096: Cluster Analysis to Identify Biomarkers of Treatment Response Following Sirolimus Treatment for HIV Cure

Statement of Purpose, Innovation or Hypothesis: Despite successful inhibition of viral replication with antiretroviral therapy (ART), HIV persists indefinitely without a cure due to host’s incapability to clear the viral reservoir [1]. Sirolimus is a powerful inhibitor mechanistic target of rapamycin (mTOR) signaling pathway with known effects to decrease viral reservoir size in people with HIV (PWH) by regulating immunomodulatory activities and blocking cell turnover mediated homeostasis [2]. Here we propose a clustering analysis to identify immune and viral biomarkers of treatment response to sirolimus during a clinical AIDS Clinical Trials Group Study to reduce HIV viral reservoirs in PWH (A5337).

Description of Methods & Materials: The A5337 study was a 32 participant, phase I/II, open label, single-arm clinical trial to evaluate the safety and efficacy of daily sirolimus administration for 20-week to reduce HIV viral reservoirs. Flow cytometric analysis was used to quantify the biomarkers percentage of T-cell activation and proliferation as well as frequencies of T-cells expressing intracellular cytokines, degranulation, granzyme B, and perforin independent of and in response to the stimulations by peptides pools including cytomegalovirus (CMV), HIV group specific antigen (gag), and staphylococcal enterotoxin B (SEB). HIV reservoirs (cell associated [ca] DNA and RNA) and soluble inflammatory cytokines (e.g., IL-6, D-Dimer) were also measured. Fold biomarker changes were reported as ratios of post sirolimus (20 weeks) to baseline measures of each biomarker. Spearman’s rank correlation was used to evaluate biomarker fold change relative to average sirolimus exposure (PK trough) over 20 weeks for all participants. Heatmap was generated using Python, and biomarkers with low fold changes excluded (0.5 - 1.5 folds).

Data & Results: Hierarchical clustering of the average sirolimus concentration and biomarkers correlation matrix (Fig. 1), demonstrated upregulation of immuno-responsive biomarkers stimulated by gag with increasing sirolimus exposure, indicated by expression of CD107a and MIP-1beta on CD4 T-cells. Conversely higher sirolimus exposures, were closely clustered with decreases in gag-specific IL-2, TNF-alpha, and IFNgamma production by CD8 T-cells, inflammatory cytokines D-Dimer and IL-6, and a decrease in caRNA expression.

Interpretation, Conclusion or Significance: Sirolimus treatment demonstrated its potential in modulating immune responses against HIV and regulating reservoir size in PWH. Increased expression of CD107a, degranulation marker for T cells, is associated with enhanced cytotoxic activity [3]. Conversely, lower IL-2 responses could decrease T cell proliferation and survival, but may affect other cell types expressing IL-2 which need to be explored further [4]. Overall, sirolimus could mediate cytotoxic, antibody-production and proliferative responses of the immune system to HIV, which are essential for controlling HIV replication and potentially reducing the latently infected cells/HIV reservoir. Increases in CD107a and MIP1-beta are consistent with those found following ex vivo immune checkpoint blockade and studies relating chemokine response to HIV suppression, respectively [5]. Our study initiated a novel PKPD approach to characterize biomarkers response to sirolimus exposure. The results could lay a foundation in the optimization of sirolimus target trough for HIV cure. Furthermore, these pathways advance understanding of HIV mechanisms of persistence and may serve as biomarkers of response in future clinical trials.

Disclosures:

Citations/References: [1] Vanhamel+ J Virus Erad., 2019. [2] Chi Nat. Rev. Immunol., 2012. [3] Aktas+ Cell Immunol., 2008 [4] Abbas, AJP, 2020. [5] Chiu+ J Immunol., 2022.

Additional Information/Authors: N/A