Mechanistic Understanding for the Greater Sensitivity of Monkeys to Antisense Oligonucleotide–Mediated Complement Activation Compared with Humans

Abstract

Differences in sensitivity of monkeys and humans to antisense oligonucleotide (ASO)-induced complement alternative pathway (AP) activation were evaluated in monkeys, humans, and in serum using biochemical assays. Transient AP activation was evident in monkeys at higher doses of two 29-O-methoxyethyl (29-MOE) ASOs (ISIS 426115 and ISIS 183750). No evidence of AP activation was observed in humans for either ASO, even with plasma ASO concentrations that reached the threshold for activation in monkeys. The absence of complement activation in humans is consistent with a query of the Isis Clinical Safety Database containing 767 subjects. The in vivo difference in sensitivity was confirmed in vitro, as monkey and human serum exposed to increasing concentrations of ASO indicated that monkeys were more sensitive to AP activation with this class of compounds. The mechanistic basis for the greater sensitivity of monkeys to AP activation by 29-MOE ASO was evaluated using purified human or monkey factor H protein. The binding affinities between a representative 29-MOE ASO and either purified protein are similar. However, the IC 50 of fluid-phase complement inhibition for monkey factor H is about 3-fold greater than that for human protein using either monkey serum or factor H-depleted human serum. Interestingly, there is a sequence variant in the monkey complement factor H gene similar to a single nucleotide polymorphism in humans that is correlated with decreased factor H protein function. These findings show that monkeys are more sensitive to 29-MOE ASO-mediated complement activation than humans likely because of differences in factor H inhibitory capacity.

Nucleic Acid Polymers with Accelerated Plasma and Tissue Clearance for Chronic Hepatitis B Therapy

“…Complement activation is common in cynomolgus monkeys with PS-ONs 25 and is likely the cause of vasculitis, which is common with i.v. PS-ON administration in this monkey species 26 .…”

Integrated Safety Assessment of 2′-O-Methoxyethyl Chimeric Antisense Oligonucleotides in NonHuman Primates and Healthy Human Volunteers

“…The interaction of 2′MOE chimeric ASOs with Factor H (alternative complement pathway) in NHPs has been well described. 30,31 The transient inhibition of Factor H upon 2′MOE ASO binding results in activation of the alternate complement pathway and increased production of complement split products Bb and C3a. In NHPs, there was a dose-dependent increase in the incidence of elevated complement Bb (>2× ULN) following 2′MOE ASO treatment ( Table 1 ).…”

“…This is particularly important since it is known that NHPs are more sensitive to complement activation than humans. 30,31 Thus it is gratifying that, overall, NHPs were reasonably predictive of human responses to ASOs. However, there were several important differences.…”

“…22,30,31 Chronic low level activation can lead to depletion of complement, sensitivity to infectious disease and damage to the vascular system and kidney. 22 Fortunately, none of these effects have been observed in humans, and particular attention has focused on complement activation in clinical trials of ASOs.…”

A Randomized, Double‐Blind, Placebo‐Controlled, First‐Time‐in‐Human Study to Assess the Safety, Tolerability, and Pharmacokinetics of Single and Multiple Ascending Doses of GSK3389404 in Healthy Subjects

“…PK sampling was also conducted on days 8 and 30 in part 1 and days 8 and 15 in part 2 (predose samples). Following the final study drug administration on day 22 (part 2), serial blood samples were collected predose and 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 48, and 72 hours postdose (days [22][23][24][25], and on days 29, 36, 50, 71, and 113. Urine samples for assessment of the albumin/creatinine ratio were collected at screening, on day −1, predose, and 24 and 72 hours postdose, and on days 8 and 30 in part 1.…”