Supratik Basu

Treatment of Acute Renal Failure Secondary to Multiple Myeloma with Chemotherapy and Extended High Cut-Off Hemodialysis

BACKGROUND AND OBJECTIVES Extended hemodialysis using a high cut-off dialyzer (HCO-HD) removes large quantities of free light chains in patients with multiple myeloma. However, the clinical utility of this method is uncertain. This study assessed the combination of chemotherapy and HCO-HD on serum free light chain concentrations and renal recovery in patients with myeloma kidney (cast nephropathy) and dialysis-dependent acute renal failure. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS An open-label study of the relationship between free light chain levels and clinical outcomes in 19 patients treated with standard chemotherapy regimens and HCO-HD. RESULTS There were sustained early reductions in serum free light chain concentrations (median 85% [range 50 to 97]) in 13 patients. These 13 patients became dialysis independent at a median of 27 d (range 13 to 120). Six patients had chemotherapy interrupted because of early infections and did not achieve sustained early free light chain reductions; one of these patients recovered renal function (at 105 d) the remaining 5 patients did not recover renal function. Patients who recovered renal function had a significantly improved survival (P < 0.012). CONCLUSION In dialysis-dependent acute renal failure secondary to myeloma kidney, patients who received uninterrupted chemotherapy and extended HCO-HD had sustained reductions in serum free light chain concentrations and recovered independent renal function.

Plasmacytoma relapses in the absence of systemic progression post‐high‐dose therapy for multiple myeloma

Abstract:  Autologous (ASCT) and allogeneic stem cell transplantations (alloBMT) are well‐established therapies for multiple myeloma. However, patients continue to relapse at a constant rate. We present here 15 out of 163 patients who underwent SCT and relapsed with plasmacytomas only without evidence of bone marrow disease progression (14/147 post‐ASCT and 1/16 post‐alloBMT). The median time from SCT to plasmacytoma relapse was 24 months. The sites of plasmacytoma included bone, skin, rectum, and testicles. Five patients were treated with local radiotherapy, while seven patients received a combination of radiotherapy and chemotherapy or thalidomide, and two patients received chemotherapy alone with or without thalidomide. The recipient of alloBMT was initially treated with VAD‐chemotherapy and local radiotherapy followed by a mini‐allograft from the original donor. Eleven patients died at a median of 10 months following diagnosis of the plasmacytoma. Four are still alive, 12–20 months post‐plasmacytoma diagnosis. These cases of unconventional disease recurrence are likely to be seen due to sub‐clinical seeding of tumour cells suggestive of the presence of an extramedullary (EM) clone of plasma cells with a high degree of chemoresistance. We also review all the available data in the literature for the optimal therapy for patients with isolated EM relapse.

Bortezomib, low‐dose intravenous melphalan, and dexamethasone for patients with relapsed multiple myeloma

This multicenter phase I/II study investigated the maximum tolerated dose (MTD), safety, and efficacy of low dose intravenous (IV) melphalan in combination with bortezomib for patients with relapsed multiple myeloma (MM). Patients received bortezomib 1·3 mg/m2 on days 1, 4, 8, and 11 and escalating doses of IV melphalan (2·5–10·0 mg/m2) on day 2 of a 28‐day cycle for a maximum of eight cycles. Dexamethasone 20 mg was added for progressive or stable disease. Fifty‐three patients were enrolled. The MTD was defined at melphalan 7·5 mg/m2 and bortezomib 1·3 mg/m2. The overall response rate (ORR) was 68% (23% complete or near‐complete responses [CR/nCR]) whilst at the MTD (n = 33) the ORR was 76% (34% CR/nCR). After median follow‐up of 17 months, the median progression free survival was 10 months, rising to 12 months at the MTD (P < 0·05 vs. non‐MTD regimens). The median overall survival was 28 months, but was not yet reached at the MTD. Grade 3/4 adverse events included thrombocytopenia (62%), neutropenia (57%), infection (21%), and neuropathy (15%). Bortezomib and low‐dose IV melphalan combination therapy is a safe and highly effective regimen for patients with relapsed MM. These data suggest further investigation of this combination is warranted.

Elevated, combined serum free light chain levels and increased mortality: a 5-year follow-up, UK study

Aims Abnormal serum free light chain (FLC) ratios are diagnostically important in almost all plasma cell disorders. However, absolute increases in polyclonal FLC levels are often discarded as inconsequential. Here we report an association between increased combined polyclonal FLC (cFLC: FLCκ plus FLCλ) concentrations and mortality. Methods 723 patients sent for 30 routine haematological assessments were enrolled. Patients with a confirmed monoclonal gammopathy were removed. The remaining 527 patients were followed up for up to 4.5 years. Statistical analysis was performed using SPSS (V.19). Results During follow-up, there were 99 deaths (18.8%). Kaplan-Meier survival analysis revealed 29% of these deaths occurred within the first 100 days (N=29). Multivariate analysis identified only cFLC >65 mg/l, albumin <33 g/l and estimated glomerular filtration rate <30 ml/min/1.73 m2 to be independently associated with mortality within 100 days and 4.5 years with, cFLC having the highest HR of 7.1. A simple risk stratification model based only on albumin and cFLC identified 86% mortality within 100 days and 62% over 4.5 years. Conclusions Elevated cFLC is significantly associated with increased mortality and with albumin can be used to identify patients at risk of mortality at 4.5 years with high-risk patients detected within 100 days.

Quantification of polyclonal free light chains in clinical samples using a single turbidimetric immunoassay.

Abstract Background: Elevated polyclonal serum free light chain (FLC) levels have been associated with increased mortality and disease activity in many conditions. Currently, polyclonal FLC quantification requires summation of individual FLCκ and FLCλ assays. Here we present a single assay for combined FLC (cFLC, Combylite™) which reduces assay time and eliminates potential imprecision errors incurred by summating FLC assays (ΣFLC). Methods: Sheep FLCκ- and FLCλ-specific antibodies were conjugated to latex microparticles to quantify FLCκ and FLCλ in a single assay. Combylite results were compared to ΣFLC (Freelite®) in 132 healthy controls and 1127 patient samples. The utility of cFLC for predicting all-cause mortality in a haematological referral population was evaluated. Results: cFLC and ΣFLC results were highly concordant (Passing-Bablok equation y=0.98x–1.59 mg/L, R2=0.96). Combylite assay imprecision was low at concentrations around the upper normal range [coefficient of variation (CV) 5.5%, 54 mg/L] and the upper limit of the measuring range (CV 5.5%, 170 mg/L). cFLC levels were significantly raised in disease states compared with healthy controls. Additionally, cFLC >65 mg/L was associated with shorter overall survival in a haematological referral population (hazard ratio=4.5, p<0.001). Conclusions: cFLC values obtained using Combylite were comparable to ΣFLC results over a wide concentration range, were elevated in diseases characterised by B cell activation and were associated with increased mortality in a haematological referral population. These observations indicate the Combylite assay has value for investigating the role of B cell activation in disparate disease groups and could be considered as a surrogate indication of B cell function.

Response to Pretorius: ‘Evaluation of the N Latex FLC free light chain assay on the Siemens BN analyser’

Dear Editor, We read with interest the article by Pretorius et al. comparing the new N Latex FLC (Siemens) and Freelite assays (The Binding Site) for the measurement of serum free light chains (FLC). The authors carefully pointed out the deficiencies in Freelite, but were less critical of N Latex. International guidelines recommend the use of serum FLC analysis for monitoring monoclonal gammopathies (MG) and, alongside serum protein electrophoresis, for the detection of MG. This was based upon retrospective analysis of 428 MG samples with Freelite and subsequently validated in prospective studies. Although Pretorius et al. reported significant quantitative differences between the two assays and reported clinical information on only 16 samples, they conclude that the N Latex assays can be used in clinical practice on the basis of the assay’s analytical performance; a safer conclusion would be that separate clinical validation studies are required. The study design concerns us. The expression of serum free light chains is highly variable in MG. In diseases such as AL amyloidosis, serum concentrations may be close to normal. Why then have the authors excluded 58% of their samples (those ,50 mg/L by Freelite), risking biasing their analysis? Clinical data were presented only for samples giving grossly discrepant results, mainly limited to the initial diagnoses. Importantly, the N Latex assays gave normal FLC ratios for three patients with known B-lymphoproliferative disorders. In this highly selected population 3% of the samples would not have been identified by the N Latex. Antigen excess is a common problem in nephelometric assays. The incidence of antigen excess for Freelite is well documented while data for N Latex, which has antigen excess protection, are sparse. Pretorius et al. evaluated the antigen excess performance of the N Latex assay in samples where excess had been identified by Freelite, leading inherently to a bias when comparing antigen excess susceptibility of the two assays. We recommend the authors repeat their analysis on all samples identified as discordant between the two assays. The experiment comparing the precision of the two assays does not provide a fair comparison. The FLC value of the five serum pools used was determined by the N Latex assay. There was a large discrepancy between the FLC levels measured by the N Latex assays and Freelite with the latter giving 25–40% lower values for kappa and lambda. In consequence, for the lower level samples the precision for Freelite was tested at the lowest point of the dynamic ranges, while with the N Latex assays, precision was tested at least 50% above the bottom of the dynamic range. Nevertheless, we agree with the authors that non-linearity of FLC assays is a property of the individual sample and not method specific. Similarly, aggregation will cause an over estimation of the light chain concentration in both assays. We question the logic for suggesting a change in the reference range of the N Latex assay. The N Latex FLC was calibrated against Freelite; therefore, a recalibration of the N latex assay based on the differences in monoclonal samples cannot be justified. Furthermore, changing the reference range for serum FLC would prevent the use of Freelite as a predicate device. In summary, the data presented highlight that the two assays are different and does not provide support for the clinical utility of N Latex FLC. Prospective, clinically relevant studies are required to assess the utility of the N Latex assay and until these are reported its use should be limited to academic comparison studies.

Use of free light chain measurements as prediction of response to induction chemotherapy

Chromosomal translocations lead to oncogene activation in a significant number of haematological malignancies. Those involving the immunoglobulin heavy chain locus, IGH, at chromosome band 14q32 are frequently observed in B-cell malignant proliferation. A small number have been described in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL). However, their biological and clinical significance is currently unknown. Detailed fluorescence in situ hybridisation (FISH) and molecular studies were carried out on a series of BCP-ALL patients with chromosomal abnormalities involving 14q32. Novel and recurrent translocations affecting different chromosomes were highlighted. Refined FISH mapping identified putative IGH partner genes at, or flanking, the translocation breakpoints. Four translocations: two previously reported, t(14;19)(q32;q13), t(8;14)(q11;q32), and two novel, t(14;14)(q11;q32)/ inv(14)(q11q32) and t(14;20)(q32;q13), were identified. Molecular analyses showed that four different members of the CAATT enhancer binding protein (CEBP) gene family were involved: CEBPA (19q13, n59), CEBPD (8q11, n58), CEBPE (14q11, n53) and CEBPB (20q13, n52). One patient with a t(14;19)(q32;q13) was observed to involve the fifth family member CEBPG (19q13, n51). Breakpoints were located within the 30 untranslated region (UTR) of CEBPA and either 30 UTR or 50 of CEBPE, whereas breakpoints in 8q11 were B30 kb centromeric of CEBPD. Where material was available, over-expression of target genes was shown by quantitative real-time PCR. Overall, this study has demonstrated for the first time the involvement of five members of the same gene family in a single subtype of haematological disease. It has indicated that transcriptional upregulation of CEBP gene family members, by juxtaposition to IGH, is important in BCP-ALL: a mechanism in complete contrast to that involving CEPBA in acute myeloid leukaemia.

Serological normalisation as a surrogate marker for minimal residual disease negativity in multiple myeloma

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Neoplastic plasma cells generate an inflammatory environment within bone marrow and markedly alter the distribution of T cells between lymphoid compartments

Monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) are characterised by the accumulation of malignant plasma cells within bone marrow and lead to a range of abnormalities in the peripheral blood T cell repertoire. We investigated the level of inflammatory chemokines within the bone marrow and blood of patients with MGUS and MM and related this to the pattern of chemokine receptor expression on T cells in both compartments. The expression of a wide range of chemokine ligands for CXCR3 and CCR4 was markedly increased within the bone marrow of patients with MGUS and MM compared to healthy donors. The most marked effects were seen for CCL4 and CXCL9 which were increased by 4 and 6 fold respectively in the bone marrow of patients with myeloma. The expression of CXCR3 and CCR4, the major TH1 and TH2-associated chemokine receptors, was increased substantially on T cells within the bone marrow of patients whereas the percentage of CXCR3-expressing T cells within blood was correspondingly decreased. The presence of even small numbers of neoplastic plasma cells or associated stroma can therefore generate an inflammatory chemokine tumour microenvironment. This leads to the selective recruitment or retention of specific T cell subsets which is likely to underlie many of the features regarding the peripheral T cell repertoire in myeloma and may also contribute to the immune suppression associated with this disease. This local inflammatory reaction may represent a tumour-specific immune response or may itself play an important role in tumour progression and as such may offers a potential novel target for therapeutic intervention.