A Randomized, Controlled Trial of Panax quinquefolius Extract (CVT-E002) to Reduce Respiratory Infection in Patients With Chronic Lymphocytic Leukemia

Background Chronic lymphocytic leukemia (CLL) patients are at high risk for acute respiratory illness (ARI). Objective We evaluated the safety and efficacy of a proprietary extract of Panax quinquefolius, CVT-E002, in reducing ARI. Methods This was a double-blind, placebo-controlled, randomized trial of 293 subjects with early-stage, untreated CLL conducted January-March 2009. Results ARI was common, occurring on about 10% of days during the study period. There were no significant differences of the 2 a priori primary end points: ARI days (8.5 ± 17.2 for CVT-E002 vs 6.8 ± 13.3 for placebo) and severe ARI days (2.9 ± 9.5 for CVT-E002 vs 2.6 ± 9.8 for placebo). However, 51% of CVT-E002 vs 56% of placebo recipients experienced at least 1 ARI (difference, -5%; 95% confidence interval [CI], -16% to 7%); more intense ARI occurred in 32% of CVT-E002 vs 39% of placebo recipients (difference, -7%; 95% CI, -18% to 4%), and symptom-specific evaluation showed reduced moderate to severe sore throat (P = 004) and a lower rate of grade >3 toxicities (P = 02) in CVT-E002 recipients. Greater seroconversion (4-fold increases in antibody titer) vs 9 common viral pathogens was documented in CVT-E002 recipients (16% vs 7%, P = 04). Limitations Serologic evaluation of antibody titers was not tied to a specific illness, but covered the entire study period. Conclusion CVT-E002 was well tolerated. It did not reduce the number of ARI days or antibiotic use; however, there was a trend toward reduced rates of moderate to severe ARI and significantly less sore throat, suggesting that the increased rate of seroconversion most likely reflects CVT-E002-enhanced antibody responses.