Evaluating Methotrexate Toxicity and Its Association with ABCB1 Genetic Polymorphism in Children with Acute Lymphoblastic Leukemia

Background: Acute lymphoblastic leukemia (ALL) is among the most prevalent type of hematologic malignancy in children. The Children’s Oncology Group protocol recognizes methotrexate (MTX) as a therapy for this problem in children, despite its several complications. The relationship between MTX toxicity and ATP-binding cassette subfamily B member 1 (ABCB1) SNPs in ALL children patients has been investigated in many studies. Objectives: Regarding the controversial findings reported by these studies, the present work aims to evaluate Methotrexate toxicity and its association with ABCB1 Genetic Polymorphism in ALL pediatric patients. Methods: Blood samples were collected from pediatric ALL patients. Next, DNA was extracted and polymerase chain reaction (PCR) was conducted using 300 μMol/μL of direct primers in 50 µL as the ultimate volume. ABCB1 gene was amplified using the PCR technique, and 0.5% agarose gel electrophoresis was used to identify reaction products. Afterward, the PCR fragments’ length was proved by observing through UV-transilluminator. Finally, liver and blood toxicity was studied in all cases under treatment with MTX. Results: In the present study, 81 children with ALL (36 females and 45 males) with a mean age of 6.32 ± 3.08 years old were examined. The ABCB1 1199 G->A gene mutation frequency and the ABCB1 3435 C->T gene mutation frequency was 4.9 and 70.4%, respectively. The results showed no statistically significant difference between leukopenia, gastrointestinal toxicity, renal toxicity, hepatotoxicity, anemia, thrombocytopenia, and neutropenia in cases having homozygous heterozygous ABCB1 3435 C->T and ABCB1 1199 G->A mutant polymorphisms than those having ordinary polymorphism. Conclusions: Overall, it seems that C3435 T, G1199A, and ABCB1 are not significant MTX toxicity markers in pediatric ALL cases.

Potential contributors to low dose methotrexate toxicity in a patient with rheumatoid arthritis and pernicious anemia: case report

Background Low dose methotrexate toxicity rarely occurs, but may present with severe complications, such as pancytopenia, hepatotoxicity, mucositis, and pneumonitis. Known risk factors for methotrexate toxicity include dosing errors, metabolic syndrome, hypoalbuminemia, renal dysfunction, lack of folate supplementation, and the concomitant use of drugs that interfere with methotrexate metabolism. Vitamin B12 deficiency leads to megaloblastic anemia and may cause pancytopenia, but its role in methotrexate toxicity has not been described. Case presentation We present a case of a patient with rheumatoid arthritis who was admitted with febrile neutropenia, pancytopenia, and severe mucositis, likely secondary to low dose methotrexate toxicity. She had multiple factors that potentially contributed to the development of toxicity, including concurrent sulfasalazine use for rheumatoid arthritis. An evaluation of the patient’s macrocytic anemia revealed pernicious anemia. The patient’s illness resolved with cessation of methotrexate and sulfasalazine, leucovorin treatment and vitamin B12 repletion. Conclusions This case illustrates the multiple factors that may potentially contribute to low dose methotrexate toxicity and highlights the importance of testing for vitamin B12 deficiency in rheumatoid arthritis patients with macrocytic anemia. Addressing all the modifiable factors that potentially contribute to low dose methotrexate toxicity may improve outcomes.