Assessment of the Potential for Veverimer Drug-Drug Interactions.

Veverimer is a polymer being developed as a potential treatment of metabolic acidosis in patients with chronic kidney disease. Veverimer selectively binds and removes hydrochloric acid from the gastrointestinal tract, resulting in an increase in serum bicarbonate. Veverimer is not systemically absorbed, so potential drug-drug interactions (DDIs) are limited to effects on the absorption of other oral drugs through binding to veverimer in the gastrointestinal tract or increases in gastric pH caused by veverimer binding to hydrochloric acid. In in vitro binding experiments using a panel of 16 test drugs, no positively charged, neutral, or zwitterionic drugs bound to veverimer. Three negatively charged drugs (furosemide, aspirin, ethacrynic acid) bound to veverimer; however, this binding was reduced or eliminated in the presence of normal physiologic concentrations (100-170 mM) of chloride. Veverimer increased gastric pH in vivo by 1.5-3 pH units. This pH elevation peaked within 1 hour and had returned to baseline after 1.5-3 hours. Omeprazole did not alter the effect of veverimer on gastric pH. The clinical relevance of in vitro binding and the transient increase in gastric pH was evaluated in human DDI studies using two drugs with the most binding to veverimer (furosemide, aspirin) and two additional drugs with pH-dependent solubility effecting absorption (dabigatran, warfarin). None of the four drugs showed clinically meaningful DDI with veverimer in human studies. Based on the physicochemical characteristics of veverimer and results from in vitro and human studies, veverimer is unlikely to have significant DDIs. SIGNIFICANCE STATEMENT: Patients with chronic kidney disease, who are usually on many drugs, are vulnerable to drug-drug interactions (DDIs). The potential for DDIs with veverimer was evaluated based on the known site of action and physicochemical structure of the polymer, which restricts the compound to the gastrointestinal tract. Based on the findings from in vitro and human studies, we conclude that veverimer is unlikely to have clinically significant DDIs.

Incidence and management of myelosuppression in patients with chronic- and accelerated-phase chronic myeloid leukemia treated with omacetaxine mepesuccinate.

Omacetaxine mepesuccinate (Synribo) is an inhibitor of protein synthesis indicated for the treatment of patients with chronic- or accelerated-phase chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors. Myelosuppression is the most common and clinically significant toxicity experienced by patients treated with omacetaxine. Here, we further examine the patterns of hematologic toxicity observed in clinical trials and describe the approach to management as well as resolution of events. Omacetaxine-related myelosuppression typically occurs more frequently during induction cycles. In general, the myelosuppression observed with omacetaxine treatment is manageable and reversible, and long-term administration is feasible. Careful monitoring, dose delays and reduction in administration days, and appropriate supportive care are critical for successful management of hematologic toxicity. Concerns regarding myelosuppression, observed with many cancer treatments, should not prevent eligible patients from receiving omacetaxine, particularly CML patients with unsatisfactory responses to multiple lines of prior treatment.