Common genetic variants are associated with accelerated bone mineral density loss after hematopoietic cell transplantation.

BACKGROUND: Bone mineral density (BMD) loss commonly occurs after hematopoietic cell transplantation (HCT). Hypothesizing that genetic variants may influence post-HCT BMD loss, we conducted a prospective study to examine the associations of single nucleotide polymorphisms (SNP) in bone metabolism pathways and acute BMD loss after HCT. METHODS AND FINDINGS: We genotyped 122 SNPs in 45 genes in bone metabolism pathways among 121 autologous and allogeneic HCT patients. BMD changes from pre-HCT to day +100 post-HCT were analyzed in relation to these SNPs in linear regression models. After controlling for clinical risk factors, we identified 16 SNPs associated with spinal or femoral BMD loss following HCT, three of which have been previously implicated in genome-wide association studies of bone phenotypes, including rs2075555 in COL1A1, rs9594738 in RANKL, and rs4870044 in ESR1. When multiple SNPs were considered simultaneously, they explained 5-35% of the variance in post-HCT BMD loss. There was a significant trend between the number of risk alleles and the magnitude of BMD loss, with patients carrying the most risk alleles having the greatest loss. CONCLUSION: Our data provide the first evidence that common genetic variants play an important role in BMD loss among HCT patients similar to age-related BMD loss in the general population. This infers that the mechanism for post-HCT bone loss is a normal aging process that is accelerated during HCT. A limitation of our study comes from its small patient population; hence future larger studies are warranted to validate our findings.

Accelerated bone mineral density loss occurs with similar incidence and severity, but with different risk factors, after autologous versus allogeneic hematopoietic cell transplantation.

Bone mineral density (BMD) loss occurs commonly in patients after allogeneic hematopoietic cell transplantation (HCT), primarily because of steroid use, but little is known about BMD change post-autologous HCT. In a prospective study of 206 consecutive first HCT patients, we measured acute BMD change at the lumbar spine and dual femur between baseline and day +100, and evaluated risk factors for bone loss. Accelerated BMD loss in this 4-month period occurred after both autologous and allogeneic HCT with similar severity (median, 0.03 g/cm(2) versus 0.03 g/cm(2) at the spine; 0.03 g/cm(2) versus 0.05 g/cm(2) at the femur, respectively). This is equivalent to 7 to 17 years' worth of bone loss by aging. Risk factors for BMD loss were different between autologous and allogeneic HCT patients: lymphoma was associated with greater bone loss after autologous HCT than myeloma, whereas higher steroid dose was the most significant risk factor after allogeneic HCT. Multivariable risk models explained 11% to 30% of the variation in HCT-related BMD change. Surprisingly, BMD loss post-autologous HCT occurred with similar incidence and severity to allogeneic HCT, even in the absence of steroid use. Evaluation of clinical strategies to prevent and reverse HCT-related BMD loss is necessary in both autologous and allogeneic HCT patients.

A deletion polymorphism in glutathione-S-transferase mu (GSTM1) and/or theta (GSTT1) is associated with an increased risk of toxicity after autologous blood and marrow transplantation.

Toxicity after blood and marrow transplantation (BMT) has interindividual variability that may be explained by common genetic polymorphisms in critical pathways. The glutathione-S-transferase (GST) isoenzymes detoxify the reactive oxygen species generated by chemotherapy agents and radiation. We investigated whether deletion polymorphisms in 2 GST genes (GSTM1 and GSTT1) were associated with toxicity after autologous or allogeneic BMT. The study population was selected from 699 consecutive BMT patients from 2 centers in Buffalo, NY, and Moscow, Russia, of whom 321 (203 autologous, 118 allogeneic BMT) had available banked samples and amplifiable DNA. Fifty percent of patients were homozygous null for GSTM1, which did not vary by center; however, the GSTT1 homozygous null deletion polymorphism occurred more frequently in patients treated in Moscow (38% versus 18%, P < .001). Overall grade 2-4 regimen-related toxicity occurred in 56%, with nearly 1 in 5 patients having 2 or more organ systems affected. Among autologous BMT patients, a deletion polymorphism in 1 or both genes was significantly associated with increased occurrence of overall toxicity (71% versus 56%, P = .034) and mucositis (74% versus 55%, P = .006). GSTM1 and/or GSTT1 deletion polymorphisms were not associated with toxicity after allogeneic BMT. Future studies may allow for individualized genetic risk stratification.

A comparison of measured creatinine clearance versus calculated glomerular filtration rate for assessment of renal function before autologous and allogeneic BMT.

Common blood and marrow transplantation (BMT) eligibility criteria include a minimum glomerular filtration rate (GFR) that may vary by regimen intensity. GFR is often estimated by measurement of creatinine clearance in a 24-hour urine collection (24-hr CrCl), an inconvenient and error-prone method that overestimates GFR. The study objectives were to determine which of 6 GFR calculations: Cockroft-Gault (CG), modified CG (mCG), Modification of Diet in Renal Disease 1 (MDRD1), MDRD2, Jelliffe, and Wright, consistently underestimated measured 24-hr CrCl pre-BMT. We retrospectively analyzed 98 consecutive allogeneic (n = 48) or autologous (n = 50) adult BMT patients from January 2006 to April 2007. All 6 formulas were significantly (P < .001) correlated with 24-hr CrCl with R = 0.64 (Wright), 0.63 (CG), 0.61 (mCG), 0.61 (Jelliffe), 0.54 (MDRD2), and 0.50 (MDRD1). When compared to the measured 24-hr CrCl, MDRD2 consistently underestimated it in the highest proportion of patients (66%, P < .001), compared with MDRD1 (65%, P < .001), Jelliffe (61%, P = NS), mCG (55%, P = NS), Wright (34%, P < .001), and CG (34%, P = .001). Measured 24-hr CrCl, pre-BMT serum Cr, and all 6 equations were not predictive of renal regimen-related toxicity (RRT) post-BMT. The Wright and CG formulas are closest to, but overestimate 24-hr CrCl in 66% of patients. In comparison, MDRD2 consistently underestimates 24-hr CrCl in 66%. Although MDRD2 is the most conservative formula, all 6 formulas gave reasonable estimates of GFR and any of the 6 equations can replace the measured 24-hr CrCl. Larger analyses and transplantation of patients with GFR <50 mL/min may better define subgroups at risk for renal RRT.