Busulfan and melphalan conditioning is superior to melphalan alone in autologous stem cell transplantation for high-risk MM

Historical Perspective of High-Dose Therapy Followed by Autologous Stem Cell Transplantation in Multiple Myeloma

BACKGROUND

High-dose therapy (HDT) followed by autologous stem cell transplantation (ASCT) has become part of standard of care (SOC) in newly diagnosed multiple myeloma. In this review, we provide a historical perspective on ASCT since its introduction in the 1990s.

SUMMARY

Overall survival (OS) benefit for HDT followed by ASCT was demonstrated in studies comparing HDT with ASCT to standard-dose therapy (SDT) before the era of novel agents. Conditioning is done with melphalan 200 mg/m2. Lower doses (MEL140, MEL150) for older patients with comorbidities are safe and have comparable results. The addition of busulfan to melphalan improves progression-free survival (PFS) but not OS. HDT with ASCT after induction with novel agents prolongs PFS but not OS compared to SDT alone. The benefit is more evident in patients with high-risk cytogenetics. Mobilization can be achieved with granulocyte colony-stimulating factor alone, but is improved with the addition of chemotherapy. Plerixafor reduces mobilization failure and enables sufficient stem cell collection after induction with novel agents. ASCT is safe with a low rate of mortality (1%), and selected patients can be managed as outpatients.

KEY MESSAGES

HDT followed by ASCT remains part of SOC due to its PFS benefit and relatively low toxicity.

Optimizing high dose melphalan

Melphalan, has been a major component of myeloma therapy since the 1950s. In the context of hematopoietic cell transplantation (HCT), high dose melphalan (HDM) is the most common conditioning regimen used due to its potent anti-myeloma effects and manageable toxicities. Common toxicities associated with HDM include myelosuppression, gastrointestinal issues, and mucositis. Established approaches to reduce these toxicities encompass dose modification, nausea prophylaxis with 5HT3 receptor antagonists, cryotherapy, amifostine use, and growth factors. Optimization of melphalan exposure through personalized dosing and its combination with other agents like busulfan, or bendamustine show promise. Propylene glycol-free melphalan (Evomela) represents a novel formulation aiming to enhance drug stability and reduce adverse effects. This review explores strategies to enhance the efficacy and mitigate the toxicity of HDM in multiple myeloma. Future directions involve exploring these strategies in clinical trials to improve the safety and efficacy of HDM, thereby enhancing outcomes for multiple myeloma patients undergoing autologous HCT.

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.

First-line treatment of multiple myeloma in both transplant and non-transplant candidates

INTRODUCTION

The last decade's progress in the treatment of newly diagnosed multiple myeloma has relied on the synergistic combination of agents with different mechanisms of action, basically proteasome inhibitors, immunomodulatory agents, and monoclonal antibodies, in order to achieve the deepest possible response early in the course of treatment. Following induction, several therapeutic strategies aim to improve and maintain response.

AREAS COVERED

The manuscript reviews available data for the treatment of newly diagnosed multiple myeloma patients with a focus on most recent induction and maintenance combinations and the still important role of autologous stem transplantation. Future perspectives in the light of initial results from ongoing clinical trials are also addressed.

EXPERT OPINION

Remarkable progress has been made in myeloma treatment due to the integration of immunomodulators, proteasome inhibitors, monoclonal antibodies, and high dose therapy in the frontline setting. Upfront therapy may be further improved intensifying induction combinations, adapting high dose therapy and consolidation strategies to the patient's profile, improving maintenance in high-risk individuals, or limiting maintenance duration in those with a better prognosis. Evidence needs to be reviewed, taking into account the therapeutic objectives at each treatment stage and patient specific risk factors.

Perspectives on the Risk-Stratified Treatment of Multiple Myeloma

The multiple myeloma treatment landscape has changed dramatically. This change, paralleled by an increase in scientific knowledge, has resulted in significant improvement in survival. However, heterogeneity remains in clinical outcomes, with a proportion of patients not benefiting from current approaches and continuing to have a poor prognosis. A significant proportion of the variability in outcome can be predicted on the basis of clinical and biochemical parameters and tumor-acquired genetic variants, allowing for risk stratification and a more personalized approach to therapy. This article discusses the principles that can enable the rational and effective development of therapeutic approaches for high-risk multiple myeloma.

Pathogenesis and treatment of multiple myeloma

Multiple myeloma (MM) is the second‐ranking malignancy in hematological tumors. The pathogenesis of MM is complex with high heterogeneity, and the development of the disease is a multistep process. Chromosomal translocations, aneuploidy, genetic mutations, and epigenetic aberrations are essential in disease initiation and progression. The correlation between MM cells and the bone marrow microenvironment is associated with the survival, progression, migration, and drug resistance of MM cells. In recent decades, there has been a significant change in the paradigm for the management of MM. With the development of proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, chimeric antigen receptor T‐cell therapies, and novel agents, the survival of MM patients has been significantly improved. In addition, nanotechnology acts as both a nanocarrier and a treatment tool for MM. The properties and responsive conditions of nanomedicine can be tailored to reach different goals. Nanomedicine with a precise targeting property has offered great potential for drug delivery and assisted in tumor immunotherapy. In this review, we summarize the pathogenesis and current treatment options of MM, then overview recent advances in nanomedicine‐based systems, aiming to provide more insights into the treatment of MM.

KRD vs. VRD as induction before autologous hematopoietic progenitor cell transplantation for high-risk multiple myeloma

Bortezomib, lenalidomide, and dexamethasone (VRD) induction is standard prior to autologous hematopoietic cell transplantation (auto-HCT) in newly diagnosed, high-risk multiple myeloma (ND-HRMM). Carfilzomib (K) is another proteasome inhibitor approved for MM. In this single-center, retrospective analysis, we compared outcomes in ND-HRMM with pre-transplant KRD or VRD induction. High-risk was defined by t(4:14), t(14:16), 1q21 gain/amplification, or del(17p). Primary endpoints were progression-free (PFS) and overall survival (OS). Of 121 ND-HRMM patients, 63 received KRD, and 58 received VRD. Post-induction, complete (CR), very good partial (VGPR), partial response (PR), and overall response (ORR) rates were 23.8%/49.2%/25.4%/98.4% with KRD, and 19%/46.6%/27.6%/93.1% with VRD. At day 100 post-auto-HCT, these were 38.1%/42.9%/19%/100% with KRD, versus 35.1%/49.1%/12.3%/94.8% with VRD. Pre-auto-HCT, 11 (18.3%) KRD and 7 (12.5%) VRD patients had minimal residual disease (MRD)-negative CR (p = 0.45). Post-auto-HCT, 14 (41.2%) and 13 (43.3%) patients had MRD-negative CR (p = 1.000). Median PFS was 38.2 (95%CI 28.7-NA) and 45.9 months (95%CI 43.2-NA) for KRD and VRD, respectively (p = 0.25). Respective 3-year PFS and OS were 53.5% (95%CI 41.1-69.6) and 95.2% (95%CI 90-100) for KRD and 64% (95%CI 51.6-79.5) and 84.2% (95%CI 73.5-96.3, p = 0.30) for VRD. Overall, KRD induction pre-auto-HCT does not improve outcomes. Prospective, randomized studies are needed to confirm these findings.

Bortezomib and high-dose melphalan conditioning regimen in frontline multiple myeloma: an IFM randomized phase 3 study

High-dose melphalan (HDM) and transplantation are recommended for eligible patients with multiple myeloma. No other conditioning regimen has proven to be more effective and/or safer. We previously reported in a phase 2 study that bortezomib can safely and effectively be combined with HDM (Bor-HDM), with a 32% complete response (CR) rate after transplantation. These data supported a randomized phase 3 trial. Randomization was stratified according to risk and response to induction: 300 patients were enrolled, and 154 were allocated to the experimental arm (ie, arm A) with bortezomib (1 mg/m2 intravenously [IV]) on days -6, -3, +1, and +4 and melphalan (200 mg/m2 IV) on day -2. The control arm (ie, arm B) consisted of HDM alone (200 mg/m2 IV). There were no differences in stringent CR + CR rates at day 60 posttransplant (primary end point): 22.1% in arm A vs 20.5% in arm B (P = .844). There were also no differences in undetectable minimum residual disease rates: 41.3% vs 39.4% (P = .864). Median progression-free survival was 34.0 months for arm A vs 29.6 months for arm B (adjusted HR, 0.82; 95% CI, 0.61-1.13; P = .244). The estimated 3-year overall survival was 89.5% in both arms (hazard ratio, 1.28; 95% CI, 0.62-2.64; P = .374). Sixty-nine serious adverse events occurred in 18.7% of Bor-HDM-treated patients (vs 13.1% in HDM-treated patients). The proportion of grade 3/4 AEs was similar within the 2 groups (72.0% vs 73.1%), mainly (as expected) blood and gastrointestinal disorders; 4% of patients reported grade 3/4 or painful peripheral neuropathy in arm A (vs 1.5% in arm B). In this randomized phase 3 study, a conditioning regimen with Bor-HDM did not improve efficacy end points or outcomes compared with HDM alone. The original trial was registered at www.clinicaltrials.gov as #NCT02197221.

Real-world long-term outcomes in multiple myeloma with VRD induction, Mel200-conditioned auto-HCT, and lenalidomide maintenance

Standard-of-care for newly-diagnosed, autologous hematopoietic stem cell transplantation (auto-HCT)-eligible, multiple myeloma (MM) patients includes bortezomib, lenalidomide, and dexamethasone (VRD) induction followed by melphalan 200 mg/m² (Mel200)-conditioned auto-HCT and lenalidomide maintenance. We completed a retrospective case series assessing outcomes of 187 MM patients who received this regimen at our institution. The 100-day non-relapse mortality incidence was zero. Before auto-HCT, 9.6 and 52.9% of patients achieved a complete response (CR) or ≥ very good partial response (VGPR), respectively. At day-100 post-transplant, 29.4 and 74.9% had achieved a CR/stringent-CR (sCR) or ≥ VGPR, respectively. At the last evaluation, 57.2% of patients had CR/sCR and 87.1% had ≥ VGPR. Median follow-up, progression-free survival (PFS), and overall survival (OS) were 63.2, 50, and 101.7 months, respectively. The 5-year PFS and OS were 43.1 and 79%. High-risk cytogenetics was associated with worse outcomes. This study illustrates that VRD induction, Mel200-conditioned auto-HCT, and lenalidomide maintenance are associated with good outcomes in MM.