Validation of Tie2 as the First Tumour Vascular Response Biomarker for VEGF Inhibitors: VALTIVE1

Tumours require a blood supply to provide them with oxygen and nutrients and to enable spread of cancer through blood vessels to other organs (metastasis). The formation of new blood vessels is known as angiogenesis, which is controlled by a growth factor (like a hormone) called Vascular Endothelial Growth Factor (VEGF). Many drugs have been developed that block VEGF and, in most tumour types, including ovarian cancer, the addition of VEGF inhibitors (VEGFi) to conventional anti-cancer therapy postpones recurrence of the disease. In ovarian cancer, VEGFi improve the overall outcome from the cancer in patients who have advanced stage and high-risk disease. VEGFi are now widely used in cancer medicine, yet until now there have not been any biomarkers (tests) that could be used to tell patients and their doctors whether the drugs were working or not. This is important, as VEGFi have side effects that are unpleasant for the patient. Additionally, VEGFi treatments are expensive.

The VALTIVE team has discovered the first biomarker that informs doctors whether a VEGFi is blocking a tumour's blood supply. The test involves measuring a protein in the blood called Tie2, which can be measured from routine blood tests that patients have when going to the hospital. If the test shows that the amount of Tie2 decreases in the blood, it means that tumour blood vessels are blocked by VEGFi; if, on the contrary, the level increases, the blood vessels have escaped the control of VEGFi.

The investigators have shown that the Tie2 test works in their initial studies in ovarian and bowel cancer. In these studies, the Tie2 blood test was based in the research laboratories. The investigators now wish to establish the test in the Christie Hospital NHS Biochemistry laboratory in Manchester so that it can be used in clinical practice rather than just as a research tool. The investigators wish to measure the relationship between loss of control of VEGF inhibitors as measured by TIE 2 and other standard ways of measuring loss of control of the tumour like increases on CT scans. There are several reasons why this test is needed for patients with ovarian cancer:

• VEGFi are effective during a patient's first or subsequent treatments for advanced ovarian cancer, but it is not clear which individuals are benefitting from treatment whilst they are on treatment.

• Patients who have already had one course of VEGFi can be re-treated successfully.

• Patients can avoid needless side effects, if there is a way of demonstrating that the treatment is of no benefit to them.

• This test will help doctors choose the best drug to control ovarian cancer and how long to continue treatment. This is very important, since other maintenance therapies are now available and the optimal duration of VEGFi therapy is well known.

• Around the world many teams are developing new combination treatments including VEGFi. If these new combinations prove effective, it would be possible to use them as efficiently as possible, as they will be very expensive and may therefore be less accessible to patients.

These issues highlight the critical need to establish a test in the NHS that tells patients and their doctors when VEGFi are working and when they stop working.

In VALTIVE1 study, blood samples will be taken from patients who are receiving a VEGFi called bevacizumab for ovarian cancer. Patients' management will not change during their participation to the trial. The analysis of the blood sample will support the hypothesis that patients whose Tie2 level decreases in response to bevacizumab will have ovarian cancer that is controlled for much longer than those where the Tie2 level does not decrease. These results will be used to design a second trial where the investigators will prove conclusively the value of the Tie2 test.

The purpose of VALTIVE1 is to optimise sample acquisition time points and analytical algorithms to support the design of VALTIVE2, a randomised discontinuation trial. In VALTIVE2, Tie2-defined, vascular non-responding patients will be randomly allocated to stop bevacizumab after 9 weeks, by when a response can be detected, or to continue bevacizumab for the conventional year of treatment.

Both VALTIVE 1 and VALTIVE2 will test the theory that there is no advantage in continuing bevacizumab in a patient whose Tie2 level does not reduce in response to VEGFi.