Background and Objectives: Infections are the most common and potentially life-threatening complications of the treatment of children with acute lymphoblastic leukemia (ALL). The aim of this study was to determine epidemiological, clinical, and microbiological characteristics of infections in pediatric patients with ALL. Materials and Methods: Twenty-three children (16 males and 7 females, with a mean age of 5.9 years (range of 1.3 to 12.2 years)) with ALL, treated at the Division of Hematology, Oncology, and Clinical Genetics, Department of Pediatrics, Clinical Hospital Center Rijeka, Croatia, from 1 January 2015 to 31 December 2020, were included in the study. Results: One hundred and four infectious episodes (IEs) were reported (an average of 4.5 IE per patient). IEs were more frequent in the intensive phases of antileukemic treatment. Neutropenia was present in 48 IEs (46.2%) with a duration greater than 7 days in 28 IEs (58.3%). The respiratory tract was the most common infection site (48.1%). We documented 49 bacterial (47.1%), 4 viral (3.9%), 4 fungal (3.9%), and 10 mixed isolates (9.6%), while in 37 IEs (35.6%), a pathogen was not isolated. The most common causes of bacteremia were coagulase-positive staphylococci. The most frequent empirical therapy was third- and fourth-generation cephalosporins, followed by piperacillin/tazobactam. The modification of first-line antimicrobial therapy was performed in 56.9% of IEs. Granulocyte-colony stimulating factor was administered in 53.8% of IEs, and intravenous immunoglobulins were administered in 62.5% of IEs. One patient required admission to the intensive care unit. No infection-related mortality was reported. Conclusions: ALL patients have frequent IEs. Close monitoring, the identification of risk factors, the rapid empirical use of antibiotics in febrile neutropenia, and the timely modification of antimicrobial therapy play key roles in reducing infection-related morbidity and mortality in children with ALL.

Background and Objectives: Infections are the most common and potentially life-threatening complications of the treatment of children with acute lymphoblastic leukemia (ALL). The aim of this study was to determine epidemiological, clinical and microbiological characteristics of infections in pediatric patients with ALL. Materials and Methods: Twenty-three children (16 male and 7 female, mean age 5.9 years [range 1.3 to 12.2 years]) with ALL, treated at the Division of Hematology, Oncology and Clinical Genetics, Department of Pediatrics, Clinical Hospital Center Rijeka, Croatia, from January 1, 2015 to December 31, 2020, were included in the study Results: One hundred and four infectious episodes (IEs) were reported (average 4.5 IE per patient). IEs were more frequent in the intensive phases of antileukemic treatment. Neutropenia was present in 48 IEs (46.2%) with a duration greater than 7 days in 28 IEs (58.3%). The respiratory tract was the most common infection site (48.1%). We documented 49 bacterial (47.1%), 4 viral (3.9%), 4 fungal (3.9%) and 10 mixed isolates (9.6%), while in 37 IEs (35.6%) pathogen was not isolated. The most common causes of bacteremia were coagulase-positive staphylococci. The most frequent empirical therapy was third- and fourth-generation cephalosporins, followed by piperacillin/tazobactam. Modification of the first-line antimicrobial therapy was performed in 56.9% of IEs. Granulocyte-colony stimulating factor was administered in 53.8% of IEs, and intravenous immunoglobulins in 62.5% of IEs. One patient required admission to the intensive care unit. No infection-related mortality was reported. Conclusions: ALL patients have frequent IEs. Close monitoring, identification of risk factors, rapid empirical use of antibiotics in febrile neutropenia, and timely modification of antimicrobial therapy play a key role in reducing infection-related morbidity and mortality in children with ALL.

Interindividual variability in the efficacy and toxicity of 6-mercaptopurine (6-MP) and methotrexate (MTX) drugs remains a major challenge in the treatment of pediatric acute lymphoblastic leukemia (ALL). Germline variation in pharmacogenes involved in drug metabolism, transport, and folate pathways may contribute to this variability. In this retrospective cohort study, 43 pediatric patients with ALL treated at a tertiary referral center in Croatia according to ALL IC-BFM 2002 or 2009 protocols were genotyped for eleven variants in TPMT, ITPA, NUDT15, PACSIN2, MTHFR, TYMS, SLC19A1, and SLCO1B1 genes. Associations with average 6-MP dose during maintenance therapy, MTX pharmacokinetics during consolidation and MTX-related toxicity were analyzed. A polygenic risk score (PRS) was constructed to assess cumulative genetic risk of developing toxicity when administering these two drugs. Carriers of the ITPA rs1127354 variant required significantly lower average 6-MP doses compared with wild-type carriers. The NUDT15 rs61973267 variant was associated with higher tolerated 6-MP doses after exclusion of outliers. No significant associations were observed between individual variants and MTX clearance. A trend toward reduced risk of oral mucositis was observed in carriers of the SLCO1B1 rs4149056 variant. PRS analyses that included carriers of the TPMT rs1142345 and ITPA rs1127354 variants showed a borderline association with the requirement for 6-MP dose reduction. Our findings support a role for ITPA and NUDT15 variants in modulating 6-MP dose requirements, while single-variant associations with MTX pharmacokinetics and toxicity were limited and not supported. These results underscore the complexity of antimetabolite pharmacogenetics and suggest that integrative polygenic approaches may better capture clinically relevant pharmacogenetic risk.

Background and Objectives: The incidence of colorectal cancer (CRC) in developed Western countries is constantly growing. CRC represents the third most common cancer and the second leading cancer-related cause of death worldwide. Innate and adaptive immunity play a pivotal role in the tumor response, but many of these interactions are still not well understood. Granulysin (GNLY) is an effector, cytolytic molecule, present in human cytotoxic granules of different lymphocyte subpopulations, mainly in cytotoxic T cells and NK cells. Pore-forming proteins GNLY, perforin and granzymes play a key role in cell-mediated immune responses against tumors and infections. Materials and Methods: We aimed to analyze perforin and GNLY-mediated cytotoxicity in the peripheral blood of patients with CRC by flow cytometry. Simultaneously, the cells were labeled with monoclonal antibodies against perforin, GNLY and different surface antigens (CD3, CD4, CD8 and CD56). Phenotypes of lymphocyte subpopulation and expression of perforin and GNLY were analyzed using intracellular and surface immunofluorescence. Results: Total perforin and GNLY expressions in peripheral blood mononuclear cells (PBMC) were significantly lower than in the control group. Statistically significant differences were observed in the distribution of perforin and GNLY expression in different stages of tumors classified according to Dukes’, indicating that the percentage of total perforin and GNLY was significantly diminished in accordance with tumor progression. Perforin and GNLY expression were significantly reduced in NK and NKT cells, accompanied by reduced cytolytic potential in patients with CRC and a consequent reduction in their ability to eliminate tumors and infected cells. Conclusions: The determination of cytotoxic potential may provide a valuable assessment of a patient’s immune status and represent a novel therapeutic target. Patients with CRC exhibit markedly impaired perforin- and GNLY-mediated cytotoxicity that correlates with disease progression. Assessment and restoration of cytolytic potential may therefore serve as indicators of immune competence and promising therapeutic strategies to improve perioperative and oncologic outcomes.

Background and Objectives: Incidence of colorectal cancer (CRC) in developed Western countries is constantly growing. CRC represents the third most common cancer and the second leading cancer-related cause of death worldwide. Innate and adaptive im-munity plays a pivotal role in the tumor response, but many of these interactions are still not well understood. Granulysin (GNLY) is an effector, cytolytic molecule, present in human cytotoxic granules of different lymphocyte subpopulations, mainly in cyto-toxic T cells and NK cells. Pore-forming proteins GNLY, perforin and granzymes, play a key role in cell-mediated immune responses against tumors and infections. Materials and Methods: We aimed to analyze perforin and GNLY-mediated cytotoxicity in the peripheral blood of patients with CRC by flow cytometry. Simultaneously, the cells were labelled with monoclonal antibodies against perforin, GNLY and different sur-face antigens (CD3, CD4, CD8 and CD56). Phenotypes of lymphocyte subpopulation and expression of perforin and GNLY were analyzed using intracellular and surface immunofluorescence. Results: Total perforin and GNLY expressions in peripheral blood mononuclear cells (PBMC) were significantly lower than in the control group. Statisti-cally significant differences were observed in the distribution of perforin and GNLY expression in different stages of tumors classified according to Dukes, indicating that the percentage of total perforin and GNLY were significantly diminished in accord-ance with tumor progression. Perforin and GNLY expression was significantly reduced in NK and NKT cells, accompanied by reduced cytolytic potential in patients with CRC and a consequent reduction in their ability to eliminate tumor and infected cells. Con-clusions: The determination of cytotoxic potential may provide a valuable assessment of a patient’s immune status and represent a novel therapeutic target. Patients with CRC exhibit markedly impaired perforin- and GNLY-mediated cytotoxicity that cor-relates with disease progression. Assessment and restoration of cytolytic potential may therefore serve as indicators of immune competence and promising therapeutic strate-gies to improve perioperative and oncologic outcomes.