This study aims to investigate the safety and preliminary efficacy of an innovative therapeutic strategy combining chidamide with NKG2D-directed chimeric antigen receptor natural killer (CAR-NK) cells in individuals living with HIV. The approach is predicated on the "shock and kill" paradigm: chidamide is employed to reactivate latent HIV reservoirs and upregulate surface target ligands (NKG2D ligands) on infected cells; subsequently, allogeneic NKG2D CAR-NK cells are infused to specifically recognize and eliminate these "marked" cells.

This is a phase I, open-label, single-arm clinical trial comprising two distinct stages: a dose-escalation phase (phase Ia, utilizing a "1+3+3" design) and a dose-expansion phase (phase Ib). A total of 20 HIV-infected individuals who are stable on antiretroviral therapy (ART) and have suppressed plasma viremia are planned for enrollment. Participants will receive oral chidamide over approximately five weeks, followed by two cycles of intravenous CAR-NK cell infusion.

The primary endpoint is the safety and tolerability of the regimen, with particular attention to immune-related adverse events including cytokine release syndrome (CRS). Secondary endpoints encompass exploratory assessments of potential virologic and immunologic effects, such as alterations in plasma HIV RNA, cell-associated viral nucleic acids, and CD4+ T-cell counts. This study is intended to provide initial human safety data and preliminary evidence regarding the potential of this combination strategy to contribute toward a functional cure for HIV infection.

Background and Rationale:

Currently, highly active antiretroviral therapy (HAART) effectively suppresses HIV replication; however, it fails to eradicate the latent viral reservoir, necessitating lifelong pharmacotherapy for infected individuals. This study is predicated on the "shock and kill" strategy and combines the histone deacetylase inhibitor chidamide with allogeneic chimeric antigen receptor natural killer (CAR-NK) cells targeting NKG2D ligands, aiming to explore a novel potential approach toward a functional cure for HIV infection. Preclinical investigations have demonstrated that chidamide not only reactivates latent virus but also upregulates the expression of NKG2D ligands on the surface of infected cells, while NKG2D CAR-NK cells exhibit specific recognition and elimination of such target cells, thereby establishing a clear synergistic effect between the two modalities.

Study Objectives:

Primary Objective: To evaluate the safety and tolerability of the combined therapeutic regimen in HIV-infected individuals receiving stable antiretroviral therapy.

Secondary Objectives: To preliminarily explore the impact of this regimen on virologic and immunologic parameters, including plasma HIV RNA, cell-associated viral nucleic acids, and CD4⁺ T-cell counts.

Study Design:

This is a prospective, open-label, single-arm, phase I clinical trial comprising dose-escalation and dose-expansion stages. The study is conducted in two distinct phases:

Phase Ia (Dose Escalation): A modified "1+3+3" design will be employed to evaluate the safety of three dose levels of CAR-NK cells (DL1: 5×10⁸, DL2: 1×10⁹, DL3: 2×10⁹ cells per infusion) and to determine the recommended phase II dose (RP2D). The dose-limiting toxicity (DLT) observation period is defined as 28 days following the initial cell infusion.

Phase Ib (Dose Expansion): An expansion cohort will be enrolled at the established RP2D to further assess safety and preliminary efficacy.

Study Participants:

A total of 20 HIV-infected individuals are planned for enrollment, meeting the following eligibility criteria: age 18-65 years, receipt of antiretroviral therapy (ART) for a minimum of two years, sustained virologic suppression (plasma HIV RNA <50 copies/mL), CD4⁺ T-cell count >200 cells/μL, and compliance with additional health-related inclusion criteria.

Intervention:

All enrolled participants will receive oral chidamide (10 mg twice weekly) for approximately five weeks. During this period, participants will receive two cycles of intravenous infusion of allogeneic NKG2D CAR-NK cells (each cycle consisting of two consecutive daily infusions, separated by an interval of approximately two weeks). Throughout the treatment course, participants will continue their pre-existing antiretroviral regimen without modification.

Figure 1. Schematic Diagram of Participant Follow-Up and Study Procedures

Outcome Measures:

Safety Endpoints: Incidence and characterization of adverse events (AEs), serious adverse events (SAEs), and dose-limiting toxicities (DLTs), with particular emphasis on cytokine release syndrome (CRS) and neurotoxicity.

Exploratory Efficacy Endpoints: Dynamic changes in plasma HIV RNA, cell-associated HIV RNA/DNA, and CD4⁺/CD8⁺ T-cell counts from baseline to post-treatment assessments.

Additional Exploratory Endpoints: In vivo expansion and persistence of CAR-NK cells (pharmacokinetics, PK), cytokine profiling, and alterations in senescence-associated biomarkers.

Significance of the Study:

This study represents the first-in-human evaluation of the safety profile of chidamide in combination with allogeneic NKG2D CAR-NK cell therapy in the context of HIV infection. Furthermore, it will provide preliminary clinical evidence regarding the potential of this combinatorial strategy to reduce the viral reservoir, thereby potentially opening new avenues for the development of functional cure strategies for HIV infection.

Inclusion Criteria

A participant will be deemed eligible for enrollment only if all of the following criteria are met:

1. Diagnosis of HIV infection, with a current history of highly active antiretroviral therapy (HAART) for a minimum duration of two years.

2. Age between 18 and 65 years, inclusive.

3. Plasma HIV RNA level < 50 copies/mL (virologic suppression).

4. CD4⁺ T cell count > 200 cells/μL.

5. Adequate hematologic function defined as:

   • Hemoglobin ≥ 90 g/L;
   • Platelet count ≥ 75 × 10⁹/L;
   • Absolute neutrophil count (ANC) ≥ 1.0 × 10⁹/L;
   • White blood cell count ≥ 2 × 10⁹/L.

6. Adequate hepatic and renal function defined as:

   • Serum creatinine ≤ 1.5 × upper limit of normal (ULN);
   • Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3 × ULN;
   • Total bilirubin ≤ 2 × ULN;
   • Prothrombin time (PT) prolongation < 3 seconds.

7. Hemodynamically stable with a left ventricular ejection fraction (LVEF) ≥ 45%.

8. Negative serum or urine pregnancy test for females of childbearing potential.

9. Willingness of the participant to:

   • Practice effective contraception during the study period and for one year following completion of the trial;
   • Voluntarily provide written informed consent and comply with scheduled follow up visits and study procedures.

Exclusion Criteria

Participants meeting any of the following criteria will be excluded from study participation:

1. Presence of severe cardiovascular, respiratory, or hematologic disease; active infectious disease (other than controlled HIV infection); or active malignancy.
2. Positive serology for hepatitis B surface antigen (HBsAg) or detectable hepatitis C virus RNA (HCV RNA).
3. Diagnosis of chronic kidney disease (CKD).
4. History or presence of acute or chronic pancreatitis.
5. Active severe peptic ulcer disease.
6. Current severe neurologic or psychiatric disorder.
7. History of alcohol abuse or illicit substance use disorder.
8. Known allergic diathesis or hypersensitivity to any component of the investigational agents.
9. Female participants who are pregnant, lactating, or of childbearing potential and unwilling to adhere to required contraceptive measures.
10. Concurrent use of immunosuppressive agents.
11. Any other condition that, in the opinion of the investigator, renders the participant unsuitable for study participation.

1. Participant Privacy and Confidentiality:

   Although data would be de-identified prior to sharing, the IPD encompass detailed clinical, virologic, and immunologic parameters. Given the specific sensitivities associated with the HIV-infected population and the nature of the medical information, a residual risk of re-identification through the triangulation of indirect identifiers persists. Public sharing of IPD may therefore contravene data protection regulations and the privacy assurances stipulated in the participant informed consent documentation.

2. Limitations of Informed Consent Scope:

The informed consent form executed for this study does not explicitly authorize the disclosure of participant-level raw data to third parties or its deposition in public data repositories. The investigators are bound by legal and ethical obligations to utilize the data solely within the parameters approved in the study protocol and the corresponding informed consent.