Inovio Pharmaceuticals (NYSE MKT: INO) announced Thursday preliminary results from a phase II clinical trial to treat leukemia, which the company says shows strong vaccine-specific antibody responses in all vaccinated subjects so far.
The trial tested the WT1 DNA vaccine, delivered with the company's proprietary electroporation delivery system.
The company also said that T cell immune responses, including those of the "killer T cells", were detected. Antibody and T cell responses are generally strong signals of the DNA vaccine's potential to treat the disease.
The data was presented today at the DNA Vaccines conference in San Diego, by Dr. Christian H. Ottensmeier, the trial's principal investigator, and professor of experimental cancer research at the University of Southampton, UK.
The interim results, from eight patients, are part of a phase II trial that will enroll 31 patients in the chronic myelogenous leukemia (NYSE:CML) arm. So far, 14 CML patients have been enrolled, while another 13 unvaccinated CML patients have been enrolled in the control group.
Inovio said the vaccine has been safe overall and well-tolerated.
An analysis of the T cell immune responses, as well as the impact of the vaccine on the molecular marker, BCR-ABL - which is a specific chromosomal abnormality that is associated with chronic myelogenous leukemia (CML) disease - will be conducted.
Due to the results thus far, the company said the trial is now open to enroll the acute myeloid leukemia (AML) clinical trial arm, with a total target of 37 subjects in each of the vaccinated and control groups.
The study is testing the DNA vaccine, which was developed by the University of Southampton, to treat both CML and AML. In the phase II trial, all participants initially receive six doses of two DNA vaccines, delivered at four week intervals. Vaccine responders can continue with booster shots every three months out to 24 months.
The trial is taking place at hospitals in Southampton, London and Exeter, with regulatory approval given by the UK Medicines and Healthcare Products Regulatory Authority (MHRA) and Gene Technology Advisory Committee (GTAC).
Leukemia is a cancer of the bone marrow and blood, which accounts for at least 300,000 new cases and 222,000 deaths around the world every year. Wilms' Tumor gene 1, or WT1, is highly associated with these types of cancer, Inovio noted.
"We are encouraged by preliminary phase II data showing the WT1 DNA vaccine's potential, administered with our novel delivery technology, to generate T cells and robust antibodies to treat leukemia," said Inovio's CEO, Dr. J. Joseph Kim.
"These results follow on our recent scientific breakthrough represented by our human data showing the powerful killing effect of T cells generated by our cervical dysplasia therapeutic vaccine."
Inovio's SynCon vaccines are designed to provide two capabilities not achievable with conventional vaccines: stimulation of T-cell immune responses to provide therapeutic capabilities, and universal cross-strain protection and treatment against known as well as newly emergent unmatched strains of pathogens. The company has clinical programs for cervical dysplasia, leukemia, the hep C virus, the flu and HIV.
During the third quarter, the company reported that its SynCon vaccine against cervical cancer, known as VGX-3100, achieved an "industry first" when T-cell immune responses induced by this vaccine were shown to generate a strong killing effect against cells changed by HPV into precancerous cervical dysplasias.
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