Is autologous stem cell transplantation still relevant for multiple myeloma?

Reduction rate of monoclonal protein as a useful prognostic factor in standard-risk group of newly diagnosed multiple myeloma

BACKGROUND

Multiple myeloma (MM) is a common hematologic malignancy that originates from a malignant clone of plasma cells. Solitary plasmacytoma, history of diabetes, and platelet count are considered as prognostic factors for MM. But some patients are still associated with much worse outcomes without any prognostic predictors. This study aimed to observe the reduction rate of monoclonal protein (M protein) after the first and fourth chemotherapy cycles, which is considered as a new prognostic factor for progression-free survival (PFS) in standard-risk group of newly diagnosed MM patients.

AIM

To investigate the reduction rate of M protein after first and fourth cycle chemotherapy as a useful prognostic factor.

METHODS

A total of 316 patients diagnosed with MM for the first time between 2010 and 2019 at the Lishui Municipal Central Hospital were included. All patients were diagnosed according to the National Comprehensive Cancer Network (NCCN) 2020.V1 diagnostic criteria. The risk assessment was performed by the Mayo Stratification for Macroglobulinemia and Risk-Adapted Therapy guidelines. After diagnosis, 164 patients were evaluated and underwent treatment with four to eight courses of continuous induction chemotherapy. The patients with no response after induction treatment were administered additional therapy following the NCCN 2020.V1 criteria. The following baseline data from the patients were collected: Gender, age at diagnosis, Durie-Salmon stage, glutamic-pyruvic transaminase, glutamic-oxaloacetic transaminase, catabolite activator protein, albumin/globulin ratio, lactate dehydrogenase, translocation (t)(6;14), t(11;14), maintenance regimen, total cholesterol (TC), triglyceride, and phosphorous. All baseline data and the reduction rate of M protein after each chemotherapy cycle from the first to fourth were assessed by univariate analysis. The factors influencing the overall survival and PFS were then assessed by multivariate analysis. We found the first cycle (C1) reduction rate and the fourth cycle (C4) reduction rate as predictors of PFS. Then, PFS was compared between patients with a C1 reduction rate of M protein of ≥ 25% vs < 25% and ≥ 50% vs < 50%, and between patients with a C4 reduction rate of ≥ 25% vs < 25%, ≥ 50% vs < 50%, and ≥ 75% vs < 75%.

RESULTS

Multivariate analysis revealed age [hazard ratio (HR): 1.059, 95% confidence interval (95%CI): 1.033-1.085, P ≤ 0.001], International Staging System stage (HR: 2.136, 95%CI: 1.500-3.041, P ≤ 0.001), autotransplantion (HR: 0.201, 95%CI: 0.069-0.583, P = 0.019), TC (HR: 0.689, 95%CI: 0.533-0.891, P = 0.019), C1 reduction rate (HR: 0474, 95%CI: 0.293-0.767, P = 0.019), and C4 reduction rate (HR: 0.254, 95%CI: 0.139-0.463, P = 0.019) as predictors of PFS. The Kaplan-Meier survival analysis and the log-rank tests revealed that a higher reduction rate of M protein after first cycle (≥ 50%) and fourth cycle (≥ 75%) chemotherapy was associated with a longer PFS than the lower one.

CONCLUSION

Higher reduction rates of M protein after the first and fourth chemotherapy cycles can act as advantageous prognostic factors for PFS in standard-risk group of MM patients during initial diagnosis.

Population Pharmacokinetics of Melphalan in a Large Cohort of Autologous and Allogeneic Hematopoietic Cell Transplantation Recipients: Towards Individualized Dosing Regimens

BACKGROUND AND OBJECTIVES

High-dose melphalan is an integral part of conditioning chemotherapy prior to both autologous and allogeneic hematopoietic cell transplantation. While underexposure may lead to relapse, overexposure may lead to toxicities include mucositis, diarrhea, bone marrow suppression, and rarely sinusoidal obstruction syndrome. In this study, we describe the population pharmacokinetics of high-dose melphalan as a first step towards individualized dosing.

METHODS

Melphalan samples were collected in patients receiving an allogeneic or autologous hematopoietic cell transplantation between August 2016 and August 2020 at the Memorial Sloan Kettering Cancer Center. A population-pharmacokinetic model was developed using NONMEM.

RESULTS

Based on a total of 3418 samples from 452 patients receiving a median cumulative dose of 140 mg/m2, a two-compartment population-pharmacokinetic model was developed. Fat-free mass was a covariate for clearance, central volume of distribution, and inter-compartmental clearance, while glomerular filtration rate predicted clearance. Simulation studies showed that based on fixed body surface area-based dosing, renal impairment has a higher impact in increasing melphalan exposure compared with obesity.

CONCLUSIONS

The proposed model adequately describes the population pharmacokinetics of melphalan in adult patients receiving a hematopoietic cell transplantation. This model can be used to define the therapeutic window of melphalan, and subsequently to develop individualized dosing regimens aiming for that therapeutic window in all patients.