Cytos Biotechnology Ltd (SIX:CYTN) announced results from a biochemical analysis from a phase IIa study (study 02) with the vaccine
candidate CYT006-AngQb for the treatment of hypertension. CYT006-AngQb has demonstrated in a
first phase IIa study (study 01) a significant reduction of the day-time ambulatory blood pressure of
-9 / -4 mmHg (systolic/diastolic) vs. placebo (The Lancet 2008, 371:821). In study 02 an accelerated
treatment regimen with injections at weeks 0, 2, 4, 6, and 10 was tested, while in study 01 the
vaccine was given at weeks 0, 4, and 12. This modification was anticipated to induce higher
antibody titers and, thereby, a stronger blood pressure reduction. While first study results which
were communicated on March 17, 2009 showed on average a 5-fold higher antibody titer in study 02
than in study 01, the blood pressure reductions in study 02 were much lower than in study 01; they
amounted to -2.3 / -0.4 mmHg. In order to understand this discrepancy, the biochemical properties
of the induced antibody responses were analyzed in detail. The main findings are as follows:
- Antibody affinities (i.e. the strength by which the antibodies bind angiotensin II)
determined by different biochemical methods were significantly lower in study 02 than in
study 01 (p