Phase I study of ONO-4059 (highly potent & selective oral Btk inhibitor) in patients with relapsed/refractory, high risk CLL for whom no therapy of higher priority available

Patients treated with ONO-4059 at doses ranging from 20mg-320mg (cohorts 1-5) continuously initially for up to 6 months, with option of additional dosing up to 2 years

ONO-4059-related G3 or G4 haematological toxicities infrequent and independent of dose

Only one Grade 3 non-haematological event (pyrexia) reported

Common adverse events included diarrhea and rash

Pharmacokinetics: rapid absorption and elimination, half-life: ~6 hours

Best ORR: 70%

Patients with grade 3 thrombocytopenia at study baseline had significant improvement in platelet count (>100 x 109/L) with ONO-4059 treatment

Median progression-free survival: 99 days [Range 8-268].