Aim: To determine whether immunotherapy with HPV6 L1 virus like particles (VLPs) without adjuvant (VLP immunotherapy) reduces recurrence of genital warts following destructive therapy.
Trial design: A randomized placebo controlled blinded study of treatment of recurrent genital warts amenable to destructive therapy, conducted independently in Australia and China.
Methods: Patients received conventional destructive therapy of all evident warts together with intramuscular administration of 1 µg, 5 µg or 25 µg of VLP immunotherapy, or of placebo immunotherapy (0.9% NaCl), as immunotherapy at week 0 and week 4. Primary outcome, assessed at week 8, was recurrence of visible warts.
Results: Of 33 protocol compliant Brisbane recipients of placebo immunotherapy, 11 were disease free at two months, and a further 9 demonstrated reduction of > 50% in total wart area. Wart area reduction following destructive treatment correlated with prior duration of disease. Among 102 protocol compliant Brisbane recipients of VLP immunotherapy, disease reduction was significantly greater than among the placebo immunotherapy (50% ± s.e.m. 7%) recipients for subjects receiving 5 µg or 25 µg of VLP immunotherapy/dose (71% ± s.e.m. 7%) but not for those receiving 1 µg VLP immunotherapy/dose (42% ± 7%). Of 52 protocol compliant placebo immunotherapy recipients in Wenzhou, 37 were disease free at two months, and a further 8 had > 50% disease reduction. Prior disease duration was much shorter in Wenzhou subject (8.1 ± 1.1 mo) than in Brisbane subjects (53.7 ± 5.5 mo). No significant reduction in mean wart area was observed for the 168 Wenzhou protocol compliant subjects who also received VLP immunotherapy.
Conclusions: This study confirms the findings in a previous open label trial that administration of VLP immunotherapy may assist in clearance of recurrent genital warts in patients for whom destructive therapy is unsuccessful and that unsuccessful destructive therapy is more common with increasing prior disease duration.