Inhibitor provides clinical improvement in MF
With the 300 mg IV bolus, fewer patients remained on treatment for more than 1 cycle, as compared to the other dosing cohorts. Dr Querfeld said this may be a result of lower total exposure or tolerability due to higher plasma Cmax.
She also noted that patients who received MRG-106 SQ at 600 mg or higher had a higher incidence of injection site reactions.
Safety
AEs of any grade that were attributed to MRG-106 include neutropenia (16%), injection site pain (16%), fatigue (14%), nausea (5%), pruritus (5%), and headache (5%).
Grade 3/4 AEs attributed to MRG-106 were neutropenia (5%) and pruritus (5%).
There were no serious AEs attributed to MRG-106, but there were 2 dose-limiting toxicities. One was a grade 3 tumor flare in a patient receiving the 300 mg IV bolus.
The other dose-limiting toxicity was grade 3 worsening pruritus and possible tumor flare, which occurred twice in 1 patient—with the 900 mg SQ dose and with the 300 mg IV infusion.
The 300 mg IV infusion is the anticipated phase 2 dose. 
