Methodology of clinical trials evaluating the incorporation of new drugs in the first-line treatment of patients with diffuse large B-cell lymphoma (DLBCL): A critical review

Abstract

Background: The first-line treatment of diffuse large B-cell lymphoma (DLBCL) is the combination of rituximab with CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) chemotherapy, curing approximately 60% of patients. Many clinical trials have been carried out over the last 10 years trying to improve the results of this treatment, but the appropriateness of their planning strategies could be rediscussed. Patients and methods: Reports of phase III trials evaluating the addition of molecularly targeted agents or new monoclonal antibodies to the classic R-CHOP backbone in first-line induction or maintenance treatment were reviewed. The trial design, primary end point, number of patients enrolled, patient selection criteria, treatment schedule and results were registered for each one. In addition, the phases I and II trials which preceded these phase III trials were also reviewed. Results: Among six phase III trials with results, only one trial evaluating lenalidomide maintenance after response to R-CHOP induction was positive and reached its primary end point. The other five trials did not show an improved outcome with the addition of the new agent. The preceding phases I and II trials were very heterogeneous in their end points and design. Even though most of these trials were considered positive, thus encouraging further investigation, so far they failed to predict the results of the subsequent phase III trials. Conclusion: The standard of care for DLBCL is still R-CHOP. Phase I/II trials failed to predict the results of subsequent phase III trials evaluating non-chemotherapeutic agents added to R-CHOP. The methodology of phase II trials evaluating new agents in DLBCL needs to be better defined in the future.