Dose-adjusted Lenalidomide Combined with Low-dose Dexamethasone Rescues Older Patients with Bortezomib-resistant Multiple Myeloma

Apparent diffusion coefficient measurements of bone marrow infiltration patterns in multiple myeloma for the assessment of tumor burden - a feasibility study

BACKGROUND

The purpose of our study was to explore and compare the tumor burden of different bone marrow infiltration patterns and evaluate the feasibility of apparent diffusion coefficient (ADC) value to identify patterns in multiple myeloma (MM).

PATIENTS AND METHODS

Ninety-three patients with newly diagnosed multiple myeloma and 23 controls had undergone routine magnetic resonance imaging (MRI) and diffusion-weighted MRI (DWI) from January 2019 to November 2020. Five bone marrow (BM) infiltration patterns were allocated according to routine MRI. The laboratory data and ADC values of patterns were analyzed and compared. ROC analysis was used to establish the best diagnostic ADC threshold value for identifying these patterns and distinguishing normal pattern from controls. Besides, the correlation between the ADC values of diffuse pattern and the plasma cells ratio was assessed.

RESULTS

The values of hemoglobin, beta-2 microglobulin (β2-MG), plasma cell, M protein, the percentages of stage, high-risk fluorescence in situ hybridization, and ADC values showed significant difference among patterns. ADCmean at a specific value (368.5×10-6 mm2/s) yielded a maximum specificity (95.5%) and sensitivity (92.0%) in diagnosing MM. A specific value (335.5×10-6mm2/s) yielded a maximum specificity (84.7%) and sensitivity (88.0%) in discriminating visually normal pattern in MM from controls. There was a moderate positive correlation between the plasma cells ratio and ADCs of diffuse infiltration patterns (r = 0.648, P < 0.001).

CONCLUSIONS

The bone marrow infiltration patterns in MM patients can indicate the tumor burden and ADC value has the ability to discriminate these patterns objectively.

Population pharmacokinetics of pomalidomide in patients with relapsed or refractory multiple myeloma with various degrees of impaired renal function

Pomalidomide is an immunomodulatory drug for treatment of relapsed or refractory multiple myeloma (rrMM) in patients who often have comorbid renal conditions. To assess the impact of renal impairment on pomalidomide exposure, a population pharmacokinetics (PPK) model of pomalidomide in rrMM patients with various degrees of impaired renal function was developed. Intensive and sparse pomalidomide concentration data collected from two clinical studies in rrMM patients with normal renal function, moderately impaired renal function, severely impaired renal function not requiring dialysis, and with severely impaired renal function requiring dialysis were pooled over the dose range of 2 to 4 mg, to assess specifically the influence of the impaired renal function as a categorical variable and a continuous variable on pomalidomide clearance and plasma exposure. In addition, pomalidomide concentration data collected on dialysis days from both the withdrawal (arterial) side and from the returning (venous) side of the dialyzer, from rrMM patients with severely impaired renal function requiring dialysis, were used to assess the extent to which dialysis contributes to the removal of pomalidomide from blood circulation. PPK analyses demonstrated that moderate to severe renal impairment not requiring dialysis has no influence on pomalidomide clearance or plasma exposure, as compared to those patients with normal renal function, while pomalidomide exposure increased approximately 35% in patients with severe renal impairment requiring dialysis on nondialysis days. In addition, dialysis increased total body pomalidomide clearance from 5 L/h to 12 L/h, indicating that dialysis will significantly remove pomalidomide from the blood circulation. Thus, pomalidomide should be administered post-dialysis on the days of dialysis.

Current Trends of Renal Impairment in Multiple Myeloma

BACKGROUND

Renal impairment (RI) is a common complication of multiple myeloma (MM). Around 50% of patients with MM have RI at presentation, and up to 5% require dialysis treatment. Severe acute kidney injury (AKI) as a cause of RI is a particular challenge as historically the survival of patients who sustain this complication and require dialysis is very poor. However, in this current period, survival is improving and the focus is on optimum use of novel chemotherapies and the evaluation of extra-corporeal therapies for removal of serum immunoglobulin light chains.

SUMMARY

RI in patients with MM is commonly associated with excess monoclonal free light chain (FLC) production; myeloma cast nephropathy is the predominant renal pathology in patients presenting with severe RI secondary to AKI. The majority of patients have mild to moderate RI and recover renal function. However, patients with more severe RI, in particular those with a requirement for dialysis, are less likely to recover renal function. Rapid diagnosis and prompt institution of anti-myeloma therapy is an important determinant of renal function recovery, through targeting early and sustained reduction of involved monoclonal FLC. Novel agents are associated with excellent disease response, and bortezomib is now widely used as a first-line agent in the management of MM in patients with severe RI. Extended haemodialysis using high cut-off dialysers is more effective for extracorporeal removal of FLC than plasma exchange, and clinical trials are in process. High-dose chemotherapy with autologous stem cell transplantation does have a role in patients with severe RI but requires careful patient selection.

KEY MESSAGES

RI is very common in patients with MM, and renal function recovery is associated with improved clinical outcomes. We summarise the epidemiology of MM in the UK, present the impact of RI and renal function recovery on patient outcome, and describe the current management of MM in western countries.

FACTS FROM EAST AND WEST

(1) A serum creatinine level >2 mg/dl has been reported in 16, 21, 24, and 33% of patients with MM in cohort studies from Japan, Europe, China, and Korea, respectively. A creatinine clearance rate <30 ml/min was observed in 30 and 15% of patients in Chinese and Western MM cohorts, respectively. The commonest cause of severe RI in patients with MM is myeloma cast nephropathy. (2) The efficacy of novel treatments (bortezomib, carfilzomib, thalidomide, and lenalidomide) has predominantly been assessed in Western patients. Bortezomib and dexamethasone are the current standard of care for MM and severe RI in the West. Severe RI is not a contraindication to autologous stem cell transplantation (ASCT). Most of the data are from the West; there are case reports from China describing good outcomes with ASCT. The removal of FLC by high-cut-off hemodialysis is under evaluation in randomized controlled trials (RCTs) in the West. Studies in this area are not yet conducted in China. In China, new treatments, such as bortezomib, are more widely used than before, and favorable results are being reported; however, RCT studies are still needed in this area to confirm the efficacy and safety of this and other novel treatments.