Adenovirus (Ad) infection is a significant health risk for immune-compromised pediatric patients, and can lead to serious complications such as pneumonia, urinary infections and hepatitis. Adenoviruses are endemic in military recruit populations engaging in basic training installations where they have been implicated in recurring outbreaks of febrile respiratory disease. A vaccine effective against Ad serotypes 4 and 7 has been licensed by the FDA, but the long-term availability of this vaccine is unclear, and immunization is not available for the prevention of infections by other Ad serotypes presenting a serious threat to health, including serotypes 6 and 14 which have caused fatal respiratory disease in both juvenile and adult patients. Cidofovir (CDV, HPMPC), an acyclic nucleoside phosphonate (ANP) derivative, is approved by the FDA for treatment of CMV retinitis. Although not approved by the FDA for treatment of Ad infection, it is used frequently in the clinic. CDV has relatively modest cellular anti-Ad potency due to its limited permeability and must be administered intravenously due to its low oral bioavailability. A further limitation of CDV is its renal toxicity due to concentration in kidney tissue. Recently, certain ?tunable? prodrugs of CDV and HPMPA synthesized at the Univ. of Southern California (USC) have been demonstrated to be several orders of magnitude more potent against four Ad serotypes in vitro and orally effective against Ad6 in a Syrian hamster model. The proposed research will build on these highly promising preliminary data to elucidate the SAR and mechanism of these active prodrugs and structurally related derivatives. A series of prodrug analogs will be synthesized having variable structural features in the promoiety and evaluated for anti-Ad activity vs six virulent Ad serotypes. The analogs will also be compared for stability and PK characteristics, toxicity in a hamster model, and the most promising prodrugs will be further evaluated for efficacy against Ad6 in the Syrian hamster model. This research, which will be performed by an interdisciplinary team led by Prof. Charles McKenna (USC, analog design and synthesis), Prof. Mark Prichard (Univ. of Alabama-Birmingham, in vitro studies) and Prof. William Wold (Saint Louis University, in vivo studies), has the ultimate goal of identifying and developing a safe, highly effective oral prodrug of CDV for the treatment of acute respiratory disease and disseminating infection in immune-compromised individuals.
The proposed research will address an urgent problem in the public health, the current lack of an effective chemotherapeutic to treat adenoviral infections in pediatric and immunocompromised patients. In a joint research project involving the University of Southern California, the University of Alabama Birmingham and Saint Louis University, a novel oral prodrug strategy will be evaluated for efficacy, pharmacokinetics and selectivity using in vitro and in vivo virus infection models to determine lead candidates for further preclinical and eventual clinical evaluation.