Peripheral Blood Transcript Signatures after Internal 131I-mIBG Therapy in Relapsed and Refractory Neuroblastoma Patients Identifies Early and Late Biomarkers of Internal 131I Exposures.

131I-metaiodobenzylguanidine (131I-mIBG) is a targeted radiation therapy developed for the treatment of advanced neuroblastoma. We have previously shown that this patient cohort can be used to predict absorbed dose associated with early 131I exposure, 72 h after treatment. We now expand these studies to identify gene expression differences associated with 131I-mIBG exposure 15 days after treatment. Total RNA from peripheral blood lymphocytes was isolated from 288 whole blood samples representing 59 relapsed or refractory neuroblastoma patients before and after 131I-mIBG treatment. We found that several transcripts predictive of early exposure returned to baseline levels by day 15, however, selected transcripts did not return to baseline. At 72 h, all 17 selected pathway-specific transcripts were differentially expressed. Transcripts CDKN1A (P < 0.000001), FDXR (P < 0.000001), DDB2 (P < 0.000001), and BBC3 (P < 0.000001) showed the highest up-regulation at 72 h after 131I-mIBG exposure, with mean log2 fold changes of 2.55, 2.93, 1.86 and 1.85, respectively. At day 15 after 131I-mIBG, 11 of the 17 selected transcripts were differentially expressed, with XPC, STAT5B, PRKDC, MDM2, POLH, IGF1R, and SGK1 displaying significant up-regulation at 72 h and significant down-regulation at day 15. Interestingly, transcripts FDXR (P = 0.01), DDB2 (P = 0.03), BCL2 (P = 0.003), and SESN1 (P < 0.0003) maintained differential expression 15 days after 131I-mIBG treatment. These results suggest that transcript levels for DNA repair, apoptosis, and ionizing radiation-induced cellular stress are still changing by 15 days after 131I-mIBG treatment. Our studies showcase the use of biodosimetry gene expression panels as predictive biomarkers following early (72 h) and late (15 days) internal 131I exposure. Our findings also demonstrate the utility of our transcript panel to differentiate exposed from non-exposed individuals up to 15 days after exposure from internal 131I.

Reversibility of Neuroimaging Markers Influenced by Lifetime Occupational Manganese Exposure.

Manganese (Mn) is a neurotoxicant that many workers are exposed to daily. There is limited knowledge about how changes in exposure levels impact measures in magnetic resonance imaging (MRI). We hypothesized that changes in Mn exposure would be reflected by changes in the MRI relaxation rate R1 and thalamic γ-aminobutyric acid (GABAThal). As part of a prospective cohort study, 17 welders were recruited and imaged on 2 separate occasions approximately 2 years apart. MRI relaxometry was used to assess changes of Mn accumulation in the brain. Additionally, GABA was measured using magnetic resonance spectroscopy in the thalamic and striatal regions of the brain. Air Mn exposure ([Mn]Air) and cumulative exposure indexes of Mn (Mn-CEI) for the past 3 months (Mn-CEI3M), past year (Mn-CEI12M), and lifetime (Mn-CEILife) were calculated using personal air sampling and a comprehensive work history, whereas toenails were collected for analysis of internal Mn body burden. Finally, welders' motor function was examined using the Unified Parkinson's Disease Rating Scale (UPDRS). Median exposure decreased for all exposure measures between the first and second scan. ΔGABAThal was significantly correlated with ΔMn-CEI3M (ρ = 0.66, adjusted p = .02), ΔMn-CEI12M (ρ = 0.70, adjusted p = .006), and Δ[Mn]Air (ρ = 0.77, adjusted p = .002). ΔGABAThal significantly decreased linearly with ΔMn-CEI3M (quantile regression, ß = 15.22, p = .02) as well as Δ[Mn]Air (ß = 1.27, p = .04). Finally, Mn-CEILife interacted with Δ[Mn]Air in the substantia nigra where higher Mn-CEILife lessened the ΔR1 per Δ[Mn]Air (F-test, p = .005). Although R1 and GABA changed with Mn exposure, UPDRS was unaffected. In conclusion, our study shows that effects from changes in Mn exposure are reflected in thalamic GABA levels and brain Mn levels, as measured by R1, in most brain regions.

Impairment of Motor Function Correlates with Neurometabolite and Brain Iron Alterations in Parkinson's Disease.

We took advantage of magnetic resonance imaging (MRI) and spectroscopy (MRS) as non-invasive methods to quantify brain iron and neurometabolites, which were analyzed along with other predictors of motor dysfunction in Parkinson's disease (PD). Tapping hits, tremor amplitude, and the scores derived from part III of the Movement Disorder Society-Sponsored Revision of the Unified Parkinson Disease Rating Scale (MDS-UPDRS3 scores) were determined in 35 male PD patients and 35 controls. The iron-sensitive MRI relaxation rate R2* was measured in the globus pallidus and substantia nigra. γ-aminobutyric acid (GABA)-edited and short echo-time MRS was used for the quantification of neurometabolites in the striatum and thalamus. Associations of R2*, neurometabolites, and other factors with motor function were estimated with Spearman correlations and mixed regression models to account for repeated measurements (hands, hemispheres). In PD patients, R2* and striatal GABA correlated with MDS-UPDRS3 scores if not adjusted for age. Patients with akinetic-rigid PD subtype (N = 19) presented with lower creatine and striatal glutamate and glutamine (Glx) but elevated thalamic GABA compared to controls or mixed PD subtype. In PD patients, Glx correlated with an impaired dexterity when adjusted for covariates. Elevated myo-inositol was associated with more tapping hits and lower MDS-UPDRS3 scores. Our neuroimaging study provides evidence that motor dysfunction in PD correlates with alterations in brain iron and neurometabolites.

Toenail Manganese: A Sensitive and Specific Biomarker of Exposure to Manganese in Career Welders.

Manganese (Mn) is an essential trace metal. It is also a component of welding fume. Chronic inhalation of manganese from welding fume has been associated with decreased neurological function. Currently, there is not a universally recognized biomarker for Mn exposure; however, hair and toenails have shown promise. In a cohort of 45 male welders and 35 age-matched factory control subjects, we assessed the sensitivity and specificity of toenail Mn to distinguish occupationally exposed subjects from unexposed controls. Further we examined the exposure time window that best correlates with the proposed biomarker, and investigated if non-occupational exposure factors impacted toenail Mn concentrations. Toenail clippings were analyzed for Mn using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Exposure to respirable Mn-containing particles (<4 µm) was estimated using an exposure model that combines personal air monitoring, work history information, and dietary intake to estimate an individual's exposure to Mn from inhalation of welding fume. We assessed the group differences in toenail concentrations using a Student's t-test between welders and control subjects and performed a receiver operating characteristic (ROC) curve analysis to identify a threshold in toenail concentration that has the highest sensitivity and specificity in distinguishing welders from control subjects. Additionally, we performed mixed-model regressions to investigate the association between different exposure windows and toenail Mn concentrations. We observed that toenail Mn concentrations were significantly elevated among welders compared to control subjects (6.87 ± 2.56 versus 2.70 ± 1.70 µg g-1; P < 0.001). Our results show that using a toenail Mn concentration of 4.14 µg g-1 as cutoff allows for discriminating between controls and welders with 91% specificity and 94% sensitivity [area under curve (AUC) = 0.98]. Additionally, we found that a threshold of 4.66 µg g-1 toenail Mn concentration enables a 90% sensitive and 90% specific discrimination (AUC = 0.96) between subjects with average exposure above or below the American Conference of Governmental Industrial Hygienist (ACGIH) Threshold Limit Value (TLV) of 0.02 mg m-3 during the exposure window of 7-12 months prior to the nail being clipped. Investigating which exposure window was best reflected by toenail Mn reproduced the result from another study of toenail Mn being significantly (P < 0.001) associated with exposure 7-12 months prior to the nail being clipped. Lastly, we found that dietary intake, body mass index, age, smoking status, and ethnicity had no significant effect on toenail Mn concentrations. Our results suggest that toenail Mn is a sensitive, specific, and easy-to-acquire biomarker of Mn exposure, which is feasible to be used in an industrial welder population.

Peripheral Blood Biomarkers Associated With Toxicity and Treatment Characteristics After 131I- Metaiodobenzylguanidine Therapy in Patients With Neuroblastoma.

PURPOSE: Few tools exist to predict clinical outcomes after radiopharmaceutical therapy. Our goal was to identify associations between blood-based biomarkers of radiation effect and clinical outcomes after 131I-metaiodobenzylguanidine (131I-MIBG) therapy in patients with neuroblastoma. METHODS AND MATERIALS: We conducted a prospective, single-center cohort study in children with advanced neuroblastoma treated with 131I-MIBG as monotherapy or in combination with systemic putative radiation sensitizers. We collected serial peripheral blood samples after 131I-MIBG infusions and quantified a panel of protein and messenger RNA markers. We plotted relative change from baseline to assess degree of modulation over time and then evaluated association of marker modulation with toxicity and response endpoints. RESULTS: The cohort included 40 patients (30 male/10 female; median age 7 years). We observed significant modulation of the majority of markers between baseline and hour 72 after 131I-MIBG. Greater fold increase of plasma FLT3 ligand was associated with subsequent grade 4 neutropenia (P=.039). Modulation of peripheral blood BCLXL and DDB2 was associated with grade 3+ nonhematologic toxicity (P=.043 and .048, respectively). No markers were associated with tumor response. Greater plasma FLT3 ligand, BCLXL, and BCL2 modulation was observed in patients receiving 131I-MIBG in combination with radiation sensitizers. Among 9 patients who received 2 courses, the degree of modulation in serum amylase was significantly lower after the second course (P=.012). CONCLUSIONS: Peripheral blood biomarkers relevant to radiation exposure are significantly modulated during the acute period after 131I-MIBG. The degree of modulation of a subset of these markers is associated with toxicity and receipt of concomitant radiation sensitizers.

Transcript Analysis for Internal Biodosimetry Using Peripheral Blood from Neuroblastoma Patients Treated with (131)I-mIBG, a Targeted Radionuclide.

Calculating internal dose from therapeutic radionuclides currently relies on estimates made from multiple radiation exposure measurements, converted to absorbed dose in specific organs using the Medical Internal Radiation Dose (MIRD) schema. As an alternative biodosimetric approach, we utilized gene expression analysis of whole blood from patients receiving targeted radiotherapy. Collected blood from patients with relapsed or refractory neuroblastoma who received (131)I-labeled metaiodobenzylguanidine ((131)I-mIBG) at the University of California San Francisco (UCSF) was used to compare calculated internal dose with the modulation of chosen gene expression. A total of 40 patients, median age 9 years, had blood drawn at baseline, 72 and 96 h after (131)I-mIBG infusion. Whole-body absorbed dose was calculated for each patient based on the cumulated activity determined from injected mIBG activity and patient-specific time-activity curves combined with (131)I whole-body S factors. We then assessed transcripts that were the most significant for describing the mixed therapeutic treatments over time using real-time polymerase chain reaction (RT-PCR). Modulation was evaluated statistically using multiple regression analysis for data at 0, 72 and 96 h. A total of 10 genes were analyzed across 40 patients: CDKN1A; FDXR; GADD45A; BCLXL; STAT5B; BAX; BCL2; DDB2; XPC; and MDM2. Six genes were significantly modulated upon exposure to (131)I-mIBG at 72 h, as well as at 96 h. Four genes varied significantly with absorbed dose when controlling for time. A gene expression biodosimetry model was developed to predict absorbed dose based on modulation of gene transcripts within whole blood. Three transcripts explained over 98% of the variance in the modulation of gene expression over the 96 h (CDKN1A, BAX and DDB2). To our knowledge, this is a novel study, which uses whole blood collected from patients treated with a radiopharmaceutical, to characterize biomarkers that may be useful for biodosimetry. Our data indicate that transcripts, which have been previously identified as biomarkers of external exposures in ex vivo whole blood and in vivo radiotherapy patients, are also good early indicators of internal exposure. However, for internal sources of radiation, the biokinetics and physical decay of the radionuclide strongly influence the gene expression.

Oxaliplatin hypersensitivity: case report and successful repeat desensitization.

INTRODUCTION: Oxaliplatin is a third generation organoplatinum complex used as an antineoplastic agent in combination with fluorouracil and leucovorin for colorectal carcinoma. Hypersensitivity reactions are commonly observed to oxaliplatin, with an incidence of 12% to 16%. Desensitization protocols for oxaliplatin with premedication using steroids or antihistamines have been previously reported. We present a patient who underwent successful repeat desensitization without premedication. CASE SUMMARY: A 43-year-old Asian male with metastatic rectal adenocarcinoma was started on chemotherapy with oxaliplatin and leucovorin followed by fluorouracil. Three hours after the first infusion of oxaliplatin, he developed generalized urticaria, which resolved with Benadryl. Similar symptoms developed after the second cycle. A desensitization protocol, without premedication, was developed for the third oxaliplatin cycle starting at 1:10,000 of the therapeutic dose followed by doubling doses thereafter until a cumulative goal dose of 175 mg was administered. Fluorouracil and leucovorin were then infused at the usual rates. Skin prick testing, before the procedure, using 5 mg/mL oxaliplatin was negative. Intracutaneous testing using dilutions of 1:1000, 1:100, and 1:10 were also negative. The patient was observed for 2 hours after the procedure without evidence of a hypersensitivity reaction. Two weeks later, the same protocol was successfully implemented for completion of his fourth cycle of chemotherapy and continued biweekly for a total of 11 cycles. Follow-up revealed tumor remission. CONCLUSION: A desensitization protocol without premedication may be considered in those patients with a history of oxaliplatin hypersensitivity reactions with avoidance of the cumulative exposure to pretreatment medications.