Drug-Drug Interaction Between Methotrexate and Levetiracetam Resulting in Delayed Methotrexate Elimination

Objective: To report a case of delayed methotrexate (MTX) elimination while receiving concomitant levetiracetam. Case Report: A 46-year-old man with relapsed osteosarcoma of the base of the skull receiving high-dose MTX tolerated his first cycle of MTX with elimination to nontoxic MTX levels (≤0.1 µmol/L) within 90 hours. After hospital discharge, the patient experienced seizures secondary to brain metastasis and started on levetiracetam, which was continued as maintenance therapy. The patient experienced delayed MTX elimination during cycles 2, 3, and 4 while receiving levetiracetam. On average, elimination to nontoxic MTX levels took 130 hours (106-144 hours). Before the fifth cycle of MTX, lorazepam was substituted for the levetiracetam. MTX was eliminated to nontoxic levels within 95 hours. During all cycles, the patient received standard supportive care and serum creatinine remained stable. No other drugs known to interact with MTX were administered. Discussion: This possible drug interaction has only been reported once in the pediatric population. With a score of 6 on the Drug Interaction Probability Scale for evaluating causation of drug interactions, it is probable that the delayed MTX elimination was caused by an interaction with levetiracetam. Conclusion: Coadministration of levetiracetam and MTX may result in delayed elimination of MTX, increasing the likelihood of toxicity. Consideration should be given to temporarily switching from levetiracetam to another antiepileptic (ie, lorazepam) to prevent this interaction. This is particularly important in those experiencing delayed elimination with prior cycles of concomitant MTX and levetiracetam or those at greater risk for MTX toxicity

In-class transition (iCT) of proteasome inhibitor-based therapy: a community approach to multiple myeloma management

Abstract Long-term proteasome inhibitor (PI) treatment can improve multiple myeloma (MM) outcomes, but this can be difficult to achieve in clinical practice due to toxicity, comorbidities, and the burden of repeated parenteral administration. US MM-6 (NCT03173092) enrolled transplant-ineligible patients with newly diagnosed MM to receive all-oral ixazomib-lenalidomide-dexamethasone (IRd; ≤39 cycles or until progression or toxicity) following three cycles of bortezomib-based induction. Primary endpoint: 2-year progression-free survival (PFS). Key secondary/exploratory endpoints included overall response rate (ORR), overall survival (OS), safety, quality of life (QoL), treatment satisfaction, and actigraphy. At datacut, in the fully accrued cohort of 140 patients, median age was 73 years with 42% aged ≥75 and 61% deemed frail; 10% of patients were ongoing on treatment. After a median follow-up of 27 months, the 2-year PFS rate was 71% (95% confidence interval: 61–78). ORR increased from 62% at the end of induction to 80% following in-class transition (iCT) to IRd for a median of 11 months. The 2-year OS rate was 86%. The overall safety profile/actigraphy levels were consistent with previous reports; QoL/treatment satisfaction scores were stable with ongoing therapy. iCT to IRd may allow prolonged PI-based therapy with promising efficacy and a tolerable safety profile, while maintaining QoL