Oral vorinostat (suberoylanilide hydroxamic acid, SAHA) in relapsed diffuse large B-cell lymphoma (DLBCL): Final results of a phase II trial

18511 Background: Vorinostat (Zolinza™) is a histone deacetylase inhibitor (HDACI) approved in the US for the treatment of cutaneous manifestations in patients (pts) with cutaneous T-cell lymphoma who have progressive, persistent or recurrent disease on or following 2 systemic therapies. Clinical responses with vorinostat have been reported in other lymphoma subtypes. Methods: Open-label, single-arm, nonrandomized Phase II trial of oral vorinostat 300 mg bid (initially 14 d/3 wks; amended to 3 d/wk) until disease progression or intolerable toxicity. Eligibility: measurable, relapsed/refractory DLBCL; = 2 prior systemic therapies; adequate hematologic, hepatic and renal function. Pts who had prior HDACI treatment, allogeneic transplant, or had failed > 3 prior therapies were excluded. Primary endpoint: objective response rate (ORR) measured by CT/PET. Secondary endpoints: assessment of response duration (DOR), time to progression (TTP), time to response (TTR) and safety. Results: Eighteen pts (median age, 66 y [range, 59–86 y]; median 2 prior systemic therapies) were enrolled from 5/05 - 3/06 at 8 centers. Seven pts were initially treated with 300 mg bid 14 d/3 wks, but 4 had DLT (Gr 3 muscle spasms; Gr 4 thrombocytopenia, n = 3). The schedule was amended to 300 mg bid 3 d/wk and no other pt had DLT. One pt on the 3d/wk schedule achieved a CR (TTR = 85 d; DOR = 225+ d) and the ORR was 5.6%. One pt had SD for 301 d. Sixteen pts discontinued (DC) due to PD; median TTP for all pts was 44 d. Median number of treatment cycles was 2 (range, 1–14+). Two pts received > 6 cycles (126 d). Common drug-related adverse experiences (AE; mostly = Gr 2) were diarrhea (61%), fatigue (50%), nausea (39%), anemia (33%) and vomiting (33%). Three pts had dose reduction (300 -> 200 mg bid 14 d/3 wks) and none DC due to a drug-related AE. Drug-related AE = Gr 3 included thrombocytopenia (n = 3; 300 mg bid 14 d/3 wk) and asthenia (n = 2; 300 mg bid 3 d/wk). Two pts died on study of causes unrelated to drug: PD + GI hemorrhage (d 40) and acute myocardial infarction (d 95). Conclusion: Vorinostat has modest activity in pts with relapsed DLBCL and is well tolerated at 300 mg bid 3 d/wk or 200 mg bid 14 d/3 wks. The optimal dose/schedule and predictive response biomarkers require further study. No significant financial relationships to disclose.