Bavarian Nordics MVA-BN HIV-vaccine viser lovende resultater i HIV patienter
Bavarian Nordic’s pilot HIV vaccine candidate, MVA-BN nef encoding the Nef protein of HIV, has been successfully evaluated in a therapeutic approach in a clinical phase I/II study in 14 HIV infected patients on antiretroviral therapy.
Peter Wulff, President and CEO of Bavarian Nordic: “This is a major milestone for our lead platform technology. Up to 11 months after stopping antiretroviral therapy the levels of HIV in 7 patients remained below their pre-therapy level. The MVA-BN vector, which on it’s own also serves as a 3rd generation smallpox vaccine, has now been shown also to be safe and very immunogenic in immune compromised individuals. Obviously this is not only very encouraging for our future HIV vaccines under development, but also for MVA-BN as a safe smallpox vaccine.”
As previously stated (see 23rd September 2002 press release) three vaccinations with MVA-BN nef were well tolerated and a strong immunity (antibody and cell mediated) was induced to the MVA vector in all volunteers despite their immune compromised state. This strong immunity to the vector itself had no effect on the induction of Nef specific cell mediated responses, which were observed in 11 individuals. This was even more encouraging given that all volunteers had previously been vaccinated against smallpox and that in general the largest boost to Nef specific responses were observed following the third vaccination with MVA-BN nef, when the immunity to MVA was high.
While antiretroviral therapy can successfully control HIV replication in many HIV infected individuals, the side effects of this therapy have stimulated interest in combining therapy with therapeutic vaccines to boost HIV specific immunity. Such an approach might suppress HIV replication even after interruption of antiretroviral therapy.
Interruption of antiretroviral therapy was investigated in all 14 patients two weeks after the third vaccination with MVA-BN nef. Although there was an initial increase in HIV in the blood after stopping antiretroviral therapy, the Nef specific responses induced following vaccination appeared to control this increase in a significant number of patients. Indeed, up to 11 months after stopping therapy the levels of HIV in 7 patients remained below their pre-therapy level and all these patients remain off antiretroviral therapy. Due to these extremely encouraging results the clinical trial has been extended to further monitor the HIV levels in these patients.
Earlier reports on recombinant viral vector based vaccines, including other MVA isolates, have expressed doubts on the general feasibility of raising a specific immune responses against foreign antigens in the presence of a pre-existing immunity against the vectors expressing these antigens. Obviously the present results with MVA-BN Nef clearly demonstrate that at least with MVA-BN based vaccines, a pre-existing immune to the vector does not hinder our ability to stimulate antigen specific immune responses in people.
