Purpose: Gemcitabine (G) is standard therapy for pancreatic cancer. Enzastaurin (E) inhibits PKCβ and PI3K/AKT signaling pathways with a dose-dependent effect on growth of pancreatic carcinoma xenografts. Data suggest that the GE combination may improve clinical outcomes.
Methods: Primary objective was overall survival (OS); secondary objectives assessed progression-free survival (PFS), response rate (RR), quality of life (QOL), toxicity, and relationships between biomarker expression and clinical outcomes. Patients were randomly assigned (2:1) to GE or G treatment; GE arm: E 500 mg p.o. daily; loading-dose (1200 mg; Day 1 Cycle 1 only) and G 1000 mg/m(2) i.v. Days 1, 8, and 15 in 28-day cycles; G arm: G as in GE. Biomarker expression was assessed by immunohistochemistry.
Results: Randomization totaled 130 patients (GE = 86, G = 44); 121 patients were treated (GE = 82, G = 39). GE/G median OS was 5.6/5.1 months; median PFS was 3.4/3.0 months. GE responses: 1 complete response (CR, 1.2%), 6 partial response (PR, 7.4%), and 33 stable disease (SD, 40.7%); disease control rate (DCR=CR+PR+SD, 49.4%). G responses: 2 PR (5.3%) and 16 SD (42.1%); DCR (47.4%). No QOL differences were noted between arms. GE/G Grade 3-4 toxicities included: neutropenia (18.3%/28.2%); thrombocytopenia (14.6%/25.6%); and fatigue (11.0%/7.7%). No statistically significant relationships between biomarker expression and outcomes were observed. However, patients with low expression of cytoplasmic pGSK-3β trended toward greater OS with GE treatment.
Conclusions: OS, PFS, QOL, and RR were comparable between arms. Adding E to G did not increase hematologic toxicities. GE does not warrant further investigation in unselected pancreatic cancer patients.