Kaposi's sarcoma (KS) is an angioproliferative
tumor showing an increased frequency and aggressiveness in HIV-infected subjects (
AIDS-KS), due to the combined effects of inflammatory
cytokines (IC), angiogenic factors, and the HIV-1
Tat protein. While the introduction of effective combined antiretroviral regimens greatly improved
AIDS-KS incidence and course, it continues to be an incurable disease and the development of new rational targeted
therapies is warranted. We used the BKV/Tat transgenic mouse model to evaluate the effects of IC and anti-Tat
antibodies (Abs) treatment on KS-like lesions arising in BKV/Tat mice. We demonstrated here that IC-treatment increases the severity and delays the regression of KS-like lesions. Further, anti-Tat Abs reduced KS-like lesion severity developing in IC-treated mice when anti-Tat Abs were administered at an early-stage of lesion development as compared to more advanced lesions. Early anti-Tat Abs treatment also accelerated KS-like lesion regression and reduced the rate of severe-grade lesions. This effect was more evident in the first weeks after Ab treatment, suggesting that a longer treatment with anti-Tat Abs might be even more effective, particularly if administered just after lesion development. Although preliminary, these results are encouraging, and the approach deserves further studies for the development of anti-Tat Ab-based
therapies for
AIDS-KS. Clinical studies specifically addressing the effect of anti-Tat
antibodies in treating
AIDS-KS are not yet available. Nevertheless, the effectiveness of anti-Tat
antibodies in controlling HIV/
AIDS progression, likely due to the neutralization of extracellular Tat activities, is suggested by several cross-sectional and longitudinal clinical studies, indicating that anti-Tat Ab treatment or Tat-based
vaccines may be effective to treat
AIDS-KS patients or prevent the
tumor in individuals at risk.