Purpose: To compare disease-free survival (DFS) after maintenance therapy with the selective protein kinase C β (PKCβ) inhibitor, enzastaurin, versus placebo in patients with diffuse large B-cell lymphoma (DLBCL) in complete remission and with a high risk of relapse after first-line therapy.
Patients and methods: This multicenter, phase III, randomized, double-blind, placebo-controlled trial enrolled patients who were at high risk of recurrence after rituximab-cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). Patients (N = 758) with stage II bulky or stage III to IV DLBCL, three or more International Prognostic Index risk factors at diagnosis, and a complete response or unconfirmed complete response after 6 to 8 cycles of R-CHOP were assigned 2:1 to receive oral enzastaurin 500 mg daily or placebo for 3 years or until disease progression or unacceptable toxicity. Primary end point was DFS 3 years after the last patient entered treatment. Correlative analyses of biomarkers, including cell of origin by immunohistochemistry and PKCβ expression, with efficacy outcomes were exploratory objectives.
Results: After a median follow-up of 48 months, DFS hazard ratio for enzastaurin versus placebo was 0.92 (95% CI, 0.689 to 1.216; two-sided log-rank P = .541; 4-year DFS, 70% v 71%, respectively). Independent of treatment, no significant associations were observed between PKCβ protein expression or cell of origin and DFS or overall survival.
Conclusion: Enzastaurin did not significantly improve DFS in patients with high-risk DLBCL after achieving complete response to R-CHOP. Achievement of a complete response may have abrogated the prognostic significance of cell of origin by immunohistochemistry.
Trial registration: ClinicalTrials.gov NCT00332202.
© 2016 by American Society of Clinical Oncology.