Phase 2 Study of an Intravenous Busulfan and Melphalan Conditioning Regimen for Autologous Stem Cell Transplantation in Patients with Multiple Myeloma (KMM150)

Hepatic sinusoidal obstruction syndrome/veno-occlusive disease after hematopoietic cell transplantation: historical and current considerations in Korea

Hepatic sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is a rare but severe complication of hematopoietic cell transplantation (HCT) showing high mortality. Multiple risk factors for SOS/VOD were identified, but it is often confused with other hepatic complications due to nonspecific clinical features. Therefore, diagnostic and severity criteria have been revised several times. The European Society of Blood and Marrow Transplantation suggested a new guideline that excludes the standard duration of development within 21 days, emphasizes late-onset SOS/VOD, and suggests the importance of Doppler ultrasonography. The severity criteria were further subdivided for guidance to begin active treatment using defibrotide which was approved in Korea since 2016. In a phase 3 trial, defibrotide had superior 100-day survival, compared to best available treatments (38.2% vs. 25.0%). Although several studies of SOS/VOD in Korean patients have been performed after the implementation of HCT, most involved small number of pediatric patients. Recently, the Korean Society of Blood and Marrow Transplantation investigated the incidence of SOS/VOD in the Korean population, and several influential studies of adult patients were published. Here, we summarize recent issues regarding the mechanism, diagnosis, severity criteria, prevention, and treatments of SOS/VOD in Korean patients, as well as recent analyses of nationwide incidence.

Busulfan, melphalan, and bortezomib compared to melphalan as a high dose regimen for autologous hematopoietic stem cell transplantation in multiple myeloma: long term follow up of a novel high dose regimen

Melphalan at a dose of 200 mg/m² (MEL200) remains the standard high dose therapy before autologous stem cell transplantation (ASCT) for multiple myeloma (MM). Intensifying the high dose regimen has shown promising results. We report here 7-year follow up of our novel high dose regimen of busulfan and melphalan followed by bortezomib (BuMelVel). Forty-three MM patients received BuMelVel high dose therapy with pharmacokinetic adjusted busulfan. Outcomes were compared to a matched control cohort from the CIBMTR database (n = 162) receiving MEL200. The primary endpoint was progression free survival. Five year PFS was 47% v 30% (95% CI; 32-62) in favor or the BuMelVel group (95% CI; 23-37) (p = 0.05). In multivariate analysis for PFS, BuMelVel (HR 0.65; 95% CI 0.44-0.97)(p = 0.036) was predictive. Similar to recent reports of double alkylator therapy, although depth of response was similar between the BuMelVel group and MEL200, the BUMELVEL group experienced an improved PFS.

Exploratory analysis of intensified conditioning as first line treatment for patients with high risk multiple myeloma

Multiple myeloma has extremely heterogeneous outcomes. Among prognostic factors, t(4;14) and del(17p) are rare oncogenic events associated with very poor prognosis. In an exploratory case-control study, we compared the combination of Busulfan-Melphalan or TBI-Melphalan with high dose Melphalan as a conditioning regimen in a series of 48 patients with del(17p) or t(4;14). These regimens were preceded by a Bortezomib-containing induction. Progression-free survival (PFS) was the primary endpoint whereas overall survival (OS) and complete response (CR) rate were the secondary endpoints. Twenty consecutive cases of high-risk myeloma received a reinforced conditioning regimen of Busulfan 0.8 mg/kg x4/j IV from day-6 to day-3 pre- graft (BuMel) or total body irradiation (TBI) 12 Gy (TbiMel), having received Melphalan 140 mg/m² at day-2 pre-graft. These cases were matched to 28 controls treated with Melphalan 200 mg/m² at day-2 (Mel200). After intensification ± consolidation, with a median follow-up of 6.3 years, the CR rate was higher in the BuMel/TbiMel group (65% vs 50%, P = .006). No differences were observed between both groups in terms of PFS and OS (P = .96). PFS in patients with a del(17p) mutation tended to be superior in the BuMel/TbiMel group. Our exploratory study shows that reinforcing the intensification regimen with Busulfan or TBI does not seem to improve the prognosis associated to t(4;14) and del(17p) abnormalities.

Intravenous busulfan and melphalan versus high-dose melphalan as a conditioning regimen for early autologous stem cell transplantation in patients with multiple myeloma: a propensity score-matched analysis

We compared the efficacy and toxicity of busulfan and melphalan (BUMEL) and those of high-dose melphalan (HDMEL) as conditioning regimens for autologous stem cell transplantation (ASCT) in patients with multiple myeloma (MM) through a propensity score-matched analysis. No significant difference in the complete response and overall response rate after ASCT was observed between BUMEL and HDMEL. After a median follow-up of 37.3 months in the BUMEL group and 50.8 months in the HDMEL group, the median progression-free survival was calculated to be 32.9 months and 25.2 months (p = 0.995). With respect to non-hematologic toxicities, infections were more frequently reported in the BUMEL group (p < 0.001). Three patients who received BUMEL developed veno-occlusive disease (VOD), and all of them recovered without administration of defibrotide. In conclusion, BUMEL is an effective alternative conditioning regimen in terms of efficacy, but attention should be paid to toxicities.

Autologous stem cell transplantation in elderly patients with multiple myeloma in Korea: the KMM1807 study

Autologous stem cell transplantation (ASCT) is not frequently performed for elderly patients multiple myeloma (MM) in Korea, despite its being a standardized approach for young patients. Medical records of 150 patients from 15 Korean institutions who received ASCT at age ≥ 64 years were analyzed retrospectively. Patients included had symptomatic MM, and had received their first ASCT at age ≥ 64 following induction chemotherapy. The main outcome was the response after ASCT. Overall survival (OS) and progression-free survival (PFS) were also analyzed. Median time to ASCT was 6.3 months. Complete response plus stringent complete response rate increased from 36 (24.0%) to 105 (70.0%) after ASCT, and high-quality response (≥ very good partial response) increased from 96 (64.0%) to 125 (83.3%). With a median follow-up of 32.6 months after ASCT, 5-year OS and PFS were 59.7% and 22.8%, respectively. Febrile neutropenia occurred in 43.5%, and nausea (21.3%) and stomatitis (13.2%) were common grade 3-4 non-hematologic adverse events. Of 44 deaths, disease progression (n = 23) was the most common cause of mortality, followed by infection (n = 13). Treatment-related death occurred in four cases (2.7%). ASCT is an effective and safe option for elderly MM patients and is associated with superior clinical outcomes.

Outcome of Multiple Myeloma with Chromosome 1q Gain and 1p Deletion after Autologous Hematopoietic Stem Cell Transplantation: Propensity Score Matched Analysis

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-.

Stem-cell transplantation in multiple myeloma: how far have we come?

High-dose therapy (HDT) and autologous stem-cell transplantation (ASCT) has historically been an essential part of multiple myeloma (MM) management since early studies demonstrated its efficacy in relapsed disease, and subsequent phase III trials demonstrated better responses and improved survival with this modality compared with standard chemotherapy. With further advances in the MM treatment landscape, including the development of potent novel agents, there has been an increasing debate around various aspects of ASCT, including the optimal timing, role of single versus tandem ASCT, and the practice of consolidation and maintenance therapy post-ASCT. Routine incorporation of the novel agents at each of the treatment phases, induction, consolidation when used, and maintenance has led to better responses as reflected by increasing rates of minimal residual disease (MRD) negativity, longer progression-free survival (PFS) with improvement in overall survival (OS) and in some of the trials. The phase III trials over the last decade have provided significant clarity on the current approach, and have raised important questions regarding the applicability of this modality in all patients. This review aims to summarize the latest literature in the field and discusses how these findings impact the practice of ASCT today.