METHODS: Patients aged ≥18 years previously on LTP underwent a 2-week washout prior to the requirement of ≥1 attack in a 4-week run-in period. Patients were randomized and stratified by baseline attack rate into 1 of 4 parallel 26-week treatment arms in a 3:2:2:2 ratio (placebo or lanadelumab [150mg q4wks, 300mg q4wks, 300mg q2wks]). In this exploratory analysis, the Poisson regression model was used to compare the mean HAE attack rate in the lanadelumab groups to placebo by prior LTP use. Historical, run-in, and on-study attack rates for all treatment regimens were analyzed.
RESULTS: 125 patients were randomized and treated; 60 (48%) previously used C1-INH-only LTP, 10 (8%) used other treatments and combinations, and 55 (44%) did not use LTP. In C1-INH-only LTP patients, the attack rate was significantly reduced for all lanadelumab regimens versus placebo (P<0.001); the reduction was similar in magnitude to those who did not receive prior LTP. C1-INH-only LTP users reported mean monthly attack rates (3 months prior to the study) of 4.0, 3.0, 2.7 and 2.6; during run-in 4.6, 3.3, 3.7 and 4.6; and during the treatment period 2.9, 0.5, 0.7 and 0.5, for the placebo and lanadelumab 150mg q4wks, 300mg q4wks, and 300mg q2wks groups, respectively.
CONCLUSIONS: All lanadelumab dosing regimens significantly reduced attack rates versus placebo, regardless of whether patients had received prior C1-INH LTP.