Slides
Page 1
NYSE: ANRO January 2026 1
Page 2
Disclaimer This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements regarding the progress and timing of the clinical development of the programs across our portfolio, including the expected therapeutic benefits of our programs, and potential efficacy and tolerability thereof; the timing and nature of clinical data updates and milestones across our pipeline; expectations regarding our pipeline, operating plan, use of capital, expenses and other financial results; our cash runway projection; the competitive landscape and potential market opportunities for our product candidates; our ability to successfully establish or maintain collaborations or strategic relationships for our product candidates; expectations regarding current and future interactions with the U.S. Food and Drug Administration (FDA); the capabilities and development of our biomarker platform; our plans to develop, manufacture and commercialize our current product candidates and any future product candidates; and the implementation of our business model and strategic plans for our business, current product candidates and any future product candidates. The words “may,” “might,” “will,” “could,” “would,” “should,” “plan,” “anticipate,” “intend,” “believe,” “expect,” “estimate,” “seek,” “predict,” “future,” “project,” “potential,” “continue,” “target” and similar words or expressions, or the negative thereof, are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this presentation are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this presentation, including, without limitation, risks associated with: the impact of global economic uncertainty, geopolitical instability, or public health epidemics or outbreaks of an infectious disease on countries or regions in which we have operations or do business, as well as on the timing and anticipated results of our clinical trials, strategy, future operations and profitability; the delay of any current or planned clinical trials or the development of our drug candidates; the risk that the preliminary results of our preclinical studies or clinical trials may not be predictive of future or final results in connection with future clinical trials of our product candidates; our ability to successfully demonstrate the safety and efficacy of our drug candidates; the timing and outcome of interactions with regulatory authorities; and risks associated with obtaining, maintaining and protecting our intellectual property. These and other risks, uncertainties and important factors are described in the section entitled "Risk Factors" in our most recent Form 10-K and Form 10-Q filed with the Securities and Exchange Commission. Any forward-looking statements represent our views only as of the date of this presentation and we undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, the occurrence of certain events or otherwise. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements. Certain information contained in this presentation relates to or is based on studies, publications, surveys and other data obtained from third-party sources and our own internal estimates and research. While we believe these third-party studies, publications, surveys and other data to be reliable as of the date of this presentation, we have not independently verified, and make no representation as to the adequacy, fairness, accuracy or completeness of, any information obtained from third-party sources. In addition, no independent source has evaluated the reasonableness or accuracy of our internal estimates or research and no reliance should be made on any information or statements made in this presentation relating to or based on such internal estimates and research. This presentation contains trademarks, trade names and service marks of other companies, which are the property of their respective owners. 2
Page 3
Precision Medicine for the Brain is Here. Redefining psychiatry by leveraging individuals’ neurobiology to develop personalized and highly effective medicines, helping patients get better faster. OUR MISSION 3
Page 4
Advancing a leading, clinical-stage precision medicine portfolio for the brain 6 Alto by the numbers 4 >800 Patients Dosed Across studies with Alto’s novel product candidates and precision approach Patient Impact 25+ MILLION Opportunity across the portfolio 4 Mid- to Late-Stage Data Readouts In next ~2 years Into Expected Cash Runway 2028
Page 5
Alto is the only company taking a precision biomarker-based approach to patient identification aiming to drive better clinical outcomes in CNS CNS is the next frontier in precision medicine 5 Cardiovascular / Oncology CNS / target specificity or genetics predictive biomarkers
Page 6
Unmet needs pervade mental health disorders 6 Depression and schizophrenia are leading causes of disability worldwide Lancet, 2017 13% of U.S. adults take antidepressants Brody, 2020 $280B spent on mental health services in 2020 SAMHSA
Page 7
Alto precision approach Alto’s strategy addresses a core problem in psychiatry 7 No human target engagement Uncontrolled and unmeasured patient heterogeneity Broad utilization of pharmacodynamic biomarkers Discover and prospectively replicate objective biomarkers for patient selection Characterizing drug activity and identifying responsive patient populations before advancing Current approach Unguided trial-and-error treatments in heterogeneous populations work poorly Differentiated drug profile in stratified patient populations
Page 8
Product Candidate (MOA/Target) Lead Indication Safety & Brain Effects Clinical Effect in Biomarker Positive Registration Trial(s) Next Anticipated Milestone ALTO-207 (D3/D2 & 5-HT3) Ph. 2b Initiation 1H 2026 (Topline 2027) Ph. 3 Initiation planned by early ‘27 ALTO-300 (MT1/2 & 5HT2C) Topline Data mid-2026 ALTO-100 (BDNF) Topline Data 2H 2026 ALTO-101 (PDE4) Topline Data 1Q 2026 ALTO-203 (H3) ALTO-202 (NMDA NR2B) ALTO-208 (D3/D2 & NK -1) First biomarker-driven pipeline for mental health conditions Multiple independent programs leveraging our biomarker strategy to systematically reduce development risk; all programs remain on track to achieve upcoming milestones 8 MDD MDD Phase 1 Schizophrenia (CIAS)^ Phase 3 Phase 2b Ongoing Phase 2 POC Ongoing 8 MDD Phase 2 Parkinson’s Disease ^Fast Track Designation *Study qualifying as pivotal is subject to FDA feedback and review of data Phase 2 POC Completed TRD Potentially Pivotal Study*/Phase 2b & Ph. 3 Planned Bipolar Depression Phase 2b Ongoing
Page 9
Platform
Page 10
Alto’s suite of biomarkers designed to segment patients to drive improved outcomes 10 ALTO-100 Alto Biomarker Platform Example Alto Biomarker Biomarker Characterized Population EEG Signature Likely Responder to Alto Product Candidate ALTO-300 Other Product Candidates Cognitive Profile Sleep/Activity pattern 200 300 400 500 600 0 20 40 EEG Behavior Wearable Heterogeneous Clinical Populations
Page 11
ALTO-100 biomarker is cognitive test-based ALTO-300 biomarker is EEG-based Leveraging proprietary tools, anticipating commercial scale 11
Page 12
ALTO-207 Development for TRD
Page 13
Transcription (CREB) Akt MAPK D3 receptor Plasticity Reward Nucleus accumbens Dopamine Neuron Striatal Neuron Dopamine D2 receptor (similar effects in prefrontal and limbic areas) ALTO-207: combining a dopamine D3 -preferring D3/D2 agonist with demonstrated antidepressant effects and 5-HT3 antagonist designed to reduce dose-limiting AEs 13 ALTO-207 (D3/D2 agonist & 5HT3 antagonist) pramipexole ondansetron 5-HT3 receptor Midbrain Vomiting center Gut input D2/D3 CTZ Nausea/Vomiting X CTZ: chemoreceptor trigger zone Novel antagonistic combination: ↑ D3/D2 agonism for antidepressant effects ↓ 5-HT3 activity to reduce dose-limiting AEs
Page 14
ALTO-207 (fka CTC-501) is a novel, clinically validated product candidate for a high need patient population Pramipexole has shown robust antidepressant effects but is limited by significant tolerability issues CTC-501 demonstrated clear safety benefits over pramipexole alone, achieving higher doses in Phase 1, with 5x faster titration – a Phase 2a placebo-controlled study then showed robust clinical effects Findings enable acceleration: a potentially pivotal* / planned Phase 2b TRD trial (topline data 2027) and planned Phase 3 trial start in early 2027 Efficient and straightforward 505(b)(2) regulatory pathway provides a potentially shorter time to market Strong patent protection; validated commercial approach on combination products in psychiatry; compelling commercial case with substantial need in TRD 14 *Study qualifying as pivotal is subject to FDA feedback and review of data
Page 15
Peer-reviewed publication of PAX-D study demonstrates robust clinical effects of pramipexole in TRD 15 Pramipexole augmentation for the acute phase of treatment-resistant, unipolar depression: a placebo-controlled, double-blind, randomised trial in the UK A close-up of a document AI-generated content may be incorrect. The Lancet Psychiatry • PAX-D TRD study (n=150) with a target dose of 2.5mg: • Demonstrated a large (Cohen’s d=0.87) reduction in symptoms relative to placebo at 12 weeks • High drop-out rate due to AEs Browning et al., Jul. 2025
Page 16
-20 -15 -10 -5 0 0 2 4 6 8 MADRS change from baseline Week placebo (n=34) pramipexole 0.375mg (n=36) pramipexole 1mg (n=35) Pramipexole trials showed antidepressant effect, but speed of titration and max dosage limited by nausea/vomiting 16 Cusin, Journal of Clinical Psychiatry, 2013 p=0.04 TRD study: aimed for 3mg/daily dose but only reached 1.35mg/day n=30 n=30 Adapted from Corrigan, Depression and Anxiety, 2000 Category Placebo Pramipexole 0.375 mg Pramipexole 1 mg Pramipexole 5 mg Total number of patients 34 (100) 36 (100) 35 (100) 33 (100) Number of patients with AEs 28 (82.4) 34 (94.4) 30 (85.7) 31 (93.9) Nausea 7 (20.6) 9 (25.0) 16 (45.7) 25 (75.8) Vomiting 2 (5.9) 0 4 (11.4) 13 (39.4) 5mg* Δ=7.4 *5mg arm not shown due to 23+% greater dropout than placebo by week 81mg Δ=6.0, p=0.01 MDD study: efficacy at 1mg, and bigger effect at 5mg but dramatic drop-out due to AEs PAX-D TRD study (n=150): striking and sustained clinical efficacy, but high dropout due to AEs Browning et. al., The Lancet Psychiatry, July 2025 d=0.87* QIDS-SR16 change converts to a MADRS Δ of 7.38 points* 0 5 10 15 20 25 30 pramipexole Placebo Discontinuation rate due to AEs (%) 20% stopped pramipexole due to AEs vs 5.3% for placebo (p=0.01)
Page 17
Pramipexole has exhibited field-leading effects on anhedonia measures, demonstrating potential to address a critical need in the treatment of depression 17 0.62 0.63 0.42 0.31 0.44 0.07 0.1 0.05 0.05 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 PAX-D PRIME-PAXOL X-NOVA (Ph. 2) Murrough IIT Phase 2 PoC (Nat. Medicine) Phase 2 (NPP) Ventura 1 (Ph. 3) - DARS (no SHAPS) Ventura 2 (Ph. 3) - DARS (no SHAPS) KOASTAL (Ph. 3) Pramipexole XEN1101 Aticaprant Navacaprant Cohen's D on Anhedonia (SHAPS unless noted) Comparative Effect Sizes on Anhedonia Note: The results shown above are not base d on head-to-head trials between the products or product candidates. Study designs and protocols differed, and results may not be comparable. Clear & consistent effects on anhedonia provide strong differentiation and support for ALTO-207 New result under peer review – pre-print available Oct. 29 Sources: Browning M. et al., Lancet Psychiatry (2025); Lindqvist D. et al., PRIME-PAXOL Preprint (2025); Butterfield N. N. et al., JAMA Netw Open (2025) — azetukalner, K𝑉7 opener in MDD.; Fremont et al. ASCP poster 2025; Krystal A. D. et al., Nat Med (2020), Schmidt M E et al., Neuropsychopharmacology (2024); Popova et al. 2025 ASCP Ventura-1/2 Poster; company reports
Page 18
Real world prescribing of pramipexole in MDD shows very slow titration and few get to a therapeutic dose level, limiting use 18 Data drawn from NIH’s All of Us dataset (N=633,547), focusing on those with MDD (N=113,666) • 1.8% treated with pramipexole (N=2,093) • 23.7% achieved ≥1mg/day • 1.5% achieved >1.5mg/day • Suggests the vast majority of patients are treated with sub-therapeutic doses and very few achieve TRD-level dose targets • Likely limited by AEs and practical difficulty of titration in clinical practice • Average time between dose escalation: 273 days *Cusin et al and Corrigan et al suggest 1 -1.5mg is minimally effective dose Minimally effective dose*
Page 19
0 20 40 60 80 100 0 2 4 6 Proportion tolerating dose (%) Pramipexole daily dose (mg) pramipexole CTC-501 CTC-501 (n.k.a. ALTO-207) combination approach achieved higher pramipexole doses faster and more consistently 19 Novel combination supported by Phase 1* safety data *Chase Therapeutics sponsored trial ≥2.5x increase in pramipexole tolerability 0 1 2 3 4 5 6 pramipexole ALTO-207 Maximum tolerated dose (mg) *Chase Therapeutics sponsored trial 2.3mg - Average dose achieved in PAX-D study with 28-day titration n.k.a.: now known as CTC-501 • Achieved a 2.5-fold or greater increase in the pramipexole max tolerated dose with addition of ondansetron vs. pramipexole alone • 60% tolerated max dose of CTC- 501 (6mg pramipexole), in 12 days • Supports more rapid titration to a higher and more consistent dose
Page 20
CTC-501 (n.k.a. ALTO-207) development builds on strong clinical evidence of antidepressant effects 20 4 Phase 2a: CTC -501 in MDD demonstrated significantly greater reduction in illness severity compared to placebo *Chase Therapeutics sponsored trial n.k.a.: now known as Phase 2a: MDD randomized, placebo -controlled trial (N=32) • Rapid titration to avg of 4.1mg/d pramipexole in 8 days (77% reached max 5mg/d after initial dosing schedule change) • Moderate-severe MDD (baseline MADRS CTC-501: 28.8; placebo: 28.2) 2 CTC-501 demonstrated significantly greater reduction in depressive symptoms compared to placebo 1 CTC-501 demonstrated significantly greater reduction in illness severity compared to placebo
Page 21
21 Titration AEs are related to Chase’s maximum tolerated dose-based titration schedule, which Alto aims to further optimize in planned future trials Phase 2a trial of CTC-501 (n.k.a. ALTO-207) in MDD confirmed favorable safety and tolerability profile Nausea and vomiting were the most common AEs – all were mild to moderate Post-titration AEs* CTC-501 (N=13) Placebo (N=15) Related Unrelated Related Unrelated Nausea 2 (15%) 2 (15%) 0 (0%) 2 (13%) Vomiting 1 (8%) 3 (23%) 0 (0%) 2 (13%) Headache 1 (8%) 0 (0%) 0 (0%) 0 (0%) Sleepiness 0 (0%) 0 (0%) 0 (0%) 0 (0%) *Chase Therapeutics sponsored trial n.k.a.: now known as
Page 22
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 Cusin 1.35 mg/d Corrigan 1 mg/d (target) PAX-D (8 wk) 2.3mg/d CTC-501 4.1 mg/d esketamine aripiprazole Cohen's d effect size (drug - placebo) 0 1 2 3 4 5 6 0 10 20 30 40 Total daily pramipexole dose (mg) Day FDA label PAX-D Cusin Corrigan 1mg Chase Ph 1 Chase Ph 2a ALTO-207 designed to achieve rapid antidepressant effect 22 Until CTC-501, all pramipexole depression trials followed the FDA-approved titration schedule Pramipexole targeted titration schedules CTC-501 showed the largest clinical effect, with rapid onset due to faster titration with good tolerability * Effect sizes for Cusin and Corrigan data estimated from available information; Cusin, Journal of Clinical Psychiatry, 2013; Corrigan, Depression and Anxiety, 2000; Wang et al., Medicine, 2023; Jawad et al., Exp Op Drug Saf, 2022; efficacy of other adjunctive antipsychotics is similar to aripiprazole (Wang et al) CTC-501 enabled >5x faster dosing and to a higher target clinical significance (d=0.25-0.3) Note: The resu lts shown ab ove are not based on head-to-head trials between the products or product candidates. Study designs and protocols differed, and results may not be comparable. Pramipexole alone CTC-501 Current SOC Clear dose response
Page 23
ALTO-207 positioned for potential Phase 2b/pivotal* success 23 Completed Phase 1 study demonstrated significantly improved tolerability with 5x faster dose escalation Phase 2a placebo-controlled study met its primary and secondary endpoints, showing large clinical effect sizes Highly compelling evidence for the clinical effect of pramipexole in TRD, with principal limitation being dose-related intolerability (which motivated development of CTC-501) Planned collaboration with PAX-D sites, building on their highly successful trial outcome Alto expects to initiate a Phase 2b (potentially pivotal design*) trial in TRD in 1H 2026 with TLD in 2027 Alto expects to initiate a Phase 3 trial by early 2027 *Study qualifying as pivotal is subject to FDA feedback and review of data TLD: topline data
Page 24
Intended regulatory strategy makes use of biomarkers 24 Regulatory considerations • Anticipate a regulatory path with broad TRD approval as well as potential for an enrichment marker to identify patients with even greater effect(1) • Biomarker strategy builds on Alto’s FDA interactions on enrichment markers in the ALTO- 100 program • 505(b)(2) regulatory path enables streamlined development and potentially shorter time to commercialization Dopamine-related biomarker strategy • Will focus on both clinical effect and tolerability • Biomarkers will be pre-specified key secondary measures for the Phase 2b trial and verified in Phase 3 as complementary enrichment markers • Leverage Alto’s dopamine-related EEG and behavioral assessments already employed across studies (1)Based on Chase’s interactions with the FDA to date; intended regulatory strategy is subject to FDA feedback *Study qualifying as pivotal is subject to FDA feedback and review of data
Page 25
Key attributes of ALTO-207 that mitigate likelihood of generic substitution • Strong IP portfolio covering formulation and use protects from generic combination • Simple dosing & titration regimen • Single pill/capsule for ease of administration • Clear evidence of effect of combined product, if approved • Commercial strategies can mitigate patient out- of-pocket costs and improve access Novel ALTO-207 product attributes and substantial patient risk deters off-label generic substitution 25 Auvelity (combination of buproprion and dextromethorphan) provides clear evidence that off - label combination generic substitution does not impede significant commercial success Real-world treatment demonstrates lack of generic substitution Prescribing generic components introduces substantial patient & prescriber risk • Complex regimen of pill combo likely to lead to dosing errors & severe adverse events • Unproven dose levels with non-standard combinations • Lack of formulation consistency/ quality • Off-label prescribing creates liability for physicians • Lack of payer coverage for off-label Rx
Page 26
Recent success in psychiatry strongly supports combination approach and novel mechanism 26 Recent combination analogs demonstrate… • improved tolerability, • larger effect size, • more convenient dosing, • and novel MoA in disease… can result in significant adoption by physicians and substantial commercial success If clinical effects and tolerability profile remain consistent with observed data, we expect ALTO -207, as a novel combination with a differentiated mechanism in depression, has blockbuster potential Innovation Antagonistic combination to mitigate AEs in schizophrenia (SZ) Clinical Benefit Novel MoA in SZ with Cohen’s D > 0.5 Projected/Est. Peak Revenue* $3bn - $6bn Synergistic combination of two generic medications Novel combination in MDD with similar effect size to existing Tx (d=0.35) $1bn - $3bn *Source: Bloomberg consensus estimates
Page 27
ALTO-300 Phase 2b development for MDD
Page 28
ALTO-300 proposed mechanism of action: synergy between melatonergic agonism and 5-HT2C antagonism 28 MT1/MT2 receptors 5-HT2C receptor circadian dopamine norepinephrine Mood Change activation inhibition disinhibition ALTO-300 (agomelatine) Bodinat et al., Nature Reviews, 2010 Antidepressant properties Melatonergic (MT1 and MT2) Agonism Serotonergic (5-HT2C) Antagonism Enhancement of dopaminergic input to frontal cortex Resynchronization of circadian rhythms Anxiolysis Improved sleep quality/patterns Lack of weight gain and sexual dysfunction ALTO-300 is a multi-modal antidepressant with a broad range of synergistic neurobiological effects that lead to antidepressant activity and favorable tolerability
Page 29
1 2 3 4 5 6 7 8 9 10 agomelatine esketamine quetiapine aripiprazole brexpiprazole Odds ratio of drop out due to AE 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 agomelatine esketamine quetiapine aripiprazole brexpiprazole Cohen's d effect size (drug -placebo) Unique opportunity for ALTO-300 (agomelatine) as an adjunctive treatment in MDD 29 Similar all -comer efficacy as other adjunctive treatments Favorable tolerability compared to other adjunctive treatments Meta-analytic values drawn from Cipriani et al., Lancet, 2018; Wang et al., Medicine, 2023; Jawad et al., Exp Op Drug Saf, 2022; Wei et al, J Aff Dis, 2020; Quetiapine, aripiprazole, and brexpiprazole are the atypical antipsychotics approved for MDD. Well-tolerated and validated antidepressant with Ex-U.S. approval (NCE in U.S.) ready for enhancement with a biomarker No difference in dropout due to AE in agomelatine, unlike antipsychotics and esketamine
Page 30
Head-to-head clinical trial data positions ALTO-300 favorably even against SSRI/SNRIs, setting up case for adjunctive use 30Kasper et al., International Clinical Psychopharmacology, 2013 • Greater efficacy (N=1014) vs SSRI/SNRIs (N=1013) in a pooled analysis on HDRS outcomes: p=0.013 ( Kasper, 2013) • Better treatment of anhedonia than venlafaxine XR on SHAPS ( Martinotti, 2012) • Lack of discontinuation symptoms following withdrawal vs. paroxetine (Montgomery et al., 2004) • Fewer sexual side effects than venlafaxine XR (Kennedy et al., 2008) ALTO-300 (agomelatine): superior efficacy and tolerability ALTO-300 (agomelatine) consistently better -tolerated with fewer discontinuations versus SSRI/SSNRIs due to adverse events (pooled analysis of randomized trials) Patients withdrawn for adverse events (cumulative %) Week ***p<0.001
Page 31
ALTO-300 Phase 2a study design and participant flow Discovery data set Test data set Bio- Bio+ Bio- Bio+ N 29 31 21 24 Age 43.0 (16.2) 39.7 (14.9) 39.3 (14.3) 46.4 (14.4) Female 66% 84% 71% 92% Edu (16+) 55% 39% 29% 71% BMI 31.9 (9.4) 34.4 (8.7) 29.7 (8.0) 31.4 (7.6) White 69% 77% 76% 88% MADRS 26.7 (4.3) 29.5 (5.4) 28.4 (5.7) 27.0 (4.7) HDRS 19.0 (3.8) 19.6 (4.8) 20.0 (6.2) 18.6 (5.6) CGI-S 4.4 (0.6) 4.5 (0.6) 4.7 (0.8) 4.3 (0.8) PHQ-9 14.9 (3.3) 17.3 (4.6) 16.4 (3.3) 14.8 (3.4) 31 No baseline/clinical characteristics were shown to impact results of biomarker outcomes • 25 mg single-arm for 8 weeks • ClinRO’s at baseline, weeks 1, 2, 4, 6, 8 • Full Alto biomarkers at baseline, weeks 2 & 8 • N=239 enrolled in 14 months across 8 in-clinic sites and 2 decentralized sites • Analyses focused on MADRS • Adults 18-74 years old • Moderate to severe MDD • Adjunctive (<50% response to current drug) • 45% of EEGs done at home REC 110 REO 109 REC 106 REO 109 REC 60 REO 60 REC 45 REO 48 REC = resting eyes-closed REO = resting eyes-open Baseline Demographics Treatment and Biomarkers Patient Population Baseline Severity Biomarker Data QC pass Analysis Sample EEG Discovery Test 239 194 Enrolled (MADRS≥20, PHQ≥10)
Page 32
Clinical Population is Biologically Heterogeneous Alto’s precision drug development approach 32 Candidate Biomarker Identified Statistical Analysis Plan 01 Determine Biomarker Discovery Data bio -bio + Test Data Replication: Bio + > Bio - ? 02 Prospective Biomarker Validation Efficacy in Biomarker + 03 Efficacy: Drug > PBO in Bio +?Specific vs. placebo? vs. standard-of-care? Alto Archival Data bio + (primary efficacy population) bio - Enroll based on biomarker Phase 2A Phase 2B/3 For future prospective replication of biomarker Locked & Blinded Test Data
Page 33
Treatment Outcome Identified a unique and scalable biomarker for ALTO-300 33 S1 S2 SN F1 F2 F3 F4 FN Subject (S) … (weight and reduce to key features (F)) (based on signal dynamics) negative positive … S1 S2 SN Predicted Outcome … subject Pretreatment EEG Machine Learning Biomarker Using an EEG machine learning strategy validated for other treatment biomarkers (e.g., SSRIs), a unique resting -state EEG signal from a single electrode was identified and prospectively replicated as a predictor of ALTO -300 response The biomarker is calculated from a single electrode and automatically scored, facilitating scalability
Page 34
ALTO-300 Phase 2a: prospective replication of EEG biomarker as predictive of response 34 1. Identified EEG signature as predictive 2. Prospectively label patients as bio+/- -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 0 2 4 6 8 MADRS LSM Change From Baseline Week d=0.32 p=0.15 d=0.32 p=0.10 d=0.40 p=0.05 d=0.51 p=0.03 d=0.63 p=0.03 EEG Biomarker + (n=24) EEG Biomarker - (n=21) Prospective Replication in Test Dataset Determine Biomarker N=60 N=45 01 02 Prospective Biomarker Validation 34 bio -bio +
Page 35
0 10 20 30 40 50 60 1 2 4 6 8 % of Patients Achieving ≥ 50% Improvement Week Biomarker positive patients derived greater benefit from ALTO-300 35 EEG Biomarker + (n=55) EEG Biomarker – (n=50) p=0.07 p=0.02 p=0.01 p=0.07 p=0.23 CGI – Clinician Global Impression of change HAM-D – Hamilton Depression Rating Scale EEG biomarker positive patients observed to achieve more robust clinical response to ALTO-300 • Response rates (MADRS reduction ≥50%) were higher in Bio + • Positive effects observed across CGI and HAM-D
Page 36
ALTO-300 biomarker: a measure of reduced neural signaling stability 36 r • Greater EEG irregularity (i.e., biomarker positivity) is associated with decreased neural connectivity • Across multiple independent datasets (N=784), biomarker positive patients demonstrated reduced medial prefrontal neural connectivity, an area important for MDD Ravindran et al, ACNP 2024
Page 37
1.84 1.86 1.88 1.9 1.92 1.94 1.96 veh 0.05 0.1 0.2 0.3 0.6 Gamma sample entropy Human and preclinical data demonstrates the link between the mechanism of ALTO-300 and its EEG biomarker 37 • Administrated 5-HT2C agonists (R0-0175, YM348) in independent preclinical studies • Dose-related increase in EEG irregularity (entropy) using the same measure as the human biomarker • Also led to anhedonic phenotype More biomarker (+) -like R0 60-0175 (n=13) Guo et al, SOBP 2025 • The biomarker signal reflects increased neural variability, which dopamine acts to reduce • ALTO-300’s MOA includes 5-HT2C antagonism and leads to an increase in dopamine • Studies test mechanistic link between ALTO-300’s EEG biomarker and 5-HT2C/dopamine activity: increased 5-HT2C activity (which reduces dopamine) or directly depleting dopamine drives the ALTO -300 response biomarker Sundar et al, SOBP 2025 (data from Larson, PLOS One, 2015) More biomarker (+) -like • Cross-over of dietary dopamine precursor depletion (APTD) or placebo • Increase (d=0.94) in EEG irregularity using same biomarker as for as ALTO-300 selection Rodent 5-HT2C agonists Human dopamine depletion (n=12) Vs. placebo or vehicle: * p<0.05; ** p<0.01, *** p<0.001 0.76 0.765 0.77 0.775 0.78 0.785 0.79 placebo APTD Gamma sample entropy ** YM348 (n=10) mg/kg ***** 1.84 1.86 1.88 1.9 1.92 1.94 veh 0.75 1.25 2.5 4 Gamma sample entropy mg/kg * ** ***
Page 38
EEG model prediction is specific to ALTO-300 as it does not predict greater placebo or SSRI/SNRI response 38 -12 -10 -8 -6 -4 -2 0 0 2 4 6 8 HDRS change from baseline Week d=-0.04 p=0.53 Apply the ALTO-300 EEG biomarker to: -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 0 2 4 6 8 HDRS change from baseline Week Biomarker + (n=58) Biomarker - (n=66) d=-0.11 p=0.75 d=-0.21 p=0.86 d=-0.15 p=0.85 d=-0.14 p=0.84 d=-0.13 p=0.81 d=-0.09 p=0.69 Placebo-Treated Patients Biomarker + (n=418) Biomarker - (n=353) SSRI/SNRI-Treated Patients
Page 39
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 agomelatine esketamine quetiapine aripiprazole brexpiprazole Phase 2a Cohen's d effect size (drug -placebo) Estimated placebo-adjusted ALTO-300 response: biomarker positive patients 39 The results shown above are not based on head-to-head trials between the products or product candidates . Study designs and protocols differed, and results may not be comparable. Meta-analytic values drawn from Cipriani et al., Lancet, 2018; Wang et al., Medicine, 2023; Jawad et al., Exp Op Drug Saf, 2022. Quetiapine, aripiprazole, and brexpiprazole are atypical antipsychotics approved in MDD. Meta-analytic all-comer effect sizes at primary endpoint timepoint across studies ALTO-300 EEG Bio + ALTO-300: Robust clinical response observed in biomarker positive patients
Page 40
40 No unexpected AEs in the completed ALTO-300 study Agomelatine has a favorable established tolerability profile Overall Treatment Emergent Adverse Events (TEAEs) Safety Analysis Set N (%) Total Participants 239 At least one TEAE 172 (72.0) No TEAE 67 (28.0) SAEs (none related) 6 (2.5) AEs leading to Discontinuation 12 (5.0) % of TEAEs Related TEAEs (by TEAE) 35.7 Note: participants may have had more than one AE TEAEs for ≥5% of the Population Safety Analysis Set N (%) Headache 35 (14.6) Nausea 18 (7.5) Dyspepsia 15 (6.3) Insomnia 15 (6.3) COVID 19 Infection 14 (5.9) Rash (10 from wearable) 12 (5.0) TEAEs consistent with prior agomelatine studies
Page 41
Plot from Koesters et al., Br J Psych, 2013 Test for subgroup differences: Chi2 = 0.02, df = 1 (P = 0.88), I2 = 0% ALTO-300 at 25mg maintains efficacy while avoiding LFT elevation 41 LFT – Liver Function Test AST – Aspartate Aminotransferase ALT – Alanine Transaminase ULN – Upper Limit of Normal Agomelatine concerns are more historical/contextual, not clinically meaningful, and less frequent than with antipsychotics (adjunctive MDD comparator drugs) • Novartis US studies showed placebo - like LFT rate with 25 mg: • 25mg: 0.3% • Placebo: 0.3% • 50mg: 3.7% • Alto’s Phase 2a showed no LFT elevation (>3x ULN) • Even when LFTs increase (mainly 50mg), they are reversible and do not result in liver failure Placebo-like LFT rate for 25mgWe selected the 25mg dose as meta-analyses show similar efficacy as 50mg 25mg and 50mg approved in EU/Australia
Page 42
Large-scale and real-world use demonstrates agomelatine- induced LFT elevation is low and adaptive 42 Acute studies using the 25mg dose (n=4,957) shows placebo -like LFT rate consistent with Alto’s Phase 2a results where no patient exceeded >3x ULN (even with baseline allowance of up to 2x ULN) Agomelatine safety supported by low LFT elevation rate following long -term use • VIVALDI real-world evidence: Patients (n=3,317) treated with 25-50mg agomelatine over 12 weeks demonstrated very low rates of LFT elevation (~0.2%; Laux et al., Pharmacopsychiatry, 2012) No difference in the rate of acute liver injury in agomelatine patients (n=74,440) versus conventional SSRI citalopram (n=782,812), following long -term use • Even observed a trend in the dataset that suggests less of a risk of acute liver injury with agomelatine vs. citalopram as comparator antidepressant (Pladevall-Vila et al., CNS drugs, 2019) LFT monitoring not required for approved antipsychotics despite higher rate of LFT elevation, which is expected to guide the label for ALTO-300 • Approved antipsychotics shown to induce LFT elevation at greater rates (comparable or higher than 50mg agomelatine) and occasionally result in severe or fatal hepatic injury (Marwick et al., Clin Neuropharm , 2012) Extensive long -term safety and real - world evidence builds confidence in lack of liver signal for selected 25mg dose of ALTO -300 LFT monitoring not expected for ALTO-300 label Analysis of patients treated with agomelatine (25 or 50mg/day) demonstrated effects of LFTs are adaptative (n=7,605) • Onset of LFT elevation at any dose (mainly driven by 50mg) occurred early , before 12 weeks in 64 % of patients and was not cumulative • Withdrawal of agomelatine led to rapid recovery . The median time to recovery (to <2x ULN) was 14 days following treatment withdrawal • Liver function tests recovered in 36 % of patients despite continuation of agomelatine • No cases of acute liver failure or fatal outcome occurred Perlemuter et al., CNS Drugs, 2016
Page 43
• Design follows FDA’s enrichment guidelines: powered primary outcome in EEG biomarker positive patients • Includes participants with and without the biomarker and randomization stratified by biomarker status • Site-based and decentralized – sites and participants blinded to biomarker status • Primary MDD but allows co -morbid anxiety disorders and PTSD • Central review (MGH-CTNI SAFER interview) of all participants before randomization • Favorable outcome from interim analysis informs final sample size; ~200 biomarker positive patients targeted for the final analysis sample to achieve adequate powering ALTO-300 Phase 2b biomarker-guided trial in MDD 43 1:1 Randomization 25 mg QHS ALTO-300 PRIMARY OUTCOME: MADRS change in EEG biomarker + population at week 6 8-Week Open Label Extension Wearable Behavior EEG Placebo 25 mg QHS ALTO-300 Screening Period 6-Week Double-Blind Treatment Period QHS = Once daily at bedtime Evaluating ALTO-300 as an adjunctive to an existing antidepressant with an insufficient response
Page 44
Patients prospectively excluded following detailed site and subject case review -- includes removal of 4 entire sites from analysis sample for study conduct issues identified by Alto Per protocol, excluded for mITT* defined MDD symptom threshold Continue study with sample re- estimation: Enroll Bio + target N of ~200 patients in final analysis sample Stop early for success: If interim analysis achieves p-value <0.005 Futility: Non-binding futility recommendation based on effect size threshold of Cohen’s d < 0.20 Interim analysis on ALTO-300 Phase 2b informs final sample size 171 119 Biomarker Positive 87 Biomarker Negative 28 52 4 Outcome ^ITT = Intention to Treat *mITT = Modified Intention to Treat According to standard ⍺ spend calculation for a study with 1 interim analysis, conservative success stopping criterial of p≤~0.005 results in final analysis success threshold of p<0.049 Patients enrolled as of Dec. 17, 2024 interim cutoff ITT^ population following site and subject review mITT* biomarker positive Interim analysis population Note: Site and patient exclusions prospectively determined by a blinded review committee 44
Page 45
ALTO-101 Development for CIAS
Page 46
PDE4i represents a historically validated mechanism to address cognition ALTO-101, a novel PDE4 inhibitor, in development for CIAS with a validated mechanism and demonstrated pro-cognitive activity 46 PDE4 inhibition has shown clear pro-cognitive effects in humans (including CIAS) Historical roflumilast studies provide external support for ALTO-101 in cognition and EEG 0.0 0.2 0.4 0.6 0.8 1.0 0.5mg 1.5mg placebo-adjusted effect size (d) d=0.33 p=0.09 d=1.05 p<0.001 improvement Theta response (placebo adjusted) ALTO-101 has demonstrated statistically significant effects vs. placebo on Theta response in Phase 1 1 Direct effects on best EEG biomarker of CIAS2 ALTO-101 has demonstrated clear pro-cognitive effects in humans3 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.5mg 1.5mg placebo-adjusted effect size (d) d=0.32 p=0.16 d=0.63 p=0.006 Processing speed (placebo -adjusted) improvement Good correlation between theta response & cognition, supported by ALTO-101 effects on cognition in human Phase 1 study Ongoing POC study: theta response EEG (primary) and cognition (secondary)
Page 47
Theta EEG response is the best index of CIAS pathophysiology 47 • EEG biomarkers indexing cognition-relevant neural circuitry have been extensively studied in schizophrenia • They provide a biological measure of the processes accounting for disorder pathophysiology • Alto put all established biomarkers head-to-head In each dataset: • Theta response was more sensitive than all other EEG biomarkers, including the most commonly-used; mismatch negativity (MMN) • Largest case-control difference • Strongest correlation with cognitive deficit Discovery dataset Replication dataset #1 Replication dataset #2 Schizophrenia (SCZ) N=257; Healthy (HC) N=251 Schizophrenia (SCZ) N=251; Healthy (HC) N=236 Schizophrenia (SCZ) N=128; Healthy (HC) N=241 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 HC SCZ Theta response (ITC) d=0.67 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 HC SCZ Theta response (ITC) d= 0.74 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 HC SCZ Theta response (ITC) d= 0.64
Page 48
Theta response in the ALTO-101 POC study: linking biology of CIAS to drug mechanism and clinical meaningfulness 48 Cortical circuit disruptions in schizophrenia • Post-mortem data in schizophrenia consistently shows a reduction in cortical inhibitory interneurons (especially somatostatin [SST] and parvalbumin [PV] types) • SST generate theta; PV generate gamma (both reduced in patients) • Reduction in SST or PV neurons leads to cognitive deficits • EEG theta response is an index of interneuron functioning ALTO-101 impacts key cognitive circuitry PDE4 inhibition: ↑ cAMP ↑ interneuron activity, plasticity ↑ theta response ↑ cognition Improved functioning cortical response to inputs improves POC trial primary outcome principal neuron SST PV
Page 49
ALTO-101 improves theta response, and with it, cognition 49 ALTO-101 Phase 1 data (N=40, healthy volunteer, crossover) Dose-dependent increase in theta response and processing speed Greater increase in theta response by ALTO -101 correlates with greater improvements in processing speed Processing speed is the most impaired cognitive domain in CIAS and is associated with disability 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.5mg 1.5mg placebo-adjusted effect size (d) d=0.32 p=0.16 d=0.63 p=0.006 Processing speed (placebo -adjusted) Change in speed Change in theta improvement 0.00 0.02 0.04 0.06 0.08 0.10 0.12 veh 0.003 0.03 0.1 Post – pre change in theta response mg/kg MK-801 0.1mg/kg in all arms 0.0 0.2 0.4 0.6 0.8 1.0 0.5mg 1.5mg placebo-adjusted effect size (d) d=0.33 p=0.09 d=1.05 p<0.001 improvement Theta response (placebo adjusted) ALTO-101 preclinical data Dose-dependent increase in theta response mirrors humans -0.06 -0.05 -0.04 -0.03 -0.02 -0.01 0.00 0.01 veh 0.1 mg/kg Post – pre change in theta response p<0.001 p<0.001 MK-801, an NMDA antagonist used to model schizophrenia, reduces theta EEG response ALTO-101 dose- dependently rescues the MK-801 deficit ALTO-101 improves cognition in separate experiments
Page 50
Additional evidence for PDE4 inhibition targeting of cognition and its neural circuitry in humans (including CIAS) 50 Gilleen et al., J Psychopharm, 2020 8-day crossover in 18 patients w/ CIAS using roflumilast (PDE4i) Demonstrated significant improvement in the mismatch negativity, a commonly -used EEG biomarker reduced in patients -1 -0.8 -0.6 -0.4 -0.2 0 0.5mg 1.5mg placebo-adjusted effect size (d) d=0.38 p=0.07 d=0.53 p=0.017 Mismatch negativity (placebo -adjusted) improvement improvement improvement 250μg d=0.61 p=0.04 ALTO-101 Phase 1 data (N=40, healthy volunteer, crossover) Dose-dependent increase in mismatch negativity Significant improvement in verbal memory with 250μg roflumilast as well (d=0.77, p=0.044; Gilleen et al, Psychopharm, 2018) Roflumilast also improves memory in: • Older healthy volunteers (Blokland et al, Neurobiol of Aging, 2019) • Younger healthy volunteers (Van Duinen et al, Neuropharmacology, 2018)
Page 51
Transdermal formulation: greater drug exposure and improved tolerability profile • Goal of TDS formulation: Eliminate rapid Cmax related AEs and maintain steady exposure • Healthy Volunteer (age 40-64) PK and Tolerability Study. 15 participants (1 did not complete TDS period due to positive urine drug screen). • TDS achieved similar Cmax as oral, but for longer and more consistently • AUC 62% and 170% greater for TDS on day 1 and 2 respectively (day 1 p=0.01; day 2 p<0.001) vs. oral • Even with higher AUC, TDS reduced typical AEs • Overall well-tolerated with no discontinuations. All AEs were mild, no SAEs reported • TDS showed favorable adhesion properties. No application site reactions that led to patch removal or intolerance. • Allows QD dosing in trials (vs. BID or TID for oral) 51 0 5 10 15 20 25 30 35 0 4 8 12 16 20 24 28 32 36 40 44 48 Mean (SEM) Plasma Concentration (ng/mL) Nominal Time (hrs) ALTO-101 ORAL ALTO-101 TDS Day 2 of Transdermal Dosing Related Adverse Events >5% ALTO-101 Oral Formulation (N = 15) ALTO-101 TDS Formulation (N = 14) PDE-4i Class-Related AEs Dizziness, n (%) 6 (40.0) 1 (7.1) Nausea, n (%) 3 (20.0) 0 Diarrhea, n (%) 1 (6.7) 0 Dyspepsia, n (%) 1 (6.7) 0 Vertigo, n (%) 1 (6.7) 0 Other AEs Headache, n (%) 2 (13.3) 5 (35.7) Administration site pruritus, n (%) 0 2 (14.3) Asthenia, n (%) 1 (6.7) 0
Page 52
Phase 2 POC study in cognitive impairment in schizophrenia 52 Study Population: Adults 21-55 years old with a diagnosis of schizophrenia for > 1 year and sufficient cognitive impairment Design: A two-way crossover, double-blind, placebo-controlled study with ALTO- 101 and placebo: Treatment Periods 1 + 2: • Randomized, 2-way crossover, washout separates the two periods • Evaluation of EEG and cognitive markers Number of participants: 60-70 completers (two dosing periods each) Primary outcome: Theta response Other outcome measures: Cognition ( processing speed, memory ), PK, safety, tolerability Proof-of-concept study is designed to provide clear understanding of effects on well characterized EEG markers and cognitive performance Topline data readout expected 1Q 2026 Treatment Period 1: Treatment Period 2: Safety Follow-up Visit • 2-way Cross-over, Double-blind, Placebo -controlled design Safety Follow-up VisitScreening Visits 1 and 2 Washout 6-14 days Daily ALTO-101 TDS for 10 days Daily PBO TDS for 10 days Daily ALTO-101 TDS for 10 days Daily PBO TDS for 10 days
Page 53
PDE4 inhibition is relevant across numerous high-need therapeutic areas 53 • Schizophrenia • Bipolar • PTSD • Depression • Substance Dependence • Multiple Sclerosis • Fragile X • Allergic Encephalomyelitis • ALS • Migraine • Glioblastoma • Alzheimer's • Huntington Disease • Anxiety Disorders • Dementia • Cerebrovascular Disorder • Mild Cognitive Impairment • ADHD • Parkinson’s Disease • Autism Spectrum Disorders • Frontotemporal Dementia • Developmental Delay • Learning Disabilities CNS • Plaque Psoriasis • Psoriatic Arthritis • COPD • Asthma • Atopic Dermatitis • Psoriasis & Eczema • Rosacea • Palmoplantar Pustulosis • Nummular Eczema • Pruritus • Rheumatoid Arthritis • Lupus (SLE) • Crohn's • Idiopathic Pulmonary Fibrosis $2.2bn 2022 SALES $0.3bn 2021 SALES ALTO-101 NON - CNS INDICATIONS Bold denotes approved indications Available medications are non-brain penetrant and only approved outside CNS – both come with substantial tolerability and dosing limitations
Page 54
ALTO-100 MDD and Bipolar Depression
Page 55
ALTO-100 offers a novel therapeutic option for depression with poor memory/cognition by enhancing hippocampal neuroplasticity Reduction in hippocampal plasticity and neurogenesis (contributing to mood + memory) Healthy Post-treatment Increase in Plasticity & Neurogenesis ALTO-100 Hippocampus BDNF Transcription TrkB Akt MEK GPCRs Depression with poor memory/cognition 55
Page 56
ALTO-100: developed to enhance hippocampal neuroplasticity, and improve cognition and mood 56 Identified based on a neurogenesis functional screen Evidence of working through BDNF , a core molecular mechanism important for hippocampal plasticity and mood Preclinically, increases synaptic and cellular plasticity across multiple time scales, hippocampal volume Novel, potentially first-in- class molecular mechanism (direct molecular target identified by Alto) Hippocampal Volume Transcription (CREB) Glutamate BDNF Akt MEK AMPAR NMDAR GPCRsTrkB Plasticity Neurogenesis Increased hippocampal synaptic plasticity and volume preclinically
Page 57
Rationale for ALTO-100 in poor memory/cognition patients with bipolar depression 57 • Bipolar disorder long thought to involve reduced neuroplasticity in the hippocampus, similar to MDD • Reduced hippocampal volume • Memory and broader cognitive deficits (as or more frequent than MDD) • Cellular and molecular evidence of neuroplasticity deficits • BDNF and related plasticity pathways implicated • Poor memory/cognition patients have worse outcomes • Greater treatment resistance and disability, more likely to have future mood episodes, related to genetic risk, persists across disease phases • Current treatment options are more limited than MDD as only approved therapies are antipsychotics • High side effect burden with limited efficacy • Patients spend more time depressed than manic, often needing chronic treatment • Mood stabilizers are not effective for bipolar depression • Strong biological and clinical rationale for ALTO-100 as a putative pro-plasticity intervention for patients with reduced hippocampal plasticity (poor memory marker) Soeiro-de-Souza et al, Acta Psych Scan, 2012
Page 58
• Design follows FDA’s enrichment guidelines: powered primary outcome in memory biomarker positive patients • Includes participants with and without the biomarker and randomization stratified by biomarker status • Monotherapy or adjunctive treatment to an existing antidepressant with an insufficient response • Site-based and decentralized – sites, participants and Alto staff blinded to biomarker status • Primary MDD but allows co -morbid anxiety disorders and PTSD • Central review (MGH-CTNI SAFER interview) of all participants before randomization Completed ALTO-100 Phase 2b biomarker-guided trial in MDD 58 1:1 Randomization 40 mg BID ALTO-100 PRIMARY OUTCOME: MADRS change in cognitive biomarker + population at week 6 7-Week Open Label Extension Wearable Behavior EEG Placebo 40 mg BID ALTO-100 Screening Period 6-Week Double-Blind Treatment Period N=301
Page 59
Phase 2B study flow 59 mITT sample Primary Analysis Sample Poor memory Good memory 301 287 196 91 Enrolled (ITT sample) (Site baseline MADRS≥20) 135 mono 61 adj 46 ALTO-100 45 PBO ITT = Intention-to-treat mITT = modified intention-to-treat 97 ALTO-100 99 PBO 67 ALTO-100 68 PBO 30 ALTO-100 31 PBO Monotherapy and adjunctive High rate of study-level QC pass: • Biomarkers done after SAFER interview • Broad set of biomarkers collected beyond memory as supports broader Alto platform • Cognition: 95% all battery, 99% memory test • EEG: 93% • Wearables (7 days pre-baseline): 83% Screening visit structure (key elements): 1. Visit 1: • Severity and diagnosis (at site), PHQ • SAFER including MADRS (MGH)** 2. Visit 2: • Biomarker baseline (at site), PHQ 3. Visit 3: • Clinical baseline MADRS (at site), PHQ * Inclusion requires PHQ -9≥10 at visit 1 and 2 to ensure stability ** Inclusion requires SAFER MADRS ≥22 (Includes mono and adj)
Page 60
Summary of ALTO-100 Phase 2b MDD results 60 Analysis Population Sample Size (n) Mean Baseline MADRS (SD) Week 6 LSM MADRS Change (SE) Cohen’s d pALTO-100 Placebo ALTO-100 Placebo ALTO-100 Placebo All Bio + mITT (Primary) 97 99 31.2 (5.4) 31.5 (5.4) -10.3 (1.0) -9.8 (1.0) 0.05 > 0.1 Monotherapy Bio + mITT (Key Secondary) 67 68 31.0 (4.8) 32.2 (5.3) -9.9 (1.2) -11.1 (1.1) -0.13 > 0.1 Adjunctive Bio + mITT (pre-specified secondary, not powered) 30 31 31.5 (6.6) 30.1 (5.4) -11.5 (1.8) -7.3 (1.7) 0.47 0.09 Clinically meaningful signal in the adjunctive subgroup provides confidence in continuing the Phase 2b study of ALTO-100 as an adjunctive treatment in bipolar depression; ALTO-300 is being studied as an adjunctive treatment in MDD
Page 61
Adjunctive population demonstrated clinically meaningful response to ALTO-100 and had significantly higher compliance 61 We believe the adjunctive signal is the most indicative of the ALTO -100 effect based on the clinically meaningful signal & high compliance rate Compliance rate among monotherapy and adjunctive patients in PK sample* 56% 100% Monotherapy (N=36) Adjunctive (N=17) Clear drug effect in prespecified adjunctive population *Only a subset of sites within the study were setup to evaluate PK levels PK Sample: Sample of patients from overall study who had blood draws to evaluate pharmacokinetic levels The study included Bio+ patients taking ALTO-100 as monotherapy (69%) and those taking it adjunctive to an antidepressant (31%)
Page 62
Evidence of drug effect & biomarker enrichment observed in the compliant population in additional analyses 62 Bio + confirmed compliant patients vs. all placebo Bio + vs. bio – in confirmed compliant patients Retrospective analyses conducted within population with measurable PK levels of ALTO-100, including monotherapy and adjunctive use
Page 63
ALTO-100 was well tolerated 63 TEAEs for ≥5% of the Population Safety Analysis Set ALTO-100 (%) Placebo (%) Headache % (related %) 10% (6.7%) 12.7% (10%) Overall Treatment Emergent Adverse Events (TEAEs) Safety Analysis Set ALTO-100 N (%) Placebo N(%) Total Participants 149 150 At least one TEAE 66 (44.3%) 61 (40.7%) Related TEAE 38 (25.5%) 38 (25.3%) AEs leading to discontinuation 6 (4%) 2 (1.3%) Note: participants may have had more than one AE • TEAEs consistent with prior ALTO-100 studies *No related serious adverse events were observed
Page 64
• Design follows FDA’s enrichment guidelines: powered primary outcome in memory biomarker positive patients • Includes participants with and without the biomarker and randomization stratified by biomarker status • Sites, participants and Alto staff blinded to biomarker status • Central review (MGH-CTNI SAFER interview) of all participants before randomization • 96% PK positivity in blinded analysis of 1 st cohort – supporting efforts to reduce non -compliance risk ALTO-100 Phase 2b biomarker-guided trial in bipolar depression 64 1:1 Randomization 40 mg BID ALTO-100 PRIMARY OUTCOME: MADRS change in cognitive biomarker + population at week 6 7-Week Open Label Extension Wearable Behavior EEG Placebo 40 mg BID ALTO-100 Screening Period 6-Week Double-Blind Treatment Period N ≈ 200 Alto received $11.7 M funding award from Wellcome Trust to support study Evaluating ALTO-100 as an adjunctive treatment to an existing mood stabilizer (no antipsychotics)
Page 65
ALTO-203 Novel H3 inverse agonist
Page 66
ALTO-203: An investigational H3 inverse agonist with effects across multiple major neurotransmitter systems 66 ↑ neurotransmitter release Region- and receptor-specific effects (mood, cognition, energy, motivation, wakefulness) H3 ALTO-203 (H3 inverse agonist) Dopamine Main effect of enhancing release Norepinephrine Acetylcholine Histamine • Mood • Reward Processing • Sustained Attention • Alertness • Sustained Attention • Sustained Attention • Learning and Memory • Wakefulness
Page 67
ALTO-203 showed ability to increase reward system dopamine, unlike the only approved H3 (pitolisant)* *Study conducted prior to Alto acquisition 67 Uguen et al., BJP , 2013 Pitolisant does not increase reward system dopamine (modafinil used as a comparator) ALTO-203 results plotted as percent increase over baseline from 0-150min post-dose, to compare to timing of pitolisant/modafinil study outcome (* p<0.05; ** p<0.01) ALTO-203 increases dopamine release in the reward system (nucleus accumbens) in a dose-related manner 100 120 140 160 180 0.001 0.01 0.3 10 % increase over baseline dose (mg/kg, i.p.) ** ** *
Page 68
Positive pharmacodynamic effects from exploratory proof-of-concept study of ALTO-203 Effects replicated key findings from completed Phase 1 study 68 Study Population: Patients with MDD with anhedonia and who were not on an antidepressant (monotherapy) Design: Two sequential double-blind, placebo-controlled treatment periods: • Single-dose: randomized, 3-way crossover. Evaluation of PD measures (positive emotion, cognition, reward processing tests) • Multi-dose: Participant continues to take Tx #3 dose once daily for 28 days. Focus on safety and PK but will also measure MDD and anhedonia symptoms Number of participants: 63 completers of 3-way crossover (single-dose period) Improvements in sustained attention Reduction in EEG theta/beta ratio Increase in wakefulness Greater attention improvements in high theta/beta individuals Improvements in alertness, mood Phase 1 High placebo response Phase 2a Topline pre-specified results Identified an EEG biomarker predictive of patient response • Theta/beta ratio: commonly used EEG index of cortical arousal and attentional control
Page 69
Biotech leadership team with extensive late-stage precision psychiatry experience 69 Executive management team Jessica Powell Chief Development Officer Melissa Berman VP, Finance & Accounting and Controller Amit Etkin, MD PhD Chief Executive Officer Nick Smith Chief Financial Officer and Chief Business Officer Adam Savitz, MD PhD Chief Medical Officer Michelle Moran VP, Quality Assurance Erin McQuade General Counsel and Chief Administrative Officer Michael Hanley Chief Operating Officer Patricio O’Donnell, MD PhD VP, Translational Medicine Husseini Manji, MD Former Global Head of Neuroscience JNJ Gwill York Founding Managing Director, Lighthouse Capital Partners Andrew Dreyfus Former President and CEO, Blue Cross Blue Shield of MA Christopher Nixon Cox CEO, Lightswitch Capital Amit Etkin, MD, PhD CEO, Alto Neuroscience Board of directors Jonathon Parker, PhD SVP, Head of Regulatory Affairs Christopher Martin VP, CMC Operations Raymond Sanchez, MD Senior Advisor Bain Capital Life Sciences
Page 70
Multiple near-term clinical milestones expected 70 Capitalized through multiple clinical milestones: $184.2mm^ as of October 31, 2025→ Expected cash runway into 2028, now including expanded execution on ALTO-207 for TRD ALTO-300 Phase 2b MDD data (mid -2026) ALTO-101 CIAS POC data (1Q 2026) ALTO-100 Phase 2b BPD data (2H 2026) 2026 ALTO-207 Phase 2b (potentially pivotal*) TRD data 2027 ^Cash & cash equivalents – unaudited and inclusive of $50mm of gross proceeds from PIPE transaction announced Oct. 2025 *Study qualifying as pivotal is subject to FDA feedback and review of data ALTO-207 Phase 3 initiation ALTO-207 Phase 2b Initiation (1H 2026)