CytoDyn, Inc. (Pink Sheets:CYDY) has begun full humanization of
Cytolin®, the Company’s unique immune therapy for treating HIV/AIDS.
Although a murine (mouse) version of Cytolin® was used for previous
human experience that included some 200 patients successfully treated
for up to two years, as well as an encouraging Phase I(b)/II(a) study,
the Company believes that a fully-humanized version is necessary for the
clinical trial that is expected to follow the current one (described at http://clinicaltrials.gov)
for the reasons explained below.
Unlike the other monoclonal antibodies that have been approved for
treating diseases such as cancer and rheumatoid arthritis, Cytolin® is
not a “neutralizing” antibody, meaning it does not initiate
phagocytosis, the process that removes unwanted substances and cells
from the body. As a result, HAMA (Human Anti-Mouse Antibodies), which
are a natural response to murine antibodies, did not block the
therapeutic effect of Cytolin® during previous human experience, even
though HAMA are known to have this effect on neutralizing antibodies,
making some form of humanization mandatory for those other antibodies.
To the contrary, there is some evidence that HAMA may have increased the
length of time that Cytolin® remained bound to the targeted cytotoxic T
cells that would otherwise have destroyed healthy CD4+ T cells, thereby
increasing the duration of the therapeutic effect of Cytolin®. Since
therapeutic antibodies usually cost thousands of dollars per treatment,
a product that needs to be administered less often could provide a
meaningful reduction in costs.