Results: Nine patients enrolled with a median age of 71 (range: 61-85 years), 67% female with baseline IPSS-R, IPSS-M and mutation data shown in Table. By IPSS-M, 3, 3, 1, 2 patients were low, moderately-low, moderately high, and high-risk categories. All IPSS-M lower risk mutant patients had splicing mutations. The median number of mutations was 2 (range 0-5). 100% of patients were ESA refractory. Additionally, 33% and 56% were refractory to lenalidomide and luspatercept therapy, respectively. Eight (89%) patients were PRBC dependent at baseline (56% [n=5] with high transfusion burden).

The median follow-up duration was 6.1 months (range 3-17.8). The most common adverse events were neutropenia (n=7), followed by thrombocytopenia (n=4), and abnormal liver function tests (n=4). There were two grade 3 adverse events including thrombocytopenia and colitis, both unrelated to study treatment. There were no dose-limiting toxicities or serious adverse events in the phase 1 portion. All patients achieved the best response as stable disease, and no one had progression disease. No patients achieved objective response or significant reduction in transfusion burden. There was no statistical improvement in total QUALMS score from baseline to end of treatment (P=0.72) nor in the individual components (i.e. physical burden, benefit finding and emotional burden, P=0.69, P=0.91, P=0.630; respectively) although several patients had individual improvements.

The percentage of PBMCs with ASC specks at baseline ranged from 0.3945-2.978% (median 1.93%). ASC specks decreased significantly after cycle 1 of therapy and were durably suppressed over the course of treatment in a majority of patients (Figure). Extracellular IL-1β in bone marrow plasma robustly increased with treatment and remained elevated (representing non-functional IL-1β [canakinumab bound IL-1β]; P=0.002 cycle 6 versus baseline), supporting pharmacodynamic effect with no differences observed between DL1 and DL2.

Conclusions: The combination of canakinumab and darbepoetin was safe and well tolerated and 300mg of canakinumab is the RP2D. Canakinumab inhibited inflammasome activation as evidenced by a reduction of ASC specks although this did not translate to clinical responses. Phase 2 of the study will focus on patients with lower transfusion burden and molecular subsets with highest IL-1β expression (e.g. TET2/DNMT3A mutant).