Phase II trial of imiquimod and HPV therapeutic vaccination in patients with vulval intraepithelial neoplasia

Abstract

Background: Vulval intraepithelial neoplasia (VIN) is a premalignant condition, which is frequently associated with type HPV16 infection, and multifocal disease has high rates of surgical treatment failure.

Methods: We report a phase II clinical trial of the topical immunomodulator, imiquimod, for 8 weeks, followed by 3 doses (weeks 10, 14 and 18) of therapeutic human papillomavirus (HPV) vaccination (TA-CIN, fusion protein HPV16 E6E7L2) in 19 women with VIN grades 2 and 3. Histology and HPV testing of biopsies were performed at weeks 0, 10, 20 and 52. Intralesional infiltration of T-cell subsets and lymphocyte proliferation for HPV systemic immune responses were also assessed.

Results: Lesion response (complete regression of VIN on histology) was observed in 32% (6 out of 19) of women at week 10, increasing to 58% (11 out of 19) at week 20 and 63% (12 out of 19) at week 52. At this time, 36% (5 out of 14) of lesions showed HPV16 clearance and 79% (15 out of 19) of women were symptom free. At week 20, after treatment with imiquimod and vaccination, there was significantly increased local infiltration of CD8 and CD4 T cells in lesion responders; in contrast, non-responders (persistent VIN by histology) showed an increased density of T regulatory cells. After vaccination, only lesion responders had significantly increased lympho-proliferation to the HPV vaccine antigens.

Conclusion: The therapeutic effect of treatment depends on the differential immune response of responders and non-responders with affect locally and systemically.

Figure 1

(A) Reduction in lesion size. Reduction in lesion size by 100%, >50% but <100 and <50% at baseline (week 0), after imiquimod (week 10), after vaccination (week 20), primary end point (week 52) and follow-up (62 weeks after primary end point) in the group (n=19). (B) Lesion and symptom responses. Lesion response (complete disappearance of VIN on histology), symptom response (regression to mild/none symptoms), absence of HPV16 on biopsy at baseline (week 0), after imiquimod (week 10), after vaccination (week 20) and primary end point (week 52) in the group (n=19).

Figure 2

Box-feather plots showing median and quartile lymphoproliferation responses. The figures show stimulation indices of proliferation in response to PHA (A), TA-CIN (B), HPV-16L2 (C), GST-E6 (D), GST-E7 (E) and TA-GW (F) in the whole group (n=19), lesion responders (R; n=12) and lesion non-responders (NR; n=7) at baseline (week 0), after imiquimod (week 10) and after vaccination (week 20). P-values that are statistically significant for stimulation indices (SI) at week 20 compared with week 0 are shown. The Wilcoxon's signed-ranks test was used to determine the significance of within-group differences before and after treatment. A P-value of ⩽0.05 was considered significant.

Figure 3

Median/scatter-dot plot of lesion-associated immune cells in the group (G), lesion responders (R) and non-responders (NR). The figure shows median number (density per unit area) of CD4, CD8 and FoxP3CD4 cells before treatment (week 0), after imiquimod (week 10) and after vaccination (week 20) in the group (G), lesion responders (R) and non-responders (NR). The P-values for statistically significant difference in the number of cells either at week 10 or week 20 compared with week 0 are shown. The Wilcoxon's signed-ranks test was used to determine the significance of within-group differences before and after treatment. A P-value of ⩽0.05 was considered significant.