Clinical trial experience with CA4P anticancer therapy: focus on efficacy, cardiovascular adverse events, and hypertension management

Combretastatin A4-phosphate (CA4P) is a vascular-disrupting agent (VDA) in clinical development for the treatment of ovarian and other cancers. In contrast to antiangiogenic agents, such as bevacizumab, which suppress the development of new tumor vasculature, VDAs target established tumor vasculature. These differing but complementary mechanisms of action are currently being explored in clinical trials combining CA4P and bevacizumab. Clinical experience to date has highlighted an important need to better understand the cardiovascular adverse events of CA4P, both alone and in combination with antiangiogenic agents, which can also be associated with cardiovascular adverse events. An acute but transient increase in blood pressure is often the most clinically relevant toxicity associated with CA4P. Increases in CA4P-related blood pressure typically occur 0.5 to 1 h after initiation of the 10-min infusion, peak by 2 h, and return to baseline 3 to 4 h after the infusion. Post-infusion increases in blood pressure are likely to recur in subsequent treatment cycles; however, the severity does not appear to increase with successive cycles. Other cardiovascular adverse events, such as transient, predominantly grade 1–2 tachycardia, bradycardia, QTc prolongation, and in rare cases myocardial ischemia, have also been observed with CA4P but at markedly lower frequencies than hypertension. The clinical trial experience with CA4P suggests that cardiovascular assessment of patients prior to CA4P treatment and careful management of blood pressure during CA4P treatment can largely mitigate the risk of cardiovascular adverse events. Accordingly, we have developed a blood pressure management algorithm for use in the ongoing phase II/III FOCUS study of the triple combination of CA4P with physician’s choice chemotherapy and bevacizumab.