Impact of MTHFR Polymorphisms C677T and A1298C in Acute Lymphoblastic Leukemia and Burkitt Lymphoma Patients Exposed to Methotrexate and Asparaginase

Background: Asparaginase (Asp) and high-dose methotrexate (HDMTX) are pivotal drugs in the treatment of aggressive hematological malignancies as acute lymphoblastic leukemia (ALL) and Burkitt lymphoma (BL). Asp and MTX present specific drug-related toxicities; for Asp, prothrombotic alteration of the coagulation profile, hepatobiliary and pancreatic toxicities, for MTX, renal, hepatobiliary, hematologic, gastro-intestinal and neuro- toxicity. The 5,10-methylenetetrahydrofolate reductase (MTHFR) is the enzyme involved in conversion of homocysteine into methionine. MTHFR most frequent single nucleotide polymorphisms C677T and A1298C are associated with reduced enzymatic activity up to 60%, that implies hyperhomocysteinemia and increased toxicity of MTX. Numerous studies have explored the relationship between C677T and A1298C polymorphisms of MTHFR and MTX toxicity and/or outcome in children ALL, but results are controversial. Nevertheless, it is common practice to reduce MTX dosage in adult patients in homozygosis.

Aims: To explore the relationship between the MTHFR C677T and A1298C polymorphisms in homozygosis and development of MTX toxicity in a cohort of adult patients; furthermore, to evaluate the relationship with thrombotic risk in patients exposed to Asp.

Materials and Methods: Data from consecutive adult onco-hematologic patients for whom MTHFR C677T and A1298C polymorphism analysis was available, treated with chemotherapeutic regimens containing HDMTX and/or Asp was retrospectively collected at a single center Italian institution. Adverse events (AEs) were graded according to CTCAE 5.0. Statistical analysis was performed with R language. The impact of MTHFR polymorphisms was evaluated by mean of a multivariate analysis adjusting Odds Ratio (OR) estimates for drug dosage and disease status.

Results: Data from 78 patients, 57 affected by ALL, 3 by mixed phenotype leukemia (MPAL) and 18 by BL, was retrospectively collected. Overall, 13 (16.7%) of patients were 677TT and 8 (10.3%) were 1298CC. Patients with ALL/MPAL received mostly pediatric-inspired chemotherapy regimens (containing MTX 2.5 - 5 g/m ² and Asp 1000-2000 UI/m ²), patients with BL received modified Rituxumab (R)-BFM protocol (MTX 1.5 g/m2); age/comorbidities-adjusted dose reduction was performed according to institutional guidelines. Median age for ALL and BL patients was 37.5 (IQR 27.0-54.2) and 33.5 (26.0-49.7) years, respectively; 54/78 (69.2%) of patients were male. Patients received a median of 3 (IQR 2-6) cycles containing HDMTX and/or Asp, for a total number of 299 cycles (94 containing Asp, 184 HDMTX and 24 both); 142 (48.0%) cycles were administered for active disease (AD), at diagnosis/relapse, and 154 (52.0%) in complete remission (CR). The impact of different dosages of Asp < 1000 UI/m ² and ≥ 1000 UI/m² and of HDMTX <1.5 g/m ² and ≥ 1.5 g/m ² as well as the impact of disease status (AD vs CR) on AEs was explored.

Concerning Asp therapy and thrombotic risk, 13 deep vein thrombosis (DVT) were observed, but no association between 677TT nor 1298CC was appreciated. AD status was strongly related to DVT (21.4% vs 1.8%, p 0.003). Coherently with the MTHFR-independent drug's mechanism of action, the polymorphisms had no impact on the development of Asp-related toxicities. Diversely, concerning HDMTX, in multivariate analysis, patients with 677TT were more likely to experience AST increase grade ≥3 (OR 10.55, 95%CI 1.34-83.09) while a protective role versus any grade GGT increase was observed (OR 0.09, 95%CI 0.01-0.71) (Figure 1A). Patients with 1298CC exhibited a superior incidence any grade AST/ALT increase, not confirmed for grade ≥3 (Figure 1B). No significant superior toxicity was observed in terms of renal, gastro-intestinal, hematologic AEs.

The impact of a MTX dose reduction >25% of expected dose was then explored in a homogeneous population of 45 front-line pediatric-regimen treated ALL patients (35 received MTX dose ≥75% and 10 < 75%) and no impact in terms of OS and RFS was appreciated.

Conclusions: The analysis ofMTHFR polymorphisms in adult patients is useful in identifying patients at higher risk for transaminitis, providing a biological parameter to integrate with hepatosteatosis, liver stiffness evaluation and BMI, for a comprehensive hepatic baseline evaluation. Patients at higher risk for hepatic complications may benefit from MTX dose reduction with no impact on disease outcome.