Treatment optimization and genomic outcomes in refractory severe aplastic anemia treated with eltrombopag.

Eltrombopag (EPAG) received approval from the US Food and Drug Administration for the treatment of refractory severe aplastic anemia (rSAA) based on treatment of 43 patients with doses escalating from 50 to 150 mg daily for 12 weeks. Response kinetics suggested that more prolonged administration of EPAG at a dose of 150 mg could speed and improve response rates. We enrolled 40 patients with rSAA in a study of EPAG 150 mg daily, with a primary end point of response at 24 weeks. Twenty (50%) of 40 patients responded at 24 weeks; 5 (25%) of 20 would have been deemed nonresponders at 12 weeks, the end point of the previous study. Fifteen of the 19 responding patients continuing on EPAG had drug discontinued for robust response; 5 of the 15 required EPAG re-initiation for relapse, with all recovering response. To analyze risk of clonal progression, we combined long-term data from the 83 patients with rSAA enrolled in both studies. Evolution to an abnormal karyotype occurred in 16 (19%), most within 6 months of EPAG initiation. Targeted deep sequencing/whole-exome sequencing was performed pre-EPAG and at primary response end point and/or time of clonal evolution or longest follow-up. Cytogenetic evolution did not correlate with mutational status, and overall mutated allele fractions of myeloid cancer genes did not increase on EPAG. In summary, extended administration of EPAG at a dose of 150 mg for 24 weeks rescued responses in some patients with rSAA not responding at 12 weeks. The temporal relationship between clonal evolution and drug exposure suggests that EPAG may promote expansion of dormant preexisting clones with an aberrant karyotype. The studies were registered at www.clinicaltrials.gov as #NCT00922883 and #NCT01891994.

Timed sequential salvage chemotherapy for relapsed or refractory acute myeloid leukemia.

Therapy for those with relapsed or refractory acute myeloid leukemia is suboptimal. Studies have suggested that timed sequential salvage combination cytotoxic chemotherapy may have particular utility for that indication. We report here a series of ten such adult patients treated sequentially at a single center with EMA (cytarabine 500 mg/m2/day as continuous infusion on days 1-3 and days 8-10, mitoxantrone 12 mg/m2/day on days 1-3, and etoposide 200 mg/m2/day as continuous infusion on days 8-10). The overall complete remission rate was 40% (including 3 of 4 of those with relapsed disease) but use of this regimen was associated with prolonged cytopenia and a high rate of infectious adverse events. Even with the availability of modern infectious prophylaxis and therapies, the EMA regimen is likely best reserved for those with relapsed disease treated with curative intent prior to an allogeneic hematopoietic cell transplant.