Phase II study of enzastaurin, a protein kinase C beta inhibitor, in patients with relapsed or refractory diffuse large B-cell lymphoma.

PURPOSE: Protein kinase C beta (PKCbeta) was identified by gene-expression profiling, preclinical evaluation, and independent immunohistochemical analysis as a rational therapeutic target in diffuse large B-cell lymphoma (DLBCL). We conducted a multicenter phase II study of a potent inhibitor of PKCbeta, enzastaurin, in patients with relapsed or refractory DLBCL. PATIENTS AND METHODS: Enzastaurin was taken orally once daily until disease progression or unacceptable toxicity occurred. Study end points included freedom from progression (FFP) for > or= two cycles (one cycle = 28 days), objective response, and toxicity. RESULTS: Fifty-five patients (median age, 68 years) were enrolled. Patients had received a median number of two prior therapies (range, one to five); six patients relapsed after high-dose therapy and autologous stem-cell transplantation. Only one grade 4 toxicity (hypomagnesemia) occurred. Grade 3 toxicities included fatigue (n = 2), edema (n = 1), headache (n = 1), motor neuropathy (n = 1), and thrombocytopenia (n = 1). No grade 3 or 4 neutropenia occurred. No deaths or discontinuations due to toxicity were reported. Fifteen patients completed less than one cycle of therapy. Twelve of 55 patients (22%; 95% CI, 13% to 46%) experienced FFP for two cycles, and eight patients remained free from progression for four cycles (15%; 95% CI, 6% to 27%). Four patients (7%; 95% CI, 2% to 18%), including three complete responders and one patient with stable disease, continue to experience FFP 20+ to 50+ months after study entry. CONCLUSION: Treatment with enzastaurin was well-tolerated and associated with prolonged FFP in a small subset of patients with relapsed or refractory DLBCL. Further studies of enzastaurin in DLBCL are warranted.

Interleukins 18 and 21: biology, mechanisms of action, toxicity, and clinical activity.

Interleukins 18 and 21 have been described, and the effect of each upon immune response and experimental tumors in animals has been the subject of much recent work. Both interleukins have shown antitumor effects in animals, which in some models are striking for their duration, specificity, and ability to protect against rechallenge with the same tumor. These characteristics suggest immunologic involvement in the antitumor response, and several papers suggest involvement of both innate and adaptive immune mechanisms. Recent early phase I clinical trials in human cancer patients have demonstrated evidence of clinical response. This review discusses the biology, preclinical animal tumor model data, and early clinical trial findings.