Oral azacitidine compared with standard therapy in patients with relapsed or refractory follicular helper T-cell lymphoma (ORACLE): an open-label randomised, phase 3 study.

BACKGROUND: Follicular helper T-cell lymphomas (TFHL) harbour frequent alterations in genes that regulate DNA methylation. Preliminary reports suggest that treatment with 5-azacitidine has clinical activity in patients with relapsed or refractory TFHL. We aimed to compare the oral form of azacitidine with investigator's choice standard therapy (ICT; ie, gemcitabine, bendamustine, or romidepsin) in patients with relapsed or refractory TFHL. METHODS: Patients older than 18 years with relapsed or refractory TFHL (angioimmunoblastic T-cell lymphoma, follicular lymphoma, or nodal T-cell lymphoma with phenotype, ie, positive with two or more markers among CD10, BCL6, CXCL13, PD1, or ICOS) based on the 2017 WHO classification of haematological neoplasms, with an Eastern Cooperative Oncology Group performance status score of 0-3, were recruited in university hospitals from five European countries and from Japan. Patients were randomly assigned 1:1 to treatment with either azacitidine given at a dose of 300 mg once a day (200 mg in Japanese patients) for 14 days in a 28-day cycle or gemcitabine, bendamustine, or romidepsin according to the investigator's choice. Random assignment was stratified by the number of previous lines of therapy and by the presence of previous or concomitant myeloid malignancy. The primary endpoint was investigator-assessed progression-free survival, presented in the intention-to-treat population. This Article is the final analysis of this trial, registered at ClinicalTrials.gov (Europe NCT03593018 and Japan NCT03703375). FINDINGS: 86 patients (median age 69 years [IQR 62-76], 50 patients were male, 36 were female) were enrolled between Nov 9, 2018, to Feb 22, 2021; 42 in the azacitidine group and 44 in the ICT group. With a median follow-up of 27·4 months (IQR 20·2-32·9), the median progression-free survival was 5·6 months (95% CI 2·7 -8·1) in the azacitidine group versus 2·8 months (1·9-4·8) in the ICT group (hazard ratio of 0·63 (95% CI 0·38-1·07); 1-sided p=0·042). Grade 3-4 adverse events were reported in 32 (76%) of 42 patients in the azacitidine group versus 42 (98%) of 43 patients in the ICT group. The most adverse grade 3 or worse adverse events were haematological (28 [67%] of 42 patients vs 40 [93%] of 43 patients), infection (8 [19%] and 14 [33%]), and gastrointestinal (5 [12%] vs 1 [2%] for azacitidine and ICT, respectively). There were two treatment-related deaths in the azacitidine group (one endocarditis and one candidiasis) and three in the ICT group (one heart failure, one COVID-19, and one cause unknown). INTERPRETATION: Although the pre-specified primary outcome of the trial was not met, the favourable safety profile suggests that azacitidine could add to the treatment options in these difficult to treat diseases especially in combination with other drugs. Trials with combination are in preparation in a platform trial. FUNDING: Bristol-Myers Squibb. TRANSLATION: For the French translation of the abstract see Supplementary Materials section.

Detailed analysis of metastatic colorectal cancer patients who developed cardiotoxicity on another fluoropyrimidine and switched to S-1 treatment (subgroup analysis of the CardioSwitch-study).

BACKGROUND AND PURPOSE: The CardioSwitch-study demonstrated that patients with solid tumors who develop cardiotoxicity on capecitabine or 5-fluorouracil (5-FU) treatment can be safely switched to S-1, an alternative fluoropyrimidine (FP). In light of the European Medicines Agency approval of S-1 in metastatic colorectal cancer (mCRC), this analysis provides more detailed safety and efficacy information, and data regarding metastasectomy and/or local ablative therapy (LAT), on the mCRC patients from the original study. MATERIALS AND METHODS: This retrospective cohort study was conducted at 12 European centers. The primary endpoint was recurrence of cardiotoxicity after switch. For this analysis, safety data are reported for 78 mCRC patients from the CardioSwitch cohort (N = 200). Detailed efficacy and outcomes data were available for 66 mCRC patients. RESULTS: Data for the safety of S-1 in mCRC patients were similar to the original CardioSwitch cohort and that expected for FP-based treatment, with no new concerns. Recurrent cardiotoxicity (all grade 1) with S-1-based treatment occurred in 4/78 (5%) mCRC patients; all were able to complete FP treatment. Median progression-free survival from initiation of S-1-based treatment was 9.0 months and median overall survival 26.7 months. Metastasectomy and/or LAT was performed in 33/66 (50%) patients, and S-1 was successfully used in recommended neoadjuvant/conversion or adjuvant-like combination regimens and schedules as for standard FPs. INTERPRETATION: S-1 is a safe and effective FP alternative when mCRC patients are forced to discontinue 5-FU or capecitabine due to cardiotoxicity and can be safely used in the standard recommended regimens, settings, and schedules.

Hand-foot syndrome in cancer patients on capecitabine: examining prevalence, impacts, and associated risk factors at a cancer centre in Malaysia.

INTRODUCTION: Hand-foot syndrome (HFS) significantly impacts quality of life in cancer patients undergoing capecitabine treatment. This study assessed capecitabine-associated HFS prevalence, its impacts on chemotherapy treatment, and identified risk factors in multiracial Malaysian patients. METHODS: We included adult cancer patients receiving capecitabine at Sarawak General Hospital for at least two cycles from April 1, 2021 to June 30, 2022. HFS rates, time to HFS, and proportions of HFS-related treatment modifications were determined. Characteristics between patients with and without HFS were compared and multivariable logistic regression was used to identify risk factors for all-grade HFS and grade ≥2. RESULTS: Among 369 patients, 185 (50.1%) developed HFS, with 14.6% experiencing grade ≥2 and 21.6% (40/185) underwent treatment modifications. Risk factors for all-grade HFS include older age (OR 1.03 95%CI 1.01, 1.06), prior chemotherapy (OR 2.09 95%CI 1.22, 3.58), higher capecitabine dose (OR 2.96 95%CI 1.62, 5.38), prolonged treatment (OR 1.36 95%CI 1.21, 1.51), folic acid intake (OR 3.27 95%CI 1.45, 7.35) and lower neutrophil count (OR 0.77 95%CI 0.66, 0.89). For HFS grade ≥2, older age (OR 1.04 95%CI 1.01, 1.08), female sex (OR 2.10 95%CI 1.05, 4.18), Chinese race (OR 2.10 95%CI 1.06, 4.18), and higher capecitabine dose (OR 2.62 95%CI 1.28, 5.35) are significant risk factors. Use of calcium channel blockers were associated with reduced risks of all-grade HFS (OR 0.27, 95%CI 0.12, 0.60) and grade ≥2 (OR 0.21 95%CI 0.06, 0.78). CONCLUSION: This study provides real-world data on capecitabine-induced HFS in Malaysian patients and identifies risk factors that may offer insights into its understanding and management.

Contribution of aldehyde oxidase to methotrexate-induced hepatotoxicity: in vitro and pharmacoepidemiological approaches.

BACKGROUND: Methotrexate (MTX) is partially metabolized by aldehyde oxidase (AOX) in the liver and its clinical impact remains unclear. In this study, we aimed to demonstrate how AOX contributes to MTX-induced hepatotoxicity in vitro and clarify the relationship between concomitant AOX inhibitor use and MTX-associated liver injury development using the U.S. Food and Drug Administration Adverse Event Reporting System (FAERS). METHODS: We assessed intracellular MTX accumulation and cytotoxicity using HepG2 cells. We used the FAERS database to detect reporting odds ratio (ROR)-based MTX-related hepatotoxicity event signals. RESULTS: AOX inhibition by AOX inhibitor raloxifene and siRNA increased the MTX accumulation in HepG2 cells and enhanced the MTX-induced cell viability reduction. In the FAERS analysis, the ROR for MTX-related hepatotoxicity increased with non-overlap of 95% confidence interval when co-administered with drugs with higher Imax, u (maximum unbound plasma concentration)/IC50 (half-maximal inhibitory concentration for inhibition of AOX) calculated based on reported pharmacokinetic data. CONCLUSION: AOX inhibition contributed to MTX accumulation in the liver, resulting in increased hepatotoxicity. Our study raises concerns regarding MTX-related hepatotoxicity when co-administered with drugs that possibly inhibit AOX activity at clinical concentrations.

Lethal Capecitabine Toxicity in Patients With Complete Dihydropyrimidine Dehydrogenase Deficiency Due to Ultra-Rare DPYD Variants.

A DPD deficiency should be considered in case of severe toxicity even in the absence of common risk variants in DPYD.

TNF-α promoter hypomethylation is frequent in oncopediatric patients who recovered from mucositis.

The aim of this study was to investigate the DNA methylation profile in genes encoding catalase (CAT) and superoxide dismutase (SOD3) enzymes, which are involved in oxidative stress mechanisms, and in genes encoding pro-inflammatory cytokines interleukin-6 (IL6) and tumor necrosis factor-alpha (TNF-α) in the oral mucosa of oncopediatric patients treated with methotrexate (MTX®). This was a cross-sectional observational study and the population comprised healthy dental patients (n = 21) and those with hematological malignancies (n = 64) aged between 5 and 19 years. Oral conditions were evaluated using the Oral Assessment Guide and participants were divided into 4 groups: 1- healthy individuals; 2- oncopediatric patients without mucositis; 3- oncopediatric patients with mucositis; 4- oncopediatric patients who had recovered from mucositis. Methylation of DNA from oral mucosal cells was evaluated using the Methylation-Specific PCR technique (MSP). For CAT, the partially methylated profile was the most frequent and for SOD3 and IL6, the hypermethylated profile was the most frequent, with no differences between groups. For TNF-α, the hypomethylated profile was more frequent in the group of patients who had recovered from mucositis. It was concluded that the methylation profiles of CAT, SOD3, and IL6 are common profiles for oral cells of children and adolescents and have no association with oral mucositis or exposure to chemotherapy with MTX®. Hypomethylation of TNF-α is associated with oral mucosal recovery in oncopediatric patients who developed oral mucositis during chemotherapy.

Genetic polymorphisms and clinical parameters associated with renal toxicity in Thai hematologic malignancy patients receiving high dose methotrexate.

High-dose methotrexate (HD-MTX) is a widely used chemotherapy regimen for hematologic malignancies such as lymphomas and acute lymphoblastic leukemia, but its use can lead to adverse effects, including acute kidney injury (AKI), impaired liver function, and mucositis, causing extended hospital stays and delayed subsequent chemotherapy. Our study aimed to investigate the predictive factors for renal toxicities associated with HD-MTX in Thai patients undergoing treatment for hematologic malignancies. We enrolled 80 patients who underwent MTX-containing regimens, analyzing 132 chemotherapy cycles. The most common disease was primary central nervous system lymphoma (33%). Genetic polymorphisms were examined using the MassARRAY® system, identifying 42 polymorphisms in 25 genes. Serum creatinine and MTX levels were measured 24 and 48 h after MTX administration. For the primary outcome, we found that the allele A of MTRR rs1801394 was significantly related to renal toxicity (odds ratio 2.084 (1.001-4.301), p-value 0.047). Patients who exceeded the MTX threshold levels at 24 h after the dose had a significantly higher risk of renal toxicity (OR (95%CI) = 6.818 (2.350-19.782), p < 0.001). Multivariate logistic regression analysis with a generalized estimated equation revealed hypertension and age as independent predictors of increased MTX levels at 24 h after the given dose.

Capecitabine-induced severe adverse events-therapeutic drug monitoring and DPYD-gene analysis are recommended.

In this report, two cases of patients with severe adverse events after an adjuvant treatment with capecitabine are described in detail. The first patient suffered from a severe ileocolitis, where ultimately intensive care treatment, total colectomy and ileum resection was necessary. The second patient experienced a toxic enteritis, which could be managed conservatively. Post-therapeutic DPYD genotyping was negative in the former and positive in the latter case. Patients can be categorised in normal, moderate and poor DPYD metabolisers to predict the risk of adverse events of capecitabine treatment. Guidelines in various European countries recommend pretherapeutic DPYD genotyping, whereas it is not recommended by the National Comprehensive Cancer Network in the USA. Irrespective of DPYD genotyping, strict therapeutic drug monitoring is highly recommended to reduce the incidence and severity of adverse events.

Efficacy of adjuvant capecitabine in residual triple negative breast cancer: a multicenter observational Turkish Oncology Group (TOG) study.

BACKGROUND: Triple negative breast cancer (TNBC) is characterized by high rates of recurrence, especially in patients with residual disease after neoadjuvant chemotherapy (NAC). Capecitabine is being used as standard adjuvant treatment in residual TNBC. We aimed to investigate the real-life data regarding the efficacy of capecitabine in residual TNBC. DESIGN AND METHODS: In this retrospective multicenter study, TNBC patients with residual disease were evaluated. Patients, who received standard anthracycline and taxane-based NAC and adjuvant capecitabine were eligible. Overall survival (OS), disease free survival (DFS) and toxicity were analyzed. RESULTS: 170 TNBC patients with residual disease were included. Of these, 62.9% were premenopausal. At the time of analysis, the recurrence rate was 30% and death rate was 18%. The 3-year DFS and OS were 66% and 74%, respectively. In patients treated with adjuvant capecitabine, residual node positive disease stood out as an independent predictor of DFS (p = 0.024) and OS (p = 0.032). Undergoing mastectomy and the presence of T2 residual tumor was independent predictors of DFS (p = 0.016) and OS (p = 0.006), respectively. CONCLUSION: The efficacy of capecitabine was found lower compared to previous studies. Selected patients may have further benefit from addition of capecitabine. The toxicity associated with capecitabine was found lower than anticipated.

L-Glutamine Substantially Improves 5-Fluorouracil-Induced Intestinal Mucositis by Modulating Gut Microbiota and Maintaining the Integrity of the Gut Barrier in Mice.

SCOPE: This study investigates the potential of glutamine to mitigate intestinal mucositis and dysbiosis caused by the chemotherapeutic agent 5-fluorouracil (5-FU). METHODS AND RESULTS: Over twelve days, Institute of Cancer Research (ICR) mice are given low (0.5 mg kg-1) or high (2 mg kg-1) doses of L-Glutamine daily, with 5-FU (50 mg kg-1) administered between days six and nine. Mice receiving only 5-FU exhibited weight loss, diarrhea, abnormal cell growth, and colonic inflammation, correlated with decreased mucin proteins, increased endotoxins, reduced fecal short-chain fatty acids, and altered gut microbiota. Glutamine supplementation counteracted these effects by inhibiting the Toll-like receptor 4/nuclear factor kappa B (TLR4/NF-κB) pathway, modulating nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) oxidative stress proteins, and increasing mammalian target of rapamycin (mTOR) levels, thereby enhancing microbial diversity and protecting intestinal mucosa. CONCLUSIONS: These findings underscore glutamine's potential in preventing 5-FU-induced mucositis by modulating gut microbiota and inflammation pathways.

A successful desensitization in an adult patient with ARA-C infusion reaction.

INTRODUCTION: Cytarabine (ARA-C) is an antimetabolite agent used especially in the treatment of hematologic malignancies. Infusion reactions have an important place among the side effects that may occur due to treatment. Clinical findings of infusion reactions resemble allergic reactions. CASE REPORT: 47-year-old male patient with a diagnosis of B-cell Acute Lymphoblastic Leukaemia developed infusion reaction during ARA-C treatment. MANAGEMENT & OUTCOME: There was no alternative treatment option for his existing malignant disease, we decided ARA-C desensitization. DISCUSSION: We would like to describe a successful desensitization protocol in an adult patient who experienced a reaction during ARA-C infusion.

Risk factors associated with high-dose methotrexate induced toxicities.

INTRODUCTION: High-dose methotrexate (HDMTX) therapy poses challenges in various neoplasms due to individualized pharmacokinetics and associated adverse effects. Our purpose is to identify early risk factors associated with HDMTX-induced toxicities, paving the way for personalized treatment. AREAS COVERED: A systematic review of PubMed and Cochrane databases was conducted for articles from inception to July 2023. Eligible studies included reviews, clinical trials, and real-world analyses. Irrelevant studies were excluded, and manual searches and citation reviews were performed. Factors such as MTX exposure, drug interactions, demographics, serum albumin, urine pH, serum calcium, and genetic polymorphisms affecting MTX transport (e.g. SLCO1B1), intracellular folate metabolism (MTHFR), cell development (ARID5B), metabolic pathways (UGT1A1, PNPLA3), as well as epigenetics were identified. EXPERT OPINION: This comprehensive review aids researchers and clinicians in early identification of HDMTX toxicity risk factors. By understanding the multifaceted risk factors associated with hematologic malignancies, personalized treatment approaches can be tailored to optimize therapeutic outcomes.

A novel large intragenic DPYD deletion causing dihydropyrimidine dehydrogenase deficiency: a case report.

BACKGROUND: Dihydropyrimidine dehydrogenase (DPD), is the initial and rate-limiting enzyme in the catabolic pathway of pyrimidines. Deleterious variants in the DPYD gene cause DPD deficiency, a rare autosomal recessive disorder. The clinical spectrum of affected individuals is wide ranging from asymptomatic to severely affected patients presenting with intellectual disability, motor retardation, developmental delay and seizures. DPD is also important as the main enzyme in the catabolism of 5-fluorouracil (5-FU) which is extensively used as a chemotherapeutic agent. Even in the absence of clinical symptoms, individuals with either complete or partial DPD deficiency face a high risk of severe and even fatal fluoropyrimidine-associated toxicity. The identification of causative genetic variants in DPYD is therefore gaining increasing attention due to their potential use as predictive markers of fluoropyrimidine toxicity. METHODS: A male infant patient displaying biochemical features of DPD deficiency was investigated by clinical exome sequencing. Bioinformatics tools were used for data analysis and results were confirmed by MLPA and Sanger sequencing. RESULTS: A novel intragenic deletion of 71.2 kb in the DPYD gene was identified in homozygosity. The deletion, DPYD(NM_000110.4):c.850 + 23455_1128 + 8811del, eliminates exons 9 and 10 and may have resulted from a non-homologous end-joining event, as suggested by in silico analysis. CONCLUSIONS: The study expands the spectrum of DPYD variants associated with DPD deficiency. Furthermore, it raises the concern that patients at risk for fluoropyrimidine toxicity due to DPYD deletions could be missed during pre-treatment genetic testing for the currently recommended single nucleotide polymorphisms.

Topical Diclofenac for Prevention of Capecitabine-Associated Hand-Foot Syndrome: A Double-Blind Randomized Controlled Trial.

PURPOSE: Hand-foot syndrome (HFS) is a dose-limiting side effect of capecitabine. Celecoxib prevents HFS by inhibiting cyclooxygenase-2 (COX-2) that is upregulated because of the underlying associated inflammation. However, systemic side effects of celecoxib have limited routine prescription. Topical diclofenac inhibits COX-2 locally with minimal risk of systemic adverse events. Therefore, we conducted this study to assess the efficacy of topical diclofenac in the prevention of capecitabine-induced HFS. METHODS: In this single-site phase III randomized double-blind trial, we enrolled patients with breast or GI cancer who were planned to receive capecitabine-based treatment. Participants were randomly assigned in a 1:1 ratio to receive topical diclofenac or placebo gel for 12 weeks or until the development of HFS, whichever occurred earlier. The primary end point was the incidence of grade 2 or 3 HFS (Common Terminology Criteria for Adverse Events version 5), which was compared between the two groups using simple logistic regression. RESULTS: In total, 264 patients were randomly assigned to receive topical diclofenac gel (n = 131) or placebo (n = 133). Grade 2 or 3 HFS was observed in 3.8% of participants in the diclofenac group compared with 15.0% in the placebo group (absolute difference, 11.2%; 95% CI, 4.3 to 18.1; P = .003). Grade 1-3 HFS was lower in the diclofenac group than in the placebo group (6.1% v 18.1%; absolute risk difference, 11.9%; 95% CI, 4.1 to 19.6). Capecitabine dose reductions because of HFS were less frequent in the diclofenac group (3.8%) than in the placebo group (13.5%; absolute risk difference, 9.7%; 95% CI, 3.0 to 16.4). CONCLUSION: Topical diclofenac prevented HFS in patients receiving capecitabine. This trial supports the use of topical diclofenac to prevent capecitabine-associated HFS.

Additive effects of TPMT and NUDT15 on thiopurine toxicity in children with acute lymphoblastic leukemia across multiethnic populations.

BACKGROUND: Thiopurines such as mercaptopurine (MP) are widely used to treat acute lymphoblastic leukemia (ALL). Thiopurine-S-methyltransferase (TPMT) and Nudix hydrolase 15 (NUDT15) inactivate thiopurines, and no-function variants are associated with drug-induced myelosuppression. Dose adjustment of MP is strongly recommended in patients with intermediate or complete loss of activity of TPMT and NUDT15. However, the extent of dosage reduction recommended for patients with intermediate activity in both enzymes is currently not clear. METHODS: MP dosages during maintenance were collected from 1768 patients with ALL in Singapore, Guatemala, India, and North America. Patients were genotyped for TPMT and NUDT15, and actionable variants defined by the Clinical Pharmacogenetics Implementation Consortium were used to classify patients as TPMT and NUDT15 normal metabolizers (TPMT/NUDT15 NM), TPMT or NUDT15 intermediate metabolizers (TPMT IM or NUDT15 IM), or TPMT and NUDT15 compound intermediate metabolizers (TPMT/NUDT15 IM/IM). In parallel, we evaluated MP toxicity, metabolism, and dose adjustment using a Tpmt/Nudt15 combined heterozygous mouse model (Tpmt+/-/Nudt15+/-). RESULTS: Twenty-two patients (1.2%) were TPMT/NUDT15 IM/IM in the cohort, with the majority self-reported as Hispanics (68.2%, 15/22). TPMT/NUDT15 IM/IM patients tolerated a median daily MP dose of 25.7 mg/m2 (interquartile range = 19.0-31.1 mg/m2), significantly lower than TPMT IM and NUDT15 IM dosage (P < .001). Similarly, Tpmt+/-/Nudt15+/- mice displayed excessive hematopoietic toxicity and accumulated more metabolite (DNA-TG) than wild-type or single heterozygous mice, which was effectively mitigated by a genotype-guided dose titration of MP. CONCLUSION: We recommend more substantial dose reductions to individualize MP therapy and mitigate toxicity in TPMT/NUDT15 IM/IM patients.

Atherosclerosis Vindicated: A Case of Chest Pain Due to Capecitabine-Induced Coronary Artery Spasm.

BACKGROUND Capecitabine and other 5-fluorouracil prodrugs are medications widely employed in treating solid tumors, including breast and colorectal cancer. However, they carry a notable risk for cardiotoxicity, including coronary vasospasm, possibly related to their impact on vascular endothelium and smooth muscle. CASE REPORT We present a case of a 45-year-old male with a pancreatic neuroendocrine tumor who developed exertional chest pain after starting capecitabine. Initial evaluations in the emergency department, including a 12-lead electrocardiogram and cardiac enzymes, were normal, but suspicion for coronary vasospasm persisted due to the temporal relationship with drug initiation and symptom characteristics. A graded exercise test reproduced his symptoms, accompanied by hyperacute peaked T waves and subsequent ST segment elevations in the inferior leads. Coronary angiography revealed patent coronary arteries, rendering provocative testing unnecessary due to a high clinical suspicion of capecitabine-induced vasospasm. Discontinuing the patient's medication was a more efficient approach than continuing additional cardiac workup while the drug was still administered. After multidisciplinary discussion, capecitabine was discontinued, leading to symptom resolution and a negative repeat graded exercise test. CONCLUSIONS This case underscores the potential for capecitabine to induce coronary artery vasospasm, emphasizing the importance of prompt medication cessation. Patients receiving capecitabine therapy and experiencing chest pain should undergo an evaluation with consideration of capecitabine-induced vasospasm in the differential diagnosis. Prompt recognition and medication cessation are critical to prevent serious cardiovascular complications including death. In our patient, discontinuing capecitabine resolved his symptoms, emphasizing the significance of discontinuing the causative drug and seeking alternative chemotherapy regimens.

Chemotherapeutic metabolism presenting as a recalcitrant case of hand-foot syndrome and mucositis.

INTRODUCTION: Mercaptopurine (6MP) and methotrexate (MTX) are commonly used for maintenance chemotherapy for acute lymphoblastic leukemia (ALL). These medications have been associated with various side effects such as myelosuppression, colitis, and thyroiditis in addition to numerous cutaneous adverse events. Cutaneous side-effects most reported include mucositis, alopecia, xerosis, and pruritus. We report an interesting case of hand-foot syndrome to 6MP in a child on maintenance therapy for B-cell ALL from an alteration in medication metabolism. CASE: We report a 10-year-old male on maintenance chemotherapy for pre-Bcell ALL who presented to the hospital with worsening oral lesions and erythematous, fissured plaques on the palms and soles. Maintenance therapy consisted of IV vincristine and 5-day pulse of steroids every 12 weeks, daily 6MP, and weekly MTX, which were increased to ≥ 150% of standard dosing due to persistent absolute neutrophil counts > 1500. Metabolites obtained on admission demonstrated elevated 6MMP metabolites at 35,761 (normal < 5700). TPMT and NUDT15 enzyme activity were normal and no alterations in genotyping were discovered. OUTCOME: Patient's oral chemotherapy, including both 6MP and MTX, were stopped and allopurinol 100 mg daily was initiated, which lead to overall improvement. DISCUSSION: Clinical findings of acute mucositis and worsening of hand-foot syndrome, in the setting of inadequate myelosuppression in a child on maintenance therapy for ALL should raise concerns to consider altered metabolism pathway leading to toxic metabolite buildup. Allopurinol can play in improving cutaneous manifestation and chemotherapeutic dosing in patients with altered metabolism.

Integrating rare genetic variants into DPYD pharmacogenetic testing may help preventing fluoropyrimidine-induced toxicity.

Variability in genes involved in drug pharmacokinetics or drug response can be responsible for suboptimal treatment efficacy or predispose to adverse drug reactions. In addition to common genetic variations, large-scale sequencing studies have uncovered multiple rare genetic variants predicted to cause functional alterations in genes encoding proteins implicated in drug metabolism, transport and response. To understand the functional importance of rare genetic variants in DPYD, a pharmacogene whose alterations can cause severe toxicity in patients exposed to fluoropyrimidine-based regimens, massively parallel sequencing of the exonic regions and flanking splice junctions of the DPYD gene was performed in a series of nearly 3000 patients categorized according to pre-emptive DPD enzyme activity using the dihydrouracil/uracil ([UH2]/[U]) plasma ratio as a surrogate marker of DPD activity. Our results underscore the importance of integrating next-generation sequencing-based pharmacogenomic interpretation into clinical decision making to minimize fluoropyrimidine-based chemotherapy toxicity without altering treatment efficacy.