Repeated treatments with ingenol mebutate for prophylaxis of UV-induced squamous cell carcinoma in hairless mice

TY - JOUR

T1 - Repeated treatments with ingenol mebutate for prophylaxis of UV-induced squamous cell carcinoma in hairless mice

AU - Erlendsson, Andrés M

AU - Thaysen-Petersen, Daniel

AU - Bay, Christiane

AU - Lerche, Catharina M

AU - Philipsen, Peter A.

AU - Wulf, Hans Christian

AU - Zibert, John R.

AU - Hædersdal, Merete

PY - 2016/10

Y1 - 2016/10

N2 - Background and Aim: The incidence of squamous cell carcinomas (SCC) is increasing, and effective chemopreventative strategies are needed. We hypothesized that repeated treatments with ingenol mebutate (IngMeb) would postpone development of SCC in hairless mice, and that application of a corticosteroid would reduce IngMeb-induced local skin responses (LSRs) without affecting tumor postponement. Methods: Hairless mice (n = 150; 6 groups á 25 mice) were irradiated with solar simulated ultraviolet radiation (UVR) until SCC developed. During UV-irradiation and before tumor development, five single treatments (Tx) with IngMeb were given at four-week intervals (days 21, 49, 77, 105, 133). Clobetasol propionate (CP) was applied once daily for 5 days prior to IngMeb, as well as 6 h and 1 day post treatment. Tumor formation was evaluated weekly for 52 weeks. LSR (scale 0–24) were assessed at baseline, 1 h, 6 h, 1-, 2-, 3-, 4-, 5-, 6-, and 7 days after each IngMeb treatment. Results: IngMeb significantly delayed tumor development compared to UVR alone (UVR day 168 vs. UVR + IngMeb day 189; p = 0.025). LSR included erythema, flaking, crusting, bleeding, vesiculation, and ulceration. The composite LSR-scores were of moderate intensity in non-UV irradiated skin (max LSR IngMeb Tx 1–5: 1.5–2.5) and more pronounced in photodamaged skin (max LSR Tx 5; IngMeb 1.5 vs. UVR + IngMeb 1.8; p < 0.001). LSR intensity correlated with tumor development by means of greater composite LSR-score resulted in longer tumor-free survival (r2 = 0.257, p < 0.001). Contrary to our hypothesis, concurrent CP increased LSR (max LSR Tx 1–5: UVR + CP + IngMeb 3.2–4.9 vs. UVR + IngMeb 1.3–2.2, p < 0.001) and postponed tumor development compared to IngMeb alone (UVR + CP + IngMeb day 217 vs. UVR + IngMeb day 189, p < 0.001). Conclusion: Repeated field-directed treatments with IngMeb delay development of UV-induced SCC in hairless mice, and increased IngMeb induced LSRs correlated with improved clinical outcomes. The findings highlight the potential of IngMeb as a prophylactic remedy for SCC in humans.

AB - Background and Aim: The incidence of squamous cell carcinomas (SCC) is increasing, and effective chemopreventative strategies are needed. We hypothesized that repeated treatments with ingenol mebutate (IngMeb) would postpone development of SCC in hairless mice, and that application of a corticosteroid would reduce IngMeb-induced local skin responses (LSRs) without affecting tumor postponement. Methods: Hairless mice (n = 150; 6 groups á 25 mice) were irradiated with solar simulated ultraviolet radiation (UVR) until SCC developed. During UV-irradiation and before tumor development, five single treatments (Tx) with IngMeb were given at four-week intervals (days 21, 49, 77, 105, 133). Clobetasol propionate (CP) was applied once daily for 5 days prior to IngMeb, as well as 6 h and 1 day post treatment. Tumor formation was evaluated weekly for 52 weeks. LSR (scale 0–24) were assessed at baseline, 1 h, 6 h, 1-, 2-, 3-, 4-, 5-, 6-, and 7 days after each IngMeb treatment. Results: IngMeb significantly delayed tumor development compared to UVR alone (UVR day 168 vs. UVR + IngMeb day 189; p = 0.025). LSR included erythema, flaking, crusting, bleeding, vesiculation, and ulceration. The composite LSR-scores were of moderate intensity in non-UV irradiated skin (max LSR IngMeb Tx 1–5: 1.5–2.5) and more pronounced in photodamaged skin (max LSR Tx 5; IngMeb 1.5 vs. UVR + IngMeb 1.8; p < 0.001). LSR intensity correlated with tumor development by means of greater composite LSR-score resulted in longer tumor-free survival (r2 = 0.257, p < 0.001). Contrary to our hypothesis, concurrent CP increased LSR (max LSR Tx 1–5: UVR + CP + IngMeb 3.2–4.9 vs. UVR + IngMeb 1.3–2.2, p < 0.001) and postponed tumor development compared to IngMeb alone (UVR + CP + IngMeb day 217 vs. UVR + IngMeb day 189, p < 0.001). Conclusion: Repeated field-directed treatments with IngMeb delay development of UV-induced SCC in hairless mice, and increased IngMeb induced LSRs correlated with improved clinical outcomes. The findings highlight the potential of IngMeb as a prophylactic remedy for SCC in humans.

KW - Clobetasol propionate

KW - Corticosteroid

KW - Inflammation

KW - Local skin responses

KW - Skin cancer

U2 - 10.1016/j.jphotobiol.2016.08.022

DO - 10.1016/j.jphotobiol.2016.08.022

M3 - Journal article

C2 - 27567085

AN - SCOPUS:85015355356

SN - 1011-1344

VL - 163

SP - 144

EP - 149

JO - Journal of photochemistry and photobiology. B, Biology

JF - Journal of photochemistry and photobiology. B, Biology

ER -