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January 2026 NASDAQ: STRO
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This presentation and the accompanying oral presentation contain “forward -looking” statements that are based on our management’s beliefs and assumptions and on information currently available to management. Forward -looking statements include all statements other than statements of historical fact contained in this presentation, including information concerning our future financial performance; business plans and objectives; anticipated preclinical and clinical development activities, inc luding enrollment and site activation; timing of announcements of clinical results, trial initiation, and regulatory filings; outcome of regulatory decisions; and our expectations about our c ash runway; potential benefits of our product candidates and platform; potential expansion into other indications and combinations, including the timing and development activities related to such expansion; potential growth opportunities, financing plans, potential future milestone and royalty payments, competitive position, industry environment and potential market opportunitie s for our product candidates. Forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors, including risks and uncertainties related to our cash forecasts, our and our collaborators’ ability to advance our product candidates, the receipt, feedback and timing of potential regulatory submis sions, designations, approvals and commercialization of product candidates and the design, timing and results of preclinical and clinical trials and our ability to fund development activiti es and achieve development goals. It is not possible for our management to predict all risks, nor can we assess the impact of all factors on our business or the extent to which any facto r, or combination of factors, may cause actual results to differ materially from those contained in any forward -looking statements we may make. These factors, together with those that may be de scribed in greater detail under the heading “Risk Factors” contained in our most recent Annual Report on Form 10 -K, Quarterly Report on Form 10 -Q and other reports the company fi les from time to time with the Securities and Exchange Commission, may cause our actual results, performance or achievements to differ materially and adversely from those anticipat ed or implied by our forward -looking statements. You should not rely upon forward -looking statements as predictions of future events. Although our management believes that the e xpectations reflected in our forward -looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances desc ribed in the forward-looking statements will be achieved or occur. Moreover, neither we nor our management assume responsibility for the accuracy and completeness of the forward -looking statements. We undertake no obligation to publicly update any forward-looking statements for any reason after the date of this presentation to conform these statements to actual r esults or to changes in our expectations, except as required by law. This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In additi on, projections, assumptions, and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncerta inty and risk. Forward-Looking Statements NON-CONFIDENTIAL 2
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Delivering the Next-Generation of ADC Therapeutics Proprietary Platform Creates Best -in-Class ADCs At the forefront of next-gen ADCs, with improved antibody, linker, and payload for superior safety and efficacy Single-payload ADCs for complex targets where competition is limited Dual-payload ADCs, with partnered and wholly-owned programs, to overcome ADC resistance and delay progression 2H 2025 2026 2026 / 2027 STRO-004: TF-Targeting ADC STRO-006: ITGB6-Targeting ADC STRO-227: PTK7-Targeting dpADC Three INDs in Three Years Multiple candidates advancing in parallel for large market opportunities Well-Capitalized Runway into at least mid-2027, including certain expected near -term milestone payments 3NON-CONFIDENTIAL ITGB6 – Integrin-beta 6; IND – Investigational new drug; TF – Tissue factor ✓
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Differentiated Pipeline of Single- and Dual-Payload ADCs NON-CONFIDENTIAL 4 SINGLE-PAYLOAD ADCs: dpADC – Dual-payload ADC; NHP – Non-human primate; IND – Investigational new drug; ITGB6 – Integrin-beta 6; PTK7 – Protein Tyrosine Kinase 7; TF – Tissue factor Overcome Resistance and Delay Progression DUAL-PAYLOAD ADCs: STRO-227: PTK7-Targeting dpADC Supercharged ADCs with best-in-class potential, combining different payloads to achieve improved clinical benefit, tolerability, and duration of response 2026 / 2027 IND submission expected Well-tolerated at 25 mg/kg in NHPs Focused on Complex Targets Expressed Across Many Tumor Types STRO-006: ITGB6-Targeting ADC Best-in-class potential, designed for improved clinical benefit, stability, potency, and tumor selectivity Well-tolerated at 25 mg/kg in NHPs IND submission expected2026 STRO-004: TF-Targeting ADC Ph 1 ongoing; initial data expectedMid-2026 Best-in-class potential, designed for improved clinical benefit, stability, potency, and tumor selectivity Well-tolerated at 50 mg/kg in NHPs
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Next-Generation ADCs Enabled by Sutro’s Proprietary Platform
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Designed to Deliver: 6 Proprietary platform enables enhanced ADCs Precision Site-specific conjugation using non-natural amino acids and click chemistry for uniform and stable molecules Versatility Increased flexibility on linker- payload number, placement, or combinations enables industry-leading PK and safety profile Scalability Same cell-free system from discovery to commercial scale with consistent quality NON-CONFIDENTIAL PK – Pharmacokinetics
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Sutro’s Platform Designed to Optimize Every Component of the ADC Expanding the therapeutic window to minimize toxicity and maximize efficacy Ab – Antibody; DAR – Drug to antibody ratio; ILD – Interstitial lung disease; PK – Pharmacokinetic NON-CONFIDENTIAL 7 LINKER ▸Stabilized β-glu linker with non-natural amino acids; optimized linker-payload number and placement ▸Tumor-selective cleavage reduces off -target toxicity 3 2 PAYLOAD ▸High DAR exatecans; stable PK ▸Multiple payload combinations with novel modalities ANTIBODY ▸High throughput screening identifies Ab with ideal attributes ▸Reduced ILD risk enabled by Fc -silent design 1 2 3 1 OBJECTIVE Increasing ADC drug exposure leads to greater safety and efficacy
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Our Proprietary Platform Enables Industry-Leading ADC Exposure, a Key Driver of Safety and Efficacy 8 0 1,000 2,000 3,000 4,000 5,000 6,000 0 0.5 1 1.5 2 a b c d e f g h i j STRO-ADC DAR8 Enhertu DAR8 STRO-ADC DAR8 STRO-ADC DAR8 NON-CONFIDENTIAL a. Dato-DXd (DAR4); b. AMT-562-T800 (DAR4); c. ETx-22 (DAR8); d. AMT-562-T1000 (DAR4); e. Ilfinitamab (DAR4); f. PL2201 (DAR6); g. DS-600 (DAR8); h. SKB264 (DAR8); i. DB-1310 (DAR8); j. MTX-13 (DAR8) Ab – Antibody; DAR – Drug to antibody ratio; MMAE – Monomethyl auristatin E; NHP – Non-human primate; ORR – Objective response rate; PK – Pharmacokinetic Exatecan/Topo1i ADCs Sutro ADC Therapeutics Better PK Less ADC Clearance Less Systemic Toxicity Choosing the right combination of sites can result in optimized pharmacokinetics 0 100 200 300 400 Site combo A Site combo B Site combo C Site combo D Total Ab (ng/mL) Time post-dose (hr) 100,000 10,000 1,000 100 Conjugated PL Exposure [h ug/mL] PL Dose @ HNSTD [mg/kg] DAR16 ADCsComparing ADC Exposure in NHPs at Highest Non-Severely Toxic Dose
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STRO-004 Potential Best-in-Class Exatecan ADC Targeting Tissue Factor
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STRO-004: Potent TF-Targeting Exatecan ADC Engineered for Robust Exposure and Efficacy 50x preclinical exposure vs approved TF ADC LINKER ▸β-glu linker with site-specific conjugation for stability and tumor-selective cleavage 3 2 PAYLOAD ▸DAR 8; safely boosts potency ▸Drives efficacy in low -copy targets ANTIBODY ▸Tumor targeting, does not interfere with TF biology ▸Fc-silent to reduce ILD risk 1 UPCOMING MILESTONES Phase 1 trial in a range of solid tumors, with initial data expected mid -2026 2 3 1 NON-CONFIDENTIAL 10 DAR – Drug to antibody ratio; ILD – Interstitial lung disease; IND – Investigational new drug; TF – Tissue factor
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Current Standard of Care in R/R % ORR mOS 18%1 11-12 months1 8%2 ~6 months2 6-32%3-5 5-8 months3-5 6-40%6-8 11-16 months6-8 13-44%9-11 10-12 months9-11 Significant Unmet Need Across Large Oncology Patient Populations NON-CONFIDENTIAL 11 200,000 150,000 75,000 65,000 15,000Cervical Pancreatic HNSCC* CRC Lung CRC – Colorectal cancer; HNSCC – Head and neck squamous cell carcinoma; ORR – Overall response rate; OS – Overall survival; TF – Tissue factor. *Includes ~60K oral cavity and pharynx plus ~15K larynx. Sources: 1. Vergote et al. 2024; 2. Wang-Gillam 2019; 3. Vermorken 2010; 4. Ferris et al. 2017; 5. Soulieres et al. 2022; 6. Prager et al., 2023; 7. Peeters et al., 2015; 8. Sobrero et al., 2020; 9. Paz-Ares et al. 2024; 10. Ahn et al. 2024; 11. Sands et al. 2025. Incidence (U.S.) and Relapsed/Refractory ORR and OS Benchmarks Across Select Relevant Tumor Types Incidence (U.S.) and relapsed/refractory ORR and OS benchmarks across select relevant tumor types
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Skin Toxicities Human Keratinocytes STRO-004: Favorable In Vitro Tolerability Profile vs. Approved TF ADC NON-CONFIDENTIAL 12 Eye Inflammation Human Corneal Epithelial Cells Approved TF ADC (DAR4 -MMAE)STRO-004 (DAR8-exatecan) DAR – Drug to antibody ratio; MMAE – Monomethyl auristatin E; TF – Tissue factor 1% 46% 0% 10% 20% 30% 40% 50% STRO-004 Tisotumab Up to 70% of Tivdak-treated patients have treatment -emergent bleeding adverse events STRO-004 Reduced Bleeding Risk Inhibition of coagulation, expressed as % inhibition of Factor X (FX) conversion in an in vitro assay
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STRO-004: Promising Anti-Tumor Activity in Multiple TF-Expressing Cancer Models NON-CONFIDENTIAL 13 -100 -50 0 50 100 % tumor volume change from baseline STRO-004 % Best Response in PDX Models of Solid Tumors HNSCC NSCLC Pancreatic cancer CRC DCR: 28/30 ORR: 22/30 STRO-004 ORR CR PR SD Cancer N (%) HNSCC 17 11 (65) 0 11 (65) 4 (24) NSCLC 7 5 (71) 3 (43) 2 (29) 2 (29) PDAC 5 5 (100) 1 (20) 4 (25) 0 CRC 1 1 (100) 1 (100) 0 0 STRO-004 5 mg/kg *Interim Best Overall Response (BOR), model ongoing DCR: 28/30 (93%) ORR: 22/30 (73%) CR – Complete response; CRC – Colorectal cancer; DCR – Disease control rate; HNSCC – Head and neck squamous cell carcinoma; NSCLC – Non-small cell lung cancer; ORR – Overall response rate; PDX – Patient-derived xenograft; PR – Partial response; SD – stable disease; TF – Tissue Factor
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Dose Level 1 Dose Escalation Advanced Solid Tumors with Tissue Factor Expression Dose Level 5 Dose Level 2 Dose Level 3 Dose Level 4 HNSTD of 50 mg/kg permits high entry into dose escalation ladder - Shortens time to observing activity - Increases probability of wide therapeutic window – facilitates dose optimization • Early detection of activity • Early characterisation of safety profile • Early transition to registrational development path Recommended Dose 1 Recommended Dose 2 Tumor type eligibility Selected for TF expression: Colorectal Cervical NSCLC HNSCC Bladder PDAC • Better for patients • Early signs of activity • Relevant to look at safety in potential-forward indications Move Forward with Recommended Dose(s) 14 HNSCC – Head and neck squamous cell carcinoma; HNSTD – Highest non-severely toxic dose; NSCLC – Non-small cell lung cancer; PDAC - Pancreatic ductal adenocarcinoma; TF – Tissue factor NON-CONFIDENTIAL Detailed Monotherapy Development Strategy: Phase 1 Trial Ongoing Initial data expected in mid-2026 Endometrial
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STRO-006 Potential Best-in-Class Exatecan ADC Targeting Integrin-Beta 6
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LINKER ▸β-glu linker with robust in vivo stability to minimize premature release and enhance PK and tolerability 3 PAYLOAD ▸ High stable DAR (8) ▸ Potent anti-tumor activity with bystander effect 2 ANTIBODY ▸High affinity to ITGB6 without effect on TGF β signaling ▸Fc-silent to reduce ILD risk 1 UPCOMING MILESTONES IND filing planned for 2026 2 3 1 STRO-006: Selective ITGB6-Targeting Exatecan ADC for Leading Tolerability and PK STRO-006 is designed for superior selectivity, safety and stability NON-CONFIDENTIAL 16 DAR – Drug to antibody ratio; ILD – Interstitial lung disease; IND – Investigational new drug; ITGB6 – Integrin-beta 6; PK – Pharmacokinetic; TGFβ – Transforming growth factor-beta
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ITGB6 Expression has Unique Promise in NSCLC as well as Other Common Solid Tumors STRO-006 is designed for monotherapy and combination use, expanding its therapeutic reach NON-CONFIDENTIAL 17 200,000 150,000 75,000 40,000 Incidence (U.S.) Across Select Relevant Tumor Types TNBC HNSCC CRC Lung ITGβ6 expression assumptions are based on a weighted average of expression as reported in publicly available literature and triangulated with internal Sutro data on file. Criteria for positivity differs across studies, overall positive staining/overexpression % is used CRC – Colorectal cancer; HNSCC – Head and neck squamous cell carcinoma; ITGB6 – Integrin beta 6; NSCLC – Non-small cell lung cancer; TNBC – Triple-negative breast cancer
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STRO-006 Has Shown Superior Activity to Competitor ADCs in Preclinical Models Expressing ITGB6 NON-CONFIDENTIAL 18 Non-squamous NSCLC PDX, mut -EGFR Squamous NSCLC PDX, WT -EGFR Bladder CDX, SW780 0 10 20 30 0 500 1000 1500 2000 Days post dose initiation Tumor volume (mm3) adeno NSCLC PDX (CTG-0743) H score: 136 (Seagen) Vehicle STRO-006, 3 mg/kg aITGB6 ADC (DAR4 MMAE), 3 mg/kg STRO-006, 10 mg/kg 0 10 20 30 40 50 0 500 1000 1500 Days post dose Relative Tumor Volume (%) SW780 (UCC) ITGB6-moderate 0 10 20 30 0 500 1000 1500 2000 2500 Days post dose initiation Tumor volume (mm3) Vehicle STRO-006, 3 mg/kg aITGB6 ADC (DAR4 MMAE), 3 mg/kg STRO-006, 10 mg/kg Vehicle aITGB6 ADC (DAR8 AMDCPT), 1 mg/kg STRO-006, 1 mg/kg CDX – Cell-line derived xenograft; DAR – Drug to antibody ratio; ITGB6 – Integrin beta-6; MMAE – Monomethyl Auristatin E (tubulin inhibitor); NSCLC – Non-small cell lung cancer; PDX – Patient-derived xenograft
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Superior Anti-Tumor Activity and Greater Duration of Response Following a Single Dose of STRO-006 in HNSCC PDX Models 19 -100 -50 0 50 100 150 200 % tumor volume change from baseline % Best Response in PDX Models of HNSCC STRO-006 5 mg/kg aITGB6 ADC (DAR4 MMAE) 5 mg/kg STRO-006 DCR: 14/17 ORR: 12/17 aITGB6 DAR4 MMAE ADC DCR: 11/17 ORR: 8/17 *: interim readout, model ongoing * * * * * * * * * * * % Best Response PDX Models of HNSCC STRO-006 5 mg/kg alTGB6 ADC (DAR4 MMAE) 5 mg/kg *interim BOR, model ongoing STRO-006 aITGB6 ADC, DAR4 MMAE Cancer n ORR CR PR SD ORR CR PR SD HNSCC, n (%) 17 12 (71) 0 12 (71) 2 (12) 8 (47) 0 8 (47) 3 (18) NON-CONFIDENTIAL BOR – Best overall response; DAR – Drug to antibody ratio; DCR – Disease control rate; HNSCC – Head and neck squamous cell carcinoma; ITGB6 – Integrin beta 6; ORR – Overall response rate; PDX – Patient-derived xenograft ADC Response (below baseline) at end of study STRO-006 7/11 (64%) aITGB6 DAR4 MMAE 3/11 (27%) 20 40 60 -100 -50 0 50 100 150 200 Days Change from Baseline (%) STRO-006 5 mg/kg 19 20 40 60 -100 -50 0 50 100 150 200 Days Change from Baseline (%) aITGB6 ADC (DAR4. MMAE) 5 mg/kg Landmark Response
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Delivering Dual-Payloads: The Next Revolution in ADCs
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Dual-Payload ADCs: Potential to Become Future Standard of Care • Overcomes resistance resulting from conventional ADCs • Reduces toxicity over ADC combination approaches • Unique benefits from simultaneous delivery of payloads within the tumor cells • Simplified development path compared to combination treatment regimens • Unlocks broader market potential across tumor types Combination treatment approaches have been shown to improve outcomes in oncology vs single agent chemotherapy and remain standard of care in many therapeutic areas Dual-Payload ADCs: Targeted Combination Therapy to Improve Outcomes NON-CONFIDENTIAL 21
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Tailored Ratios Proprietary Cell-Free Platform Positions Sutro at the Forefront of Dual-Payload Innovation NON-CONFIDENTIAL Enables novel drug combinations and tuning of ratios with the broadest payload diversity to overcome tumor resistance and improve tolerability Multiple Modalities Well-tolerated in non-human primates at 25 mg/kg (2XQ3W) with dual cytotoxin ADCSafety Topo1 x Tubulin Topo1 x DDRi Topo1 x IO DAR 4+4 DAR 4+2 DAR 8+4 DAR 8+2 DAR – Drug to antibody ratio; DDRi – DNA damage response inhibitors; IO – Immuno-oncology 22
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Sutro’s First Wholly-Owned Dual-Payload ADC Targeting PTK7 23 • Broad expression across high-need indications and associated with poor prognosis • Anti-tumor clinical activity of an anti-PTK7 ADC has been demonstrated across multiple tumor types • First-generation anti-PTK7 ADC was constrained by dose-limiting safety, underscoring need for next- generation ADC with greater specificity and a wider therapeutic index *1: https://pmc.ncbi.nlm.nih.gov/articles/PMC9401513/ 2: *for Ovarian (Pt-resistant)/TNBC/NSCLC 3: The most common, treatment-related adverse events for PF-06647020 administered every 3 weeks were nausea, alopecia, fatigue, headache, neutropenia, and vomiting (45%–25%); 25% of patients had grade ≥ 3 neutropenia. Two patients experienced dose-limiting toxicities (grade 3 headache and fatigue) at the highest every 3 weeks dose evaluated. NON-CONFIDENTIAL Breast Cancer Xenograft Model UPCOMING MILESTONES IND filing anticipated in 2026 -2027 A clinically validated, pan-tumor target enriched on tumor-initiating cells
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Area Target Linker Payload DAR NHP HNSTD Highest Clinical Phase Enhertu HER-2 GGFG Deruxtecan 8 30 mg/kga (Q3Wx3) Approved Datroway Trop-2 GGFG Deruxtecan 4 10 mg/kgb (Q3Wx5) Approved MK-1022 HER-3 GGFG Deruxtecan 8 30 mg/kgc (Q3Wx5) 3 MK-2400 B7-H3 GGFG Deruxtecan 4 30 mg/kgd (Q2Wx3) 3 MK-5909 CDH6 GGFG Deruxtecan 8 30 mg/kge (Q3Wx3) 2/3 Rina-S FOLR1 Val-Cit Exatecan 8 30 mg/kgf (Q3Wx2) 3 Sutro dpADC PTK7 β-Glu Exatecan + MMAE 8 + 2 25 mg/kg (Q3Wx2) Preclinical aPMID: 27026201 bPMID: 34413126 cPMID: 31471314 dPMID: 35149548 ePMID: 38205802 fDOI:10.1158/1538-7445.AM2023-CT244 Sutro Dual-Payload ADC: Preclinical Tolerability Meets Single- Payload Benchmarks Even with Added MMAE Payload NON-CONFIDENTIAL 24
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0 10 20 30 40 0 500 1000 1500 Days Post Dose Relative Tumor Volume (%) HCT-116 Tumor Growth Curves Vehicle control Trastuzumab DAR4 MTI (MMAE) ADC (5 mg/kg) Trastuzumab DAR8 Topo1i ADC (5 mg/kg) Trastuzumab DAR8 Topo1i + DAR4 MTI (MMAE) dpADC (5 mg/kg) CRC Xenograft Tumor Growth Curve Mice with Enhertu-resistant tumors were switched onto STRO-002 treatment and subsequently onto dual-payload ADC after exhibiting STRO-002 resistance Dual-Payload ADCs Have Overcome Resistance and Driven Tumor Regression in Preclinical Models 10 mg/kg Enhertu 10 mg/kg STRO-002 10 mg/kg SP12576 NON-CONFIDENTIAL 25 Dual-Payload ADC Induces Tumor Regression After Sequential ADC Resistance Dual-Payload ADCs Have Improved In Vivo Efficacy in an MTI-Resistant CRC Xenograft Model CRC – Colorectal cancer; DAR – Drug to antibody ratio; MMAE – Monomethyl auristatin E; MTI – Microtubule inhibitor
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iADC: Dual-Payload ADC Combining Tumor-Targeted Delivery of a Cytotoxin and Immune Stimulator Strategic partnership with Astellas to deliver new treatment options for cold tumors and patients unresponsive to existing cancer immunotherapies Combining a cytotoxin and immune modulator gives potential to: ▸Act alone by stimulating the immune system and priming new populations of immune cells ▸Synergize with other immune therapies that remove inhibitory signals on the immune system (e.g. checkpoint inhibitors) ▸Address hard-to-treat cancers by activating a robust anti -tumor immune response NON-CONFIDENTIAL 26 PARTNERSHIP UPDATE First program expected to enter the clinic in early 2026 iADC -- Immunostimulatory ADC; IND – Investigational new drug
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Pipeline of Next-Generation Single- and Dual-Payload ADCs PROGRAM MODALITY/TARGET INDICATION DISCOVERY PRECLINICAL PHASE 1/1B PHASE 2 PHASE 3/ REGISTRATIONAL MILESTONES WHOLLY-OWNED PROGRAMS STRO-004 Tissue Factor ADC Solid Tumors Initial Phase 1 data expected mid-2026 STRO-006 Integrin αvβ6 Solid Tumors IND submission expected 2026 STRO-227 PTK7 Dual-Payload ADC Solid Tumors IND submission expected 2026-2027 STRO-00Y Dual-Payload ADC Solid Tumors PARTNERED PROGRAMS VAX-24 24-Valent Conjugate Vaccine Invasive Pneumococcal Disease VAX-31 31-Valent Conjugate Vaccine Invasive Pneumococcal Disease Undisclosed Programs Immunostimulatory ADCs (iADCs) Cancers 1st program expected to enter clinic in early 2026 NON-CONFIDENTIAL 27