Xcellerex, Inc. today announced that it has initiated a Phase I clinical
trial of XRX-001, a novel, prophylactic vaccine against yellow fever, a
tropical virus disease that is often fatal. The company is developing
the vaccine to prevent yellow fever in persons traveling to tropical
countries where yellow fever is endemic. The only currently available
yellow fever vaccine is an attenuated, live vaccine with rare but
potentially serious adverse effects. XRX-001 is an inactivated virus
vaccine adsorbed to alum adjuvant. Because it is inactivated and
non-replicating, it is anticipated to significantly reduce the risks of
serious and fatal adverse events that are sometimes associated with the
live yellow fever vaccine. In addition, the absence of foreign proteins
derived from hens’ eggs should also reduce the risk of allergic
reactions and eliminate the need to exclude egg-allergic people from
vaccination. In addition, Xcellerex believes that the XRX-001 vaccine
should not be subject to the precautions and contraindications of the
currently marketed live vaccine. These precautions and
contraindications, which are all related to potential serious outcomes
of replicating live virus infection, include age <9 months or >65 years,
immune suppression due to thymectomy, HIV/AIDS, cancer, treatment with
immunosuppressive medications or radiation, and pregnancy.
“The introduction of a non-replicating vaccine against yellow fever into
clinical development is important because there are increasing
constraints on the use of the live vaccine”
The double-blind, controlled Phase I trial will enroll 60 healthy
subjects divided into three groups. Two groups of volunteers will
receive two different dose levels of XRX-001 and the third will receive
placebo. The primary objective of the trial is to evaluate the safety
and tolerability of XRX-001 vaccine, and secondary objectives will
assess the neutralizing antibody response--an accepted correlate of
protective immunity to yellow fever. In a second parallel trial, the
Company will compare the antibody response in those receiving XRX-001 to
travelers receiving the currently-marketed vaccine.