Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses. Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial. iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival

Implementation of paediatric precision oncology into clinical practice: The Individualized Therapies for Children with cancer program ‘iTHER’

iTHER is a Dutch prospective national precision oncology program aiming to define tumour molecular profiles in children and adolescents with primary very high-risk, relapsed, or refractory paediatric tumours. Between April 2017 and April 2021, 302 samples from 253 patients were included. Comprehensive molecular profiling including low-coverage whole genome sequencing (lcWGS), whole exome sequencing (WES), RNA sequencing (RNA-seq), Affymetrix, and/or 850k methylation profiling was successfully performed for 226 samples with at least 20% tumour content. Germline pathogenic variants were identified in 16% of patients (35/219), of which 22 variants were judged causative for a cancer predisposition syndrome. At least one somatic alteration was detected in 204 (90.3%), and 185 (81.9%) were considered druggable, with clinical priority very high (6.1%), high (21.3%), moderate (26.0%), intermediate (36.1%), and borderline (10.5%) priority. iTHER led to revision or refinement of diagnosis in 8 patients (3.5%). Temporal heterogeneity was observed in paired samples of 15 patients, indicating the value of sequential analyses. Of 137 patients with follow-up beyond twelve months, 21 molecularly matched treatments were applied in 19 patients (13.9%), with clinical benefit in few. Most relevant barriers to not applying targeted therapies included poor performance status, as well as limited access to drugs within clinical trial. iTHER demonstrates the feasibility of comprehensive molecular profiling across all ages, tumour types and stages in paediatric cancers, informing of diagnostic, prognostic, and targetable alterations as well as reportable germline variants. Therefore, WES and RNA-seq is nowadays standard clinical care at the Princess Máxima Center for all children with cancer, including patients at primary diagnosis. Improved access to innovative treatments within biology-driven combination trials is required to ultimately improve survival

Regulation of type III iodothyronine deiodinase expression in human cell lines

Type I iodothyronine deiodinase (D1) and type II iodothyronine deiodinase (D2) catalyze the activation of the prohormone T4 to the active hormone T3; type III iodothyronine deiodinase (D3) catalyzes the inactivation of T4 and T3. D3 is highly expressed in brain, placenta, pregnant uterus, and fetal tissues and plays an important role in regulating thyroid hormone bioavailability during fetal development. We examined the activity of the different deiodinases in human cell lines and investigated the regulation of D3 activity and mRNA expression in these cell lines, as well as its possible coexpression with neighboring genes Dlk1 and Dio3os, which may also be especially important during development. D1 activity and mRNA were only found in HepG2 hepatocarcinoma cells, and D2 activity was observed in none of the cell lines. D3 activity and mRNA was found in ECC-1 endometrium carcinoma cells, MCF-7 mammacarcinoma cells, WRL-68 embryonic liver cells, and SH-SY5Y neuroblastoma cells, but not in the HepG2 hepatocarcinoma cell line or in any choriocarcinoma or astrocytoma cell line. We demonstrated that the phorbol ester 12-O-tetradecanoylphorbol-13-acetate increased D3 activity 2- to 9-fold in ECC-1, MCF-7, WRL-68, and SH-SY5Y cells. Estradiol increased D3 activity 3-fold in ECC-1, but not in any other cells. Dexamethasone decreased D3 activity in WRL-68 cells only in the absence of fetal calf serum. Incubation with retinoids increased D3 activity 2- to 3-fold in ECC-1, WRL-68, and MCF-7 cells but decreased D3 activity in SH-SY5Y cells. D3 expression in the different cells was not affected by cAMP or thyroid hormone. Interestingly, D3 mRNA expression in the different cell lines strongly correlated with Dio3os mRNA expression and in a large set of neuroblastoma cell lines also with Dlk1 expression. In conclusion, we identified different human D3-expressing cell lines, in which the regulation of D3 expression is cell type-specific. Our data suggest that estradiol may be one of the factors contributing to the induction of D3 activity in the pregnant uterus and that in addition to gene-specific regulatory elements, more distant common regulatory elements also may be involved in the regulation of D3 expressio

Characterization of human iodothyronine sulfotransferases

Sulfation is an important pathway of thyroid hormone metabolism that facilitates the degradation of the hormone by the type I iodo-thyronine deiodinase, but little is known about which human sulfo-transferase isoenzymes are involved. We have investigated the sul-fation of the prohormone T4, the active hormone T3, and the metabolites rT3 and 3,39-diiodothyronine (3,39-T2) by human liver and kidney cytosol as well as by recombinant human SULT1A1 and SULT1A3, previously known as phenol-preferring and monoamine-preferring phenol sulfotransferase, respectively. In all cases, the sub-strate preference was 3,39-T2.. rT3. T3. T4. The apparent Km values of 3,39-T2 and T3 [at 50 mmol/L 39-phosphoadenosine-59-phos-phosulfate (PAPS)] were 1.02 and 54.9 mmol/L for liver cytosol, 0.64 and 27.8 mmol/L for kidney cytosol, 0.14 and 29.1 mmol/L for SULT1A1, and 33 and 112 mmol/L for SULT1A3, respectively. Th

Iodothyronine levels in the human developing brain: major regulatory roles of iodothyronine deiodinases in different areas

12 pages, 8 figures, 3 tables.-- et al.Thyroid hormones are required for human brain development, but data on local regulation are limited. We describe the ontogenic changes in T(4), T(3), and rT(3) and in the activities of the types I, II, and III iodothyronine deiodinases (D1, D2, and D3) in different brain regions in normal fetuses (13-20 wk postmenstrual age) and premature infants (24-42 wk postmenstrual age). D1 activity was undetectable. The developmental changes in the concentrations of the iodothyronines and D2 and D3 activities showed spatial and temporal specificity but with divergence in the cerebral cortex and cerebellum. T(3) increased in the cortex between 13 and 20 wk to levels higher than adults, unexpected given the low circulating T(3). Considerable D2 activity was found in the cortex, which correlated positively with T(4) (r = 0.65). Cortex D3 activity was very low, as was D3 activity in germinal eminence and choroid plexus. In contrast, cerebellar T(3) was very low and increased only after midgestation. Cerebellum D3 activities were the highest (64 fmol/min.mg) of the regions studied, decreasing after midgestation. Other regions with high D3 activities (midbrain, basal ganglia, brain stem, spinal cord, hippocampus) also had low T(3) until D3 started decreasing after midgestation. D3 was correlated with T(3) (r = -0.682) and rT(3)/T(3) (r = 0.812) and rT(3)/T(4) (r = 0.889). Our data support the hypothesis that T(3) is required by the human cerebral cortex before midgestation, when mother is the only source of T(4). D2 and D3 play important roles in the local bioavailability of T(3). T(3) is produced from T(4) by D2, and D3 protects brain regions from excessive T(3) until differentiation is required.This work was supported by European Community Grant QLG-2000-00930, Netherlands Organization for Scientific Research Grant 903-40-204, Fondo de Investigacion Sanitaria RCMN (C03/08) from Inst. de Salud Carlos III, Chief Scientists Office Scottish Executive (K/MRS/50/C741), and Tenovus Scotland/Leng Trust.Peer reviewe

Potent inhibition of estrogen sulfotransferase by hydroxylated metabolites of polyhalogenated aromatic hydrocarbons reveals alternative mechanism for estrogenic activity of endocrine disrupters

Polyhalogenated aromatic hydrocarbons (PHAHs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenylethers, and bisphenol A derivatives are persistent environmental pollutants, which are capable of interfering with reproductive and endocrine function in birds, fish, reptiles, and mammals. PHAHs exert estrogenic effects that may be mediated in part by their hydroxylated metabolites (PHAH-OHs), the mechanisms of which remain to be identified. PHAH-OHs show low affinity for the ER. Alternatively, they may exert their estrogenic effects by inhibiting E2 metabolism. As sulfation of E2 by estrogen sulfotransferase (SULT1E1) is an important pathway for E2 inactivation, inhibition of SULT1E1 may lead to an increased bioavailability of estrogens in tissues expressing this enzyme. Therefore, we studied the possible inhibition of human SULT1E1 by hydroxylated PHAH metabolites and the sulfation of the different compounds by SULT1E1. We found marked inhibition of SULT1E1 by various PHAH-OHs, in particular by compounds with two adjacent halogen substituents around the hydroxyl group that were effective at (sub)nanomolar concentrations. Depending on the structure, the inhibition is primarily competitive or noncompetitive. Most PHAH-OHs are also sulfated by SULT1E1. We also investigated the inhibitory effects of the various PHAH-OHs on E2 sulfation by human liver cytosol and found that the effects were strongly correlated with their inhibitions of recombinant SULT1E1 (r = 0.922). Based on these results, we hypothesize that hydroxylated PHAHs exert their estrogenic effects at least in part by inhibiting SULT1E1-catalyzed E2 sulfation