Current Trends of Renal Impairment in Multiple Myeloma

Healthcare resource use and costs associated with chronic kidney disease in US private insurance patients with multiple myeloma

OBJECTIVES

Within a median 1.2 years after patients have an initial diagnosis with multiple myeloma, up to 61% were diagnosed with renal impairment and 50% were diagnosed with chronic kidney disease. This study estimated economic burden associated with chronic kidney disease in multiple myeloma patients in the US.

METHODS

In this retrospective cohort study, patients ≥18 years old with ≥1 inpatient or ≥ 2 outpatient multiple myeloma diagnoses between 1 January 2008 and 31 March 2015 were identified from MarketScan® Commercial and Medicare Supplemental Databases. Chronic kidney disease patients had ≥1 diagnosis of chronic kidney disease Stages 1-5 (first chronic kidney disease diagnosis date = index date) on or after the first multiple myeloma diagnosis, and were propensity score matched 1:1 to multiple myeloma patients without chronic kidney disease, end-stage renal disease, dialysis, or other type of chronically impaired renal function. All patients had ≥six-month continuous enrollment prior to index date and were followed for ≥one month from index date until the earliest of inpatient death, end of continuous enrollment, or end of the study period (30 September 2015). The per-patient per-year healthcare resource utilization and costs were measured during follow-up. Costs were total reimbursed amount in 2016 US dollars.

RESULTS

A total of 2541 multiple myeloma patients with chronic kidney disease stages 1-5 and 2541 matched controls met the study criteria and were respectively 69.3 and 69.6 years, 54.5% and 55.3% men, and had 572.2 and 533.4 mean days of follow up. Compared to controls, chronic kidney disease patients had significantly (all P < 0.001) higher proportions (57.1% vs. 32.1%) and frequency (1.2 vs. 0.5) of inpatient admissions, frequency of emergency room visits (5.1 vs. 3.3), and total costs ($106,634 vs. $71,880). Sensitivity analyses found that patients with chronic kidney disease, end-stage renal disease, or dialysis had $78,455 ( P < 0.001) higher costs (per-patient per-year) than matched controls.

CONCLUSIONS

The economic burden associated with chronic kidney disease in patients with multiple myeloma was estimated to be between $34,754 and $78,455 per-patient per-year. Given its substantial clinical and economic impact, preservation of renal function is important in multiple myeloma patient care.

Renal Involvement in Multiple Myeloma

Multiple myeloma (MM) is a plasma cell disorder that represents almost 10% of haematologic malignancies. Renal impairment, one of the most common complications of MM that occurs in 20–50% of patients, can present in a variety of forms and is associated with increased mortality. Myeloma cast nephropathy is the most common cause of kidney disease in MM patients, presenting as acute kidney injury in the majority of patients. The recent introduction of new chemotherapy agents, autologous stem cell transplantation, and the development of novel techniques of light chain removal have been associated with improved renal and patient outcomes in MM patients. Nevertheless, dialysis-dependent patients with MM have higher mortality than other dialysis patients and may be considered for kidney transplantation only if sustained remission has been achieved and sustained for at least 3 years, bearing in mind the risk of disease recurrence. The authors review the most frequent renal manifestations associated with MM, namely myeloma cast nephropathy, light-chain amyloidosis, and monoclonal immunoglobulin deposition disease, focussing on the therapeutic options for acute and chronic kidney disease.

Tumor Cell-Derived Microvesicles Induced Not Epithelial-Mesenchymal Transition but Apoptosis in Human Proximal Tubular (HK-2) Cells: Implications for Renal Impairment in Multiple Myeloma

Renal impairment (RI) is one of the hallmarks of multiple myeloma (MM) and carries a poor prognosis. Microvesicles (MVs) are membrane vesicles and play an important role in disease progression. Here, we investigated the role of MVs derived from MM cells (MM-MVs) in RI of MM. We found that MM-MVs significantly inhibited viability and induced apoptosis, but not epithelial-mesenchymal transition in human kidney-2 (HK-2), a human renal tubular epithelial cell line. The protein levels of cleaved caspase-3, 8, and 9, and E-cadherin, were increased, but vementin levels were decreased in the HK-2 cells treated with MM-MVs. Through a comparative sequencing and analysis of RNA content between the MVs from RPMI8226 MM cells (RPMI8226-MVs) and K562 leukemia cells, RPMI8226-MVs were enriched with more renal-pathogenic miRNAs, in which the selective miRNAs may participate in the up-regulation of the levels of cleaved caspase-3. Furthermore, the levels of CD138+ circulating MVs (cirMVs) in the peripheral blood were positively correlated with the severity of RI in newly-diagnosed MM. Our study supports MM-MVs representing a previously undescribed factor and playing a potential role in the development of RI of MM patients, and sheds light on the potential application of CD138+ cirMV counts in precise diagnosis of RI in MM and exploring MM-MVs as a therapeutic target.

Multiple Myeloma Tumor Cells are Selectively Killed by Pharmacologically-dosed Ascorbic Acid

High-dose chemotherapies to treat multiple myeloma (MM) can be life-threatening due to toxicities to normal cells and there is a need to target only tumor cells and/or lower standard drug dosage without losing efficacy. We show that pharmacologically-dosed ascorbic acid (PAA), in the presence of iron, leads to the formation of highly reactive oxygen species (ROS) resulting in cell death. PAA selectively kills CD138⁺ MM tumor cells derived from MM and smoldering MM (SMM) but not from monoclonal gammopathy undetermined significance (MGUS) patients. PAA alone or in combination with melphalan inhibits tumor formation in MM xenograft mice. This study shows PAA efficacy on primary cancer cells and cell lines in vitro and in vivo.

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Pharmacologically-dosed ascorbic acid kills Multiple Myeloma cells.

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Pharmacologically-dosed ascorbic leads to apoptosis-inducing factor 1 cleavage.

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Pharmacologically-dosed ascorbic lowers melphalan dosage.

Multiple myeloma (MM) remains a difficult to cure disease in the majority of cases. Several preclinical and clinical studies have shown that ascorbic acid in pharmacologic doses (PAA) selectively kills cancer cells, while sparing normal cells. This article reveals the biological mechanism by which PAA exerts its anti-cancer effects and should lead to the development of an innovative therapy in MM.