AZD-9773(BTG Ltd.)

This trial compared the efficacy/safety of two IV doses of AZD9773, a polyclonal antibody to tumor necrosis factor-α, in adult patients with severe sepsis/septic shock.

Multicenter, randomized, double-blind, placebo-controlled phase IIb trial.

ICUs in seven countries (Australia, Belgium, Canada, Czech Republic, Finland, France, and Spain).

Patients 18 years old or older with severe sepsis and/or septic shock. Patients were required to have 1) objective clinical evidence of infection; 2) at least two of four systemic inflammatory response syndrome criteria; and 3) cardiovascular and/or respiratory sepsis-related failure.

Patients were randomized 1:1:1 to a single loading infusion of AZD9773 250 U/kg followed by 50 U/kg every 12 hours (low dose, n = 100), a single loading infusion of AZD9773 500 U/kg followed by 100 U/kg every 12 hours (high dose, n = 100), or placebo (n = 100) for 5 days. Follow-up assessments were performed up to day 90.

Mean number of ventilator-free days (primary endpoint) did not differ between low-dose (19.7 d) or high-dose AZD9773 (17.3 d) and placebo (18.3 d) (one-sided p = 0.18 and 0.74, respectively). Mortality rates were comparable across treatment groups; relative risk of death versus placebo at day 29 was 0.80 for low-dose AZD9773 (one-sided p = 0.25) and 1.64 for high-dose AZD9773 (p = 0.97). Most patients experienced at least one treatment-emergent adverse event (87.8% in AZD9773-treated patients, 92.9% in placebo patients) although most were mild/moderate in nature. No differences in the incidence of adverse events or laboratory or vital sign abnormalities were observed between groups.

AZD9773 rapidly and efficiently decreased plasma tumor necrosis factor-α concentration in patients with severe sepsis/septic shock, but this effect did not translate into clinical benefit.

TNF-α neutralization is associated with increased mortality in mouse cecal ligation puncture (CLP) models. AZD9773 is an ovine polyclonal human TNF-α immune Fab, with pharmacological properties that differ from previously studied anti-TNF-α agents. We explored the safety and efficacy of therapeutically administered AZD9773 in mouse CLP sepsis.

A moderate/severe-grade CLP model resulting in 20-30 % 5-day survival and a mild-grade CLP model resulting in ~70 % 5-day survival were established in human TNF-α transgene/murine TNF null (Tg1278/-/-) mice.

Mice received saline resuscitation and imipenem administration every 12 h (0-72 h post-CLP). AZD9773 (or DigiFab control) was dosed 24, 36, 48 and 60 h post-CLP.

Therapeutic dosing of AZD9773 in moderate/severe-grade CLP resulted in significantly increased survival (>70 %) compared with DigiFab (27 %, P < 0.05). Therapeutic dosing of AZD9773 in mild-grade CLP did not significantly affect survival outcome compared with DigiFab or imipenem alone (~60-70 % survival).

These data demonstrate that TNF-α neutralization can improve survival in moderate/severe CLP sepsis. TNF-α suppression in mild-grade models was not associated with survival benefit and did not increase 5-day mortality. These findings suggest that therapeutic benefit following TNF-α attenuation in models of sepsis may depend on model severity.