Non-producer multiple myeloma presenting with acute hyperammonemic encephalopathy: case report.

BACKGROUND: Hyperammonemic encephalopathy (HE) is a rare and life-threatening complication of multiple myeloma, with underlying mechanisms that are not fully understood. In contrast to previously reported cases, most of which have been associated with IgG or IgA isotypes, we describe a patient with HE as the presenting symptom of non-producer multiple myeloma (NPMM). CASE PRESENTATION: A 60-year-old man developed lethargy that progressed into coma. He was found to have an elevated ammonia level, despite normal hepatic function. He was diagnosed with HE secondary to NPMM, demonstrating 80% plasma cells without light chain expression in the bone marrow and absence of a monoclonal protein in the serum or urine, including by matrix-assisted laser desorption ionization time-of-flight mass-spectrometry (MASS-FIX). Myeloma-directed therapy with daratumumab, bortezomib, cyclophosphamide and dexamethasone successfully reversed his HE. At clinical relapse, he received salvage chemotherapy followed by venetoclax therapy, leading to a short period of neurological recovery. CONCLUSIONS: This case demonstrates that HE can occur in a patient with NPMM and challenges the mechanism suggested by limited prior studies; i.e., that excess ammonia in multiple myeloma arises from degradation of M-proteins. We postulate that the neoplastic plasma cells in NPMM have amplified amino acid metabolism, despite lacking detectable intracellular or secreted immunoglobulins.

Validation of algorithms to select patients with multiple myeloma and patients initiating myeloma treatment in the national Veterans Affairs Healthcare System.

BACKGROUND: We aimed to evaluate and compare the performance of multiple myeloma (MM) selection algorithms for use in Veterans Affairs (VA) research. METHODS: Using the VA Corporate Data Warehouse (CDW), the VA Cancer Registry (VACR), and VA pharmacy data, we randomly selected 500 patients from 01/01/1999 to 06/01/2021 who had (1) either one MM diagnostic code OR were listed in the VACR as having MM AND (2) at least one MM treatment code. A team reviewed oncology notes for each veteran to annotate details regarding MM diagnosis and initial treatment within VA. We evaluated inter-annotator agreement and compared the performance of four published algorithms (two developed and validated external to VA data and two used in VA data). RESULTS: A total of 859 patients were reviewed to obtain 500 patients who were annotated as having MM and initiating MM treatment in VA. Agreement was high among annotators for all variables: MM diagnosis (98.3% agreement, Kappa = 0.93); initial treatment in VA (91.8% agreement; Kappa = 0.77); and initial treatment classification (87.6% agreement; Kappa = 0.86). VA Algorithms were more specific and had higher PPVs than non-VA algorithms for both MM diagnosis and initial treatment in VA. We developed the "VA Recommended Algorithm," which had the highest PPV among all algorithms in identifying patients diagnosed with MM (PPV = 0.98, 95% CI = 0.95-0.99) and in identifying patients who initiated their MM treatment in VA (PPV = 0.93, 95% CI = 0.90-0.96). CONCLUSION: Our VA Recommended Algorithm optimizes sensitivity and PPV for cohort selection and treatment classification.

Peripheral blood monocyte count is a dynamic prognostic biomarker in multiple myeloma.

With the growing knowledge of multiple myeloma (MM) pathobiology and the introduction of novel therapies, risk stratification continues to evolve. Myeloid-derived suppressor cells and tumor-associated macrophages, derived from peripheral blood monocytes, support malignant plasma cell proliferation in the bone marrow. Because peripheral blood absolute monocyte count (AMC) is thought to reflect the bone marrow microenvironment, we sought to evaluate the prognostic significance of AMC in MM. We retrospectively analyzed 10 822 patients newly diagnosed with MM between 2000 and 2019 at Veteran's Administration hospitals. We obtained AMC closest to diagnosis and every 3 months thereafter up to 2.5 years. Patients were stratified into 4 groups: low, normal, elevated, and severely elevated AMC (<0.2, 0.2-<0.8, 0.8-<1.25, and ≥1.25 × 103/mm3, respectively). Abnormal AMC at diagnosis was observed in 25.3% of the patients and was associated with an inferior overall survival (OS). In patients with low, severely elevated, elevated, and normal AMC, respectively, median OS at diagnosis was 2.3, 2.7, 3.1, and 3.6 years (P < .001) and at 2.5 years was 2.0, 2.6, 3.4, and 3.9 years (P < .001). Patients with normal AMC at diagnosis who developed an abnormal AMC >1 year after diagnosis also had an inferior OS relative to patients who maintained a normal AMC. Abnormal AMC was also associated with inferior OS independent of validated prognostic markers, including the international staging system and lactate dehydrogenase. Our findings provide novel clues for future prospective studies on the functional role of monocytes in MM, which could be a readily available metric for risk stratification.

Modified High-Dose versus High-Dose Melphalan Conditioning in Older Patients Undergoing Autologous Stem Cell Transplantation for Immunoglobulin Light Chain Amyloidosis.

High-dose melphalan and autologous stem cell transplantation (HDM/SCT) induces deep hematologic responses (HR) in patients with newly diagnosed systemic immunoglobulin light-chain (AL) amyloidosis. Modifying melphalan conditioning dose (mHDM <140 mg/m2) is considered in older patients because of concerns regarding tolerability. Age does not predict frailty, and dose modification could compromise responses in an era where effective non-transplant regimens are available. We analyzed 43 patients ≥ 65 years with AL amyloidosis who underwent SCT at Boston University Amyloidosis Center between 2011 and 2020. Median age was 66 years (range 65-68) versus 69 years (range 65-76) in the HDM and mHDM groups, respectively. HR of ≥ very good partial response at 12 months was 66.7% versus 42.3% for patients treated with HDM versus mHDM. Median progression-free survival (PFS) from day 0 of SCT was not reached versus 12.0 months (P =.13); grade ≥ 3 non-hematologic transplant-related toxicities occurred in 87.5% versus 76.9%; and transplant-related mortality was 0% versus 2.3% in the HDM versus mHDM group, respectively. In carefully selected older patients with AL amyloidosis, HDM is well tolerated. Use of mHDM results in reduced HR and PFS; an important consideration with the advent of highly effective non-transplant therapies.

Prevalence of plasma cell and lymphoproliferative disorders among blood relatives of patients with light chain amyloidosis.

With limited existing data on hereditary factors in light chain (AL) amyloidosis, we conducted a study of patients with plasma cell dyscrasias or lymphoproliferative disorders in their family history. Among 1621 patients, we identified 44 probands (2·7%) with 52 relatives affected. The most common disorders in family members were multiple myeloma (48%) and AL amyloidosis (18%). Light chain isotype was 100% congruent in families with known clonal immunoglobulin for both members. Despite matching light chain isotype, organ involvement varied between members in families with multiple cases of AL amyloidosis. These findings help generate hypotheses about familial influences in AL amyloidosis.

Characterization of Mesoamerican Nephropathy in a Kidney Failure Hotspot in Nicaragua.

BACKGROUND: Mesoamerican nephropathy (MeN) is a kidney disease of unknown cause that mainly affects working-age men in Central America. Despite being a major cause of morbidity and mortality in this region, its clinical characteristics have not been well defined. STUDY DESIGN: Cross-sectional family-based study. SETTING & PARTICIPANTS: 266 members of 24 families with high chronic kidney disease (CKD) burdens in a MeN hotspot in Northwestern Nicaragua. We compared clinical and biochemical characteristics of affected individuals first with their unaffected relatives and then with NHANES (National Health and Nutrition Examination Survey) participants with CKD in order to reveal identifying features of MeN. PREDICTOR: CKD defined as serum creatinine level ≥ 1.5mg/dL in men and ≥1.4mg/dL in women. OUTCOMES: Clinical and biochemical parameters, including serum sodium, potassium, bicarbonate, calcium, magnesium, phosphorus, and uric acid. RESULTS: Hyperuricemia, in many cases severe, was common among patients with MeN. Uric acid levels in patients with MeN were higher than those in NHANES participants (mean, 9.6 vs 7.4mg/dL for men in each group) despite more frequent use of uric acid-lowering medications in Nicaraguan individuals (71.7% vs 11.2%). In multivariable linear mixed-effects regression analysis, uric acid levels were 2.0mg/dL (95% CI, 1.0-3.0; P<0.001) higher in patients with MeN compared with their NHANES counterparts after adjusting for age, estimated glomerular filtration rate, and uric acid-lowering therapies. In contrast to prior reports, hyponatremia and hypokalemia were not common. LIMITATIONS: CKD defined by single serum creatinine measurement; population likely not representative of full MeN phenotype spectrum across Central America; major differences between MeN and NHANES groups in important characteristics such as age, ancestry, and recruitment method. CONCLUSIONS: Hyperuricemia out of proportion to the degree of decreased kidney function was common among Nicaraguan patients with MeN. Our results suggest that rather than being solely a consequence of CKD, hyperuricemia may play a role in MeN pathogenesis, a hypothesis that deserves further study.