Distinct cellular and therapeutic effects of obatoclax in rituximab-sensitive and -resistant lymphomas.

Bcl-2 proteins represent a rheostat that controls cellular viability. Obatoclax, a BH3-mimetic, has been designed to specifically target and counteract anti-apoptotic Bcl-2 proteins. We evaluated the biological effects of obatoclax on the anti-tumour activity of rituximab and chemotherapy agents. Obatoclax induced cell death of rituximab/chemotherapy-sensitive (RSCL), -resistant cell lines (RRCL) and primary tumour-cells derived from patients with B-cell lymphomas (N=39). Obatoclax also enhanced the activity of rituximab and had synergistic activity when combined with chemotherapy agents. The ability of Obatoclax to induce PARP cleavage varied between patient samples and was not observed in some RRCL. Inhibition of caspase activity did not affect obatoclax activity, suggesting the existence of caspase-independent death pathways. Autophagy was detected by LC3 conversion and/or electron microscopy in RRCL and in patient-derived tumour cells. Moreover, obatoclax activity was inhibited by Beclin-1 knockdown. In summary, obatoclax is an active Bcl-2 inhibitor that potentiates the activity of chemotherapy agents and, to a lesser degree, rituximab. Defining the molecular events triggered by obatoclax is necessary to further its clinical development and identify potential biomarkers that are predictive of response.

Activated Akt and Erk expression and survival after surgery in pancreatic carcinoma.

BACKGROUND: Long-term survival of surgically resectable pancreatic cancer patients is uncommon. The epidermal growth factor receptor (EGFR) and the phosphoinositol-3-kinase pathways are often activated in pancreatic cancer, and an understanding of their role in resected cases may help refine adjuvant therapy. METHODS: We investigated the expression of EGFR, Erk, Akt, and their phosphoforms (p-) in pancreatectomy specimens and correlated these with survival. Thirty-nine consecutive surgically resected pancreatic adenocarcinoma cases were included. Immunohistochemical staining of paraffin-embedded blocks was performed by using monoclonal antibodies against EGFR, Erk, p-Erk, Akt, and p-Akt. A standard immunoperoxidase technique was used to detect the avidin-biotin peroxidase complex. Immunostaining was visually scored with the histoscore method by two surgical pathologists. RESULTS: Patient characteristics were as follows: 17 men and 22 women; median age, 66 years; and American Joint Committee on Cancer stage I, 5 patients; stage II, 4 patients; stage III, 27 patients; and stage IV, 3 patients. The tumor was World Health Organization grade 1 in 4, grade 2 in 17, and grade 3 in 18 cases. Adjuvant therapies were chemotherapy (n = 6), radiotherapy (n = 1), and chemoradiotherapy (n = 17). Immunohistochemistry revealed positive expression of EGFR in 30.8%, Erk in 92.3%, p-Erk in 45.9%, Akt in 71.8%, and p-Akt in 20.5% of cases. On univariate analyses, tumor grade (P = .0098), p-Akt (P = .0003), and p-Erk (P = .0052) expression correlated with survival. On multivariate analyses, age (P = .0002; hazard ratio [HR], 1.8), grade (P = .00318; HR, 3.0), Akt (P = .0433; HR, .4), p-Akt (P = .0002; HR, .2), and p-Erk (P = .0003; HR, 3.5) expression correlated significantly with survival. CONCLUSIONS: p-Erk and p-Akt expression may have prognostic and therapeutic implications in pancreatic cancer.

Should adjuvant therapy remain the standard of care for patients with resected adenocarcinoma of the pancreas?

Adenocarcinoma of the pancreas continues to be a formidable disease. In the United States, patients who have had resected disease are generally offered adjuvant chemoradiation. The current National Comprehensive Cancer Network practice guidelines uniformly support this practice. We reviewed seven selected series to evaluate the efficacy of adjuvant therapy for patients who had resected adenocarcinoma of the pancreas. Current evidence-based analysis demonstrates that an adjuvant therapy regimen as a standard of care is lacking. We, therefore, believe that it should be used judiciously because its benefit is confined to only a fraction of patients treated by complete resection (R0); patients with residual microscopic disease (R1) derived negligible benefits. Given the financial constraints and the small effect that current therapies have on this fatal disease, clinicians should concentrate on developing novel therapies and new paradigms to address this age-old problem.