Gemcitabine (2\',2\'-difluoro-2\'-deoxycytidine), a widely used anticancer drug, is considered a gold standard in treating aggressive pancreatic cancers. Gamma-proteobacteria that colonize the pancreatic tumors contribute to chemoresistance against gemcitabine by metabolizing the drug to a less active and deaminated form. The gemcitabine transporters of these bacteria are unknown to date. Furthermore, there is no complete knowledge of the gemcitabine transporters in Escherichia coli or any other related proteobacteria. In this study, we investigate the complement of gemcitabine transporters in E. coli K-12 and two common chemoresistance-related bacteria (Klebsiella pneumoniae and Citrobacter freundii). We found that E. coli K-12 has two high-affinity gemcitabine transporters with distinct specificity properties, namely, NupC and NupG, whereas the gemcitabine transporters of C. freundii and K. pneumoniae include the NupC and NupG orthologs, functionally indistinguishable from their counterparts, and, in K. pneumoniae, one additional NupC variant, designated KpNupC2. All these bacterial transporters have a higher affinity for gemcitabine than their human counterparts. The highest affinity (KM 2.5-3.0 μΜ) is exhibited by NupGs of the bacteria-specific nucleoside-H+ symporter (NHS) family followed by NupCs (KM 10-13 μΜ) of the concentrative nucleoside transporter (CNT) family, 15-100 times higher than the affinities reported for the human gemcitabine transporter hENT1/SLC29A1, which is primarily associated with gemcitabine uptake in the pancreatic adenocarcinoma cells. Our results offer a basis for further insight into the role of specific bacteria in drug availability within tumors and for understanding the structure-function differences of bacterial and human drug transporters.

Gemcitabine is a widely used antimetabolite drug of pyrimidine structure, which can exist as a free-base molecular form (Gem). The encapsulated forms of medicinal drugs are of interest for delayed and local drug release. We utilized, for the first time, a novel approach of mechano-chemistry by liquid-assisted grinding (LAG) to encapsulate Gem on a \"matrix\" of porphyrin aluminum metal-organic framework Al-MOF-TCPPH2 (compound 2). The chemical bonding of Gem to compound 2 was studied by ATR-FTIR spectroscopy and powder XRD. The interaction involves the C=O group of Gem molecules, which indicates the formation of the encapsulation complex in the obtained composite. Further, the delayed release of Gem from the composite was studied to phosphate buffered saline (PBS) at 37 °C using an automated drug dissolution apparatus equipped with an autosampler. The concentration of the released drug was determined by HPLC-UV analysis. The composite shows delayed release of Gem due to the bonded form and constant concentration thereafter, while pure Gem shows quick dissolution in less than 45 min. Delayed release of Gem drug from the composite follows the kinetic pseudo-first-order rate law. Further, for the first time, the mechanism of delayed release of Gem was assessed by the variable stirring speed of drug release media, and kinetic rate constant k was found to decrease when stirring speed is decreased (diffusion control). Finally, the prolonged time scale of toxicity of Gem to pancreatic cancer PANC-1 cells was studied by continuous measurements of proliferation (growth) for 6 days, using the xCELLigence real-time cell analyzer (RTCA), for the composite vs. pure drug, and their differences indicate delayed drug release. Aluminum metal-organic frameworks are new and promising materials for the encapsulation of gemcitabine and related small-molecule antimetabolites for controlled delayed drug release and potential use in drug-eluting implants.

OBJECTIVE: Patients with dihydropyrimidine dehydrogenase (DPD) deficiency are at high risk for severe and fatal toxicity from fluoropyrimidine (FP) chemotherapy. Pre-treatment DPYD testing is standard of care in many countries, but not the United States (US). This survey assessed pre-treatment DPYD testing approaches in the US to identify best practices for broader adoption.
METHODS: From August to October 2023, a 22-item QualtricsXM survey was sent to institutions and clinicians known to conduct pre-treatment DPYD testing and broadly distributed through relevant organizations and social networks. Responses were analyzed using descriptive analysis.
RESULTS: Responses from 24 unique US sites that have implemented pre-treatment DPYD testing or have a detailed implementation plan in place were analyzed. Only 33% of sites ordered DPYD testing for all FP-treated patients; at the remaining sites, patients were tested depending on disease characteristics or clinician preference. Almost 50% of sites depend on individual clinicians to remember to order testing without the assistance of electronic alerts or workflow reminders. DPYD testing was most often conducted by commercial laboratories that tested for at least the four or five DPYD variants considered clinically actionable. Approximately 90% of sites reported receiving results within 10 days of ordering.
CONCLUSIONS: Implementing DPYD testing into routine clinical practice is feasible and requires a coordinated effort among the healthcare team. These results will be used to develop best practices for the clinical adoption of DPYD testing to prevent severe and fatal toxicity in cancer patients receiving FP chemotherapy.

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OBJECTIVE: Hypoxia is an important cause of chemotherapy resistance in gastric cancer. However, little is known about the growth of gastric cancer under purely hypoxia conditions. This study aims to study the effect of hypoxia on the growth patterns of gastric cancer cells and explore the response of gastric cancer cells to the chemotherapeutic drug 5-fluorouracil (5-FU) in a hypoxic environment.
METHODS: Gastric cancer cells MKN45 were cultured under 1% oxygen hypoxia and conventional air conditions. An intervention group with the addition of the chemotherapeutic drug 5-FU was also established. The proliferation and apoptosis of gastric cancer cells under different oxygen conditions and intervention groups were detected using the cell counting kit-8 (CCK-8) method, JC-1 mitochondrial membrane potential assay, and Annexin-V/PI double staining method. Cell cycle changes were detected by flow cytometry, and mitochondrial changes were detected using electron microscopy.
RESULTS: In the absence of 5-FU intervention, compared with the normoxia group, the hypoxia group showed higher rates of early and late apoptosis and higher cell death rates as indicated by the JC-1 mitochondrial membrane potential assay, Annexin-V/PI double staining, and CCK-8 results. Flow cytometry results showed that the cell cycle was arrested in the G0/G1 phase without progression. Electron microscopy revealed more severe mitochondrial destruction. However, with 5-FU intervention, the hypoxia group showed lower apoptosis rates, more cell cycle progression, and less mitochondrial destruction compared with the normoxia group.
CONCLUSIONS: Hypoxic environments promote apoptosis and even death in gastric cancer cells, but hypoxia counteracts the efficacy of the chemotherapeutic drug 5-FU, which may contribute to 5-FU chemotherapy resistance.
目的: 缺氧是造成胃癌化学治疗(以下简称“化疗”)耐药的重要原因，但目前对单纯缺氧环境下胃癌的生长情况了解甚少，本研究通过观察缺氧对胃癌细胞生长的影响，探讨缺氧环境中胃癌细胞对化疗药物5-氟尿嘧啶(5-fluorouracil，5-FU)的反应。方法: 设置缺氧(1%氧气)及常规空气环境，将胃癌细胞MKN45分别置于上述环境中培养，同时设立化疗药物5-FU干预组。采用细胞计数试剂盒-8(cell counting kit-8，CCK-8)法、JC-1线粒体膜电位法及Annexin-V/PI双染法检测不同氧含量环境中、不同干预组胃癌细胞的增殖及凋亡情况，流式细胞术检测细胞周期的改变，在电镜下观察细胞线粒体变化情况。结果: 不加5-FU干预的情况下，缺氧组与常氧组相比，JC-1线粒体膜电位法、Annexin-V/PI双染法及CCK-8检测结果显示胃癌细胞早期凋亡、晚期凋亡率更高，细胞死亡率更高；流式细胞术检测结果显示细胞周期被阻止在G0/G1期，不进展；电镜结果显示线粒体破坏更严重。而在加入5-FU干预的情况下，缺氧组与常氧组相比，凋亡率低，细胞周期更易进展，线粒体破坏更少。结论: 缺氧环境促进胃癌细胞凋亡甚至死亡，但是缺氧环境对化疗药物5-FU的起效产生反作用，可能是造成5-FU化疗耐药的因素。.

BACKGROUND: Severe cutaneous adverse reactions (SCARs) arising from drug interactions can carry life-threatening implications and result in lasting effects. SCARs can be triggered by various factors, with trimethoprim/sulfamethoxazole identified as a primary culprit. Anticonvulsants and antineoplastic agents have been noted as secondary triggers. Notably, antineoplastics linked to SCARs include immunomodulatory agents. The higher mortality rates among cancer patients with SCARs underscore the significance of comprehending cancer--specific risk factors. Our objective is to present the case of a boy with acute lymphocytic leukemia (ALL) who developed Stevens-Johnson syndrome (SJS) following MTX treatment.
METHODS: We present the case of a three-year-old male patient diagnosed with ALL who developed Stevens-Johnson syndrome (SJS) subsequent to the administration of MTX, following the \"BFM 2009\" protocol. He had undergone intrathecal MTX administration on six previous occasions. Our patient received IVIG at a dose of 2g/kg along with steroids, resulting in partial clinical improvement after 21 days. An innovative protocol was developed, involving IVIG before MTX infusion and dexamethasone before MTXi, with folinic acid rescue. Intravenous immunoglobulin (IVIG) mitigates SJS/TEN via type IV hypersensitivity down-regulation and apoptosis curbing.
CONCLUSIONS: As far as we know, the prophylactic use of IVIG to counteract SCARs in a pediatric leukemia patient represents uncharted territory. Moreover, research into the immune system dynamics within these patients and the preservation of indispensable treatments should involve allergist-immunologists as part of the multidisciplinary team attending to neoplastic conditions.

We present two cases of metastatic colorectal cancer where a liver injury developed while receiving capecitabine. In both cases, the patients were switched from oral capecitabine to a continuous intravenous 5-fluorouracil infusion and were able to continue treatment without a relapse of hepatotoxicity.

OBJECTIVE: The cardiotoxicity related to 5-Fluorouracil (5-FU) in cancer patients has garnered widespread attention. The systemic immune-inflammation index (SII) has recently been identified as a novel predictive marker for the development of cardiovascular illnesses in individuals without pre-existing health conditions. However, it remains unclear whether the levels of SII are linked to cardiotoxicity related to 5-FU. This retrospective study aims to fill this knowledge gap by examining the correlation between SII and cardiotoxicity related to 5-FU in a colorectal cancer cohort.
METHODS: The study comprised colorectal cancer patients who received 5-FU-based chemotherapy at the affiliated cancer hospital of Guizhou Medical University between January 1, 2018 and December 31, 2020. After adjustment for confounders and stratification by tertiles of the interactive factor, linear regression analyses, curve fitting and threshold effect analyses were conducted.
RESULTS: Of the 754 patients included final analysis, approximately 21% (n = 156) of them ultimately experienced cardiotoxicity related to 5-FU. Monocytes (M) was found as an influential element in the interaction between SII and cardiotoxicity related to 5-FU. In the low tertile of M (T1: M ≤ 0.38 × 109/L), increasing log SII was positively correlated with cardiotoxicity related to 5-FU (Odds Ratio [OR], 8.04; 95% confidence interval [95%CI], 1.68 to 38.56). However, a curvilinear relationship between log SII and cardiotoxicity was observed in the middle tertile of M (T2: 0.38 < M ≤ 0.52 × 109/L). An increase in log SII above 1.37 was shown to be associated with a decreased risk of cardiotoxicity (OR, 0.14; 95%CI, 0.02 to 0.88), indicating a threshold effect. In the high tertile of M (T3: M > 0.52 × 109/L), there was a tendency towards a negative linear correlation between the log SII and cardiotoxicity was observed (OR, 0.85; 95%CI, 0.37 to 1.98).
CONCLUSIONS: Our findings suggest that SII may serve as a potential biomarker for predicting cardiotoxicity related to 5-FU in colorectal cancer patients. SII is an independent risk factor for cardiotoxicity related to 5-FU with low monocytes levels (T1). Conversely, in the middle monocytes levels (T2), SII is a protective factor for cardiotoxicity related to 5-FU but with a threshold effect.

OBJECTIVE: Hematotoxicity is a life-threatening condition that has become the major cause of drug discontinuation in patients with acute lymphoblastic leukemia (ALL). The nudix hydrolase 15 (NUDT15) gene polymorphism (c.415C>T) is reported to have an association with the hematotoxicity of 6-mercaptopurine (6-MP) as maintenance therapy in patients with ALL. However, the prevalence of this genetic polymorphism in the Indonesian population is unknown. This study aimed to assess the frequency of NUDT15 polymorphism among Indonesian pediatric patients with ALL and its association with the hematotoxicity of 6-MP.
METHODS: A total of 101 stored DNA samples from pediatric patients with ALL receiving 6-MP treatment were used for genetic testing. Direct sequencing was conducted to determine the NUDT15 c.415C>T genotype. Chi-square or Fisher\'s exact test were employed to examine the association between the NUDT15 c.415C>T genotype and hematotoxicity.
RESULTS: All (100%) of the DNA samples from patients with ALL treated with 6-MP exhibited a homozygous variant of the NUDT15 c.415C>T genotype, 70.3% of which showed hematotoxicity to some extent. We found no significant differences in NUDT15 gene polymorphism among patients with ALL with different states of hematotoxicity.
CONCLUSIONS: The observed high frequency of NUDT15 c.415C>T in our study population might explain the elevated prevalence of 6-MP-associated hematotoxicity in pediatric patients with ALL within the Indonesian population. Our study provides new insight regarding the NUDT15 gene polymorphism and its relation to hematotoxicity. Further studies are required to determine the necessity of adjusting the initial dose of 6-MP for Indonesian pediatric patients with ALL.

OBJECTIVE: Fluoropyrimidine-related toxicity and mortality risk increases significantly in patients carrying certain DPYD genetic variants with standard dosing. We implemented DPYD genotyping at a multisite cancer center and evaluated its impact on dosing, toxicity, and hospitalization.
METHODS: In this prospective observational study, patients receiving (reactive) or planning to receive (pretreatment) fluoropyrimidine-based chemotherapy were genotyped for five DPYD variants as standard practice per provider discretion. The primary end point was the proportion of variant carriers receiving fluoropyrimidine modifications. Secondary end points included mean relative dose intensity, fluoropyrimidine-related grade 3+ toxicities, and hospitalizations. Fisher\'s exact test compared toxicity and hospitalization rates between pretreatment carriers, reactive carriers, and wild-type patients. Univariable and multivariable logistic regression identified factors associated with toxicity and hospitalization risk. Kaplan-Meier methods estimated time to event of first grade 3+ toxicity and hospitalization.
RESULTS: Of the 757 patients who received DPYD genotyping (median age 63, 54% male, 74% White, 19% Black, 88% GI malignancy), 45 (5.9%) were heterozygous carriers. Fluoropyrimidine was modified in 93% of carriers who started treatment. In 442 patients with 3-month follow-up, 64%, 31%, and 30% of reactive carriers, pretreatment carriers, and wild-type patients had grade 3+ toxicity, respectively (P = .085); 64%, 25%, and 13% were hospitalized (P < .001). Reactive carriers had 10-fold higher odds of hospitalization compared with wild-type patients (P = .001), whereas no significant difference was noted between pretreatment carriers and wild-type patients. Time-to-event of toxicity and hospitalization were significantly different between genotype groups (P < .001), with reactive carriers having the earliest onset and highest incidence.
CONCLUSIONS: DPYD genotyping prompted fluoropyrimidine modifications in most carriers. Pretreatment testing reduced toxicities and hospitalizations compared with reactive testing, thus normalizing the risk to that of wild-type patients, and should be considered standard practice.