Potential Biomarker for Reduction of Viral Load Identified for Vacc-4x
Exploratory, ad hoc, subset analysis of previous large Vacc-4x Phase II study identifies patients more likely to respond to Vacc-4x (“Responders”)
(Oslo, Norway, 4 February 2014) Bionor Pharma ASA (OSE: BIONOR) announces that further analysis of the large Vacc-4x Phase II trial, completed in 2010, identified anti-C5 antibodies as potential biomarker for the Company’s lead vaccine candidate Vacc-4x. Biomarkers may predict how well an HIV infected patient will respond to Vacc-4x. Response to Vacc-4x was defined as the reduction in viral load following a 6 months scheduled interruption of standard HIV treatment (ART) compared to the subjects’ historic viral load values (pre-ART values). The analysis showed that patients more likely to respond to Vacc-4x, or responders, were characterized by pre-existing high levels of anti-C5 antibodies prior to Vacc-4x vaccination in the 2010 study.
As previously reported, the 2010 Vacc-4x study determined that patients vaccinated with Vacc-4x experienced a 60% or log 0.4 reduction in median viral load compared to their pre-ART viral load following a 6 month ART treatment interruption. Some patients responded however more profoundly than others. Patients whose baseline anti-C5 levels were above 4µg/ml had a median viral load reduction of log 0.94 or 88% (p=0.005, n=12) compared to the median pre-ART values. Patients with anti-C5 antibodies below 4µg/ml had a median viral load reduction of only 0.20 log or 37% (p=0.019, n=27) compared to pre-ART values.
“The results from the subset analysis from the 2010 Vacc-4x trial are highly intriguing as they imply that the reduction in viral load is improved in patient populations with high levels of anti-C5 antibodies. This indicates that anti-C5 antibodies can be used as biomarker to predict improved response to Vacc-4x vaccination. Biomarkers are commonly used in other therapeutic areas like oncology to identify “responders” to treatment” says CEO Dr. Anker Lundemose “The identification of a responder profile for Vacc-4x could prove to be an important step for Bionor Pharma in our pursuit to find a functional cure for HIV patients.”
In conjunction with developing Bionor Pharma’s second HIV vaccine candidate, Vacc-C5 (Phase I/II), a test to quantify the presence of antibodies to C5 and gp41 was developed. These so-called “anti-C5 antibodies” were measured in the 2010 Vacc-4x study using the Vacc-C5 test. Bionor Pharma has filed patent applications covering the use of anti-C5 antibodies as biomarkers for improved vaccine response as well as companion diagnostic assays measuring antibodies.
Approximately 21 % of the patients that were analyzed in the 2010 Vacc-4x study had antibody levels above 4µg/ml prior to Vacc-4x vaccination. Confirmation of anti-C5 antibodies as a genuine biomarker for improved response to Vacc-4x is subject to a larger prospective trial and the approval of such trial by regulators. Such clinical study will be incorporated into the future clinical development strategy.
About the 2010 Vacc-4x trial
The study was a phase II randomized, multicenter, double-blind, placebo-controlled multinational clinical trial of Vacc-4x. The trial enrolled 137 patients and was conducted at clinical trial sites in UK, US, Germany, Italy and Spain between July 2008 and June 2010. The 52-week follow-up period was completed in June 2011. The study is registered with Clinicaltrials.gov with the identifier NCT00659789. The results of the study have previously been released November 18 2010.
For subjects in the study that completed a 6 month treatment interruption of ART, there was a 64% reduction in median viral load set point between the two groups which was statistically significant (Vacc-4x 22300 copies/mL, n=56; and placebo 61900 copies/mL, n=25; p=0.040) corresponding to a 0.44 log reduction. For subjects with a pre-ART value available, a reduction in the median viral load set point of 0.40 log, compared to pre-ART values was observed (24150 compared to 60470 copies/mL, p=0.0001) in the Vacc-4x group (n=45). This result was in contrast to the placebo group where no reduction was observed (n=18) (50400 compared to 52731 copies/mL, log 0.02, p=0.980).
33 patients from the trial are currently enrolled in the Company’s Phase II Vacc-4x Reboost trial which investigates whether, upon booster immunizations, the viral load can be reduced even further on a second treatment interruption. The trial expects to read out late Q1 2014.
Bionor Pharma ASA
CEO Anker Lundemose Tel +47 23 04 09 60
CFO Synne H Røine Tel +47 99 22 98 92