[Show abstract][Hide abstract] ABSTRACT: Multiple myeloma is the most frequent indication for high-dose melphalan (HDM) chemotherapy with autologous stem cell transplantation (ASCT). Gastrointestinal symptoms represent the most significant non-hematological toxicity of HDM. However, specific, especially genetic, predictors of their incidence or clinical severity are lacking. The amino acid transporters LAT1 and LAT2 encoded by the SLC7A5 and SLC7A8 genes, respectively, are the principal mediators of melphalan uptake into cells. To determine whether genetic variability at these loci contributed to inter-individual differences in the development of gastrointestinal complications of HDM, we analyzed single-nucleotide polymorphisms (SNPs) in these genes in 135 patients with multiple myeloma treated with HDM and ASCT and need for total parenteral nutrition (TPN). Seven SNPs in SLC7A5 and twenty in SLC7A8 were genotyped. Multiple analyses indicated that one SNP in the first intron of SLC7A5, rs4240803, significantly associated with TPN use (OR= 0.45, 95% CI 0.25 - 0.79, p = 0.007). Further, every haplotype that correlated with TPN requirement incorporated this SNP. These results suggest that variability in melphalan transport impacts mucosal injury after HDM. This finding could help in individualizing the dose of this effective and widely used chemotherapeutic agent for multiple myeloma.
Biology of blood and marrow transplantation: journal of the American Society for Blood and Marrow Transplantation 04/2014; 20(7). DOI:10.1016/j.bbmt.2014.03.022 · 3.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Measurement of minimal residual disease is routine in diseases such as chronic myelogenous leukemia, precursor B cell acute lymphoblastic leukemia, and acute promyelocytic leukemia because it provides important prognostic information. However, the role of minimal residual disease testing has not been widely adopted in multiple myeloma (MM), with other parameters such as the International Staging System (ISS) and cytogenetic analysis primarily guiding therapy and determination of prognosis. Until recently, achieving a complete response (CR), as defined by the International Myeloma Working Group (IMWG) criteria, was rare in patients with MM. The use of novel agents with or without autologous peripheral blood stem cell transplantation (auto-PBSCT) has significantly increased CR rates, thus increasing overall survival (OS) rates. The majority of patients with MM have persistent levels of residual disease that are below the sensitivity of bone marrow (BM) morphology, protein electrophoresis with immunofixation, and light chain quantitation even after attaining CR and will eventually relapse. Measurement of minimal residual disease by more sensitive methods, and the use of these methods as a tool for predicting patient outcomes and guiding therapeutic decisions, has thus become more relevant. Methods available for monitoring minimal residual disease in MM include PCR and multiparameter flow cytometry (MFC), both of which have been shown to be valuable in other hematologic malignancies; however, neither has become a standard of care in MM. Here, we review current evidence for using minimal residual disease measurement for risk assessment in MM as well as incorporating pretreatment factors and posttreatment minimal residual disease monitoring as a prognostic tool for therapeutic decisions, and we outline challenges to developing uniform criteria for minimal residual disease monitoring.
Biology of blood and marrow transplantation: journal of the American Society for Blood and Marrow Transplantation 05/2012; 18(12). DOI:10.1016/j.bbmt.2012.05.009 · 3.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transforming growth factor β (TGF-β) is an abundant bone matrix protein that influences osteoblast and osteoclast interactions to control bone remodeling. As such, TGF-β represents an obvious pharmacologic target with the potential to regulate both bone formation and resorption to improve bone volume and strength. To investigate the skeletal effect of TGF-β inhibition in vivo, we used an antibody (1D11) specifically directed at all three isoforms of TGF-β. Normal mice were treated with 1D11 or control antibody (4 weeks), and cortical and trabecular bone was assessed by micro-computed tomographic (µCT) scanning. Bone volume and cellular distribution were determined by histomorphometric analysis of vertebrae and long bones. Also, whole-bone strength was assessed biomechanically by three-point bend testing, and tissue-level modulus and composition were analyzed by nanoindentation and Raman microspectroscopy, respectively. TGF-β blockade by 1D11 increased bone mineral density (BMD), trabecular thickness, and bone volume by up to 54%, accompanied by elevated osteoblast numbers and decreased osteoclasts. Biomechanical properties of bone also were enhanced significantly by 1D11 treatment, with increased bending strength and tissue-level modulus. In addition, Raman microspectroscopy demonstrated that 1D11-mediated TGF-β inhibition in the bone environment led to an 11% increase in the mineral-to-collagen ratio of trabecular bone. Together these studies demonstrate that neutralizing TGF-β with 1D11 increases osteoblast numbers while simultaneously decreasing active osteoclasts in the marrow, resulting in a profound increase in bone volume and quality, similar to that seen in parathyroid hormone (PTH)-treated rodent studies.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 11/2010; 25(11):2419-26. DOI:10.1002/jbmr.139 · 6.83 Impact Factor