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

Busulfan, melphalan and carfilzomib high-dose chemotherapy and autologous haematopoietic stem cell transplantation in multiple myeloma

The standard of care for fit, newly diagnosed multiple myeloma patients includes induction therapy followed by consolidative high-dose chemotherapy with melphalan and autologous stem cell transplant (AHSCT). Intensified preparative regimens, such as busulfan and melphalan (BuMel), have shown promise to lengthen progression-free survival (PFS). We previously reported that the addition of bortezomib to BuMel improved PFS compared to melphalan alone in CIBMTR-matched controls. We now integrate the second-generation protease inhibitor, carfilzomib, before and after BuMel (BuMelCar) in a phase I/II trial with carfilzomib. Patients with NDMM, relapsed/refractory MM (RRMM) and those failing prior AHSCT were eligible. Primary end-points were safety and tolerability. Secondary end-points included minimal residual disease negativity rates, PFS and OS. The study enrolled 19 patients. 73% were high risk either due to R-ISS III status, adverse genetics or relapsed after prior AHSCT. The maximum tolerated dose (MTD) of carfilzomib was determined to be 36 mg/m2. Noted grade 3 toxicities were febrile neutropenia (79%), mucositis (21%) and diarrhoea (16%). The 2-year PFS for the whole cohort and MTD was 89% and 100% respectively. 80% of all patients and 82% of patients in the MTD cohort achieved MRD negativity. Further studies regarding this regimen are planned.

Busulfan and thiotepa as a conditioning regimen for autologous stem cell transplantation in patients with multiple myeloma: A study of the Korean Multiple Myeloma Working Party (KMMWP-1801 study)

Background

Autologous stem cell transplantation (ASCT) remains the standard of care for patients with newly diagnosed multiple myeloma (MM). Several attempts to improve the efficacy of conditioning regimens have been conducted in MM, but no more effective regimen than conventional high-dose melphalan has been introduced.

Objective

In this study, the efficacy and toxicity of busulfan and thiotepa (BuTT) and those of high-dose melphalan (HD-MEL) were compared retrospectively as a conditioning regimen for ASCT in patients with MM.

Study design

Included in the analysis were 114 patients who received BuTT and 114 patients who received HD-MEL treatment between March 2008 and May 2020. The BuTT regimen consisted of intravenous thiotepa 5 mg/kg once a day from days 7 to 6, followed by intravenous busulfan 3.2 mg/kg once a day from days 5 to 3. The HD-MEL conditioning regimen consisted of melphalan 100 mg/m² once a day from days 3 to 2.

Results

The overall response rate after ASCT did not differ between BuTT and HD-MEL (94.7% in BuTT vs. 97.4% in HD-MEL, p = 0.333). After a median follow-up of 47.6 months, progression-free survival (PFS) tended to be longer in the BuTT group (median PFS, 41.5 months vs. 30.3 months; hazard ratio (HR), 0.706; 95% confidence interval (CI), 0.497–1.004, p = 0.053). In the subgroup analysis of patients who did not proceed to maintenance or consolidation treatment after ASCT, the difference in PFS became more significant (median PFS, 41.5 months vs. 24.4 months; HR, 0.621; 95% CI, 0.388–0.993; p = 0.047). Additionally, the BuTT group had fewer adverse events, such as grade 3 or 4 stomatitis and diarrhea, than the HD-MEL group (stomatitis, 10.5% vs. 23.7%, p = 0.013; diarrhea, 10.5% vs. 25.4%, p = 0.005). There was no difference in the occurrence of venous-occlusive disease (2.6% in BuTT vs. 0.9% in HD-MEL, p = 0.622).

Conclusion

Our study results suggest that BuTT is an effective alternative conditioning regimen with reduced toxicity in patients with newly diagnosed MM.

Long-term outcomes of busulfan plus melphalan-based versus melphalan 200 mg/m2 conditioning regimens for autologous hematopoietic stem cell transplantation in patients with multiple myeloma: a systematic review and meta-analysis

Background

High-dose melphalan (HDMEL, 200 mg/m²) is considered as the standard conditioning regimen for autologous hematopoietic stem cell transplantation (auto-HSCT) in multiple myeloma (MM). However, whether the combination of melphalan with busulfan (BUMEL) conditioning outperforms HDMEL remains controversy. Accordingly, a systematic review and meta-analysis was carried out to compare the outcomes of HDMEL and BUMEL-based conditioning regimens in newly diagnosed MM patients having undergone auto-HSCT.

Methods

A systematic literature search was conducted in PubMed, Embase and Cochrane Library database until July 31, 2021, to identify all eligible studies comparing progression-free survival (PFS), overall survival (OS), optimal treatment response after auto-HSCT, duration of stem cell engraftment and incidence of toxic events between patients undergoing BUMEL-based and HDMEL conditioning regimens. Hazard ratio (HR), mean difference (MD) or odds ratio (OR) corresponding to 95% confidence interval (CI) were determined to estimate outcomes applying RevMan 5.4 software. Publication biases were assessed by performing Egger’s test and Begg’s test by Stata 15 software.

Results

Ten studies with a total of 2855 MM patients were covered in the current meta-analysis. The results of this study demonstrated that patients having received BUMEL-based regimen was correlated with longer PFS (HR 0.77; 95% CI 0.67~0.89, P = 0.0002) but similar OS (HR 1.08; 95% CI 0.92~1.26, P = 0.35) compared with those having received HDMEL. The differences of best treatment response after auto-HSCT and duration of neutrophil or platelet engraftment did not have statistical significance between the two groups of patients. With respect to adverse effects, the patients in BUMEL-based group were less frequently subject to gastrointestinal toxicity while the patients in HDMEL group less often experienced mucositis and infection. No significant difference was observed in hepatic toxicity between the two groups of patients.

Conclusions

In the present study, BUMEL-based conditioning was identified as a favorable regimen for a better PFS and equivalent OS as compared with HDMEL, which should be balanced against higher incidences of mucositis and infection. BUMEL-based conditioning is likely to act as an alternative strategy to more effectively improve auto-HSCT outcomes in MM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02313-z.

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 plus melphalan versus melphalan alone conditioning regimen after bortezomib based triplet induction chemotherapy for patients with newly diagnosed multiple myeloma

Background:

High dose melphalan (HDMEL) is considered the standard conditioning regimen for autologous stem cell transplantation (ASCT) in multiple myeloma (MM) patients. Recent studies showed superiority of busulfan plus melphalan (BUMEL) compared to HDMEL as a conditioning regimen. We compared the efficacy of HDMEL and BUMEL in newly diagnosed Asian MM patients, who are often underrepresented.

Methods:

This is a single-center, retrospective study including MM patients who underwent ASCT after bortezomib-thalidomide-dexamethasone (VTD) triplet induction chemotherapy between January 2015 and August 2019.

Result:

In the end, 79 patients in the HDMEL group were compared to 31 patients in the BUMEL group. There were no differences between the two groups with regards to sex, age at ASCT, risk group, and stage. The HDMEL group showed better response to pre-transplant VTD compared to BUMEL, but after ASCT the BUMEL group showed better overall response. In terms of progression-free survival (PFS), although BUMEL showed trends towards better PFS regardless of pre-transplant status and age, the difference did not reach statistical significance. The BUMEL group more often experienced mucositis related to chemotherapy, but there was no difference between the two groups with regards to hospitalization days, cell engraftment, and infection rates.

Conclusion:

BUMEL conditioning deserves attention as the alternative option to HDMEL for newly diagnosed MM patients, even in the era of triplet induction chemotherapy. Specifically, patients achieving very good partial response (VGPR) or better response with triplet induction chemotherapy might benefit the most from BUMEL conditioning. Tailored conditioning regimen, based on patient’s response to induction chemotherapy and co-morbidities, can lead to better treatment outcomes.