TPS6642^ Background: Ruxolitinib, a potent and selective oral JAK1/2 inhibitor, has demonstrated rapid and durable reductions in splenomegaly and improved MF-related symptoms and quality of life in 2 phase 3 studies in pts with PMF, PPV-MF, or PET-MF. There is considerable experience in pts who develop thrombocytopenia on study, and ruxolitinib is well-tolerated with dose adjustment. However, there is limited experience in pts with baseline thrombocytopenia as those with low PLTs (< 100 x 109/L) were excluded from the phase 3 protocols. EXPAND (Evaluating RuXolitinib in Patients with Low Baseline PlAtelet CouNts Diagnosed With Myelofibrosis) will evaluate the safety of ruxolitinib and establish the maximum safe starting dose (MSSD) in thrombocytopenic pts with MF. Methods: This is a phase 1b, open-label, dose-finding study (NCT01317875) in pts with PMF, PPV-MF, or PET-MF and baseline PLT 50-100 x 109/L. A Bayesian logistic regression model with escalation with overdose control will be used to guide dose-escalation decisions. The study consists of 2 phases: dose-escalation and safety-expansion. The starting dose is ruxolitinib 5 mg twice daily (BID) with a maximum of 15 mg BID. In the dose-escalation phase, cohorts will be: 5 mg BID, 5 mg am/10 mg pm, 10 mg BID, 10 mg am/15 mg pm, and 15 mg BID; only pts with PLT 75-100 x 109/L (1st stratum) will initially be enrolled. Once safety is established at the first 2 dose levels (5 mg BID; 5 mg am/10 mg pm), pts with PLT 50-75 x 109/L will be included (2nd stratum). Each dose level in the 2nd stratum will be open only if both that dose and the following one are deemed safe in the 1st stratum. In the safety-expansion phase, 20 pts (10 from each stratum) additional to those treated at the MSSD during dose escalation will be treated at the respective MSSD for their stratum. In cohort 1 (n = 4), 3 pts were evaluable as they completed > 28 days of treatment; 1/4 pts discontinued after 6 doses due to disease progression. No dose-limiting toxicities were observed. The second cohort (5 mg am/10 mg pm) has completed enrollment (n = 3) and is ongoing.
FRI0549 SARILUMAB, A HUMAN MONOCLONAL ANTIBODY TO THE INTERLEUKIN-6 (IL-6) RECEPTOR, IN POLYARTICULAR-COURSE JUVENILE IDIOPATHIC ARTHRITIS (PCJIA): A 12-WEEK MULTINATIONAL OPEN-LABEL DOSE-FINDING STUDY
