Camptothecin analogs as "block and lock" agents for HIV

About This Grant

Project summary/abstract Despite effective antiretroviral therapy (ART), people with HIV (PWH) continue to have chronic inflammation and comorbidities driven by low-level viral transcription from integrated HIV proviruses. Silencing this residual HIV activity could reduce immune activation and improve long-term health. Our long-term goal is to develop therapies that suppress HIV expression and inflammation in PWH on ART. Topotecan (TPT), a Camptothecin analog that inhibits Topoisomerase I, potently suppresses HIV transcription in latently infected T cells. Notably, TPT appears to inhibit HIV independent of its Topoisomerase I activity, suggesting an alternative mechanism of action. We will evaluate new Camptothecin analogs as HIV “block- and-lock” agents. Our central hypothesis is that these compounds can stably suppress HIV without harming host cells. We will pursue three aims: 1) Determine the mechanisms by which TPT inhibits HIV gene expression; 2) Identify new Camptothecin analogs with HIV inhibitory function; 3) Determine the longevity of Camptothecin analog-induced HIV suppression and validate their function using samples from PWH ex vivo. First, we will define how TPT blocks HIV by mapping epigenetic changes at the viral promoter (via CUT&RUN), testing Tat dependence, and assessing post-transcriptional effects like RNA stability and nuclear export (Aim 1). Second, we will screen Camptothecin analogs—with and without Topoisomerase I activity—to identify compounds that suppress HIV at low doses without cytotoxicity. Lead candidates will be validated in primary cells, and their mechanisms and off-target effects will be characterized (Aim 2). Third, we will test whether these compounds can durably silence HIV in latency models and in cells from PWH ex vivo (Aim 3). Completion of these studies will clarify how Camptothecin analogs suppress HIV and assess their therapeutic potential. We expect this work will enable the development of novel “block-and-lock” drugs that reduce persistent inflammation and improve health outcomes in PWH on ART.