Utility of Cytochrome P450 4F2 Genotyping to Assess Drug Interaction Risk for Brincidovovir, a Cytochrome P450 4F2 Substrate

Smallpox was eradicated in 1980 but remains a biothreat due to the potential release of variola virus into the general population. Brincidofovir, the second medicine approved by the US Food and Drug Administration to treat smallpox, is metabolized by oxidative and hydrolytic pathways. The oxidative pathway is initiated by cytochrome P450 4F2 (CYP4F2), an enzyme lacking clinical probes for drug interaction studies. The aim of this work was to assess the impact of reduced activity CYP4F2 variants (rs2108622, C/T and T/T) on brincidofovir pharmacokinetics as a surrogate for drug inhibition. Genotyping was performed on blood from healthy participants receiving oral (n = 261) and intravenous (IV, n = 49) brincidofovir across 6 phase 1 trials. Plasma concentrations were measured by validated liquid chromatography tandem mass spectrometry methods. After oral administration, subjects with the lowest activity CYP4F2 genotype (T/T) had up to 36% higher AUCinf and 29% higher Cmax while subjects with the moderate activity CYP4F2 genotype (C/T) had similar Cmax and AUCinf compared to those with the wild-type genotype. Little to no increase in brincidofovir exposure parameters was observed following IV administration. Based on the lack of significant increases in brincidofovir plasma concentrations in subjects with low activity CYP4F2, a clinically meaningful drug-drug interaction is not expected with CYP4F2 inhibitor and brincidofovir coadministration.

Development of CMX001 for the Treatment of Poxvirus Infections

CMX001 (phosphonic acid, [[(S)-2-(4-amino-2-oxo-1(2H)-pyrimidinyl)-1-(hydroxymethyl)ethoxy]methyl]mono[3-(hexadecyloxy)propyl] ester) is a lipid conjugate of the acyclic nucleotide phosphonate, cidofovir (CDV). CMX001 is currently in Phase II clinical trials for the prophylaxis of human cytomegalovirus infection and under development using the Animal Rule for smallpox infection. It has proven effective in reduction of morbidity and mortality in animal models of human smallpox, even after the onset of lesions and other clinical signs of disease. CMX001 and CDV are active against all five families of double-stranded DNA (dsDNA) viruses that cause human morbidity and mortality, including orthopoxviruses such as variola virus, the cause of human smallpox. However, the clinical utility of CDV is limited by the requirement for intravenous dosing and a high incidence of acute kidney toxicity. The risk of nephrotoxicity necessitates pre-hydration and probenecid administration in a health care facility, further complicating high volume CDV use in an emergency situation. Compared with CDV, CMX001 has a number of advantages for treatment of smallpox in an emergency including greater potency in vitro against all dsDNA viruses that cause human disease, a high genetic barrier to resistance, convenient oral administration as a tablet or liquid, and no evidence to date of nephrotoxicity in either animals or humans. The apparent lack of nephrotoxicity observed with CMX001 in vivo is because it is not a substrate for the human organic anion transporters that actively secrete CDV into kidney cells. The ability to test the safety and efficacy of CMX001 in patients with life-threatening dsDNA virus infections which share many basic traits with variola is a major advantage in the development of this antiviral for a smallpox indication.

Eradication of disseminated adenovirus infection in a pediatric hematopoietic stem cell transplantation recipient using the novel antiviral agent CMX001

Adenovirus infection is a serious and often fatal complication in hematopoietic stem cell transplant patients. There are currently no FDA-approved therapies for adenovirus infection, with only anecdotal, off-label uses described for a variety of anti-viral agents or immune therapies. We report the first case of successful eradication of disseminated adenovirus infection by the novel antiviral agent CMX001 in a severely immunocompromised pediatric stem cell transplant recipient following failure to respond to intravenous cidofovir. Complete clinical and virologic response was documented; virologic and pharmacokinetic data are reported. CMX001 is a promising new oral antiviral agent under development for the prophylaxis and treatment of severe infections caused by double-stranded DNA viruses including adenovirus in immunocompromised patients.

Inhibition of tumor necrosis factor-alpha (TNF-alpha) production and arthritis in the rat by GW3333, a dual inhibitor of TNF-alpha-converting enzyme and matrix metalloproteinases

Tumor necrosis factor-alpha (TNF)-converting enzyme (TACE) cleaves the precursor form of TNF, allowing the mature form to be secreted into the extracellular space. GW3333, a dual inhibitor of TACE and matrix metalloproteinases (MMPs), was compared with an anti-TNF antibody to evaluate the importance of soluble TNF and MMPs in rat models of arthritis. Oral administration of GW3333 completely blocked increases in plasma TNF after LPS for up to 12 h. In a model wherein intrapleural zymosan injection causes an increase in TNF in the pleural cavity, GW3333 completely inhibited the increase in TNF in the pleural cavity for 12 h. Under these dosing conditions, the plasma levels of unbound GW3333 were at least 50-fold above the IC(50) values for inhibition of individual MMPs in vitro. In a model wherein bacterial peptidoglycan polysaccharide polymers reactivate a local arthritis response in the ankle, a neutralizing anti-TNF antibody completely blocked the ankle swelling over the 3-day reactivation period. GW3333 administered b.i.d. over the same period also inhibited ankle swelling, with the highest dose of 80 mg/kg being slightly less active than the anti-TNF antibody. In a 21-day adjuvant arthritis model, the anti-TNF antibody did not inhibit the ankle swelling or the joint destruction, as assessed by histology or radiology. GW3333, however, showed inhibition of both ankle swelling and joint destruction. In conclusion, GW3333 is the first inhibitor with sufficient duration of action to chronically inhibit TACE and MMPs in the rat. The efficacy of GW3333 suggests that dual inhibitors of TACE and matrix metalloproteinases may prove therapeutic as antiarthritics.

N-hydroxyformamide peptidomimetics as TACE/matrix metalloprotease inhibitors: oral activity via P1' isobutyl substitution

N-Hydroxyformamide-class metalloprotease inhibitors were designed and synthesized, which have potent broad-spectrum activity versus matrix metalloproteases and TNF-alpha converting enzyme (TACE). Compound 13c possesses good oral and intravenous pharmacokinetics in the rat and dog.