gene at chromosome region 1q21 (1q+) is one of the most common genetic aberrations in multiple myeloma (MM). Amplification of CKS1B is frequently associated with the deletion of the CDKN2C gene at chromosome region 1p32 (1p-), which is also associated with inferior outcomes. In this retrospective study, we evaluated the outcomes of patients with 1q+ and/or 1p- after high-dose therapy and autologous hematopoietic cell transplantation (auto-HCT). From January 2006 to December 2015, 1491 newly diagnosed patients with MM underwent upfront high-dose therapy and auto-HCT at our institution. Of those, 899 had the fluorescent in situ hybridization (FISH) data available. FISH was performed at diagnosis and before the start of induction in 686 (76%) patients and after the initiation of induction therapy in 213 (24%) patients. We identified 100 patients with 1q+ and/or 1p- by FISH from the cohort of 899 patients. A control group (n = 287) with diploid cytogenetics and normal FISH panel was selected from the same cohort. From the above 2 cohorts, using a propensity score matched analysis, we identified matched controls for 85 of the 100 patients with 1q+/1p-. Patients were matched for age at auto-HCT, sex, International Staging System stage, induction regimen, creatinine level, disease status at auto-HCT, conditioning regimen, and maintenance therapy. Sixty-seven (79%), 4 (5%), and 14 (16%) patients had 1q+, 1p-, or both 1q+ and 1p-, respectively. There was no significant difference in induction therapy, preparative regimen, or maintenance therapy between the 1q+/1p- and the control group. The median follow-up time for all patients was 29.2 months (range, 0.29 to 84.96). The cumulative incidence of 100-day nonrelapse mortality was 1.2% and 0% for the 1q+/1p- and the control group, respectively. Forty-two patients (50%) in the 1q+/1p- group achieved complete response compared with 40 patients (47%) in the control group. The estimated 3-year progression-free survival (PFS) and overall survival (OS) rates were 41% and 79% for the 1q+/1p- group and 56% and 86% for the control group. Patients in the 1q+/1p- group were at significantly increased risk of progression or death compared to the control group (hazard ratio [HR], 2.21; confidence interval [CI], 1.18 to 4.16; P = .014). No significant association between OS in the 2 groups was observed. The outcome of the 1q+/1p- alone (with no additional high-risk cytogenetics) and the propensity score matched control groups was also compared. Median PFS for the 1q+/1p- alone subgroup was 26.6 months, compared with 38.8 months for the control group (HR, 1.9; CI, 0.9 to 4.08; P = .09). The median OS had not been reached for the 1q+/1p- alone subgroup and was 81.1 months for the control group (HR, 1.25; CI, 0.3 to 4.6; P= .73). 1q+/1p- abnormalities with amplification of CKS1B and deletion ofCDKN2Cgenes were associated with shorter PFS compared with a propensity score matched group of patients with diploid cytogenetics and normal a FISH panel. The outcomes of 1q+/1p- patients with MM have improved with the use of more effective induction, conditioning, and maintenance therapy compared with historical controls, but we still need more effective therapeutic approaches to fully overcome the negative impact of 1q+/1p-.

BACKGROUND: Retrospective studies suggest that conditioning therapy with busulfan plus melphalan could result in longer progression-free survival compared with melphalan alone in patients with multiple myeloma undergoing autologous haemopoietic cell transplantation (auto-HCT). We aimed to test this hypothesis in a randomised trial. METHODS: The primary objective of the study was to compare progression-free survival with conditioning of busulfan plus melphalan with melphalan alone in patients with multiple myeloma. Patients with newly diagnosed multiple myeloma who were eligible for cell transplantation, aged 70 years or younger, with at least stable disease, were randomly assigned (1:1) to treatment. Patients received either busulfan plus melphalan, with a test dose of busulfan 32 mg/m2 followed by pharmacokinetically adjusted doses on days -7, -6, -5, and -4 to achieve a target daily area under the curve (AUC) of 5000 mmol-minute and melphalan 70 mg/m2 per day on days -2 and -1 (total melphalan dose 140 mg/m2), or a melphalan dose of 200 mg/m2 on day -2. Randomisation was performed via a Clinical Trial Conduct Website at the University of Texas MD Anderson Cancer Center. The accrual is complete and final results are presented here. The study is registered with ClinicalTrials.gov, number NCT01413178. FINDINGS: Between Oct 12, 2011, and March 22, 2017, 205 patients were assessed for eligibility and randomly assigned to treatment. The primary analysis of progression-free survival was measured in 202 patients who received treatment: 104 patients in the busulfan plus melphalan group and 98 patients in the melphalan alone group. 90 days after auto-HCT, 102 (98%) of 104 patients given busulfan plus melphalan and 95 (97%) of 98 patients given melphalan alone achieved partial response or better. The median follow-up in the busulfan plus melphalan group was 22·6 months (IQR 15·2-47·1) and 20·2 months (IQR 8·8-46·6) in the melphalan alone group. Median progression-free survival was 64·7 months (32·9-64·7) with busulfan plus melphalan versus 43·5 months (19·9-not estimated) with melphalan alone (hazard ratio 0·53 [95% CI 0·30-0·91]; p=0·022). There were no treatment-related deaths by day 100 in either group. Grade 2-3 mucositis was observed in 77 (74%) of 104 patients in the busulfan plus melphalan group versus 14 (14%) of 98 patients in the melphalan alone group. INTERPRETATION: These findings, if confirmed in other ongoing studies, suggest that busulfan plus melphalan could replace melphalan alone as the conditioning regimen for auto-HCT in patients with newly diagnosed myeloma. FUNDING: This study was funded in part by the National Institutes of Health (NIH) through MD Andersons Cancer Center Support Grant (CA016672).