Date: 2016-08-08
Type of information: Results
phase: 1a
Announcement: results
Company: Pfenex (USA - CA)
Product: Px563L
Action
mechanism: vaccine
Disease: anthrax
Therapeutic area: Infectious diseases
Country:
Trial details:
Latest
news: * On August 8, 2016, Pfenex announced immunogenicity and safety data from the Day 70 analysis of the Px563L anthrax vaccine study. The results demonstrate tolerable safety and significant immunogenicity after only 2 doses of Px563L. The randomized, double-blind, placebo-controlled phase 1a study enrolled 3 cohorts (10 mcg, 50 mcg and 80 mcg) in a dose-escalating manner. Within each cohort, subjects received Px563L, RPA563 or placebo in an 8:8:2 ratio. Subjects were administered 2 doses of vaccine or placebo 28 days apart. The current analysis covers safety and immunogenicity assessment, including toxin-neutralizing antibody (TNA) expressed as 50% neutralizing factor (NF50), through Day 70. TNA NF50 threshold value > 0.56 has been correlated with significant survival after anthrax exposure in animal models. After administration of 2 doses, 100% of Px563L subjects achieved a TNA NF50 > 0.56 at Day 70 for both the 10 mcg and 80 mcg dose cohorts, and 87.5% achieved the target threshold in the 50 mcg dose cohort (Table 1 and Figure 1). For comparison, after subcutaneous (SC) administration of 3 Biothrax® doses (currently approved anthrax vaccine), 57.9% of subjects achieved a TNA NF50 >0.56 at Day 70 (Vaccine 2014; 32:2217-2224). An additional criterion for assessing anthrax vaccine immunogenicity success is for the lower confidence limit (LCL), or the lower bound of the two-sided 95% confidence interval for the percentage of subjects who met or exceeded the TNA threshold (TNA NF50 > 0.56), to be greater than or equal to 40%. All doses of Px563L were above the LCL at Day 70 (Figure 1 and Table 1), having demonstrated this activity after only 2 doses (10 mcg: 74%, 50 mcg: 55%, 80 mcg 74%). For comparison, Biothrax reported a LCL of 50.4% at Day 70 (Vaccine 2014; 32:2217-2224) following a three-dose regimen (Table 1). Only mild Grade 1 injection site reactions were observed at the 10 mcg and 50 mcg Px563L doses as well as for all RPA563 doses. At the 80 mcg Px563L dose, in addition to Grade 1 findings, there were two Grade 2 reports of erythema (redness). There were no other Grade 2 or higher injection site reactions, specifically injection site pain, arm motion limitation, tenderness or swelling.
