Regression of colon ca liver mets with oncolytic HSV

LUGANO, Switzerland—Interim results of a phase I/II trial of NV1020, an oncolytic herpes simplex virus (HSV), in refractory metastatic colorectal cancer patients are encouraging, Axel Mescheder, MD, said at a poster session of the 2007 European Society for Medical Oncology (ESMO) Conference (abstract 47P).

The ongoing study is being conducted at seven US cancer centers, with Tony Reid, MD, of the University of California, San Diego, as principal investigator. Dr. Mescheder is head of Clinical Research and Development at MediGene AG, Martinsried, Germany, which is developing the virus.

In the dose-escalation trial, NV1020 was administered as four weekly intra-arterial infusions to colorectal cancer patients who had failed first-line therapy and had metastases to the liver. Viral therapy was followed by two cycles of second-line chemotherapy with FDA- approved agents. Dose escalation up to 1 X 10⁸ pfu was performed without dose-limiting toxicities, and the maximum tolerated dose was not reached.

Dr. Mescheder reported that several patients had tumor regression. He cited one patient who showed a distinct response. At study entry, the patient, who had received FOLFOX as first-line therapy, had 10 measurable hepatic masses and 4 measurable pulmonary nodules. The hepatic tumors had an initial enlargement after NV1020 infusion, followed by regression. Six months post-treatment, PET showed no measurable FDG uptake within the lungs and near-complete resolution of the liver masses. The patient survived for 12 months.

Dr. Mescheder noted that "treatment options for patients with colorectal cancer metastatic to the liver who fail first-line therapy are sparse." Regional chemotherapy results in higher tumor regression rates, he said, but has only modest effects on overall survival. Since mortality and morbidity are high in these patients, new treatment options, especially as second-line therapy, are needed. "We are hoping to extend overall survival with NV1020," he said. Dr. Mescheder concluded, "dose escalation with NV1020 was completed without significant toxicities, and several clinical responses were observed." Additional patients are being enrolled into an expansion cohort at the highest dose.