THRD Third Harmonic Bio Inc

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Exhibit 99.1

Third Harmonic Bio Announces First Quarter 2024 Financial Results and Provides Business Update

U.S. FDA clears Investigational New Drug application for THB335

Phase 1 SAD/MAD clinical trial initiated and subject screening underway, with results expected during 1H’25

Strengthened leadership team with the appointment of Christopher J. Dinsmore, Ph.D., to Chief Scientific Officer, Dennis Dean, Ph.D., to Chief Non-Clinical Development Officer, and the promotion of Jennifer Dittman to Chief Development Operations Officer

Strong financial position with cash and cash equivalents totaling $262.8 million as of March 31, 2024

SAN FRANCISCO, CA, May 15, 2024 (GLOBE NEWSWIRE) — Third Harmonic Bio, Inc. (Nasdaq: THRD), a clinical stage biopharmaceutical company focused on advancing the next wave of medicine for dermal, respiratory, and gastrointestinal inflammatory diseases, today announced financial results for the first quarter March 31, 2024, recent business updates, and anticipated milestones.

As part of its business update, the Company announced U.S. FDA clearance of its Investigational New Drug (IND) application to initiate a first-in-human clinical trial of THB335, a potent, highly selective, oral, small molecule KIT inhibitor that is in development for the treatment of mast cell-mediated diseases, with an initial focus in chronic spontaneous urticaria (CSU). The Company has initiated a Phase 1 single and multiple ascending doses (SAD/MAD) clinical trial of THB335 to evaluate safety, pharmacokinetics, and pharmacodynamics in healthy volunteers, and expects to report clinical results from the trial during the first half of 2025. The Phase 1 trial is expected to be followed by a Phase 2 trial in CSU, with planned rapid expansion into additional mast cell-mediated disorders.

“With the initiation of THB335 clinical trials, we are advancing the development of our potentially best-in-class oral KIT inhibitor toward becoming an important treatment for patients living with chronic spontaneous urticaria and other mast-cell mediated inflammatory diseases,” said Natalie Holles, Chief Executive Officer at Third Harmonic Bio. “We are continuing to conduct our development efforts with urgency given the significant unmet need in CSU and the potentially transformative benefit that TBH335 may deliver to patients.”

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The Phase 1 SAD/MAD clinical trial of THB335 is being conducted in healthy volunteers to assess safety and tolerability, characterize pharmacokinetics, and to measure the pharmacodynamic effect by reductions in serum tryptase, a biomarker associated with mast cell activation and correlated with clinical response in urticaria studies. Results are expected in the first half of 2025.

Leadership Team Updates

The Company also announced the appointment and promotion of key executive leaders to the organization. Christopher J. Dinsmore, Ph.D., was appointed to Chief Scientific Officer, Dennis Dean, Ph.D., was appointed to Chief Non-Clinical Development Officer, and Jennifer Dittman was promoted to Chief Development Operations Officer.

“We are excited to expand the executive team with the appointments of Chris, Dennis and Jennifer to their respective leadership roles in these critical discovery, research and development functions,” continued Natalie Holles. “In addition to their outstanding collective track record in our industry, all three embody our core operating principles of open collaboration, enterprise-level thinking and drive. I look forward to our future achievements under this outstanding leadership team.”

Chris is a seasoned leader with a strong track record of advancing early targets to drug candidate identification and through clinical development. In his role as Chief Scientific Officer, he will oversee the Company’s scientific research strategy from discovery through preclinical proof-of-concept, IND filing, and also support early clinical development. Chris joins Third Harmonic Bio from Kronos Bio, where he was Chief Scientific Officer, responsible for the discovery functions, and played a key role in the company’s initial public offering and partnership with Genentech. Prior to Kronos, he served as an Entrepreneur-in-Residence at Third Rock Ventures, focusing on the launch of new biomedical companies. Earlier in his career, he served as Vice President, Head of Chemistry, of Forma Therapeutics, where he oversaw chemistry functions in support of discovery and early development. He began his career at Merck Research Laboratories where he held positions of increasing responsibility in discovery chemistry. He received his Ph.D. in organic chemistry from University of Minnesota, Minneapolis, and was a NIH Postdoctoral Fellow in organic chemistry at Harvard University.

Dennis brings extensive experience across multiple therapeutic areas of drug discovery and development, with a particular focus in DMPK, preclinical safety assessment, clinical pharmacology, biomarkers, and modeling and simulation. In his role as Chief Non-Clinical Development Officer, he will be responsible for leading the selection of high-quality development candidates, including toxicology, DMPK and translation functions. Prior to joining Third Harmonic Bio, Dennis has served as Chief Development Officer of IFM Therapeutics,

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where he oversaw preclinical and clinical development, advancing multiple programs into early clinical development leading to three acquisitions by global pharmaceutical companies. Before IFM Therapeutics, he was Senior Vice President, Head of Preclinical Development at Vertex Pharmaceuticals, where he linked key preclinical translational groups, effectively progressed the pipeline, and bridged transition for discovery into development. Earlier in his career, he held positions of increasing responsibility in DMPK at Merck Research Laboratories. He received his Ph.D. in medicinal chemistry at State University of New York, Buffalo, and was a Postdoctoral Fellow at Emory University.

Jennifer joined Third Harmonic Bio in November 2022 as Vice President of Regulatory Affairs. In her expanded role as Chief Development Operations Officer, she is now responsible for regulatory affairs, program management, quality, and CMC. Prior to joining Third Harmonic Bio, Jennifer was Vice President of Regulatory Affairs and Medical Writing at Generation Bio, where she was responsible for platform and pipeline regulatory activities. Before Generation Bio, she held roles of increasing responsibility at Vertex Pharmaceuticals, most recently serving as Executive Director, Therapeutic Area Head, in Regulatory Affairs, where she helped set the global regulatory strategy for multiple pipeline products in development, including small molecule and gene therapy/editing programs. Earlier in her career, Jennifer served in roles of increasing responsibility in Regulatory Affairs at bluebird bio and was Adjunct Faculty in the Regulatory Affairs program at Northeastern University. She holds a M.S. in regulatory affairs for drugs, biologics, and medical devices from Northeastern University.

Summary of Financial Results

Cash Position: Cash and cash equivalents totaled $262.8 million as of March 31, 2024. Based on the company’s current operating plan, Third Harmonic Bio believes that its existing cash and cash equivalents will be sufficient to fund its operating expenses and capital expenditure requirements through at least 2026.

R&D Expenses: Research and development (R&D) expenses decreased to $6.2 million for the three months ended March 31, 2024, from $6.7 million for the same period in 2023. The decreases were primarily due to decreases in development costs relating to the termination of the THB001 program, partially offset by increases in research costs relating to the nonclinical development of THB335 and other next-generation discovery efforts.

G&A Expenses: General and administrative (G&A) expenses decreased to $5.1 million for the three months ended March 31, 2024, from $5.3 million for the same period in 2023. The decreases were primarily attributable to decreases in non-cash stock-based compensation.

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Net Loss: Net loss for the three months ended March 31, 2024, decreased to $7.9 million from a net loss of $9.1 million for the same period in 2023. The decreases were primarily due to increases in interest income and decreases in operating expenses.

About Third Harmonic Bio, Inc.

Third Harmonic Bio is a clinical stage biopharmaceutical company focused on advancing the next wave of medicine for dermal, respiratory, and gastrointestinal inflammatory diseases through the development of novel, highly selective, small-molecule inhibitors of KIT, a cell surface receptor that serves as the master regulator of mast cell function and survival. Early clinical studies demonstrate that KIT inhibition has the potential to revolutionize the treatment of a broad range of mast-cell-mediated inflammatory diseases, and that a titratable, oral small molecule inhibitor may provide the optimal therapeutic profile against this target. Third Harmonic Bio’s lead product candidate, THB335, is a titratable, oral, small molecule inhibitor that is currently in a Phase 1 clinical trial. For more information, please visit the Third Harmonic Bio website: www.thirdharmonicbio.com.

Forward-Looking Statement

This press release contains “forward-looking” statements within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995, including, but not limited to, statements regarding the expected timing for clinical trials and regulatory submissions for THB335, planned clinical and development activities and timelines, and the sufficiency of Third Harmonic Bio’s cash and cash equivalents to fund its operating expenses and capital expenditure requirements through at least 2026. Forward-looking statements can be identified by words such as: “anticipate,” “intend,” “plan,” “goal,” “seek,” “believe,” “project,” “estimate,” “expect,” “strategy,” “future,” “likely,” “may,” “should,” “will” and similar references to future periods. These statements are subject to numerous risks and uncertainties, including risks and uncertainties related to Third Harmonic Bio’s cash forecasts, ability to advance its product candidates, the receipt and timing of potential regulatory submissions, designations, approvals and commercialization of product candidates, our ability to protect our intellectual property, the timing and results of preclinical and clinical trials, changes to laws or regulations, market conditions, geopolitical events, and further impacts of pandemics or health epidemics, that could cause actual results to differ materially from what Third Harmonic Bio expects. Further information on potential risk factors that could affect Third Harmonic Bio’s business and its financial results are detailed under the heading “Risk Factors” included in Third Harmonic Bio’s Quarterly Report on Form 10-Q for the three months ended March 31, 2024, filed with the U.S. Securities and Exchange Commission (SEC) on May 15, 2024, and in Third Harmonic Bio’s other filings filed from time to time with the SEC. Third Harmonic Bio undertakes no obligation to publicly update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise.

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Investor and Media Contact:

Lori Murray

lori.murray@thirdharmonicbio.com

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THIRD HARMONIC BIO, INC.

Condensed consolidated balance sheet data

(Unaudited)

(In thousands)

 

		December 31, 2023				March 31, 2024
Assets
Cash and cash equivalents		$	269,070			$	262,826
Other current assets			3,376				2,771
Non-current assets			5,265				4,924
Total assets		$	277,711			$	270,521
Liabilities
Current liabilities		$	5,418			$	4,018
Non-current liabilities			3,208				3,002
Total liabilities			8,626				7,020
Stockholders’ equity			269,085				263,501
Total liabilities and stockholders’ equity		$	277,711			$	270,521

THIRD HARMONIC BIO, INC.

Condensed consolidated statements of operations

(Unaudited)

(In thousands of, except per share and share amounts)

 

		Three Months Ended March 31,
		2023				2024
Operating expenses:
Research and development		$	6,737			$	6,226
General and administrative			5,251				5,064
Total operating expenses			11,988				11,290
Loss from operations			11,988				11,290
Other (income) expense, net			(2,903	)			(3,434	)
Net loss		$	9,085			$	7,856
Net loss per share of common stock, basic and diluted		$	0.23			$	0.20
Weighted-average common stock outstanding, basic and diluted			39,438,572				40,213,158

Exhibit 99.2 On advancing the next wave of FOCUSED medicine for inflammatory diseases MAY 2024 ©2024 THIRD HARMONIC BIO

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Forward Looking Statements This presentation contains forward-looking statements within the meaning of, and made pursuant to the safe harbor provisions of, the Private Securities Litigation Reform Act of 1995. Any statements made in this presentation that are not statements of historical fact, including statements about our beliefs and expectations, are forward-looking statements and should be evaluated as such. Forward-looking statements include information concerning the anticipated profile, efficacy and target indications of THB335, the expected timing of clinical trials of THB335 and the expected development and timeline for clinical and non-clinical studies of THB335 candidate. These statements often include words such as “anticipate,” “expect,” “suggests,” “plan,” “believe,” “intend,” “estimates,” “targets,” “projects,” “should,” “could,” “would,” “may,” “will,” “forecast” and other similar expressions. These forward-looking statements are contained throughout this presentation. We base these forward-looking statements on our current expectations, plans and assumptions that we have made in light of our experience in the industry, as well as our perceptions of historical trends, current conditions, expected future developments and other factors we believe are appropriate under the circumstances at such time. As you read and consider this presentation, you should understand that these statements are not guarantees of future performance or results. The forward-looking statements are subject to and involve risks, uncertainties and assumptions, and you should not place undue reliance on these forward-looking statements. Although we believe that these forward- looking statements are based on reasonable assumptions at the time they are made, you should be aware that many factors could affect our actual results or results of operations and could cause actual results to differ materially from those expressed in the forward-looking statements. Factors that may materially affect such forward-looking statements include: our limited operating history and that we have not completed any clinical trials beyond Phase 1 and have not had any product candidates approved for commercial sale; our significant net losses incurred since inception and the likelihood of incurring additional losses for the foreseeable future; our need for substantial additional funding; the early stage of development of our programs and the possibility they may fail in development; our future performance is substantially dependent on our ability to identify and develop future product candidates; legal and regulatory risks; and intellectual property-related risks, among others. Additional risks and uncertainties that could affect our financial results and business are more fully described under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the three months ended March 31, 2024, filed with the SEC on May 15, 2024, and our other SEC filings, which are available on the Investor & Media page of our website at https://ir.thirdharmonicbio.com/ and on the SEC’s website at www.sec.gov. These cautionary statements should not be construed by you to be exhaustive and are made only as of the date of this presentation. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events, or otherwise, except as required by applicable law. This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In addition, projections, assumptions, and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty and risk. 2

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Recent Highlights • THB335 U.S. IND cleared; Phase 1 SAD/MAD trial underway with results expected in 1H’25 • Appointed Chris Dinsmore, Ph.D., to Chief Scientific Officer, Dennis Dean, Ph.D., to Chief Non-Clinical Development Officer and promoted Jennifer Dittman to Chief Development Operations Officer • Planning rapid advancement to robust Phase 2 study in CSU to support accelerated path to registration studies • Planned expansion into additional mast-cell mediated inflammatory disorders at Phase 2, including severe asthma • Next-generation medicinal chemistry efforts continue to support “pipeline-in-a-target” potential • Cash and cash equivalents of $262.8M as of March 31, 2024 3

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THRD: Focused on KIT to Treat Mast Cell-Mediated Inflammatory Diseases LARGE ESTABLISHED KIT: A NOVEL, MARKETS WITH HIGH CLINICALLY VALIDATED “PIPELINE-IN-A-TARGET” CLINICAL CANDIDATE: UNMET NEED TARGET THB335 POTENTIAL Millions of patients living Clinical validation of KIT Highly selective, oral small Developing a franchise of KIT with severe mast cell-mediated as potentially transformative target for molecule with potential to optimize inhibitors as potential treatment diseases; high residual need despite mast cell-mediated diseases therapeutic index and offer patient options for a range of dermal, multiple approved products convenience over injectables airway, and GI inflammatory diseases 4

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High Disease Burden in Chronic Spontaneous Urticaria A severe, yet undertreated dermal inflammatory condition “Out there, it’s a horrible • Prevalence: More than 1.5 million patients or 0.5-1% 1 point prevalence; ~70-80% female, mean age ~46 years world for urticaria patients” • Disease impact: CSU severely impairs quality of life, causes significant physical discomfort and emotional distress, including anxiety, depression, insomnia and social isolation • Limited treatment options: Oral anti-histamines effective in only ~50% of patients; single biologic therapy approved for second-line use • New treatment options are imperative to driving disease awareness, diagnosis and treatment 1 Marcus Mauer MD, LifeSci Immunology and Inflammation Day, May 10, 2022 5

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KIT is the Master Regulator of Mast Cell Function and Survival Oral small molecule approach to KIT offers multiple potential therapeutic advantages SCF dimer KIT Cytokines KIT receptor Allergen • Targeting mast cell vs specific activating Dimerization pathways or downstream mediators IgE Other provides broad approach to addressing stimuli disease symptoms • Emerging clinical validation for potential P P best-in-disease efficacy in CSU P P P P THB335 INTRACELLULAR SMALL MOLECULE (KIT inhibitor) INHIBITION • Potential for therapeutic index optimization KIT inhibitor reduces mast cell KIT inhibitor reduces • Patient and medical practice convenience proliferation, differentiation, and survival mast cell degranulation • Avoids risk of mAb-mediated mast cell activation/anaphylaxis 6

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Early Clinical Proof-Of-Concept Demonstrated With THB001 Discontinued cold inducible urticaria study results 1 THB001 MEAN TEMPTEST AND SERUM TRYPTASE CLINICAL RESPONSES GENERATED AT LOWEST TempTest (°Celsius) Serum Tryptase (µg/L) 30 6 PLANNED DOSE 25 5 • Rapid tryptase reduction: -83% mean change from 20 4 baseline by week 1 15 3 • Strong correlation between serum tryptase 10 2 reduction and clinical response 5 1 LLOQ Complete response • 4/5 patients achieved clinical response (2 CRs, 2 Baseline Week 1 Week 2 Week 4 Week 6 Week 8 Week 10 Week 12 EOT PRs) despite early termination of study Study Week 1 THB001 MEAN ANC BY VISIT 6000 SAFETY SUMMARY 5500 5000 4500 • No serious or severe adverse events (AEs) 4000 3500 • Two moderate AEs of transaminitis which 3000 2500 resolved at weeks 17 and 25 of follow-up 2000 1500 1000 • All other AEs were mild, reversible, and consistent Baseline Week 1 Week 2 Week 4 Week 6 Week 8 Week 10 Week 12 EOT with KIT biology Study Week 1 Data are mean +/- SE ANC = absolute neutrophil count; CR = complete response; EOT = end of treatment; LLOQ = lower limit of quantitation; PR = partial response 7 Note: Individual subject data available in appendix Neutrophils abs. (/cmm)

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THB001 Showed Evidence of Reactive Metabolite Formation Mechanistic studies provide potential basis for observed transaminitis 14 [ C] THB001 COVALENT PROTEIN ADDUCT FORMATION IN HUMAN LIVER MICROSOMES IS REDUCED IN THE PRESENCE OF GSH OR CYP INHIBITION p<0.05 THB001 140 120 Reactive metabolite 100 “Detoxification” pathway 80 (+) Literature 60 1 cut-off Diol Oxidative stress GSH adduct Protein adducts 40 20 0 Diclofenac THB001 THB001+GSH THB001+ABT LIVER DAMAGE POSITIVE RELATIVE CYP CONTROL METABOLITE INHIBITOR SCAVENGER 1 CYP = cytochrome P450; GSH = glutathione Published literature cut-off: Evans D.C. et al. Chem Res Toxicol 2004 8 Covalent Protein Adduct (pmol/mg equivalent)

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THB335: A Next-Generation, Potent, and Highly Selective Wild-Type KIT Inhibitor U.S. IND cleared with Phase 1 trial underway • Low nanomolar KIT potency with excellent kinome selectivity in biochemical and cell-based assays • Peripherally restricted biodistribution • Structural and metabolic improvements vs THB001 to address DILI risk THB335 • Favorable nonclinical pharmacokinetic profile, including high oral bioavailability, Product Profile metabolic stability, and long circulating half-life • No off-target toxicology findings in IND-enabling studies, consistent with THB001 experience through chronic studies in rodent and non-rodent species • New composition of matter IP; base patent term through 2043 DILI = drug-induced liver injury 9

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THB335 In Vitro Pharmacology Overview Potent, selective, reversible KIT kinase inhibitor DiscoverX KinomeSCAN @ 1μM BIOCHEMICAL CELLULAR Kinase K HTRF KIT Multiple D Target (nM) IC (nM) (nM) 50 1 2 Percent Control KIT 1.5 16.1 5.0 – 7.9 0% 3 2 CSF1R 33 56 >3000 – >10000 KIT 0.1% PDGFRα NT 2710 NT 0.1-1% 4 PDGFRβ 34 737 >3000 1-5% 5-10% 2 ABL1 NT NT >10000 10-35% > 35% 2 DDR1 NT NT 7800 FLT3 >1000 NT NT 1 M-07e pKIT IC (KIT) 50 2 HEK293 nanoBRET EC (KIT, CSF1R, ABL1, DDR1) 50 3 M-NFS-60 EC (CSF1R) 50 10 4 A10 EC (PDGFRβ) 50

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THB335 is Metabolically Distinct from THB001 Next-generation structural modifications functionally block the site of reactive metabolite formation MASS SPEC EXTRACTION ION CHROMATOGRAMS • Diol formed via a reactive epoxide identified as major Human Liver Microsomes metabolite of THB001 – GSH adduct formation associated with detoxification THB001 Diol major metabolite pathways • Next-generation structural modifications functionally block the reactive metabolic pathway – No evidence of diol or GSH adduct formation across species and test systems THB335 1 THB001 THB732 THB335 SYSTEM SPECIES ASSAY GSH Diol GSH Diol GSH Diol No Diol Detected human liver In vitro human NT ‒ ‒ ‒ + + microsomes rat plasma ‒ ‒ ‒ ‒ + + dog plasma In vivo ‒ ‒ ‒ ‒ + + human plasma + + 1 THB732 is a next-generation tool compound with high structural similarity to THB335 11 Relative abundance

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Next-Gen is Phenotypically Distinct from THB001 in Human Hepatocyte Culture No evidence for induction of oxidative stress pathways with next-generation analog of THB335 BULK RNA SEQ ANALYSIS VS VEHICLE CONTROL AT DAY 21 1 5 Detoxification Signals Oxidative Stress (NRF2) 2 Xenobiotic Metabolism 3 Liver Detoxification Ph I_II_III SPHEROID MODEL 2 Biological Oxidations Primary human hepatocytes co-cultured with 2 CYP450 Arranged by Substrate Kupffer and endothelial cells to 2 Ph I Function of Compounds replicate physiologic liver functions 2 PhII Conjugation of Compounds (e.g., drug metabolism, cytokine responses) 2 Xenobiotics 4 Metabolism Xenobiotics FDR<0.001 2 Metapathway Biotrans Ph I_II FDR<0.01 2 Oxidation by CYP 450 21-DAY DRUG TREATMENT 7 20 2.5 7.5 (uM) 7 20 2.5 7.5 (uM) At 100% and 90% cell viability 6 6 THB001 THB732 THB001 THB732 concentrations TRANSCRIPTOMIC ANALYSIS 1,5 Assess changes in gene sets associated with detoxification and oxidative stress vs control 1 2 3 4 Gene sets derived from Molecular Signatures Database (MSigDB), Insphero and Toxicogenomics. NES = normalized enrichment score 5 Kang, W., et al.. Toxicol Sci, 2020. 177(1): p. 121-139. FDR = false discovery rate 12 6 THB732 is a next-generation tool compound with high structural similarity to THB335 FC = fold change

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THB335 Drives Dose-Dependent Mast Cell Depletion and Efficacy In Vivo Rat passive cutaneous anaphylaxis (PCA) model supports PK/PD correlation across species and test systems RAT THB335 PCA DAY 27 CONCENTRATION (ng/mL) THB335 5 mg/kg 100000 PO: Days 1-27 25 mg/kg 100 mg/kg 10000 10xIC50 Anti-DNP antibody 1000 5xIC50 Intradermal: Day 27 IC50 100 10 HSA-DNP/Evans Blue 0 10 20 30 Intravenous: Day 28 Time (h) 2 MAST CELL DENSITY (mm ) MEAN EVANS BLUE (ng/mL) 100 15000 80 10000 60 * 40 * 5000 Measure mast Measure cutaneous 20 cell depletion anaphylaxis (Evans blue) * * 0 0 Control 5 mg/kg 25mg/kg 100mg/kg Vehicle 5mg/kg 25mg/kg 100mg/kg Desloratadine Error bars indicate SEM 13 * P < 0.0001 2 Mast cell Density (mm )

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Nonclinical Findings of KIT Inhibition Are Well-Characterized Across Programs Subchronic and chronic toxicology studies of THB001 completed at up to >10x clinical exposures • No evidence of pharmacologically relevant activity against other kinases • Demonstrated reversibility of all effects Reproductive toxicology studies completed for THB001 • No functional effect on fertility in either sex at all doses tested Improved solubility of THB335 enables more rigorous nonclinical toxicology assessments • IND-enabling studies included doses at >30x predicted exposure margin to clinical doses Leveraging our experience to prioritize speed to Phase 2 with THB335 • Initiating reproductive and chronic toxicology studies to support rapid advancement toward late-stage clinical development 14

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THB335 Phase 1 SAD/MAD in Healthy Participants U.S. IND cleared, and trial initiated with data expected in 1H’25 Study Design • Randomized, placebo-controlled, double-blind, single and 14-day multiple ascending dose design Key Objectives • Assess safety and tolerability • Characterize pharmacokinetics – PK modeling based on nonclinical studies completed to-date supports QD dosing • Measure pharmacodynamic effect characterized by reduction in serum tryptase – Highly correlated with clinical response in urticaria studies Results expected in the first half of 2025 SAD = Single ascending dose; MAD = Multiple ascending dose 15

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“Pipeline-in-a-Target” Potential with KIT Inhibition • Robust Phase 2 CSU study to support planned direct advancement to Phase 3 registrational studies • In parallel with CSU, planning to initiate Phase 2 studies in additional mast-cell mediated inflammatory disorders – Meaningful opportunity in severe asthma, where mast Mast cells play a central role in pathophysiology and clear Cell-Mediated need exists for new oral therapies Diseases • Discovery and medicinal chemistry efforts continue to support KIT inhibition franchise expansion – Developing differentiated target product profiles to address multiple disease/tissue targets 16

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Third Harmonic Bio Next Steps Advancing THB335 into the clinic with a longer-term view toward franchise expansion • THB335 U.S. IND cleared; Phase 1 SAD/MAD trial underway with results expected in 1H’25 • Planning rapid advancement to robust Phase 2 study in CSU to support accelerated path to registration studies • Planned expansion into additional mast-cell mediated inflammatory disorders at Phase 2, including severe asthma • Next-generation discovery and medicinal chemistry efforts continue to support “pipeline-in-a-target” potential • Cash and cash equivalents of $262.8M as of March 31, 2024 17

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Previously Presented Data APPENDIX 18

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1 First-Generation THB001 Phase 1b CINDU Study Overview Discontinued dose escalation study designed to interrogate potential for therapeutic index optimization DESIGN AND OBJECTIVES STUDY SCHEMATIC • 3 doses (1:1:1) of THB001 (total N=30) for 12 weeks • Pharmacokinetics and serum tryptase levels THB001 200mg BID • Mean reduction in critical temperature threshold (CTT) Follow-up (n=10) 12 WEEKS TX 4 WEEKS STUDY DISPOSITION SRC • Enrolled 5 subjects in 200mg BID dose cohort before THB001 300mg BID SCREENING study discontinuation Follow-up 4 Weeks (n=10) 12 WEEKS TX 4 WEEKS • 1 subject completed 12 weeks of treatment SRC • 2 subjects discontinued at week 8 due to DILI AEs THB001 400mg BID Follow-up (n=10) • 2 remaining subjects were discontinued from study drug 12 WEEKS TX 4 WEEKS at weeks 3 and 4 and were followed for safety 1 Chronic Inducible Urticaria SRC=safety review committee 19

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Serum Tryptase µg/L First-Generation THB001 Phase 1b CINDU Study Efficacy Summary 4 of 5 subjects reached partial (n=2) or complete (n=2) responses at lowest planned dose of 200mg BID SUBJECT 1 >> SUBJECT 2>> SUBJECT 3>> SUBJECT 4 >> SUBJECT 5 >> PARTIAL RESPONSE PARTIAL RESPONSE NO RESPONSE COMPLETE RESPONSE COMPLETE RESPONSE 7 6 23 5 18 4 3 13 2 8 1 3 0 Study Day 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 Baseline Treatment Post-Treatment • Rapid tryptase reduction: -83% mean change from baseline by week 1 • Strong correlation between serum tryptase reduction and clinical response consistent with other published urticaria clinical data • 4/5 patients achieved clinical response despite early termination of study TempTest complete response ≤ 4°C Note: Negative TempTest results (complete response) are shown at 3° C. Serum Tryptase values below lower limit of quantitation are shown at 0 µg/L. Empty circles indicate results post treatment. Serum lower limit of quantitation = 1 µg/L 20 TempTest °C

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First-Generation THB001 Phase 1b CINDU Study Safety Summary THB001 HEMATOLOGY Hemoglobin and neutrophil count by subject over time Hemoglobin (g/dL) 16 • No serious or severe AEs Baseline 15 • Two moderate AEs of transaminitis which resolved 14 13 at weeks 17 and 25 of follow-up 12 • All other AEs were mild 11 11 Neutrophils abs. (/cmm) – Overall profile consistent with on-target effects 8000 of KIT inhibition observed in the Phase 1a 7000 6000 study (e.g., hair color change) 5000 4000 – Hematologic profile similar to Phase 1a and 3000 2000 trend toward stabilization of values observed as 1000 1000 expected -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Study Day Baseline Treatment Post-Treatment Subject: Subject 1 Subject 2 Subject 3 Subject 4 Subject 5 21

v3.24.1.1.u2

Document and Entity Information	May 15, 2024
Cover [Abstract]
Amendment Flag	false
Entity Central Index Key	0001923840
Document Type	8-K
Document Period End Date	May 15, 2024
Entity Registrant Name	THIRD HARMONIC BIO, INC.
Entity Incorporation State Country Code	DE
Entity File Number	001-41498
Entity Tax Identification Number	83-4553503
Entity Address, Address Line One	1700 Montgomery Street
Entity Address, Address Line Two	Suite 210
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94111
City Area Code	(209)
Local Phone Number	727-2457
Written Communications	false
Soliciting Material	false
Pre Commencement Tender Offer	false
Pre Commencement Issuer Tender Offer	false
Security 12b Title	Common Stock, par value $0.0001 per share
Trading Symbol	THRD
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

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