OXB-301

Vaccines in combination with chemotherapy have been shown to be safe in different tumor types. We investigated the immunological activity of the TroVax® vaccine in combination with pemetrexed-cisplatin chemotherapy in malignant pleural mesothelioma (MPM). In this first line, open-label, single-arm, phase 2 study, patients with locally advanced or metastatic MPM were enrolled. Eligible patients received up to 9 intramuscular injections of TroVax®, starting two weeks before chemotherapy and continuing at regular intervals during and after chemotherapy to 24 weeks. The primary endpoint was the induction of cellular or humoral anti-5T4 immune response (defined as a doubling of either response at any of six follow-up time points), with a target response rate of 64%. Of 27 patients, enrolled between Feb 2013-Dec 2014, 23 (85%) received at least three doses of TroVax® and one cycle of chemotherapy and were included in the per-protocol analysis (PPA). 22/23 patients (95.6%) developed humoral or cellular immune response to 5T4. Thus, the study reached its primary endpoint. Disease control was observed in 87% of patients (partial response: 17.4%, stable disease: 69.6%). The median progression-free survival was 6.8 months and median overall survival 10.9 months. Treatment-related adverse events were comparable to those observed in patients with chemotherapy alone. Translational immunology studies revealed a circulating baseline immune signature that was significantly associated with long-term (>20 months in n = 8/23, 34.8%) survival. In this phase 2 trial, TroVax® with pemetrexed-cisplatin chemotherapy showed robust immune activity, acceptable safety and tolerability to warrant further investigation in a phase 3 setting.

We developed an outcomes model to select patients for renal cell cancer vaccine immunotherapy.

We examined clinical data from 2 phase II studies of modified vaccinia Ankara as vector to express 5T4 (MVA-5T4), calculated progression-free survival (PFS) and overall survival (OS), and created risk groups based on the number of factors involved.

Median OS was 12.4 months; median PFS was 3.6 months. Significant factors (p<0.05) included neutrophils (both), bone metastases (OS), ECOG performance status (OS), lactate dehydrogenase levels (both), prior therapy with tyrosine kinase inhibitors plus immunotherapy (OS), Fuhrman grade (OS), and 5T4-specific ELISPOT response (PFS). By group, median OS was not reached in patients with favorable risk (censored at cutoff), was 13.7 months in those with intermediate risk and 4.0 months in those with poor risk.

Further validation of this model will identify the patients most likely to respond to MVA-5T4 and provide a framework for outcomes models for other vaccine therapies.