Freeline Therapeutics Holdings Plc

Freeline Therapeutics — Technical Presentation (October 2023)

28 slides from Freeline Therapeutics's technical presentation, Oct 6, 2023

1. Slide 1: FLT201: Initial Clinical Data

   FLT201: Initial Clinical Data October 6, 2023

2. Slide 2: Legal disclaimer

   Legal disclaimer This presentation contains statements that constitute “forward looking statements” as that term is defined in the United States Private Securities Litigation Reform Act of 1995, including statements that express the opinions, expectations, beliefs, plans, objectives, assumptions or

3. Slide 3: Creating better gene therapies for chronic debilitating diseases

   Creating better gene therapies for chronic debilitating diseases Potential first- and Compelling initial clinical data best-in-class lead program Robust enzyme activity and favorable Highly differentiated gene therapy safety and tolerability in first two candidate FLT201 for Gaucher disease patients

4. Slide 4: Lead clinical program with first- and best-in-class potential

   Lead clinical program with first- and best-in-class potential with research extending innovation into larger disease area Indication Approximate Research Preclinical Phase 1/2 Phase 3 Worldwide patient # rights Gaucher Wholly owned Disease Type 1 ~18K $1B-plus peak sales potential FLT201 GBA1-linked

5. Slide 5: FLT201 in Gaucher Disease

   FLT201 in Gaucher Disease

6. Slide 6: Gaucher disease type 1 is a debilitating, chronic and progressive disorder

   Gaucher disease type 1 is a debilitating, chronic and progressive disorder with life-altering symptoms Deficiency of GCase enzyme needed Affects multiple organs, leading to wide range of to metabolize Gb-1 in the lysosome symptoms and shortening life span1 Normal GCase GCase function deficiency Redu

7. Slide 7: Existing therapies poorly address certain aspects of disease

   Existing therapies poorly address certain aspects of disease LENGTHY INFUSION PEAKS AND TROUGHS in enzyme levels between EVERY TWO WEEKS infusions allow harmful substrates to build back up Easier to reach organs: liver, spleen ERT Enzyme replacement Harder to reach therapy current standard organs: b

8. Slide 8: Despite treatment with ERT, many patients continue to have disease progression

   Despite treatment with ERT, many patients continue to have disease progression and debilitating symptoms After 10+ years on ERT up to 60% still experience symptoms1 bone pain enlarged liver enlarged spleen low blood counts 68% have pulmonary dysfunction at 43% 56% 61% 43% baseline with most likely n

9. Slide 9: SRT offers an oral treatment option, but tolerability, compliance and perceived lack of efficacy limit its use

   SRT offers an oral treatment option, but tolerability, compliance and perceived lack of efficacy limit its use In study of 1388 patients who were either on SRT or ERT: Substrate reduction 36% 80% therapy (SRT) represents less than 20% of patients on SRT switched to or went back to ERT cited adverse

10. Slide 10: FLT201 has potential to deliver continuous level of enzyme and penetrate deeper tissues

    FLT201 has potential to deliver continuous level of enzyme and penetrate deeper tissues that existing therapies do not reach SINGLE DOSE Potent liver-directed AAVS3 capsid Easier to reach GCase organs: liver, spleen variant 85 with prolonged half-life = more enzyme available to be delivered to cell

11. Slide 11: Our engineered GCase variant has substantially longer half-life than wildtype

    Our engineered GCase variant has substantially longer half-life than wildtype Key features of GCase variant 85 structure GCase variant Two internal amino acid substitutions W312C E235 A341C • Does not impinge on the active site E340 20-fold increase in half-life in lysosomal • Minimizes 3D structura

12. Slide 12: FLT201 shows high and durable GCase expression in non-human primates

    FLT201 shows high and durable GCase expression in non-human primates Plasma 10000 Achieved steady increases in GCase Male (n=3) plasma levels GCase Activity (nmol/h/ml) 1000 Female (n=3) • A single injection of FLT201 was well tolerated 100 • Additional data from this study shows durable 10 expressi

13. Slide 13: FLT201 demonstrated uptake in key tissues in Gaucher mice

    FLT201 demonstrated uptake in key tissues in Gaucher mice Untreated 600 2x1011 vg/kg 500 Leukocytes are GBA1var85 2x1012 vg/kg 400 a marker of GCase activity (% relative to WT) broad cellular 300 uptake 200 100 Normal Leukocytes Spleen Bone Marrow Lung Data represented as mean ± SD. n= 9 to 16 per t

14. Slide 14: FLT201 demonstrates persistent coverage, while ERT is rapidly eliminated

    FLT201 demonstrates persistent coverage, while ERT is rapidly eliminated Untreated ERT ERT GBA1var85 (1h post-dose) (24h post-dose) (steady state) Spleen Bone marrow Lung Anti-GCase – DAB, Haematoxylin counterstain, AAV8 ERT=Velaglucerase alfa 14

15. Slide 15: FLT201 demonstrates superior substrate elimination vs. ERT in all key tissues in Gaucher mice

    FLT201 demonstrates superior substrate elimination vs. ERT in all key tissues in Gaucher mice Hexosylsphingosine (pmol/mg) Hexosylsphingosine (pmol/mg) 10 Liver 10 Spleen 8 8 6 6 4 4 2* **** 2 **** **** * * * * * 0 * W 0 2x101 2x101 2x101 ER 0 WT 0 2x1010 2x1011 2x1012 ERT T 0 1 AAV8-FLT201 2 T AAV8

16. Slide 16: Patient 1 and Patient 2 Data

    Patient 1 and Patient 2 Data

17. Slide 17: GALILEO-1 Phase 1/2 dose-finding trial design

    GALILEO-1 Phase 1/2 dose-finding trial design First-in-human, open-label, multicenter study Establish a dose that Patient population: delivers sustained Adults with Gaucher Highest Dose Type 1 previously Higher Doses increases in treated with ERT or SRT 1.1e13 vg/kg GCase activity to Higher Dose If

18. Slide 18: Baseline patient characteristics

    Baseline patient characteristics PATIENT 1 PATIENT 2 Dose (vg/kg) 4.5 x 1011 4.5 x 1011 Absolute dose (vg) 2.835 x 1013 2.84 x 1013 Gaucher therapy at baseline ERT SRT Age 35 25 Gender Male Male Body weight 63kg 63.1kg Plasma GCase activity (µmol/L/h) 0.07 0.014 DBS GCase activity (µmol/L/h) 0.3 0.3

19. Slide 19: FLT201 has been well-tolerated with clean safety profile to date

    FLT201 has been well-tolerated with clean safety profile to date • Infusion well tolerated • No SAEs • All treatment-related AEs were Grade 1 and resolved without intervention • No ALT and AST elevations • Patient 1 through 13 weeks • Patient 2 through 6 weeks As of Sept. 27, 2023 data cutoff. 19

20. Slide 20: Patient 1: Robust increases in plasma GCase activity

    Patient 1: Robust increases in plasma GCase activity >700-fold over Patient 1 treated at dose of 4.5e11 vg/kg baseline 80 70 Plasma GCase Activity (micromol/L/h) 60 50 40 30 20 10 NORMAL PLASMA GCASE ACTIVITY: 0.3-1.2 micromol/L/h (mean: 0.6 micromol/L/h) 0 Baseline Dosing Day 5 Week 1 Week 2 Week 3

21. Slide 21: Patient 1: Similarly robust increases in DBS GCase activity

    Patient 1: Similarly robust increases in DBS GCase activity Patient 1 treated at dose of 4.5e11 vg/kg 40 35 DBS GCase Activity (micromol/L/h) 30 25 20 15 10 5 NORMAL DBS GCASE ACTIVITY: > 1.5 micromol/L/h 0 Dosing Day 5 Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 W

22. Slide 22: Patient 1: Normalization of leukocyte GCase activity demonstrates cellular uptake

    Patient 1: Normalization of leukocyte GCase activity demonstrates cellular uptake from plasma Patient 1 treated at 4.5e11 vg/kg dose 6 Leukoctye GCase Activity (nmol/h/mg prot) 5 4 NORMAL LEUKOCYTE GCASE ACTIVITY: ≥ 3.5 nmol/h/mg 3 2 1 0 Dosing Week 1 Week 3 Week 4 Week 5 Week 7 Week 8 Week 9 Week 1

23. Slide 23: Patient replicates increases in plasma GCase activity seen in patient 1

    Patient 2 replicates increases in plasma GCase activity seen in patient 1 >300-fold Patient 2 treated at dose of 4.5e11 vg/kg over baseline 35 30 Plasma GCase Activity (micromol/L/h) 25 20 15 10 5 NORMAL PLASMA GCASE ACTIVITY: 0.3-1.2 micromol/L/h (mean: 0.6 micromol/L/h) 0 Dosing Day 3 Week 1 Week

24. Slide 24: Patient 2: Similarly robust increases in DBS GCase activity

    Patient 2: Similarly robust increases in DBS GCase activity Patient 2 treated at dose of 4.5e11 vg/kg 10 DBS GCase Activity (micromol/L/h) 8 6 4 2 NORMAL DBS GCASE ACTIVITY: > 1.5 micromol/L/h 0 Baseline Dosing Day 3 Week 2 Week 3 Week 4 Week 5 Patient taken off SRT at week 5 As of Sept. 27, 2023 da

25. Slide 25: Patient 2: Normalization of leukocyte GCase activity demonstrates cellular uptake

    Patient 2: Normalization of leukocyte GCase activity demonstrates cellular uptake, consistent with patient 1 Patient 2 treated at 4.5e11 vg/kg dose 5 Leukoctye GCase Activity (nmol/h/mg prot) 4 NORMAL LEUKOCYTE GCASE ACTIVITY: ≥ 3.5 nmol/h/mg 3 2 1 0 Screening Day 3 Week 4 Week 5 Patient taken off S

26. Slide 26: Expeditiously advancing development of FLT201

    Expeditiously advancing development of FLT201 Dosing Patient 3 in cohort 1 given compelling enzyme activity and favorable safety Three additional patients identified and in scheduling; more patients in screening Awarded ILAP designation in UK, providing enhanced regulatory interactions Plan to apply

27. Slide 27: Key takeaways

    Key takeaways Initial first-in-human clinical data demonstrate several hundred-fold increase in plasma GCase activity FLT201 is a Normalization of leukocyte GCase potential first-and provides evidence of cellular uptake best-in-class gene therapy for Favorable safety and tolerability profile Gaucher

28. Slide 28: Thank you

    FISEELI\E Thank you

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