PurposeSevere hematotoxicity in patients with thiopurine therapy has been associated with genetic polymorphisms in the thiopurine S-methyltransferase (TPMT). While TPMT genetic testing is clinically implemented for dose individualization, alterations in the nudix hydrolase 15 (NUDT15) emerged as independent determinant of thiopurine-related hematotoxicity. Because data for European patients are limited, we investigated the relevance of NUDT15 in Europeans.MethodsAdditionally to TPMT phenotyping/genotyping, we performed in-depth Sanger sequencing analyses of NUDT15 coding region in 107 European patients who developed severe thiopurine-related hematotoxicity as extreme phenotype. Moreover, genotyping for NUDT15 variants in 689 acute lymphoblastic leukemia (ALL) patients was performed.ResultsAs expected TPMT was the main cause of severe hematotoxicity in 31% of patients, who were either TPMT deficient (10%) or heterozygous carriers of TPMT variants (21%). By comparison, NUDT15 genetic polymorphism was identified in 14 (13%) patients including one novel variant (p.Met1Ile). Six percent of patients with severe toxicity carried variants in both TPMT and NUDT15. Among patients who developed toxicity within 3 months of treatment, 13% were found to be carriers of NUDT15 variants.ConclusionTaken together, NUDT15 and TPMT genetics explain ~50% of severe thiopurine-related hematotoxicity, providing a compelling rationale for additional preemptive testing of NUDT15 genetics not only in Asians, but also in Europeans.

Several subtypes of renal cell carcinoma (RCC) with different metastatic potentials and prognoses exist. In the present study, we provide novel insight into the metabolism of these different subtypes, which improves classification of subtypes and helps identify novel targets for RCC therapy.

Background The metabolic enzyme nicotinamide‐N‐methyltransferase (NNMT) is highly expressed in various cancer entities, suggesting tumour‐promoting functions. We systematically investigated NNMT expression and its metabolic interactions in clear cell renal cell carcinoma (ccRCC), a prominent RCC subtype with metabolic alterations, to elucidate its role as a drug target. Methods NNMT expression was assessed in primary ccRCC (n = 134), non‐tumour tissue and ccRCC‐derived metastases (n = 145) by microarray analysis and/or immunohistochemistry. Findings were validated in The Cancer Genome Atlas (kidney renal clear cell carcinoma [KIRC], n = 452) and by single‐cell analysis. Expression was correlated with clinicopathological data and survival. Metabolic alterations in NNMT‐depleted cells were assessed by nontargeted/targeted metabolomics and extracellular flux analysis. The NNMT inhibitor (NNMTi) alone and in combination with the inhibitor 2‐deoxy‐D‐glucose for glycolysis and BPTES (bis‐2‐(5‐phenylacetamido‐1,3,4‐thiadiazol‐2‐yl)ethyl‐sulfide) for glutamine metabolism was investigated in RCC cell lines (786‐O, A498) and in two 2D ccRCC‐derived primary cultures and three 3D ccRCC air–liquid interface models. Results NNMT protein was overexpressed in primary ccRCC (p = 1.32 × 10–16) and ccRCC‐derived metastases (p = 3.92 × 10–20), irrespective of metastatic location, versus non‐tumour tissue. Single‐cell data showed predominant NNMT expression in ccRCC and not in the tumour microenvironment. High NNMT expression in primary ccRCC correlated with worse survival in independent cohorts (primary RCC—hazard ratio [HR] = 4.3, 95% confidence interval [CI]: 1.5–12.4; KIRC—HR = 3.3, 95% CI: 2.0–5.4). NNMT depletion leads to intracellular glutamine accumulation, with negative effects on mitochondrial function and cell survival, while not affecting glycolysis or glutathione metabolism. At the gene level, NNMT‐depleted cells upregulate glycolysis, oxidative phosphorylation and apoptosis pathways. NNMTi alone or in combination with 2‐deoxy‐D‐glucose and BPTES resulted in inhibition of cell viability in ccRCC cell lines and primary tumour and metastasis‐derived models. In two out of three patient‐derived ccRCC air–liquid interface models, NNMTi treatment induced cytotoxicity. Conclusions Since efficient glutamine utilisation, which is essential for ccRCC tumours, depends on NNMT, small‐molecule NNMT inhibitors provide a novel therapeutic strategy for ccRCC and act as sensitizers for combination therapies.