Clinical Observations with Topical Liposome-Encapsulated Interferon Alpha for the Treatment of Genital Papillomavirus Infections

This study reports the formulation and preliminary clinical testing of liposomes as a topical drug delivery system for interferon a (IFN α) in the treatment of genital human papillomavirus (HPV) infections. Intron A (IFN α-2b) was encapsulated into multilamellar liposomes, composed of soya phosphatidylcholine: cholesterol: stearic acid 2:1:1.4 molar ratio, by a modified solvent evaporation method (protein to phospholipid ratio 7±103IU/mg). The liposomes were in the size range of 0.5-2 μm as determined by electron microscopy. The incorporation of IFN α into liposomes was 91.7±2.2% (n=4). In an open trial, one female patient with exophytic warts and cervical HPV (type 6/11), responded to a treatment with 2.1 ±106 IU liposomal IFN α-2b per week for 12 weeks and 7±106 IU liposomal IFN α-2b per week for an additional 6 weeks externally administered in divided doses twice a day, and simultaneously 0.7±106 IU liposomal IFN α-2b per week intravaginally. Clinically the cervical lesion completely resolved at the end of the therapy, and the exophytic lesions decreased in size. In situ hybridization showed decreased focal staining for HPV DNA in biopsy tissue after treatment. The presence of IFN α was detected in the biopsy tissue by immunostaining. The male patient, treated with 2.1±106 IU liposomal IFN α-2b per week for 8 weeks showed decreased number of lesions at the end of the observation period.