# EDGAR Filing Document

**Accession Number:** 0001813814
**File Stem:** 0001193125-26-229657
**Filing Date:** 2026-5
**Character Count:** 46385
**Document Hash:** 047d8b19b4497c3f0a9bf54529535ab1
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-229657.hdr.sgml**: 20260519

**ACCESSION NUMBER**: 0001193125-26-229657

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 52

**CONFORMED PERIOD OF REPORT**: 20260519

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260519

**DATE AS OF CHANGE**: 20260519

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Definium Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001813814
- **STANDARD INDUSTRIAL CLASSIFICATION:** MEDICINAL CHEMICALS & BOTANICAL PRODUCTS [2833]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** A1
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-40360
- **FILM NUMBER:** 26995877

**BUSINESS ADDRESS:**
- **STREET 1:** ONE WORLD TRADE CENTER
- **STREET 2:** SUITE 8500
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10007
- **BUSINESS PHONE:** 212-220-6633

**MAIL ADDRESS:**
- **STREET 1:** ONE WORLD TRADE CENTER
- **STREET 2:** SUITE 8500
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10007

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Mind Medicine (MindMed) Inc.
- **DATE OF NAME CHANGE:** 20200602

?xml version='1.0' encoding='ASCII'? 8-K

**UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549**

------

## FORM 8-K

------

**CURRENT REPORT**

**Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934**

**Date of Report (Date of earliest event reported):** May 19, 2026<br>

------

Definium Therapeutics, Inc.

**(Exact name of Registrant as Specified in Its Charter)**

------

---

| | | |
|:---|:---|:---|
| British Columbia | 001-40360 | 98-1582438 |
| **(State or Other Jurisdiction<br>of Incorporation)** | **(Commission File Number)** | **(IRS Employer<br>Identification No.)** |
| One World Trade Center<br>Suite 8500 |  |  |
| New York**,** New York |  | 10007 |
| **(Address of Principal Executive Offices)** |  | **(Zip Code)** |

---

**Registrant's Telephone Number, Including Area Code:** (212) 220-6633<br>

**(Former Name or Former Address, if Changed Since Last Report)**

------

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

**Securities registered pursuant to Section 12(b) of the Act:**

---

| | | |
|:---|:---|:---|
| **<br>Title of each class** | **Trading<br>Symbol(s)** | **<br>Name of each exchange on which registered** |
| Common Shares | DFTX | The Nasdaq Stock Market LLC |

---

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

------

## Item 8.01 Other Events.
On May 19, 2026, Definium Therapeutics, Inc. posted an updated corporate presentation on its website. A copy of the presentation is filed herewith as Exhibit 99.1 and is incorporated by reference herein.

## Item 9.01 Financial Statements and Exhibits.

---

| | |
|:---|:---|
| **Exhibit No.** | **Description** |
| 99.1 | [<u>Corporate Presentation, dated May 19, 2026</u>](dftx-ex99_1.htm) |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) |

---

------

**SIGNATURES**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

---

| | | | |
|:---|:---|:---|:---|
|  |  |  | DEFINIUM THERAPEUTICS, INC. |
| Date: | May 19, 2026 | By:  | /s/ Robert Barrow |
|  |  |  | Name: Robert Barrow<br>Title: Chief Executive Officer |

---

------

## Exhibit 99.1

![Slide 1](dftx-ex99_1s1.jpg)

Corporate Presentation May 2026

------

![Slide 2](dftx-ex99_1s2.jpg)

This presentation (the "Presentation") has been prepared by Definium Therapeutics, Inc. ("Definium", the "Company", "we", "our" or "us") solely for informational purposes. This Presentation does not constitute an offering of, or a solicitation of an offer to purchase, securities of Definium and under no circumstances is it to be construed as a prospectus or advertisement or public offering of securities. Any trademarks included herein are the property of the owners thereof and are used for reference purposes only. Such use should not be construed as an endorsement of the products or services of Definium. Any amounts are in USD unless otherwise noted. Definium's securities have not been approved or disapproved by the U.S. Securities and Exchange Commission (the "SEC") or by any state, provincial or other securities regulatory authority, nor has the SEC or any state, provincial or other securities regulatory authority passed on the accuracy or adequacy of this Presentation. Any representation to the contrary is a criminal offense. Cautionary Note Regarding Forward-Looking Statements This Presentation contains, and our officers and representatives may from time to time make, "forward-looking statements" within the meaning of applicable securities laws and are prospective in nature. Forward-looking statements are not based on historical facts, but rather on current expectations and projections about future events and are therefore subject to risks and uncertainties which could cause actual results to differ materially from the future results expressed or implied by the forward-looking statements. These statements generally can be identified by the use of forward-looking words such as "will", "may", "should", "could", "intend", "estimate", "plan", "anticipate", "expect", "believe", "potential", "continue", "budget", "scheduled", "forecasts", "intends", "anticipates", "projects" or the negative thereof or similar variations. Forward-looking statements in this Presentation include, but are not limited to, statements regarding the anticipated design, timing, progress and results of our investigational programs for DT120 oral disintegrating tablet ("ODT"), a proprietary, pharmaceutically optimized form of lysergide tartrate (including the anticipated topline readouts for the Voyage, Panorama, Emerge and Ascend studies), DT402, also referred to as R(-)-MDMA, and any other product candidates; our ability to identify new indications for our lead product candidates beyond our current primary focuses; the success and timing of our development activities; the success and timing of our planned clinical trials; our ability to meet the milestones set forth herein; the likelihood of success of any clinical trials or of obtaining U.S. Food and Drug Administration ("FDA") or other regulatory approvals; our beliefs regarding potential benefits of our product candidates; opinions of potential providers, patients and payors regarding our product candidates, if approved and commercialized; statements regarding potential reimbursement and coding for DT120, if approved and commercialized; our ability to maximize operational efficiencies through our trial designs; strategies to address drug class methodological considerations; our cash runway funding operations into 2028 based on our current operating plan and anticipated milestones; our pre-launch strategy; the potential commercial opportunity for DT120 ODT, if approved, including total addressable market; the potential delivery model for DT120 ODT, if approved; the potential for the markets that we are anticipating to access; protection of our intellectual property; and the potential for psychedelics as a class of treatment options in psychiatry. There are numerous risks and uncertainties that could cause actual results, plans and objectives to differ materially from those expressed in forward-looking statements, including history of negative cash flows, limited operating history, incurrence of future losses, availability of additional capital, compliance with laws and regulations, difficulty associated with research and development, risks associated with clinical trials or studies, heightened regulatory scrutiny, early stage product development, clinical trial risks, regulatory approval processes, novelty of the psychedelic inspired medicines industry, our ability to maintain effective patent rights and other intellectual property protection for our product candidates, our expectations regarding the size of the eligible patient populations for our lead product candidates, if approved and commercialized; our ability to identify third-party treatment sites to conduct our trials and our ability to identify and train appropriate qualified healthcare practitioners to administer our treatments; the pricing, coverage and reimbursement of our lead product candidates, if approved and commercialized; the rate and degree of market acceptance and clinical utility of our lead product candidates, in particular, and controlled substances, in general; as well as those risk factors described in the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2025 under headings such as "Special Note Regarding Forward-Looking Statements," and "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" and other filings and furnishings made by the Company with the securities regulatory authorities in all provinces and territories of Canada which are available under the Company's profile on SEDAR+ at www.sedarplus.ca and with the SEC on EDGAR at www.sec.gov. Any forward-looking statement made by Definium in this Presentation is based only on information currently available to the Company and speaks only as of the date on which it is made. Except as required by law, the Company undertakes no duty or obligation to update any forward-looking statements contained in this Presentation as a result of new information, future events, changes in expectations or otherwise. Cautionary Note Regarding Regulatory Matters The United States federal government regulates drugs through the Controlled Substances Act. DT120 ODT is a proprietary, pharmaceutically optimized form of lysergide D-tartrate and DT402, or R(-)-MDMA, is our proprietary form of the R-enantiomer of MDMA (3,4-methylenedioxymethamphetamine). Lysergide and MDMA are Schedule I substances under the Controlled Substances Act. While the Company is focused on programs using psychedelic or hallucinogenic compounds and non-hallucinogenic derivatives of these compounds, including in DT120 ODT, DT402 and its other product candidates, the Company does not have any direct or indirect involvement with the illegal selling, production or distribution of any substances in the jurisdictions in which it operates. The Company is a neuro-pharmaceutical drug development company and does not deal with psychedelic or hallucinogenic substances except within laboratory and clinical trial settings conducted within approved regulatory frameworks. The Company's products will not be commercialized prior to applicable regulatory approval, which will only be granted if clinical evidence of safety and efficacy for the intended uses is successfully developed. Market and Industry Data This Presentation includes market and industry data that has been obtained from third party sources, including industry publications. Definium believes that the industry data is accurate and that the estimates and assumptions are reasonable, but there is no assurance as to the accuracy or completeness of this data. Third party sources generally state that the information contained therein has been obtained from sources believed to be reliable, but there is no assurance as to the accuracy or completeness of included information. Although the data is believed to be reliable, Definium has not independently verified any of the data from third party sources referred to in this Presentation or ascertained the underlying economic assumptions relied upon by such sources. References in this Presentation to research reports or to articles and publications should not be construed as depicting the complete findings of the entire referenced report or article. Definium does not make any representation as to the accuracy of such information. Corporate Presentation \| May 2026 Disclaimer

------

![Slide 3](dftx-ex99_1s3.jpg)

Late-stage pipeline DT120 ODT: lead clinical program in five Phase 3 studies1 Experienced management team Proven track record in developing and commercializing novel CNS therapies Three Phase 3 readouts anticipated in 2026 driving potential billion-dollar commercial opportunities in GAD and MDD Includes four studies in progress and one in planning. Based on the Company's current operating plan and anticipated milestones. CNS: central nervous system; GAD: generalized anxiety disorder; MDD: major depressive disorder; ODT: orally disintegrating tablet Strategic focus on GAD & MDD The two largest drivers of psychiatric disease burden Comprehensive intellectual property strategy DT120 ODT patents issued covering pharmaceutical formulation, methods of manufacturing and treatment Strong financial position Cash, cash equivalents and investments of $373.4 million as of March 31, 2026; cash runway expected to extend into 20282 Corporate Presentation \| May 2026

------

![Slide 4](dftx-ex99_1s4.jpg)

Advancing Our Pipeline with Broad Therapeutic Potential PRODUCT CANDIDATE INDICATION PRECLINICAL PHASE 1 PHASE 2 PIVOTAL / PHASE 3 REGISTRATION Lysergide tartrate DT1201 Generalized Anxiety Disorder (GAD)3 Major Depressive Disorder (MDD)3 Posttraumatic Stress Disorder (PTSD) 4 Additional Indication(s)4 R(-)-MDMA DT4022 Autism Spectrum Disorder (ASD)3 Formerly known as MM120; rINN: lysergide tartrate. Formerly known as MM402. Full trial details and clinicaltrials.gov links available at definiumtx.com/clinical-digital-trials/ Studies in exploration and/or planning stage. R(-)-MDMA: rectus-3,4-methylenedioxymethamphetamine Corporate Presentation \| May 2026

------

![Slide 5](dftx-ex99_1s5.jpg)

Program Overview Lysergide tartrate DT120 01

------

![Slide 6](dftx-ex99_1s6.jpg)

Corporate Presentation \| May 2026 Target Product Profile to Address Significant Unmet Need Single dose regimen is being studied in pivotal clinical trials with primary and secondary outcome measures through 12 weeks after administration. Phase 3 studies include 40 week extension phase to characterize durability of response beyond 12 weeks in participants up until the time of discontinuation or the administration of open-label DT120. Required monitoring period for all participants in pivotal studies is 8 hours and requires that participants clear the End of Session Checklist. Ringeisen, H., et al. (2023). Mental and Substance Use Disorders Prevalence Study (MDPS): Findings Report, Zhou, Y,. Et al. (2017). Nature. Comorbid generalized anxiety disorder and its association with quality of life in patients with major depressive disorder. RTI International and current U.S. Census data and internal company estimates. 1 Dose1 Weeks of Durability1 Hours in the Clinic2 US Adults with GAD & MDD3 5-8 12+ 50M

------

![Slide 7](dftx-ex99_1s7.jpg)

DT120 Phase 2b Efficacy and Durability Demonstrates Potential Best-In-Class Profile1,3 Standardized effect size more than double the standard of care1,2,3 Comparative Effect Sizes in GAD Rapid and durable response after single administration3 Rapid Response & Remission Durable Standalone Drug Effect Limited Adverse Event (AE) Burden 1.8-point reduction in CGI-S within 24 hours (p<0.0001) 21.9-point improvement on the HAM-A at Week 12 (p=0.003) 48% of participants in remission at Week 125 Favorable tolerability with most AEs on dosing day Observed drug effect without accompanying psychotherapy 0 0.2 0.4 0.6 0.8 Cohen's d s4 DT120 100 µg2 0.81 0.38 0.36 0.17 Study MMED008 internal study documents and calculations. Comparisons to standard of care/other drug classes based on historical comparison not head-to-head comparison trial. HAM-A scores based on ANCOVA LS Mean. in Study MMED008. Effect size based on post hoc calculation using LS Mean change between group and pooled standard deviation of week 12 HAM-A scores between groups. Based on 100 µg dose group. RB Hidalgo, J Psychopharmacol. 2007 Nov;21(8):864-72. p-values not calculated for remission rates between groups. CGI-S: Clinical Global Impression – Severity scale; GAD: generalized anxiety disorder; HAM-A: Hamilton Anxiety scale; SRI: serotonin reuptake inhibitor Corporate Presentation \| May 2026

------

![Slide 8](dftx-ex99_1s8.jpg)

Primary Outcome: HAM-A Change from Baseline Source: Study MMED008 internal study documents and calculations. Full analysis set population. Based on 100 µg dose group. Based on observed MADRS score at each timepoint. Primary endpoint of the study was change in Hamilton Anxiety Scale (HAM-A) at week 4 using the MCP-Mod statistical analysis. Based on the pre-specified candidate dose response curves, the MCP-Mod model-estimated difference between 100 µg and placebo was 5.0 points versus the observed difference of 7.6 points at week 4. μg: microgram; HAM-A: Hamilton Anxiety Rating Scale; MADRS: Montgomery-Åsberg Depression Rating Scale NOTE: Significance achieved despite study not being powered for these pairwise comparisons. DT120 Showed Statistically & Clinically Significant Improvements on Anxiety and Depression Symptoms1,2 \*p<0.05; \*\*p≤0.01; \*\*\*p≤0.001 Baseline Week 1 Week 2 Week 44 Week 12 \*\*\* \*\*\* \*\*\* \*\* MADRS Change from Baseline \*\* \*\* \* \*\* Change from Baseline2 Week 12: -21.9 points Improvement over Placebo2 Week 12: -7.7 pts, p=0.003 Change from Baseline2,3 Week 12: -18.7 points Improvement over Placebo2,3 Week 12: -6.4 points, p<0.01 Baseline Week 1 Week 2 Week 4 Week 12 Placebo 100 µg Corporate Presentation \| May 2026

------

![Slide 9](dftx-ex99_1s9.jpg)

Remission (≤7) Symptoms are absent, insignificant, or clearly due to causes other than anxiety Mild (8-14) Symptoms are infrequent, with no impairment and no more than mild distress Moderate (15-23) Symptoms are more frequent, with moderate distress or limited interference with usual activities Very Severe Symptoms are incapacitating Severe (≥24) Symptoms are severe and persistent or result in severe distress or marked impairment in functioning DT120 Demonstrated Profound Changes in GAD Severity1 Source: Study MMED008 internal study documents and calculations. Full analysis set population. Response is a 50% or greater improvement on HAM-A score; Remission is a HAM-A score of ≤7; p-values not calculated. μg: microgram; HAM-A: Hamilton Anxiety Rating Scale HAM-A Response & Remission at Week 122 Median HAM-A Through Week 12 HAM-A Severity & Clinical Symptoms Baseline Week 1 Week 2 Week 4 Week 12 Week 8 Corporate Presentation \| May 2026

------

![Slide 10](dftx-ex99_1s10.jpg)

Corporate Presentation \| May 2026 DT120's Clinical Activity Stands Out Compared to Approved GAD Treatments1 1) The information presented in this slide is derived from multiple clinical trials, each conducted under distinct protocols and settings. As such, these data may not be directly comparable due to the lack of a head-to-head comparison. Differences in trial design, patient demographics, and other variables may account for variations in the observed outcomes. Study results for each drug are intended to be representative, however, multiple trials of the approved treatments have been conducted with varying results, including results that may have demonstrated a larger or smaller treatment effect than those presented. BuSpar and Xanax are approved for anxiety disorders which include GAD.; 2) R Robison, JAMA. 2025 Sep 4; e2513481. doi:10.1001/jama.2025.13481; 3) C Allgulander, Curr Med Res Opin. 2007;23(6):1245–1252; 4) JRT Davidson, Depress Anxiety. 2004;19(4):234–240; 5) K Rickels K, Am J Psychiatry 2003; 160:749-756. 2005;62(9):1022–1030; 6) AJ Gelenberg AJ, JAMA. 2000;283(23):3082–3088; 7) JJ Sramek JJ, Journal of Clinical Psychiatry. 1996;57(7):287–291; 8) K Rickels, Arch Gen Psychiatry. 2005;62(9):1022–1030. GAD: generalized anxiety disorder, Tx: treatment 2 3 4 5 6 7 8

------

![Slide 11](dftx-ex99_1s11.jpg)

Corporate Presentation \| May 2026 DT120 Delivers Clinical Activity that Stands Apart from Latest Generation of Treatments for Depression Symptoms1 1) The information presented in this slide is derived from multiple clinical trials, each conducted under distinct protocols and settings. As such, these data may not be directly comparable due to the lack of a head-to-head comparison. Differences in trial design, patient demographics, and other variables may account for variations in the observed outcomes. Study results for each drug are intended to be representative, however, multiple trials of the approved treatments have been conducted with varying results, including results that may have demonstrated a larger or smaller treatment effect than those presented. 2) Depression treatments include those indicated for MDD, TRD and BPD. Only includes results from Phase 3 studies for which MADRS data are available and which were studied as a monotherapy. Results for approved drugs as reported on US Prescribing Information. In instances with multiple studies, the most favorable US study results presented. Compass Pathways results based on Study COMP005 Adj: adjunctive; BPD: bipolar depression; GAD: generalized anxiety disorder; MDD: major depressive disorder; TRD: Treatment Resistant Depression;Tx: treatment All trademarks are property of their respective owners. 2

------

![Slide 12](dftx-ex99_1s12.jpg)

Scientific Rigor in DT120 Phase 2b Provides Confidence for Phase 3 Program Statistically significant dose response in Phase 2b Model supports 100 µg as optimal dose Results not explainable by "functional unblinding" supporting robustness of drug effect Study MMED008 internal study documents and calculations. Model-Based Dose-Response Curve1 Key Findings Corporate Presentation \| May 2026

------

![Slide 13](dftx-ex99_1s13.jpg)

DT120 was Well-Tolerated with Adverse Events Mostly Limited to Dosing Day1 Source: Study MMED008 internal study documents and calculations. Safety population. One serious adverse event (SAE) was observed in the 50 µg dose group: panic attack on study day 98 that was deemed not related to treatment. Suicidality assessment based on reported adverse events. Virtually all (99%) adverse events (AEs) were mild-to-moderate in severity Minimal (2.5%) treatment emergent AEs (TEAEs) led to study withdrawal No drug-related serious AEs (SAEs)2 Favorable tolerability profile No SAEs related to study drug No suicidal behavior or suicidality signal3 Only SAE was in 50 µg dose group and deemed unrelated2 AE profile consistent with historical studies and drug class No suicidal or self-injurious behavior No indication of increased suicidality or suicide-related risk ≤2 participants per arm reported suicidal ideation during the study Corporate Presentation \| May 2026

------

![Slide 14](dftx-ex99_1s14.jpg)

Anxiety & Depression 02

------

![Slide 15](dftx-ex99_1s15.jpg)

Corporate Presentation \| May 2026 Understanding the Patient Journey AE: adverse events; MDE: major depressive episode; PCP: primary care physician; Rx: prescription; SGA: second generation antipsychotic; SRI: serotonin reuptake inhibitors (including selective serotonin and selective serotonin and norepinephrine reuptake inhibitors); Tx: treatment Symptoms First Present Impact on life, work, relationships Impairment takes hold Discuss with PCP Prescribed SRI Hope Rx will provide relief Acutely exacerbated anxiety 4-week evaluation Dose adjustment 8-week evaluation 2-week evaluation Dose adjustment Little Evidence of Efficacy Sexual effects noted PCP switches SRI Anxiety exacerbated 12-week evaluation Dose adjustment 16-week evaluation 10-week evaluation Dose adjustment Some positive effects noted Noticeable weight gain Suppressed feelings Side effects "not worth it" Discontinue 2nd SRI Disappointment and worry Onset of depressive symptoms Referral to psychiatry Atypical antidepressant started Dose adjustment and augmentation with SGA 30-week evaluation 24-week evaluation Dose adjustment Partial response of depression Adjustment of SGA Additional Augmentation & Rx Cycles Psychiatry appt available Onset of new AEs

------

![Slide 16](dftx-ex99_1s16.jpg)

Interplay Between GAD & MDD Highlights Opportunity for a Dual Intervention1 Severe Remission Mild Moderate GAD chronic background anxiety burden Anxiety Depression Between MDEs often characterized by residual anxiety MDD major depressive episodes with inter-episode euthymia Corporate Presentation \| May 2026 1. Conceptual illustration of disease progression in comorbid GAD and MDD. GAD: generalized anxiety disorder; MDD: major depressive disorder; MDE: major depressive episode

------

![Slide 17](dftx-ex99_1s17.jpg)

Corporate Presentation \| May 2026 Clinical Outcome Assessments in GAD and MDD Share Many Domains Montgomery-Åsberg Depression Rating Scale (MADRS)2 Range: 0-60 Hamilton Anxiety Scale (HAM-A)1 Range: 0-56 1. Apparent sadness 2. Reported sadness 3. Inner Tension 4. Reduced Sleep 5. Reduced Appetite 6. Concentration Difficulties 7. Lassitude 8. Inability to Feel (Anhedonia) 9. Pessimistic Thoughts 10. Suicidal Thoughts 1. Anxious mood – worry, fear 2. Tension – restlessness, inability to relax 3. Fears – of dark, strangers, being alone, etc. 4. Insomnia 5. Intellectual – concentration, memory 6. Depressed Mood 7. Somatic (muscular) – aches, twitching 8. Somatic (sensory) – tinnitus, blurred vision 9. Cardiovascular symptoms – palpitations, chest pain 10. Respiratory symptoms – shortness of breath 11. Gastrointestinal symptoms – nausea, cramps 12. Genitourinary symptoms – frequency, libido changes 13. Autonomic symptoms – dry mouth, sweating 14. Behavior during interview – fidgeting, restlessness Psychological effects Source: Hamilton M.The assessment of anxiety states by rating. Br J Med Psychol 1959; 32:50–55. Source: Montgomery, S. A., & Åsberg, M. (1979). A new depression scale designed to be sensitive to change. British Journal of Psychiatry, 134(4), 382–389. Physical effects

------

![Slide 18](dftx-ex99_1s18.jpg)

Positioned for Success DT120 ODT Phase 3 Program 03

------

![Slide 19](dftx-ex99_1s19.jpg)

Corporate Presentation \| May 2026 Robust Phase 3 DT120 ODT Development Program Aiming for Broad Label Clinical study designs subject to change based on ongoing regulatory discussion and review, including of Phase 3 clinical trial protocols. DB: double blind; HAM-A: Hamilton Anxiety Rating Scale; MADRS: Montgomery-Åsberg Depression Rating Scale; ODT: orally disintegrating tablet; OL: open-label; RCT: randomized controlled trial Generalized Anxiety Disorder (GAD) Major Depressive Disorder (MDD) n=214 1:1 randomization Enrollment Complete DT120 ODT vs. Placebo Part A: 12-week DB, RCT Part B: 40-week Extension with OL Treatment n=245 2:1:2 randomization Enrollment Complete DT120 ODT vs. Placebo including 50 µg control Part A: 12-week DB, RCT Part B: 40-week Extension with OL Treatment n=149 1:1 randomization Enrollment Complete DT120 ODT vs. Placebo Part A: 12-week DB, RCT Part B: 40-week Extension with OL Treatment Target n=1651 2:1:2 randomization DT120 ODT vs. Placebo including 50 µg control Part A: 12-week DB, RCT Part B: 40-week Extension with OL Treatment Target n=2001 1:1 randomization DT120 ODT vs. Placebo Part A: 12-week DB, RCT Part B: 40-week Extension with OL Treatment Posttraumatic Stress Disorder (PTSD)

------

![Slide 20](dftx-ex99_1s20.jpg)

Multiple Programs with Shared Development Strategy Source: Definium internal study documents. Parameters for treatment in the open label portion of Haven are still being determined. Clinical study designs subject to change based on ongoing regulatory discussion and review, including of Phase 3 clinical trial protocols. ClinRO: clinician reported outcome; ePRO: electronic patient reported outcome; MADRS: Montgomery-Åsberg Depression Rating Scale; MDD: Major Depressive Disorder; ODT: orally disintegrating tablet DT120 ODT 100 µg Placebo Part A 12 Week Randomized, Double-Blind Part B 40 Week Extension with Opportunity for Open-Label Treatment (OLT)2 DT120 ODT 100 µg Placebo PHASE 3 STUDY1 Single Dose Primary Endpoint: MDD: MADRS at Week 6 GAD: HAM-A at Week 12 PTSD: CAPS-5 at Week 8 Up to four OLT of DT120 ODT 100 µg Single Dose Follow-up Observation PHQ-9 or GAD-7 biweekly and Central HAM-A or MADRS monthly or when PHQ or GAD exceeds threshold Potential Treatment Eligible for OLT when severity is moderate or worse HAM-A ≥ 16 or MADRS ≥ 20 DT120 ODT 50 µg control Corporate Presentation \| May 2026 3 3

------

![Slide 21](dftx-ex99_1s21.jpg)

Corporate Presentation \| May 2026 SSREs Complete and Support Confidence in Decisive Phase 3 Outcomes Phase 2b Study MMED0081,2 Internal study documents. Robison, Reid et al. "Single Treatment With MM120 (Lysergide) in Generalized Anxiety Disorder: A Randomized Clinical Trial." JAMA vol. 334,15 (2025): 1358-1372. doi:10.1001/jama.2025.13481 Non-evaluable rate based on data not available within visit analysis window as defined in study statistical analysis plan. SSREs conducted 12 weeks after enrollment of 50% of target sample size. Raw standard deviation based on observed cases at timepoint of interest. MMRM SD derived from model-based residual standard error. Power calculation based on the assumption that SSRE-observed nuisance parameters and revised target enrollment are maintained in final population and analysis. Minimum detectable difference refers to the placebo-adjusted difference above which a p-value less than 0.05 could be expected in the final analysis and are based on the SSRE-observed nuisance parameters assuming such parameters are maintained in final population and analysis; based on current enrollment at time of analysis. Δ: placebo-adjusted difference on primary endpoint; MMRM: Mixed Models or Repeated Measures; SD: standard deviation; SSRE: sample size re-estimation Enrollment Target Standard Deviation Non-evaluable rate3 Power for Δ=5 points3 Minimum detectable difference4 Observed Planned SSRE Outcome Planned SSRE Outcome 9.7 25% 200 10.0 15% 90% 3.0 200 Observed: 7.8 MMRM: 6.2 10% >99% 1.8 250 10.0 15% 90% 3.0 200 Observed: 7.6 MMRM: 7.4 6% 99% 2.4

------

![Slide 22](dftx-ex99_1s22.jpg)

Investor & Analyst Day \| April 2026 Eligibility Process in Phase 3 Supports Trial and Population Integrity Source: Definium internal study documents. CRO: contract research organization; MGH SAFER: Massachusetts General Hospital SAFER independent diagnostic interview 01 Site Diagnosis Comorbidities Severity Eligibility 02 Central Rater Severity 03 MGH SAFER Interview Diagnosis Comorbidities Severity 04 CRO Medical Team Diagnosis Comorbidities Severity Eligibility 05 Sponsor Medical Team Diagnosis Comorbidities Severity Eligibility

------

![Slide 23](dftx-ex99_1s23.jpg)

DT120 ODT Treatment Paradigm: Standalone Drug Effects with No Psychotherapeutic Intervention1 Source: Study MMED008 internal study documents. DSM: dosing session monitor; EOSC: end of session checklist DT120 Patient Journey Pre-treatment activities consist of a comprehensive informed consent process Eligibility evaluation Continuous monitoring by DSMs Music, eye shades, reading, writing Concludes when EOSC criteria met Follow-up visits for assessment only Pre-treatment During treatment Post-treatment Not Part of Patient Journey No "preparation" therapy No "assisted therapy" No psychotherapy and no therapeutic intervention beyond study drug No "integration" therapy No ongoing therapeutic engagement as part of clinical trial activities Corporate Presentation \| May 2026

------

![Slide 24](dftx-ex99_1s24.jpg)

Efficient single-visit model with full-session reimbursement streamlines administrative burden2 Corporate Presentation \| May 2026 Clinical Dosing Paradigm with Potential Translatability to Efficient Real-World Delivery1,2 Dosing and monitoring paradigm based on Phase 3 clinical protocols. Required monitoring period for all participants in pivotal studies is 8 hours and requires that participants clear the End of Session Checklist. Existing coding systems could potentially be applied or be changed for DT120. Reimbursement and coding for DT120 have yet to be established. ODT: orally disintegrating tablet DT120 ODT disintegrates in seconds 15-30 minutes (time to onset) Effects move to resolution Hour 5: Dosing Session Monitor (DSM) evaluates patient hourly with an end-of-session checklist to determine when the patient can leave safely Hour 4-6 Ordinary perception, affect, and cognition return Normal activities resume the next day, including driving Hour 6-8 and post-session Transient perceptual, affective, and cognitive drug effects vary from person to person Effects at maximum intensity Hour 2-4

------

![Slide 25](dftx-ex99_1s25.jpg)

Corporate Presentation \| May 2026 Evolution of Patient Monitoring based on Clinical Evidence & Anticipating Real-World Setting 12-hour monitoring requirement based on inclusion of 200 µg dose of DT120 in Phase 2b The required monitoring period in pivotal studies of DT120 is 8 hours and requires that participants clear the End of Session Checklist. EOSC: End of Session Checklist Phase 2 Study Pivotal-Stage Studies Expansive Research-oriented Checklist Patient-reported physical status Patient-reported mental status Assessed mental status (7 criteria) Sensory & Psychomotor status (5 criteria) DSM-5 Criteria for Hallucinogen Intoxication (9 criteria) Practice-oriented End of Session Checklist EOSC intended to inform & reflect requirements under potential REMS program Refined based on discussions with the FDA 8 Item Scale 23 Total Criteria 5-8 Hour Monitoring via EOSC2 to Inform Real-World Conditions of Safe Use 8-12 Hour Research Monitoring to Inform Phase 3 Study Design1

------

![Slide 26](dftx-ex99_1s26.jpg)

Corporate Presentation \| May 2026 Putting the Numbers in Perspective1 GAD Placebo adjusted changes in HAM-A MDD Placebo adjusted changes in MADRS The information presented in this slide on comparative treatments is derived from multiple clinical trials, each conducted under distinct protocols and settings. As such, these data may not be directly comparable due to the lack of a head-to-head comparison. Differences in trial design, patient demographics, and other variables may account for variations in the observed outcomes. Study results for each drug are intended to be representative, however, multiple trials of the approved treatments. Based on Phase 3 clinical trial protocols and SSRE results. Data on file. Median placebo-adjusted change of comparative treatments for GAD (see slide 19) Median placebo-adjusted change of comparative treatments for depression symptoms (see slide 20) R Robison, JAMA. 2025 Sep 4; e2513481. doi:10.1001/jama.2025.13481 MADRS change from Baseline to week 12 was a secondary endpoint in Study MMED008. -3.6 SRIs -3.8 Benzodiazepines -1.7 Buspirone 5.0 3.23 7.7 6.46 3.94 3.0 4.0 1.8 – 2.4 Minimum Detectable Difference2 Latest Generation of Comparative Treatments Phase 3 Powering Assumption2 Phase 2b Results in GAD5 We believe a 4.0+ point placebo-adjusted difference, along with safety and durability, could represent a best-in-class profile 1 2 3 4 5 6 7 8 Improvement

------

![Slide 27](dftx-ex99_1s27.jpg)

Corporate Presentation \| May 2026 Why We Believe DT120 ODT Is Well Positioned for Phase 3 Success Strong Phase 2b results with effects on anxiety and depression symptoms Phase 3 design enhancements support patient retention Existing and expanded key research site relationships Alignment with FDA Industry Guidance & ICH Guidelines Collaborative FDA dialogue informing Phase 3 design Continuous hands-on oversight of trial execution

------

![Slide 28](dftx-ex99_1s28.jpg)

Accelerating DT120 ODT on a Disciplined Path to NDA Submission 1. Study MMED008 internal study documents and calculations. Comparisons to standard of care/other drug classes based on historical comparison not head-to-head comparison trial. NDA: new drug application; ODT: orally disintegrating tablet FDA Breakthrough Therapy Designation Phase 2b demonstrated substantial improvement over current therapies1 Phase 3 program in alignment with FDA guidance Phase 3 study designs mirror positive Phase 2b study Corporate Presentation \| May 2026 Ready for Expeditious Path to Submission upon Phase 3 Completion Studies designed to demonstrate standalone drug effect

------

![Slide 29](dftx-ex99_1s29.jpg)

Commercial Framework Lysergide tartrate DT120 ODT 04

------

![Slide 30](dftx-ex99_1s30.jpg)

Corporate Presentation \| May 2026 The Near-Term Opportunity & Launch Source: Ringeisen, H., et al. (2023). Mental and Substance Use Disorders Prevalence Study (MDPS): Findings Report, Zhou, Y,. Et al. (2017). Nature. Comorbid generalized anxiety disorder and its association with quality of life in patients with major depressive disorder. RTI International and current U.S. Census data and internal company estimates. Veeva COMPASS Open Claims Analysis Data on File, 2017 – 2025. 50 million US Adults with GAD / MDD 26 million Diagnosed with GAD / MDD 13 million Rx Treated 4.2 million Failed by 2+ Rx Strong Patient Desire & Willingness Large & Expanding Treatment Network Payer Understanding & Intent Large & Growing Unmet Need

------

![Slide 31](dftx-ex99_1s31.jpg)

Corporate Presentation \| May 2026 Launch is Only the Starting Point for a Broader DT120 Market Opportunity 50 million US Adults with GAD / MDD 26 million Diagnosed with GAD / MDD 13 million Rx Treated 4.2 million Failed by 2+ Rx Increased screening & awareness Increased treatment of mental health disorders Removal of access barriers Source: Ringeisen, H., et al. (2023). Mental and Substance Use Disorders Prevalence Study (MDPS): Findings Report, Zhou, Y,. Et al. (2017). Nature. Comorbid generalized anxiety disorder and its association with quality of life in patients with major depressive disorder. RTI International and current U.S. Census data and internal company estimates. Veeva COMPASS Open Claims Analysis Data on File, 2017 – 2025.

------

![Slide 32](dftx-ex99_1s32.jpg)

Corporate Presentation \| May 2026 Psychiatry Continues to Evolve Toward Faster, More Targeted Intervention1-5 Institution-centered care Limited care in asylums.Early ECT, sedatives Pharmacology-based treatment Medication options in outpatient setting. TCAs, MAOIs, antipsychotics Transformative care Rapid-acting inpatient treatments with durable results.Esketamine, psychedelics, including DT120 Custodial System Outpatient Shift Episodic Care Precision Approach Pre-1950s 1950-1970 1980-Early 2000s 2005-2019 2020-Today Directly targets brain circuitry.VNS, TMS Chronic Disease Model Office-based psychiatry Pharmacological treatmentsSRIs Interventional & digital emergence 1. Potash JB et al. Psychiatr Res Clin Pract. 2025;7(2):80-90; 2. Karrouri R et al. World J Clin Cases. 2021;9(31):9350-9367; 3. Williams NR et al. J Clin Psychiatry. 2014;75(8):895-7; 4. Backman I. The Rise of Interventional Psychiatry. Accessed: Apr 16 2026. https://medicine.yale.edu/news/yale-medicine-magazine/article/the-rise-of-interventional-psychiatry/; 5. Robison R et al. JAMA. 2025;334(15):1358-1372. ECT: electroconvulsive therapy; MAOIs: monoamine oxidase inhibitors; SRI: serotonin reuptake inhibitors (including selective serotonin and selective serotonin and norepinephrine reuptake inhibitors); TCAs: tricyclic antidepressants; TMS: transcranial magnetic stimulation; VNS: vagus nerve stimulation From medication to devices, psychiatry has continually embraced innovation to expand treatment options

------

![Slide 33](dftx-ex99_1s33.jpg)

Growing Psychiatrist Awareness and Positive Sentiment Support DT120 Adoption Potential Psychiatrist Perception of DT120 1. GAD Demand Study 2024 Among Total HCP Respondents (n=273). Percentage based on top 3 box (scale 1-7) 2. DT120 Awareness and Perception Tracking: Wave 3, 2026. Total prescribers (n=135). HCP: healthcare professional; MOA: mechanism of action 58% HCPs surveyed have positive views of DT120 profile1 HCPs cite quick onset of action, symptom resolution, response and MOA as top attributes1 Awareness of DT120 has sharply increased from 27% to 64% in the last two waves of research (2024 to 2026)2 5 - 7 Positive 3 - 4 Neutral 1 - 2 Hesitant Corporate Presentation \| May 2026 33 Psychiatrist Perception of Psychedelic Treatments2

------

![Slide 34](dftx-ex99_1s34.jpg)

Strong In-Practice Intent Among High-Priority HCPs 1. GAD Target Validation Market Research, 2025. High-priority HCPs represent deciles 7-10 of GAD prescribers. In the conduct of market research, DT120 was blinded as "Treatment X" to respondents. D B I would prescribe and administer this treatment in my practice I would refer out this treatment I would only discuss if a patient brought up this treatment DT1201 \*No respondents selected would not consider I prescribe and administer this treatment in my practice Refer out for esketamine Refer out for evaluation (without specifying esketamine in referral) Esketamine1 Corporate Presentation \| May 2026 34

------

![Slide 35](dftx-ex99_1s35.jpg)

Predictive Analytics Help Focus Resources Where Adoption Potential Is Highest Priority GAD & MDD Prescribers Data-Driven Deployment Prioritizes the Highest-Value Prescriber Opportunities OR Corporate Presentation \| May 2026

------

![Slide 36](dftx-ex99_1s36.jpg)

Modest Adoption in Target Population Supports Blockbuster Revenue Opportunity Corporate Presentation \| May 2026 Source: Claims Analysis Data on File, 2026 Assuming median Spravato® surrogate pricing range; the price of DT120 has not been established. Range is based on Spravato surrogate low dose, low frequency ($28k) to high dose, high frequency ($70k) annually. Market Research, Data on file, 2026 All trademarks are property of their respective owners. 4.2 million patients have been failed by 2 or more treatments1 $2 billion revenue opportunity per 1% penetration2 Potential Revenue (billions) $2.8B $4.9B $7.0B At $28k annual price At $49k annual price At $70k annual price Potential Value ($B) for every 100,000 patients treated with DT1203

------

![Slide 37](dftx-ex99_1s37.jpg)

Program Update R(-)-MDMADT402 05

------

![Slide 38](dftx-ex99_1s38.jpg)

DT402 Phase 2a Study in Autism Spectrum Disorder (ASD) Shaw KA, Williams S, Patrick ME, et al. Prevalence and Early Identification of Autism Spectrum Disorder Among Children Aged 4 and 8 Years — Autism and Developmental Disabilities Monitoring Network, 16 Sites, United States, 2022. MMWR Surveill Summ 2025;74(No. SS-2):1–22. DOI: http://dx.doi.org/10.15585/mmwr.ss7402a1 SAE: serious adverse event; TEAE: treatment-emergent adverse event Completed Phase 1 study in 2024 Single-ascending dose study in healthy adult volunteers characterized the tolerability, pharmacokinetics and pharmacodynamics of DT402 DT402 was well-tolerated at doses up to 255 mg with no SAEs or TEAEs leading to discontinuation, supporting advancement into Phase 2 clinical trials Phase 2a study underway Single-dose, open-label study to assess early signals of efficacy of DT402 in treating core social and communication symptoms of ASD in up to 20 adult participants Study endpoints designed to characterize pharmacodynamics and clinical effects of DT402 in adults with ASD, including on multiple functional biomarkers Initial data anticipated in 2026 About ASD ASD is a neurodevelopmental condition characterized by persistent challenges with social communication, restricted interests and repetitive behavior US prevalence of approximately 1 in 31 children1 with no approved pharmacotherapies for the treatment of core symptoms of ASD Corporate Presentation \| May 2026

------

![Slide 39](dftx-ex99_1s39.jpg)

Summary 06

------

![Slide 40](dftx-ex99_1s40.jpg)

Value Creation Opportunity Shaped by Two Distinct Drivers1 Timing estimates subject to clinical progress and regulatory interactions. ASD: autism spectrum disorder; GAD: generalized anxiety disorder; TLR: topline data readout Clinical & Regulatory Execution 2026 2027 2028 Commercial Execution Value Creation Expanding Site of Care Engagement & Commercial Footprint Accelerating Scheduling & Reimbursement Optimizing Patient Care Model Emerge TLR Voyage TLR Initial DT402 Data in ASD Panorama TLR Potential Pipeline Expansion Ascend TLR Commercial Launch GAD & MDD Corporate Presentation \| May 2026

------

![Slide 41](dftx-ex99_1s41.jpg)

Financial Summary & Anticipated Milestones Excludes 0.4 million pre-funded warrants outstanding as of April 30, 2026 ASD: autism spectrum disorder; GAD: generalized anxiety disorder; G&A: general & administrative; MDD: major depressive disorder; R&D: research and development Cash, Cash Equivalents & Investments $373.4 million as of March 31, 2026 Credit Facility Up to $120 million ($41 million outstanding) as of March 31, 2026 Shares Outstanding 109.1 million1 as of April 30, 2026 First Quarter 2026 Operating Expenses $59.2 million R&D - $41.5 million G&A - $17.7 million Topline Data Readouts Emerge (MDD) Topline Readout \| late 2Q 2026 Voyage (GAD) Topline Readout \| early 3Q 2026 Panorama (GAD) Topline Readout \| late 3Q 2026 Additional Clinical Updates Ascend (MDD) Study Initiated \| 2Q 2026 Haven (PTSD) Study Initiation \| 2027 DT402 Initial Data in ASD \| 2026 Corporate Presentation \| May 2026

------

![Slide 42](dftx-ex99_1s42.jpg)