Monday, June 30, 2025 6/30/2025

Validation and characterization of Tat inhibitors identified through HTS

Award Number: R21AI158296
ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 08/12/2021
PERIOD OF PERFORMANCE END DATE: 07/31/2024

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Validation and characterization of Tat inhibitors identified through HTS - ABSTRACT Despite effective antiretroviral therapy (ART), latent proviruses can reinitiate viral production upon cell stimulation or treatment interruption. The viral Tat protein enhances transcript elongation from the HIV-1 promoter, controlling the switch between latency and active viral production. The block-and-lock functional cure aims at the transcriptional silencing of the viral reservoir rendering suppressed HIV promoters extremely difficult to reactivate from latency. The Tat inhibitor, didehydro-cortistatin A (dCA) was used to prove this concept. Combining dCA with ART, inhibits transcription and blocks viral rebound upon treatment interruption, as the promoter becomes epigenetically repressed. dCA defines a novel class of drugs that can silence and maintain a transcriptionally inactive HIV promoter, offering a novel approach in the treatment of HIV. Tat is very attractive target for therapeutic intervention because: 1) is expressed early during virus replication; 2) no cellular homologs; 3) Tat inhibitors block the feedback loop necessary for viral amplification; 4) epigenetic modifications accumulate at the HIV promoter rendering reactivation less likely. Tat is also known for its role in neurotoxicity, neurotransmitter modulation, oxidative stress, apoptosis, blood brain barrier disruption, and neuroinflammation. Thus, the immense interest in the development of Tat inhibitors to complement ART. The major hurdle towards advancing dCA into clinical trials is the cost of producing large quantities of this molecule, due to its complex structure. Additional clinical candidates, structurally distinct from dCA, that embody equivalent bioactivity are needed in the pre-clinical pipeline. We optimized a cell-based Tat transactivation assay to use in high throughput screening (HTS), with dCA as control. We combined appropriate counter-screens and a wealth of techniques to quickly ‘weed out’ small molecules that are not Tat specific. The HTS of 210,240 compounds was completed by Southern Research (SR), yielding two compounds, SRI-43627 and SRI-43050 with a selectivity index >10 that were further investigated. This initial success prompted the screen of an additional 369,203 compounds, yielding upon counter screen 29 hits to be further evaluated. In this application, we propose to perform hit validation and characterization of these compounds as well as analogs synthesized by SR as part of drug development during the compound progression pathway. We propose the following aims: Specific Aim 1. Validate Tat inhibitors based on disruption of Tat HIV-1 LTR transactivation. Specific Aim 2. Characterize the mechanism of action of selected hits. At the end of this study we expect to (a) have identified small molecules that will specifically inhibit Tat in cell-based assays. (b) have adequate metabolic stability and PK properties for future pharmacological assessment in animal models and eventually in human clinical trials.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2025 ( Subtotal = -$386 )
2025	2022	UNIVERSITY OF FLORIDA	1523 UNION RD RM 207	GAINESVILLE	FL	32611	ALACHUA	USA	Allergy and Infectious Diseases Research	000	3	2/19/2025	NON-COMPETING CONTINUATION	-$386
														Subtotal = -$386

Issue Date FY: 2023 ( Subtotal = $0 )
2023	2021	SCRIPPS RESEARCH INSTITUTE, THE	130 SCRIPPS WAY	JUPITER	FL	33458	PALM BEACH	USA	Allergy and Infectious Diseases Research	000	1	1/3/2023	NEW	$0
														Subtotal = $0

Issue Date FY: 2022 ( Subtotal = $231,250 )
2022	2022	UNIVERSITY OF FLORIDA	1523 UNION RD RM 207	GAINESVILLE	FL	32611	ALACHUA	USA	Allergy and Infectious Diseases Research	003	3	7/11/2022	NON-COMPETING CONTINUATION	$231,250
2022	2021	SCRIPPS RESEARCH INSTITUTE, THE	130 SCRIPPS WAY	JUPITER	FL	33458	PALM BEACH	USA	Allergy and Infectious Diseases Research	000	1	4/6/2022	NEW	-$141,939
2022	2021	UNIVERSITY OF FLORIDA	1523 UNION RD RM 207	GAINESVILLE	FL	32611	ALACHUA	USA	Allergy and Infectious Diseases Research	002	2	5/12/2022	CHANGE OF GRANTEE / TRAINING INSTITUTION / AWARDING INSTITUTION	-$6,292
2022	2021	UNIVERSITY OF FLORIDA	1523 UNION RD RM 207	GAINESVILLE	FL	32611	ALACHUA	USA	Allergy and Infectious Diseases Research	001	2	4/6/2022	CHANGE OF GRANTEE / TRAINING INSTITUTION / AWARDING INSTITUTION	$148,231
														Subtotal = $231,250

Issue Date FY: 2021 ( Subtotal = $277,500 )
2021	2021	SCRIPPS RESEARCH INSTITUTE, THE	130 SCRIPPS WAY	JUPITER	FL	33458	PALM BEACH	USA	Allergy and Infectious Diseases Research	000	1	8/12/2021	NEW	$277,500
														Subtotal = $277,500

Grand Total All Awards = $508,364

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Validation and characterization of Tat inhibitors identified through HTS

Award Number: R21AI158296

ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 08/12/2021

PERIOD OF PERFORMANCE END DATE: 07/31/2024

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