Vaccine works with chemotherapy in colorectal cancer

August 13, 2007

NEW YORK (Reuters Health) - Vaccination of colorectal cancer patients with modified vaccinia Ankara encoding the tumor antigen 5T4 (TroVax, Oxford BioMedica), given along with chemotherapy, induces "potent" immune responses, UK researchers report in the August 1st issue of Clinical Cancer Research.

"Our experimental cancer vaccine, TroVax, can be given to patients receiving standard chemotherapy regimens without enhancing any toxicity associated with the chemotherapy," lead investigator Dr. Richard Harrop told Reuters Health.

Dr. Harrop of Oxford BioMedica, Oxford and colleagues studied 17 patients with metastatic colorectal cancer who were given TroVax. They also received chemotherapy with 5-fluorouracil, folinic acid, and oxaliplatin.

Eleven patients were considered to be evaluable for assessment of immunologic responses. They received a total of 6 injections of TroVax, given before, during and after completion of chemotherapy.

"Potent immune responses were induced in the majority of patients," continued Dr. Harrop, "and, importantly, were shown to correlate with clinical benefit for the patient."

Overall, 6 of the 11 patients had complete or partial clinical responses -- 5 showed significant reduction in tumor volume and 1 no longer had any detectable tumors. No TroVax related adverse events were reported.

"While caution is required when interpreting results from small phase II clinical studies," said Dr. Harrop, "we believe that these observations provide good justification for continuing to develop TroVax as a means of enhancing standard therapies."

"Indeed," he concluded, "we are currently testing TroVax in a phase III trial in renal cancer patients in the US and Europe, and our partner sanofi aventis is planning a phase III study in colorectal cancer."