BU and CY as conditioning regimen for autologous transplant in patients with multiple myeloma

Busulfan/Cyclophosphamide Compared with Melphalan as a Conditioning Regimen for Autologous Transplantation of Multiple Myeloma: A Long-Term Assessment

BACKGROUND

Melphalan was poorly available in mainland China. The aim of this study is to explore the dose-adjusted busulfan/cyclophosphamide (BU/CY) as an alternative regimen in auto stem cell transplantation (ASCT) for multiple myeloma (MM).

METHODS

A total of 105 newly diagnosed MM patients undergoing ASCT during May 2012 and August 2017 were retrospectively analyzed. The BU/CY regimen was applied to 64 patients. Busulfan (9.6 mg/kg or 8.0 mg/kg in total) and cyclophosphamide (3.6 g/m2 or 3.0 g/m2 in total) were administered according to the creatinine clearance rate (CCR). A high-dose melphalan (HDMEL) regimen (200 mg/m2) was given to the other 41 patients.

RESULTS

At a median follow-up of 65 (1~119) months, estimated overall survival (OS) and progression-free survival (PFS) at 104 months in the BU/CY and HDMEL groups were 35.6% vs. 20.5% (p = 0.263) and 20.2% vs. 2.4% (p = 0.035), respectively. The median overall survival (OS) and PFS of the HDMEL and BU/CY groups were 55 vs. 70.5 months and 26 vs. 46.5 months, respectively. In multivariate analysis, the BU/CY regimen was found to be the only protective factor for PFS. No lethal toxicity was found in the BU/CY group, and treatment-related mortality (TRM) in 100 days was similar to the HDMEL group.

CONCLUSIONS

MM patients may also benefit from the dose-adjusted BU/CY regimen.

Busulfan plus melphalan versus high-dose melphalan as a conditioning regimen for autologous stem cell transplantation in multiple myeloma with high-risk features (KMM 2015)

Despite the development of effective agents for multiple myeloma (MM), the management of patients with high-risk MM (HRMM) is challenging. High-dose treatment followed by autologous stem cell transplantation (ASCT) is regarded as upfront treatment for transplant-eligible patients with HRMM. In the present study, we retrospectively investigated the efficacies of two conditioning regimens for upfront ASCT in newly diagnosed patients with MM and high-risk features: high-dose melphalan (HDMEL; 200 mg/m²) and busulfan plus melphalan (BUMEL). In total, 221 patients underwent ASCT between May 2005 and June 2021; among these 221 patients, 79 had high-risk cytogenetic abnormalities. In patients with high-risk cytogenetics, BUMEL showed a tendency toward longer overall survival (OS) and progression-free survival (PFS) compared to HDMEL (median OS; not reached vs. 53.2 months; P = 0.091, median PFS; not reached vs. 31.7 months; P = 0.062). Additionally, multivariate analysis revealed that BUMEL was significantly associated with PFS (hazard ratio = 0.37, 95% confidence interval = 0.15-0.89, P = 0.026). We compared BUMEL with HDMEL in patients with other high-risk features, such as high lactate dehydrogenase level, extramedullary disease, and poor response to frontline therapy. Notably, among patients with less than very good partial response (VGPR) to frontline therapy, median PFS was significantly longer in the BUMEL group than in the HDMEL group (55.1 vs. 17.3 months, respectively; P = 0.011). These findings indicate that BUMEL may be an effective conditioning regimen for upfront ASCT in MM patients with high-risk cytogenetics; BUMEL may be more appropriate than HDMEL for patients with less than VGPR to frontline therapy.

Autologous stem cell transplantation in multiple myeloma patients with renal impairment

Renal impairment (RI) used to exclude multiple myeloma (MM) patients from autologous stem cell transplantation (ASCT) for safety concerns. Here, we retrospectively reviewed 34 consecutively transplanted patients with creatinine clearance < 60 ml/min at ASCT in recent 5 years at our institution. Busulfan/cyclophosphamide and high-dose melphalan were both employed as conditioning regimens. We found 62% grade 1-2 oral mucositis, 12% grade 3 oral mucositis, 48% grade 3 infection, 8% grade ≥ 4 infection, 50% grade 1 transient creatinine increase, 15% cardiac adverse events, and 12% engraftment syndrome. One case of secondary platelet graft failure and 1 case of transplantation-related mortality were observed. Interleukin-6 concentration was elevated among patients with increased body temperature and/or N-terminal pro-brain natriuretic peptide during engraftment, and close monitoring of these markers may help to predict susceptibility to cardiac events and engraftment syndrome. Adverse events occurred frequently, but the majority were manageable in this cohort. ASCT would further deepen the anti-myeloma efficacy and slightly ameliorated renal function. With a median follow-up of 26.2 months post transplantation (range: 1.6-74.8 months), the median progression-free survival (PFS) and overall survival (OS) post-transplantation of patients undergoing first-line transplantation were not reached; the median PFS post-transplantation of patients undergoing rescue transplantation was 19.2 months and the median OS was not reached.

Adding bendamustine to melphalan before ASCT improves CR rate in myeloma vs. melphalan alone: A randomized phase-2 trial

Definite cure remains exceptional in myeloma patients even after high-dose chemotherapy (HDCT) with melphalan (Mel) and autologous stem cell transplantation (ASCT). Thus, improving efficacy of HDCT in MM remains an unresolved issue. This randomized phase II trial compared standard 200 mg/m² Mel HDCT to experimental HDCT with 200 mg/m² bendamustine, given both at days −4 and −3, combined with 100 mg/m² melphalan at days −2 and −1 (BenMel) before ASCT as first-line consolidation in myeloma patients. The primary endpoint aimed to identify at least a 15% improvement in the complete remission rate (stringent CR + CR) after HDCT with BenMel compared with Mel alone. A total of 120 MM patients were 1:1 randomized. The rate of sCR/CR after ASCT was higher in BenMel than in Mel treated patients (70.0% vs. 51.7%; p = 0.039). Three patients in the BenMel group (5.0%) had reversible acute renal insufficiency compared with none in Mel patients. Minimal residual disease negativity (<10-5) by flow cytometry was observed in 26 (45.6%) BenMel patients and 22 (37.9%) in the Mel group (p = 0.375). Our data suggest that BenMel HDCT is safe and improves the sCR/CR rate compared with standard Mel alone.

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.

A Phase 1 Study of Intravenous Busulfan as a Conditioning Regimen for Multiple Myeloma

The efficacy of melphalan (MEL) 140 mg/m² pre-transplant conditioning versus MEL 200 mg/m² for the elderly is still debated. We hypothesized that single-agent intravenous busulfan (BU) would show significant anti-myeloma efficacy and be better tolerated by elderly patients. A prospective 3+3 dose escalation study enrolled symptomatic multiple myeloma (MM) patients 65 years or older with SWOG performance 0–2 for treatment with intravenous BU pre-transplant at different administration levels. The primary objective was to determine the maximum tolerated dose (MTD) of BU that could be safely given over the least number of days. All patients, except one, received maintenance treatment post-transplant, mostly for 2 years. We enrolled 13 patients, mean age of 73 years (range 68–80). Pharmacokinetic analysis showed no greater than 2% accumulation in the 13 patients, confirming a lack of accumulation in the multi-dose regimen. No deaths occurred in the peri-transplant period. Grade 3/4 adverse effects were hematological, no dose-limiting toxicity was observed and MTD was not reached. Three patients developed grade 3 mucositis but none developed veno-occlusive disease. Ten (77%) patients achieved a complete remission (CR) post-transplant with a remarkably long average time to best response of 6.7 months (range: 6–14 m), and two attained a partial response. Median overall survival was 84 months (95% CI, 21–104) and the median progression-free survival was 60 months (95% CI, 9–93). Our results suggest that IV BU could be an alternative conditioning regimen to MEL 140 in elderly patients with MM, and supports future randomized trials.

Addition of doxycycline to ciprofloxacin for infection prophylaxis during autologous stem cell transplants for multiple myeloma

BACKGROUND

The most commonly used antibacterial prophylaxis during autologous stem cell transplants (ASCT) for multiple myeloma (MM) involves a fluoroquinolone, such as ciprofloxacin or levofloxacin. We assessed the impact of adding doxycycline to ciprofloxacin as routine antibacterial prophylaxis in these patients.

METHODS

We retrospectively reviewed electronic medical records and our ASCT database to analyze rates and types of bacterial infections in MM patients who underwent ASCT in our institution.

RESULTS

Among 419 patients, 118 received ciprofloxacin alone (cipro group), and 301 ciprofloxacin and doxycycline (cipro-doxy group). Neutropenic fever (NF) developed in 63 (53%) and 108 (36%) patients of the cipro and cipro-doxy groups, respectively (p = 0.010). The number of documented bacteremic episodes was 13 (11%) and 14 (4.7%) in the two groups, respectively (p = 0.017). Antimicrobial resistance and Clostridium difficile infections were uncommon. Transplant-related mortality was 1% in both groups.

CONCLUSIONS

The addition of doxycycline to standard prophylaxis with ciprofloxacin seems to reduce the number of NF episodes and documented bacterial infections in patients with MM undergoing ASCT, without increasing rate of serious complications.

Efficacy and safety of busulfan-based conditioning regimens for multiple myeloma

Multiple myeloma is a malignancy of B cells characterized by accumulation of abnormal plasma cells in the bone marrow. In the past 20 years, the use of high-dose therapies and novel agents has resulted in significant and meaningful improvements in survival. Autologous stem cell transplantation (auto-SCT) following a high-dose melphalan-conditioning regimen represents the standard of care for younger patients as well as older patients with a good performance status. A number of strategies have been proposed to improve the outcome of auto-SCTs, including the incorporation of new agents such as thalidomide, lenalidomide, and bortezomib into the induction regimen administered before auto-SCT; the administration of maintenance therapy after auto-SCT; the incorporation of novel agents into chemotherapeutic regimens after transplantation as consolidation therapy; and the use of reduced-intensity allogeneic transplantation after an initial autograft. Although these approaches have demonstrated some success in improving responses after auto-SCT, none of these strategies are curative. An additional strategy to improve outcomes after auto-SCT is to enhance the immediate pretransplant conditioning regimens by either increasing the dose of melphalan or by incorporating novel agents, such as busulfan. This literature review focuses on the efficacy and safety of busulfan-based conditioning regimens for auto-SCT in patients with multiple myeloma.

Multiple myeloma preparative regimens for high-dose therapy and autologous transplantation: what's new?

High-dose chemotherapy and autologous stem cell transplantation remains a standard procedure in relatively young and selected older patients with multiple myeloma. High-dose melphalan has remained the chemotherapeutic agent of choice based on earlier prospective randomized trials. Despite investigations involving different combinations of chemotherapeutics, radiation and novel agents with and without melphalan, none of these alternative preparative regimens have demonstrated superiority to high-dose melphalan used as a single agent in multiple published studies. In this article, we review the published literature regarding preparative regimens used in patients with multiple myeloma undergoing autologous stem cell transplantation.