In the MYF2001 trial, treatment of
Janus kinase (
JAK) inhibitor-relapsed/refractory intermediate-2 or high-risk
myelofibrosis (MF) with
imetelstat 9.4 mg/kg every 3 weeks demonstrated encouraging median overall survival of 29.9 months. To provide historical context, external real-world data (RWD) were collected from a study of 96 patients who had discontinued
ruxolitinib and were subsequently treated with best available
therapy (BAT) at Moffitt
Cancer Center. A closely matched cohort was identified using the MYF2001 eligibility criteria, including patients with MF who had discontinued
ruxolitinib due to lack or loss of response. Overall survival was measured from time of
JAK inhibitor discontinuation to death or censored at last follow-up. To improve comparability, propensity score weighting approaches using average treatment effect for overlap population (ATO) and stabilized inverse probability treatment weighting (sIPTW) were used for 10 critical baseline covariates. Fifty-seven patients treated with
imetelstat 9.4 mg/kg from MYF2001 and 38 patients treated with BAT from RWD were analyzed with improved balanced baseline covariates after propensity score adjustment, showing significantly lower risk of death with
imetelstat compared with BAT (hazard ratio: 0.35; p = 0.0019). With sIPTW, results were similar. Results of sensitivity analyses were consistent with the primary analysis. In conclusion, treatment with
imetelstat was associated with longer overall survival compared to BAT (30 vs 12 months, respectively) in closely matched patients with MF after
JAK inhibitor failure, warranting further evaluation of
imetelstat in this poor-prognosis patient population.