Piecewise HIV virus dynamic model with CD4(+) T cell count-guided therapy: I

Area of Science:

• Virology
• Mathematical Modeling
• Immunology

Background:

• Structured treatment interruptions (STIs) are proposed for HIV management but yield inconsistent clinical results.
• Previous studies on STIs have not reached a consensus on their efficacy and safety.
• Understanding the dynamic behavior of HIV during STIs is crucial for optimizing patient outcomes.

Purpose of the Study:

• To quantitatively evaluate CD4(+) T cell count-guided STI strategies for HIV management.
• To explain the controversial conclusions from different clinical studies on STIs.
• To investigate the dynamic behaviors of HIV under various STI protocols.

Main Methods:

• Utilized piecewise HIV virus dynamic models for quantitative analysis.
• Simulated STI strategies with single and threshold window controls for CD4(+) T cell counts.
• Analyzed the impact of upper and lower threshold values on CD4(+) T cell dynamics and treatment durations.

Main Results:

• CD4(+) T cell counts can be maintained above safe levels using STI with threshold controls.
• Simulations demonstrated that CD4(+) T cell counts can fluctuate or stabilize based on threshold settings.
• Threshold policy control enables stabilization of CD4(+) T cell counts at desired levels.
• Treatment durations (drug-on/drug-off) are highly sensitive to threshold choices.

Conclusions:

• CD4(+) T cell count-guided STIs can effectively maintain immune cell counts.
• Individualizing STI strategies by carefully selecting CD4(+) T cell count thresholds is critical for successful HIV management.
• Threshold sensitivity explains the failure rates associated with fixed-schedule or frequent-switch STI strategies.