Exhibit 99.3 Company Overview October 2025 NASDAQ: JBIO

Disclaimers Forward Looking Statements Certain statements in this presentation, other than purely historical information, may constitute forward-looking statements within the meaning of the federal securities laws, including for purposes of the safe harbor provisions under the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, but are not limited to, express or implied statements relating to the expectations, hopes, beliefs, intentions or strategies of Jade Biosciences, Inc. (“Jade”) regarding the future of its pipeline and business including, without limitation, expectations with respect to cash runway, Jade’s ability to achieve the expected benefits or opportunities with respect to JADE101, JADE201 and JADE-003, expected timelines for clinical trials and for interim data from the phase 1 clinical trial of JADE101, te expected timelines for initiating phase 1 clinical trials of JADE201 and JADE-003, the potential for JADE101 healthy volunteer data to be predictive of clinical efficacy, the potential of surrogate endpoints to support IgAN approval, the potential for the anti-APRIL class to become frontline treatment for IgAN, the potential of JADE101, JADE201 and any product candidate from the JADE-003 program to become best-in-class drugs and their potential therapeutic uses, mechanisms of action, efficacy, dosing, durability, safety profile and market opportunities. The words opportunity, potential, milestones, pipeline, can, goal, strategy, target, anticipate, achieve, believe, contemplate, continue, could, estimate, expect, intends, may, plan, possible, project, should, will, would and similar expressions (including the negatives of these terms or variations of them) may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. These forward-looking statements are based on current expectations and beliefs concerning future developments and their potential effects. There can be no assurance that future developments affecting Jade will be those that have been anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond Jade's control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, the risks that the ongoing trial of JADE101 and any future clinical trials may not demonstrate safety and/or efficacy; Jade may experience unanticipated costs, difficulties or delays in the product development process; JADE101, JADE201 and Jade’s future product candidates may fail in development, may not receive required regulatory approvals, or may be delayed to a point where they are not commercially viable; regulatory agencies may impose additional requirements or delay the initiation of clinical trials; risks associated with Jade’s dependence on third-party vendors for the development, manufacture and supply of its product candidates; risks relating to market conditions and the satisfaction of closing conditions of the additional financing; and the other risks, uncertainties and factors more fully described in Jade’s most recent filings with the Securities and Exchange Commission (including its Quarterly Report on Form 10-Q for the quarter ended June 30, 2025), as well as risk factors associated with companies, such as Jade, that operate in the biopharma industry. Should one or more of these risks or uncertainties materialize, or should any of Jade's assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. Nothing in this communication should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. You should not place undue reliance on forward-looking statements in this communication, which speak only as of the date they are made and are qualified in their entirety by reference to the cautionary statements herein. Jade does not undertake or accept any duty to release publicly any updates or revisions to any forward-looking statements. This communication does not purport to summarize all of the conditions, risks and other attributes of an investment in Jade. Market and Industry Data Certain information contained in this presentation and statements made orally during this presentation relate to or are based on studies, publications and other data obtained from third-party sources as well as our own internal estimates and research. While we believe these third-party sources 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. Forecasts and other forward-looking information obtained from these sources are subject to the same qualifications and uncertainties as the other forward-looking statements in this presentation. Statements as to our market and competitive position data are based on market data currently available to us, as well as management’s internal analyses and assumptions regarding the Company, which involve certain assumptions and estimates. These internal analyses have not been verified by any independent sources, and there can be no assurance that the assumptions or estimates are accurate. While we are not aware of any misstatements regarding our industry data presented herein, our estimates involve risks and uncertainties and are subject to change based on various factors. As a result, we cannot guarantee the accuracy or completeness of such information contained in this presentation. 2

Jade Biosciences is advancing potentially best-in-class therapies for autoimmune diseases Additional financing totaling $135 million in gross proceeds supports cash runway into H1 2028 MOA Program Candidate Discovery IND-enabling Phase 1 Expected Milestones Potential Indications • Interim Data: JADE-001 JADE101 IgAN anti-APRIL 1H 2026 Multiple • Planned FIH: systemic AI JADE-002 JADE201 anti-BAFF-R 1H 2026 diseases • Planned FIH: 1H 2027 JADE-003 __ Undisclosed Undisclosed Development candidates from Paragon Candidates designed to maximize clinical responses and allow patient friendly, infrequent dosing Notes: Jade has entered into exclusive license agreements with Paragon Therapeutics for JADE101 and JADE201. Jade holds an exclusive option to license JADE- 003 from Paragon. Jade has not yet entered into a license agreement with respect to JADE-003. 3 MOA – mechanism of action; FIH – First-in-Human, IgAN - IgA nephropathy; AI – autoimmune; BAFF-R – B cell-activating factor receptor

JADE101: a potentially best-in-class anti-APRIL mAb for IgAN 4

Jade is developing a potentially best-in-class anti-APRIL mAb Current treatments Mechanism has Estimated Anti-APRIL do not adequately potential to be disease- class poised to be address the need for modifying, reducing $10B+ long-term disease- pathogenic IgA and frontline treatment modifying therapy in proteinuria, stabilizing for IgAN branded a typically young IgAN kidney function market in the patient population U.S. alone JADE101 is designed Biomarker-rich and Potentially Efficient to have superior highly translational HV potency and an data expected in path to PoC best-in- extended half-life for 1H26; potential for maximal efficacy & and market surrogate endpoints class convenient dosing in future trials to support IgAN profile approval HV – healthy volunteer, mAb – monoclonal antibody, PoC – proof of concept 5 5

IgAN is a $10B+ potential market, with a need for effective and convenient therapies for life-long treatment ~169K+ IgAN patients in the U.S., with 60-75% requiring IgAN is typically diagnosed in young adults; higher proteinuria treatment per international guidelines is associated with greater risk of kidney failure Lifetime risk of progression to end-stage kidney disease ~1M+ global patients, begins at low proteinuria thresholds. significant ex-U.S. market potential 0 100 200 300 400 1,300 US ’000 Patients EU Japan China 783 1,260 169 205 103 IgAN is a progressive autoimmune kidney disease requiring lifelong treatment, with significant need for well-tolerated, disease-modifying therapies that offer convenient dosing. Notes: Per KDIGO guidelines, treatment should be initiated in all cases where patients have proteinuria ≥0.5 g/day. U.S. prevalence estimate from FDA; EU prevalence estimate from EMA; Japan / China prevalence estimates from a Novartis presentation. Estimated pricing of ~$120K-$150K per year based on Filspari and Tarpeyo. 6 Sources: 2023 Pitcher (CJASN); FDA Reviews for Filspari / Tarpeyo; EMA; Novartis; 2018 Schena (Seminars in Nephrology); Reuters IgAN est. prevalence

Updated KDIGO guidelines position the anti-APRIL class as the foundational therapy in IgAN Expanding Patient Population IgAN patients at risk of progressive kidney function loss • Kidney biopsy recommended in all adults with proteinuria ≥0.5 g/d where IgAN is a possible diagnosis In all patients these Drivers of Manage the generic • Recommends additional treatment Manage the IgAN-specific should be addressed nephron response to IgAN-induced drivers for nephron loss simultaneously should be initiated in all cases where nephron loss loss patients have proteinuria ≥0.5 g/d Lower Proteinuria Targets • Establishes new treatment goal: Reduce proteinuria maintained at <0.5 g/day, pathogenic Reduce glomerular Cardio- Blood forms of IgA and Reduce hyperfiltration and preferably <0.3 g/day vascular Treatment pressure IgA immune glomerular the impact of risk strategies control inflammation complex proteinuria on the reduction formation tubulointerstitium Redefining Treatment Strategies • New guidelines direct the use of treatments that have been proven to reduce pathogenic forms of IgA KDIGO updates anticipated to increase IgAN diagnosis, expand at-risk patient population requiring treatment, lower proteinuria target to clinical remission, and require targeted therapies that reduce pathogenic IgA. Sources: KDIGO 2025 Guidelines; 2023 Mathur (NEJM); Jade analysis 7 KDIGO – Kidney Disease Improving Global Outcomes

JADE101: Ultra-high affinity, half-life extended mAb with potential for best-in-class activity and patient convenience Femtomolar APRIL Affinity + Half Life Extension Potentially best-in-class Potential for ≤ 6 injections Avoids unnecessary efficacy per year immunosuppression Minimizes burden in a typically APRIL inhibitors demonstrate Selectively targeting APRIL provides greater proteinuria reduction and young IgAN patient population disease modifying impact while increased clinical remission rates avoiding B-cell depletion associated potentially requiring life-long therapy with higher exposures and more with BAFF inhibition (no more than Q8W or less) complete APRIL suppression 8

Reducing pathogenic IgA production by plasma cells is a potentially disease-modifying approach for IgAN Broad B-cell depletion is ineffective in IgAN… …while targeted plasma cell modulation is highly effective. • B-cell depletion with rituximab (anti-CD20) failed to reduce Gd- • APRIL and dual APRIL/BAFF neutralization result in significant and sustained IgA1, anti-Gd-IgA1 autoantibody, or proteinuria and did not depletion of Gd-IgA1, reduction in proteinuria, and eGFR stabilization. impact eGFR. • BAFF neutralization (blisibimod) did not reduce IgA or proteinuria. HIT 1 Plasma cell Mucosa & Production of galactose-deficient differentiation Bone marrow Mucosa bone marrow IgA1 (Gd-IgA1) APRIL blocking HIT 2 therapy Synthesis of anti-Gd-IgA1 autoantibodies HSC Pro B cell Large Small Immature Mature Naïve Plasma cell pre-B cell pre-B cell B cell B cell HIT 3 Autoantibodies bind Gd-IgA1 to form pathogenic immune Memory B cell complexes APRIL CD20 expression HIT 4 Deposition of immune complexes Antibody in the mesangium and initiation of BAFF dependency class-switching kidney injury APRIL dependency *Gradient indicates level of receptor expression Neutralizing APRIL depletes Gd-IgA1, reduces proteinuria, and preserves eGFR, providing a disease-modifying treatment of IgAN without impacting B-cell development and maturation. 9 Sources: 2024 Cheung (Front Nephrol); 2023 Mathur (J Clin Med)

Selective APRIL inhibition resulted in numerically greater proteinuria reduction compared to dual APRIL/BAFF in Phase 3 IgAN trials UPCR Δ from baseline (%, W36) Sibeprenlimab Atacicept Δ -51% Δ -42% (p < 0.0001) (p < 0.0001) Placebo 2.1 Atacicept Sibeprenlimab N=95 N=152 N=103 Placebo N=168 -7 Studies enrolled a high-risk, global, IgAN patient population, similar to other pivotal studies. Active treatments were well tolerated with favorable safety -46 profiles comparable to placebo. -50.2 Notes: Cross-trial comparisons are inherently limited and presented for hypothesis-generating purposes only. Data digitized from graphs where publications did not provide specific values. 10 Sources: Perkovic et al. ERA 2025 (sibeprenlimab), ORIGIN 3 clinical trial (atacicept, NCT04716231)

Deeper APRIL suppression drives Sibeprenlimab Phase 2 Data superior clinical efficacy • Highest proteinuria reduction and rates of clinical remission (proteinuria <0.3 g/day) for sibeprenlimab were accompanied by the deepest levels of APRIL suppression. • Safety profile consistent across dose levels, with no increase in overall infections. • Sibeprenlimab Phase 3 dose approximates Phase 2 % patients < 0.3 g/day at 12M mid-dose, which did not capture the full efficacy 26% expected to be available to the mechanism of action 12% 7% 3% Placebo JADE101 has potential to more completely suppress APRIL, produce larger 2 mg/kg IV proteinuria reductions and maximize ΔUPCR (% at 36w) 4 mg/kg IV remission rates in significantly more 8 mg/kg IV 13% patients than other anti-APRIL programs in development. 50% 57% 63% 400 mg SC Phase 3 dose ~ equivalent dose (3.5 mg/kg IV) Note: Estimated sibeprenlimab Phase 3 dose (400 mg SC) based on average 85 kg IgAN patient (95% CI ~50-120 kg) and 75% bioavailability. SC – subcutaneous, IV – Intravenous 11 Source: 2023 Mathur (NEJM) PROTEINURIA APRIL

No clinical evidence that inhibiting BAFF provides additional efficacy beyond APRIL alone in IgAN Phase 2 clinical trials Sibeprenlimab Zigakibart Atacicept Povetacicept MoA anti-APRIL anti-APRIL TACI-Fc Engineered TACI-Fc Status Phase 3 Phase 3 Phase 3 Phase 3 IgA Gd-IgA1 UPCR IgA Gd-IgA1 UPCR IgA Gd-IgA1 UPCR IgA Gd-IgA1 UPCR Δ from baseline in critical disease markers 33% (W36 timepoint*) 53% 60% 60% 59% 64% 63% 64% 67% 65% 69% 69% N=79 (4/8 mg/kg pooled) N=35 (600 mg) N=32 (150 mg) N=9 (80 mg) ✓ ✓ ✓ ✓ GFR stabilization (1 year) (2 years) (2 years) (1 year) Hematuria ✓ ✓ ✓ ✓ resolution ✓ ✓ ✓ ✓ Safety Well-tolerated, no overall ↑ infections, Well-tolerated (no placebo), no drug Well-tolerated, slight ↑ in infections (& Well-tolerated (no placebo) slight ↑ in URTIs vs. placebo discontinuations URTIs) vs. placebo 240 mg ↑ infections Phase 3 Dosing 400 mg SC, Q4W 600 mg SC, Q2W 150 mg SC, QW 80 mg SC, Q4W Notes: Cross-trial comparisons are inherently limited and presented for hypothesis-generating purposes only. Zigakibart IgA / Gd-IgA data at W40; UPCR data at W52 (only timepoint available); change from baseline is not placebo-controlled; N represents patients on dose(s) for which data is shown. Atacicept infections/URTIs placebo - (32%/0%), 25 mg (38%/0%), 75 mg (49%/9%), 150 mg (39%/6%). 12 Povetacicept infection rates: Grade 1/2/≥3 – 80 mg 10%/5%/0%, 240 mg 18%/27%/3%. Sibeprenlimab infections/URTIs placebo - (55%/0%), 2 mg/kg (39.5%/8%), 4 mg/kg (56%/12%), 8 mg /kg (53%/5%). Sources: 2023 Mathur (NEJM); 2024 Barratt (ERA Presentation); VERA January 2024 R&D Day; ALPN 2024 WCN Investor Update; 2024 Madan (ASN Presentation)

BAFF inhibition is accompanied by the potential for significant long-term B cell depletion Long-term BAFF inhibition … whereas chronic APRIL inhibition significantly depletes B cells… does not impact circulating lymphocytes Zigakibart 9 Lymphocytes (10 /L) ~7-year belimumab data in SLE shows long-term BAFF inhibition lowers CD19+ B cells by ~80% Long-term BAFF suppression, in an otherwise young and healthy patient population, is unnecessary given equivalent efficacy in IgAN from anti-APRILs and TACI-Fcs observed to date. 13 Sources: 2022 Struemper (Lupus Sci Med);2025 Barratt (Kidney International)

Potentially best-in-class properties of JADE101 Ultra-high (fM) APRIL binding affinity Novel IP for composition • Binds APRIL to neutralize activity of matter into mid-2040s • Greater APRIL binding affinity than sibeprenlimab, zigakibart, povetacicept and atacicept De novo antibody discovery Half-life extension through campaign pursued to achieve fully- validated YTE Fc human, potentially best-in-class modification mAb • Longer exposure intended to maximize efficacy and reduce dosing frequency Effector-null human IgG1 Fc Notes; Paragon has filed provisional patent applications covering the subject matter of JADE101, which we have exclusively licensed from Paragon. No head-to-head clinical trials have been conducted between JADE101 and the referenced drug candidates. Cross-trial comparisons are inherently limited and presented for hypothesis-generating purposes only. 14 14 fM – femtomolar

JADE101 has femtomolar affinity and a slow off-rate that is superior to other anti-APRILs currently in development APRIL affinity by SPR is highly predictive of in vivo APRIL affinity by SPR is highly predictive of potency to lower serum IgA in humans in vivo potency to lower serum IgA in humans 1000 Ataci Ziga 100 Sibe 2 R = 0.9987 10 Pove 1 0.1 1 10 100 1000 EC (ηM) 50 Source: Internal data; Benchmarks manufactured based on publicly available sequences. Atacicept APRIL KD 672 pM (Vera internal data). IgA EC estimates calculated using compartmental PK models 50 linked to indirect response models to describe IgA kinetics built using published PK and IgA concentration-time profiles for each molecule. Sibeprenlimab: Mathur, 2022 and Zhang, 2023; Ziga: ASN, 15 2021/2022 and WCN, 2021; Povetacicept: Davies, 2024; Atacicept: Willen, 2020, Nestorov, 2008/2010, Munafo, 2007). These data are derived from different trials at different points in time, with differences in trial design and populations. As a result, cross-trial comparisons cannot be made, and no head-to-head clinical trials of JADE101 and other agents have been conducted. KD(pM)

JADE101 avoids high molecular weight complex formation High MW complex formation can occur with mAbs binding trimeric proteins, such as APRIL. Avoiding high MW complexes potentially mitigates risks of immunogenicity and target mediated drug disposition (TMDD). MW - molecular weight, mAbs – monoclonal antibodies 16 Source: Filbert et al. ERA 2025 (JADE101)

JADE101 exhibits a highly differentiated NHP PK/PD profile Accompanied by deep and prolonged IgA reduction >3X increased half-life compared to sibeprenlimab* in NHPs T ~27d 1/2 T ~7d 1/2 JADE101 has the potential to extend dosing interval through low clearance via half-life extension, target-mediated drug disposition mitigation & ultra-high (fM) human affinity. 17 *Sibeprenlimab generated from publicly available sequence. YTE-Sibe was engineered on the IgG1 framework. Confirmed ADA+ samples excluded. No head-to-head clinical trials have been conducted between JADE101 and the referenced drug candidates. NHP - Non-human Primates, IV – Intravenous

Phase 1 JADE101 healthy volunteer trial ongoing; interim, biomarker-rich clinical data expected in H1 2026 Phase 1 Study Design Endpoints Randomized, double-blind, placebo-controlled SAD study Primary SC administration in healthy adult volunteers (n=32) ● Safety and tolerability SC Dose 4: Secondary & Exploratory N = 6:2 ● Pharmacokinetics ● Pharmacodynamics (APRIL, IgA, immunoglobulins) ● Immunogenicity SC Dose 3: N = 6:2 Follow Up SC Dose 2: Half-life extended antibodies require extended follow up for N = 6:2 full characterization (~1-year) and provide exposures that exceed those observed in MAD studies with typical mAbs. SC Dose 1: N = 6:2 Depth and duration of APRIL inhibition anticipated to predict clinical activity, reflect disease-modifying potential, and define dose and dose interval for IgAN patient trials Notes: ClinicalTrials.gov ID: NCT07059312. Numbers presented as subjects receiving JADE101 relative to placebo. Each cohort to include a sentinel group, n = 2 (1 JADE101, 1 placebo); remainder dosed after safety clearance. 18 SAD – Single Ascending Dose, MAD – Multiple Ascending Dose, SC - Subcutaneous

PK, APRIL and IgA HV data will define the dose and Anticipated HV data potentially positions schedule designed to fully suppress APRIL throughout the dosing interval in IgAN patients. JADE101 for accelerated development in IgAN MOA Candidate Phase 1 Interim FIH Data Potential Indications ant anit-iAPR -APRI IL L JADE101 Ongoing 1H 2026 IgAN • Anti-APRIL MOA provides biomarker rich-data expected Healthy Volunteers (HV) to be predictive of clinical efficacy • Consistent PK/PD relationships in HV and IgAN patients PK APRIL IgA UPCR o HV PK highly predictive of IgAN PK and directly linked to APRIL suppression o HV IgA reduction expected to highly correlate with IgAN IgAN Patients IgA reduction o Early IgA response expected to highly correlate with future UPCR reduction in IgAN Sources: Zigakibart: (ASN 2021/2022 and WCN2021). Sibeprenlimab: Mathur 2022 (KI Reports) for Phase 1. Chan 2023 (KI Reports) for Phase 2 IgA; Mathur 2024 (NEJM) for Phase 2 UPCR. Povetacicept: Davies 2024 (Clin Transl Sci) for Phase 1. Madan 2024 (ASN) for Phase 2. Atacicept: Willen 2020 (European Journal of Drug Metabolism and Pharmacokinetics) for Phase 1. Zigakibart: Lo 2020 (ASN) for Phase 1. Barratt 2023 (ERA) for Phase 2 IgA, Barratt 2024 (ASN abstract) for Phase 2 UPCR. Floege 2024 (ERA) for Phase 2. Mezagitamab: December 2024 Takeda SEC from 6-K for Phase 2. 19 PD – pharmacodynamics, UPCR - urine protein-to-creatinine ratio

Biomarker-rich, directly translational HV data supports the potential to accelerate clinical development IgA reduction in HVs is highly correlated with IgA …and early IgA reduction further correlates with W36 UPCR reduction in IgAN patients at multiple time points… reduction, the anticipated endpoint for accelerated approval Healthy Volunteers IgAN Patients IgAN Patients vs wk2 wk4 wk6 wk4 2 2 wk8 R =0.79 R =0.86 wk2 wk2 wk4 wk4 wk2 wk2 wk4 wk4 wk4 wk4 wk4 wk6 wk6 wk8 wk8 wk8 wk8 HV IgA Δ from baseline (%) IgAN UPCR Δ from baseline (%, W36) Notes: Sibeprenlimab IgAN IgA reductions (LHS) are average of 4 mg/kg and 8 mg/kg cohorts (HV data is from 6 mg/kg cohort); the two cohorts saw effectively equivalent IgA reduction at W4 and W8. Zigakibart UPCR data is at 52W. Atacicept IgAN W8 is average of W4 and W12 datapoints. Trend lines are best linear fit. 20 Sources: 2022 Mathur (KI Reports); 2023 Mathur (NEJM); 2020 Lo (ASN Presentation); 2023 Barratt (ERA Poster); 2024 Barratt (ERA Presentation); 2022 Dillon (ASN Poster); 2024 Tumlin (WCN Presentation); Anthera 2017 10-K; 2024 Lafayette (KI Reports); 2024 Madan (ASN Presentation) IgAN IgA Δ from baseline (%) IgAN IgA Δ from baseline (%, W8)

Minimizing injection burden for patients is a critical advantage in lifelong IgAN treatment Reducing injection frequency is anticipated to be a valuable choice driver • IgAN typically affects young JADE101 Sibeprenlimab Atacicept Povetacicept Zigakibart adults who may require lifelong therapy Target APRIL APRIL APRIL + BAFF APRIL + BAFF APRIL • Fewer subcutaneous injections ease burden, improve Format mAb mAb Fc-fusion Fc-fusion mAb adherence, and give patients APRIL K (pM) 0.046 pM 34.7 pM 672 pM 0.89 pM 94.4 pM D more freedom Human T (days) TBD ~23 days ~6.7 days ~3.7 days ~20 days 1/2 • Dose and dose frequency Dose (mg) TBD 400 mg 150 mg 80 mg 600 mg driven by potency, half-life, and Anticipated to be Dose Frequency Q4W QW Q4W Q2W TMDD threshold Q8W+ Anticipated to be Volume 2ml 1ml 1ml 2 x 2ml 2ml With ultra-high affinity and Injections per year 6 injections or less 12 injections 52 injections 12 injections 52 injections extended half-life, JADE101 has potential to offer best-in- class efficacy with the fewest injections. Injections / 10 ≤ 60 120 520 120 520 years Source: Filbert et al. ERA 2025 (JADE101), Perkovic et al. ERA 2025 (sibeprenlimab), ORIGIN 3 clinical trial (atacicept, NCT04716231), Davies, 2024 21 (Povetacicept), Barratt et al. ERA 2025 (Zigakibart)

JADE201: afucosylated anti-BAFF-R mAb 22

JADE201, a potentially best-in-class afucosylated anti-BAFF-R mAb with dual MOA B cell depletion to treat autoimmune diseases • B cell depletion has proven effective in autoimmune disease, but existing therapies like rituximab and anti-CD19 agents face limits: Incomplete B cell Residual B cells in Resistance depletion due to low secondary lymphoid Sparing pathogenic mechanisms, target receptor tissues and/or autoantibody including increased expression on some B ineffective depletion producing cells, BAFF expression cell subsets or paucity of B cells in ectopic including plasmablasts following treatment of effector cells to lymphoid tissue after 3 with rituximab 1 2 mediate killing treatment • Resistance mechanisms, particularly elevated BAFF after anti-CD20 therapy, enable autoreactive B cells to repopulate, undermining durability • Ianalumab, an afucosylated anti-BAFF-R, provided proof-of-concept for overcoming these barriers, 4 including clinical tissue B cell depletion JADE201 builds on ianalumab’s proof-of-concept, adding HLE for expected improved durability, less frequent dosing, and potentially best-in-class profile. Sources: 1. Merino-Vico Euro J Immunol 2023; 2. Ramwadhdoebe Rheumatology 2019; 3. Daneshvar E Int J Derm 2023; 4. Cornec, ACR Convergence 2025. 23 HLE – half-life extension.

JADE201's dual MOA expected to deliver deeper, more durable B cell depletion B Cell Inhibition and Depletion by BAFF Starvation Direct Cytotoxicity via Enhanced Effector Function • Mechanism works in context of low receptor • Validated mechanism that induces rapid B cell expression depletion • Relevant in secondary and ectopic lymphoid • Enhanced cytotoxicity by ADCC tissues where effector cells may be scarce • Potent depletion of circulating B cells • Avoids B cell repopulation and resistance due to increased BAFF expression following B cell depletion with anti-CD20 agents ADCC – antibody-dependent cellular cytotoxicity 24

Potentially best-in-class properties of JADE201 Binds BAFF-R broadly expressed on B cells • Enhanced ADCC activity on B cells similar to ianalumab • Blocks BAFF activity similar to ianalumab HLE via Fc LS mutation • Predicted to match, with potential for improved clinical activity due to increased exposure compared to ianalumab with less Novel IP for COM into mid 2040s frequent dosing afucosylated for enhanced ADCC 25

JADE201 retains high BAFF-R binding affinity and functional activity in preclinical studies BAFF-R Binding (HEK Cells) BAFF-R Blockade (Competition ELISA) ADCC Activity – Primary human CD19+ B Cells Additional Attributes Similar Between Clones 3000 • Affinity to human/cyno BAFF-R by SPR 2000 Media • BAFF-R binding (Raji B cells) Vehicle (0.1% PBS) • FcR binding (excluding FcRn*) ianalumab 1000 JADE201 • C1q binding 0 • ADCC activity on Raji B cells 0 0 10 100 1000 10 100 1000 Antibody Concentration (pM) *LS mutation ~10x higher affinity to FcRn. Note: These data are derived from different studies at different points in time, with differences in methodology, design and 26 populations. As a result, cross-trial comparisons cannot be made, and no head-to-head clinical trials of JADE201 and other agents have been conducted. Live B cells (count)

JADE201 demonstrates deep B cell depletion in NHPs JADE201 PK BAFF-Receptor Occupancy B Cell Depletion PK Receptor Occupancy B Cell Depletion 1000000 120 140 0.001mg/kg 0.001mg/kg 100000 100 120 0.01mg/kg 0.01mg/kg 10000 80 0.1mg/kg 100 0.1mg/kg 1000 1mg/kg 60 80 1mg/kg 10mg/kg 100 40 10mg/kg 60 10 20 40 1 0 20 0.1 -20 0.01 0 -40 Timepoints Timepoints Time Post-Treatment JADE201 demonstrates dose-dependent PK. Rapid RO observed with complete RO achieved at doses above 1 mg/kg. Deep and sustained B cell depletion achieved after single dose of JADE201 in NHPs. Notes: ADA+ not yet ID and excluded. Accelerated recovery at 10 mg/kg v 1 mg/kg potentially related to ADA or hook effect. 27 Predose 8h 24h D2 D4 D7 D14 D21 D28 D35 D42 D49 D56 D63 D77 D91 D105 D119 -1h 10 min 1h 4h 8h 24h D2 D3 D4 D7 D10 D14 D18 D21 D28 D35 D42 D49 D56 -1hr 10min 1hr 4hr 8hr Day 1 Day 2 Day 3 Day 4 Day 7 Day 10 Day 14 JADE201 Concentration (ng/ml) BAFF RO on B Cells (% Mean±SEM) Mean (±SEM) B Cell Density (count/ul) CFB (%)

JADE201 demonstrates a differentiated NHP PK profile from ianalumab HLE has potential to provide sustained BAFF receptor >2X HLE demonstrated in NHPs occupancy and improved clinical response • Ianalumab has an observed human T ~ 10 1/2 days JADE201 NHP • JADE201 with HLE has the potential to provide t = 5.4 days 1/2 complete BAFF-R coverage for an extended duration • Potential for deeper, more durable clinical responses • Extended dosing interval providing a more t = 2.7 days 1/2 convenient, infrequent SC dosing profile Note: Individual NHP time points that appear to be impacted by ADA excluded from half-life determinations and mean concentration-time plots. These data are derived from different studies at different points in time, with differences in methodology, design and populations. As a result, cross-trial comparisons cannot be made, and No head-to-head 28 clinical trials of JADE201 and other agents have been conducted.

JADE201 first-in-human trial in rheumatoid arthritis patients on track to begin in H1 2026 Phase 1 Study Design Endpoints Primary Randomized, double-blind, placebo-controlled SAD study SC administration in adults (n=36) with rheumatoid arthritis. ● Safety and tolerability SC Dose 6: Secondary & Exploratory N = 5:1 SC Dose 5: ● Pharmacokinetics N = 5:1 ● Pharmacodynamics SC Dose 4: N = 5:1 ● Immunogenicity SC Dose 3: ● B-cell depletion N = 5:1 ● DAS28 SC Dose 2: N = 5:1 SC Dose 1: N = 5:1 JADE201 preclinical profile supports potential for best-in-class clinical efficacy with convenient, patient-friendly dosing Notes: Numbers presented as subjects receiving JADE201 relative to placebo. Each cohort to include a sentinel group, n = 2 (1 JADE201, 1 placebo); remainder dosed after safety clearance. 29 DAS – Disease Activity Score

JADE201 profile expected to enable broad opportunity in multiple indications, including potential best-in-class and first-in-class Rheumatology Neurology Gastroenterology • ANCA – Associated Vasculitis • Multiple Sclerosis • Autoimmune Hepatitis • Myasthenia Gravis • Primary Biliary Cholangitis • Autoimmune Myositis • Neuromyelitis Opica Spectrum • Rheumatoid Arthritis Disorder • Sjogren’s Disease* Nephrology Dermatology • Systemic Lupus Erythematosus* • Primary Membranous • Hidradenitis Suppurativa • Systemic Sclerosis * Nephropathy • Bullous Pemphigoid • Lupus Nephritis* • Pemphigus Hematology Endocrinology • Idiopathic Thrombocytopenic • Grave’s Disease Purpura (ITP)* • Thyroid Eye Disease • Warm AIHA* Approximately 17 million patients and a total addressable market of over $80bn across potential indications Source: GlobalData and other publicly available sources (2025 forecasted sales for approved systemic advanced therapies in US/EU5/JP). *Ianalumab ongoing 30 phase 3 study; Primary endpoint met in ianalumab Phase 3 studies in Sjogren’s Disease and ITP.

Pipeline beyond JADE101 & JADE201 31

Additional Jade programs expected to focus on best-in-class product profiles in high-value autoimmune indications Autoimmune Potentially best- Potential rapid Limited Jade team indications with in-class and path to clinical competition expertise significant best-in- PoC expected market indication opportunity product profile Evaluating additional opportunities to build pipeline of potentially best-in- class autoimmune therapies. 32

Jade Biosciences is advancing potentially best-in- class therapies for autoimmune diseases Additional financing totaling $135 million in gross proceeds supports cash runway into H1 2028 MOA Program Candidate Discovery IND-enabling Phase 1 Expected Milestones Potential Indications • Interim Data: JADE-001 JADE101 IgAN anti-APRIL 1H 2026 Multiple • Planned FIH: systemic AI JADE-002 JADE201 anti-BAFF-R 1H 2026 diseases • Planned FIH: 1H 2027 JADE-003 __ Undisclosed Undisclosed Development candidates from Paragon Candidates designed to maximize clinical responses and allow patient friendly, infrequent dosing Notes: Jade has entered into exclusive license agreements with Paragon Therapeutics for JADE101 and JAD2E01. Jade holds an exclusive option to license JADE- 33 003 from Paragon. Jade has not yet entered into a license agreement with respect to JADE-003.

Current capitalization Number of Shares* Common stock Shares outstanding 45,994,894 Preferred stock (as converted to 12,622,000 common stock) Common stock equivalents Pre-funded warrants 8,777,486 Common stock & common Total outstanding 67,394,380 stock equivalents *As of October 6, 2025 34

Thank you www.JadeBiosciences.com | info@jadebiosciences.com NASDAQ: JBIO