Pharmacokinetics of High-Dose Propylene Glycol-Free Melphalan in Multiple Myeloma Patients Undergoing Autologous Hematopoietic Cell Transplantation

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.

Melphalan on day -1 versus day -2 in patients with plasma cell disorders undergoing autologous stem cell transplant

High-dose melphalan-based autologous stem cell transplant (ASCT) remains a standard of care for plasma cell disorders (PCDs). Currently, there is variability in the literature surrounding the timing of melphalan administration to avoid potential cytotoxic effects, although the administration has been safely proposed when given at least 8 hours prior to stem cell infusion. The objectives of this study were to assess differences in safety and efficacy outcomes between day -1 and day -2 single-dose melphalan administration in patients undergoing ASCT for PCDs. A retrospective chart review was performed at our institution comparing patients receiving melphalan on day -1 to an equal number of patients receiving melphalan on day -2. The primary endpoint was time to neutrophil engraftment from stem cell infusion. Univariate analyses were performed. Mean time to neutrophil engraftment from stem cell infusion was identical at 10.7 days for both cohorts (p = 0.88). Mean time to platelet engraftment from stem cell infusion was shorter with day -1 administration (17.4 vs. 18.6 days, p = 0.06). Mean time to neutrophil and platelet engraftment from melphalan infusion were significantly shorter with day -1 administration. Similar outcomes were observed for length of hospitalization, infection- and mucositis-related toxicities, hematologic response, transplant-related mortality, and overall survival. Our findings show no difference in time to neutrophil engraftment from stem cell infusion and a trend toward shorter time to platelet engraftment with day -1 administration. Based on our study, day -1 melphalan administration is an acceptable and safe practice.

Comparison of Patient Outcomes With Two Different Formulations of Melphalan as Conditioning Chemotherapy for Autologous Hematopoietic Cell Transplantation in Multiple Myeloma

BACKGROUND

High-dose melphalan (HDM) with autologous hematopoietic cell transplantation (AHCT) after induction chemotherapy is considered standard of care in transplant-eligible patients with newly-diagnosed multiple myeloma (MM). Alkeran melphalan has propylene glycol as a solvent (PG-mel) while Evomela utilizes a propylene glyclol-free formulation (PGF-mel). We evaluated the differences in efficacy and safety of the 2 formulations as there are no prospective head-to-head trials.

METHODS

We retrospectively reviewed the medical records of all 259 consecutive MM patients who received PGF-mel as part of HDM-AHCT at The Ohio State University (OSU). The comparator group was the preceding 255 patients who received PG-mel.

RESULTS

Baseline patient characteristics were similar between the 2 groups. Post-AHCT rates of relapse were comparable in the PG-mel and PGF-mel groups. Some adverse events were observed at a higher frequency in the PG-mel group compared to the PGF-mel group (grade ≥ 2 mucositis, febrile neutropenia, other infectious complications, and acute renal insufficiency). Time to neutrophil engraftment was slightly longer in the PG-mel group while time to platelet engraftment was longer in PGF-mel group. Red cell transfusion requirement was higher with the use of PG-mel but not platelet transfusion. Duration of hospitalization was slightly shorter with PGF-mel but readmission rates within 30 days of discharge were higher.

CONCLUSION

Considering possible confounding factors could possibly account for observed differences in some adverse events, the comparable treatment responses, and difference in cost of the 2 formulation, The OSU reverted to PG-mel as the preferred formulation for HDM-AHCT in MM.

A Review of Propylene Glycol-free Melphalan Conditioning for Hematopoietic Cell Transplantation for Multiple Myeloma and Light Chain Amyloidosis

Autologous hematopoietic cell transplantation (AHCT) remains a standard therapeutic option for patients with multiple myeloma (MM). Outcomes have improved for this patient group after first AHCT, with the use of novel agents in induction, as well as post-transplantation maintenance. High-dose melphalan remains the gold standard as the conditioning regimen for MM. Traditional melphalan is a lyophilized formulation that after reconstitution has insufficient chemical stability and water solubility, thus requiring the addition of propylene glycol to act as a cosolvent to improve these characteristics. After the reconstitution of melphalan with propylene glycol-containing solution, impurities can develop within 30 minutes, and if further dilution occurs, the potency of melphalan diminishes. Propylene glycol is associated with a spectrum of toxicities that can be dose limiting. Evomela is a propylene glycol-free melphalan (PGF-Mel) that at a high dose of 200 mg/² (100 mg/m²/d for 2 days) is approved for conditioning before AHCT in MM patients. Once reconstituted by directly dissolving in saline solution, PGF-Mel solution can be stored in the vial for up to 1 hour at room temperature or for up to 24 hours at refrigerated temperature (2° to 8°C) with no significant degradation. The demonstrated stability, up to 24 hours at room temperature, results in reduced handling requirements and increased convenience and flexibility of administration. Since its approval, Evomela has been the subject of several retrospective and investigator-initiated studies. This review summarizes the prospective and real-world evidence on practical aspects of PGF-Mel and critically appraises the available data and its clinical implications.

Propylene Glycol-Free Melphalan versus PG-Melphalan as Conditioning for Autologous Hematopoietic Cell Transplantation for Myeloma

High-dose melphalan (Mel) conditioning before autologous hematopoietic cell transplantation (autoHCT) is standard of care for patients with transplantation-eligible multiple myeloma. The traditional lyophilized Mel formulation has inadequate solubility and stability after reconstitution, leading to the use of propylene glycol (PG) as a solubilizing agent. A newer PG-free Mel preparation (Evomela) uses beta cyclodextrin captisol as a solubilizing agent and was approved by the United States Food and Drug Administration as a conditioning agent based on a single-phase IIb study showing bioequivalence. We compared the outcomes of consecutive patients with myeloma undergoing autoHCT using the 2 formulations of Mel for conditioning as our center switched from using the older formulation (PG-Mel) to the newer one (PGF-Mel). Of 294 autoHCT recipients, 162 received PG-Mel conditioning and 132 received PGF-Mel conditioning. The PGF-Mel group was older and had a lower average Karnofsky Performance Status score. PGF-Mel was associated with faster neutrophil recovery (median, 12 days versus 13 days; P < .001), fewer grade 3-4 infections within 30 days of autoHCT (1.5% versus 8.0%; P = .048), and a lower 30-day rehospitalization rate (6.8% versus 17.9%; P = .04), as confirmed by propensity-weighted analysis. No significant between-group differences were detected in mucositis, organ toxicity, myeloma response, or 100-day mortality.

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.

Pretransplant hemoglobin and creatinine clearance correlate with treatment-free survival after autologous stem cell transplantation for multiple myeloma

Melphalan is given at a dose of 200 mg/m² (Mel200) prior to ASCT for multiple myeloma (MM). Pharmacokinetic (PK) studies show a high degree of interpatient variability. We aimed to test the impact of clinical factors previously shown to affect melphalan PK such as hemoglobin (Hgb), fat-free mass (FFM), and creatinine clearance (CrCl) on outcomes. Median Hgb (from day -2 to -1) and FFM were grouped as low or high relative to their sample medians, and CrCl was divided into ≥60 or <60 ml/min. In 133 MM patients, median TFS (defined as time from ASCT to initiation of next subsequent line of therapy or death) was longer in patients with lower Hgb (35 vs. 16 months, p = 0.02). Patients with both lower Hgb and CrCl experienced longer TFS compared to those with higher Hgb and CrCl (35 vs. 13 months, p = 0.03). In multivariate analysis, lower hemoglobin, lower CrCl, and a combined low hemoglobin and CrCl were strongly associated with improved TFS. Patients with a lower hemoglobin or creatinine clearance experienced significantly more toxicity. We show for the first time that Hgb and CrCl are important predictors of outcomes after Mel200. PK-directed melphalan dosing may be beneficial in achieving optimal outcomes.

Comparable outcomes using propylene glycol-free melphalan for autologous stem cell transplantation in multiple myeloma

Autologous stem cell transplantation (ASCT) remains a mainstay in the treatment of multiple myeloma (MM). While the procedure is generally safe, toxicities associated with high-dose melphalan conditioning are common and significantly affect patient quality of life. Recently, a propylene glycol-free melphalan formulation (PG-free MEL; Evomela^®) was approved by the United States Food and Drug Administration as an ASCT conditioning regimen for MM. PG-free MEL is more soluble and stable than propylene glycol-solubilized melphalan (PG-solubilized MEL; Alkeran^®). As such, there is speculation that it could decrease toxicities and increase the efficacy of ASCT. We compared the outcomes of patients conditioned with PG-free MEL (n=216) to PG-solubilized MEL (n=200) at our institution. The baseline characteristics were similar between the two groups. After Day +0, there were no differences in terms of hospitalizations, neutropenic fevers, intravenous granisetron requirement, World Health Organization grade ≥2 oral/esophageal mucositis, intravenous fluid requirement, or narcotic requirement. However, PG-free MEL patients had a higher incidence of diarrhea, which was mostly C. difficile-negative (82% vs. 71%, P=0.015*). Day +100 hematologic responses and progression-free survival after ASCT were comparable. In summary, we demonstrate that switching to PG-free MEL did not significantly reduce short-term complications of ASCT or improve outcomes in MM.