The cytotoxic effects of anticancer immune cells are mediated by perforin/granzyme-B, Fas ligand and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), and therefore depend on intact apoptotic responses in target tumour cells. As killing by all three of these mechanisms is blocked by the frequently overexpressed antiapoptotic oncoprotein Bcl-2, we hypothesised that coexposure to a Bcl-2 inhibitor might enhance anticancer immune responses. We evaluated this in U937 lymphoma cells, and A02 melanoma cells, which both show strong Bcl-2 expression. Va24 þ Vb11 þ natural killer T (NKT) cells expanded from peripheral blood of normal donors (n ¼ 3) were coincubated with PKH26-labelled U937 cells, and cytotoxicity was determined by flow cytometry after annexin-V-FITC and 7-AAD staining. In all cases, addition of the HA14-1 small-molecule Bcl-2 inhibitor to the cocultures significantly increased apoptosis in the target U937 cells. Using a similar assay, killing of A02 cells by the cytotoxic T-lymphocyte clone 1H3 was shown to be amplified by coexposure to the potent small-molecule Bcl-2 inhibitor ABT-737. Experiments with immune effectors preincubated with concanamycin-A suggested that sensitisation to perforin/granzyme-B may underlie enhanced target-cell killing observed in the presence of Bcl-2 inhibitors. We conclude that immune destruction of malignant cells can be amplified by molecular interventions that overcome Bcl-2-mediated resistance to apoptosis.

Background:CYT997 is a novel microtubule inhibitor and vascular-disrupting agent with marked preclinical anti-tumour activity.Methods:This phase I dose-escalation study assessed the safety, tolerability, pharmacokinetics and pharmacodynamics of CYT997 administered by continuous intravenous infusion over 24 h every 3 weeks to patients with advanced solid tumours.Results:Thirty-one patients received CYT997 over 12 dose levels (7–358 mg m−2). Doses up to 202 mg m−2 were well tolerated. Dose-limiting toxicities were observed at 269 and 358 mg m−2, consisting of grade 3 prolonged corrected QT interval in two patients and grade 3 hypoxia and grade 4 dyspnea in one patient. All toxicities were reversible. The pharmacokinetics of CYT997 were linear over the entire dose range. Dynamic contrast-enhanced magnetic resonance imaging scans showed significant changes in tumour Ktrans values consistent with vascular disruption in 7 out of 11 evaluable patients treated at CYT997 doses of ⩾65 mg m−2. Moreover, plasma levels of von Willebrand factor and caspase-cleaved cytokeratin-18 increased post-treatment at higher dose levels. Among 22 patients evaluable for response, 18 achieved stable disease for >2 cycles.Conclusions:CYT997 was well tolerated at doses that were associated with pharmacodynamic evidence of vascular disruption in tumours.

Ephrins are cell membrane-associated signaling proteins bound by transmembrane Eph receptors on juxtaposed cells. Eph-ephrin interactions result in bidirectional signaling within both receptor- and ligand-bearing cells, with diverse consequences for cell morphology and behavior. Such interactions are especially important during early vertebrate development, and growing evidence has revealed equally important roles in adult-tissue homeostasis. As for the Eph receptors, abnormal expression of ephrins is associated with disease, especially cancer. The ephrins have received less attention than the Ephs in the literature, owing, in part, to their later discovery and that they are fewer in number. Here, we attempt to redress this imbalance and provide an 'ephrin-centric' discussion of the expression and function of ephrins in cancer.