Viridian Therapeutics : Subcutaneous IGF-1R program selection Presentation

Subcutaneous IGF-1R Program Selection

December 18, 2023

Cautionary note regarding forward-looking statements

This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may be identified by the use of words such as, but not limited to, "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "might," "plan," "potential," "predict," "project," "should," "target," "will," or "would" or other similar terms or expressions that concern our expectations, plans and intentions. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on our current beliefs, expectations, and assumptions. Forward-looking statements include, without limitation, statements regarding: the therapeutic potential and utility, efficacy and clinical benefits of VRDN-003 for Thyroid Eye Disease (TED); the expected exposure levels of VRDN-003; the safety profile of VRDN- 003; the potential dosing frequency for VRDN-003; trial designs, clinical development plans and timing for VRDN-003, including the global pivotal clinical trials of VRDN-003 in active and chronic TED patients; the expected attractiveness of VRDN-003 and convenience for patients; and anticipated work with regulatory authorities.

New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements. Such forward-looking statements are subject to a number of material risks and uncertainties including but not limited to: the potential efficacy and safety of VRDN-001,VRDN-002, and VRDN-003 for the treatment of TED; the potential for VRDN-006 and VRDN-008; the relationship between the results from the positive data from completed or ongoing clinical trials and the results of ongoing or future clinical trials; the timing, progress and plans for our ongoing or future research, pre-clinical and clinical development programs; trial protocols for ongoing clinical trials; expectations regarding the timing for IND filings; expectations regarding the timing for enrollment and data; uncertainty and potential delays related to clinical drug development; the duration and impact of regulatory delays in our clinical programs; the timing of and our ability to obtain and maintain regulatory approvals for our therapeutic candidates; manufacturing risks; competition from other therapies or products; estimates of market size; other matters that could affect the sufficiency of existing cash, cash equivalents and short-term investments to fund operations; our financial position and its projected cash runway; our future operating results and financial performance; the clinical utility of our therapeutic candidates and our intellectual property position; the timing of pre-clinical and clinical trial activities and reporting results from same, including those risks set forth under the caption "Risk Factors" in our Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (SEC) on November 13, 2023 and other subsequent disclosure documents filed with the SEC. The forward-looking statements in this presentation represent our views as of the date of this presentation. Neither we, nor our affiliates, advisors, or representatives, undertake any obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date of this presentation.

This presentation also contains estimates and other statistical data made by independent parties and by us relating to market size 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 addition, 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 uncertainty and risk.

2

Subcutaneous VRDN-003 selected and anticipated to advance to pivotal trials in TED in mid-2024

VRDN-003 sets a potential new bar for best-in-class product in TED based on Phase 1 HV study

• Extended half-life:VRDN-003half-life exceeds expectations at 40-50 days
• • 4-5xincrease compared to its parent VRDN-001, significantly longer than first-generationanti-IGFRs including teprotumumab and lonigutamab
  • VRDN-003IGF-1 increases at peak match VRDN-001 and demonstrates potential superiority to other disclosed data from IGF-1R antibodies
  • Showed substantially prolonged durability of elevated IGF-1 levels compared to VRDN-001
• Convenient dosing: Dosing interval as long as Q8W is predicted to achieve clinically meaningful exposures
• Best-in-classpatient experience expected: Anticipated 2mL low-volume (≥150mg/mL concentration), self-administered injection
• Safety profile consistent with best-in-classprofile: VRDN-003 was well tolerated with no SAEs or ADAs to date

VRDN-003 to leverage VRDN-001 IV experience to enable anticipated rapid and de-risked global pivotal development

• Expedited regulatory path potential: Next steps expected to be two pivotal trials in patients with active and chronic TED
• Optimized for speed to market: Global pivotal program expected to begin in mid-2024 pending alignment with regulators

VRDN-003 poised to enter a multi-billion-dollar TED market with a potentially best-in-class SC profile

All data regarding third-party products in this presentation are based on third-party studies and not our own. Conclusions are not based on head-to-head clinical trial results.

3 Source: Viridian clinical data on file. ADAs = antidrug antibodies, HV = healthy volunteers, IGF-1R = insulin-like growth factor-1 receptor, IV = intravenous, Q8W = once every eight weeks, SAEs = serious adverse

events, SC = subcutaneous, TED = thyroid eye disease.

VRDN-003 is nearly identical to its parent VRDN-001 and has a 4-5x extended half-life

VRDN-003VRDN-001

VRDN-003 has half-life engineering via clinically validated, 3 amino acid (YTE) modification in Fc region

VRDN-001 & VRDN-003 are nearly identical

Differ in YTE change in Fc domain to enable extended half-life

4 Source: Viridian data on file.

Thyroid eye disease represents a large market opportunity with potential for growth

Annualized

Revenues ($)

~$1.8B1

Opportunities for growth

• Continued penetration into the active US TED market
• Growth into chronic TED market
• Market expansion from subcutaneous
• Ex-USopportunity

2023 IGF-1R IV

Validated MoA

• IGF-1Rinhibition has demonstrated robust clinical efficacy in TED
• Anti-IGF-1Ris the only approved targeted therapy in TED

Potential for differentiation

• Teprotumumab has eight-dose IV regimen
• Other mAbs lack extended half-life
• Small molecules risk off-target effects

5 1 Tepezza sales were $453M in Q3 2023.

IGF-1R = insulin-like growth factor-1 receptor, IV = intravenous, mAbs = monoclonal antibodies, MoA = Mechanism of Action, SC = subcutaneous, TED = thyroid eye disease.

Later-entrant SC therapies have the potential to significantly displace incumbent IV and grow market

IV to SC with same molecule

85% of IV market converted in 2 years1

Target: CD38

• IV Launch: Nov 2015 by J&J for multiple myeloma
• SC Launch: May 2020 by J&J
• Post-SCSales Growth: 2X annual sales post- SC launch1

IV to SC with new SC entrant

30% of new prescriptions converted in 3 years2

Target: CD20

• IV Launch: Mar 2017 by Roche for multiple sclerosis
• SC Launch: Aug 2020 by Novartis
• Post-SCSales Growth: 2x combined CD20 sales post-KesimptaSC launch3,4

	Significant opportunity for a long-acting and convenient subcutaneous anti-IGF-1R therapy
6	1.https://www.fiercepharma.com/pharma/jjs-switch-iv-subcutaneous-darzalex-85-complete-us,2. Novartis 2022 Q4 results, 3. Roche Earnings, 4. Novartis Q3 2023 Earnings;
IGF-1R = insulin-like growth factor-1 receptor, IV = intravenous, SC = subcutaneous, TED = thyroid eye disease.

Phase 1 clinical trials in healthy volunteers for VRDN-003,VRDN-002, and VRDN-001

COHORT:

1

Low Dose

2

3

High Dose

4

5

Multi-Dose

VRDN-003 HV (N=34)

Single dose of SC 300 mg

VRDN-003 (n=6), placebo (n=2)

Single dose of IV 5.0 mg/kg

VRDN-003 (n=4), placebo (n=2)

Single dose of SC 600 mg

VRDN-003 (n=6), placebo (n=2)

Single dose of IV 15.0 mg/kg

VRDN-003 (n=4), placebo (n=2)

Repeat dose of SC 600 mg/300 mg

VRDN-003 (n=4), placebo (n=2); data pending

VRDN-002 HV (N=16)

COHORT:

1	Single dose of SC 300 mg
VRDN-002 (n=8)
2	Single dose of IV 3.5 mg/kg
VRDN-002 (n=8)

VRDN-001 HV (N=16)

COHORT:

1	Single dose of SC 300 mg
VRDN-001 (n=8)
2	Single dose of IV 3.5 mg/kg
VRDN-001 (n=8)

7 Source: Viridian data on file. HV = healthy volunteers, IV = intravenous, SC = subcutaneous.

Phase 1 healthy volunteer study pharmacokinetics and pharmacodynamics

VRDN-003 Phase 1 Pharmacokinetics (PK)

VRDN-003 Phase 1 Pharmacodynamics (PD)

	100
(μg/mL)	10
Concentration	1
Drug

VRDN-001 300 mg VRDN-002 300 mg

VRDN-003 300 mg VRDN-003 600 mg

Lonigutamab 250 mg

Change from Baseline IGF-1

6

4

2

VRDN-001 300 mg SC

VRDN-002 300 mg SC

VRDN-003 300 mg SC

VRDN-003 600 mg SC

Placebo

No public

lonigutamab IGF-1

data available

0.1

0

20	40	60	80	100
	Time (Days)

Fold

0

0	20	40	60	80	100
		Time (Days)

VRDN-003half-life is 4-5xVRDN-001

VRDN-003 demonstrated superior IGF-1 increases relative to

VRDN-002 and was sustained relative to VRDN-001

VRDN-003 shows potential best-in-class PK/PD and superior profile compared to all disclosed IGF-1R antibodies

All data regarding third-party products in this presentation are based on third-party studies and not our own. Conclusions are not based on head-to-head clinical trial results.

8 Source: 1. Viridian clinical data and modeling on file, 2. Keenan et al. NANOS 2023, 3. Xin et al., Clinical PK, 2021, 4. Pappos et al. Cancer 2014. IGF-1 = insulin-like growth factor 1, SC = subcutaneous.

VRDN-003 was well tolerated in healthy volunteers

	VRDN-003 (Cohorts 1-4)	VRDN-002	VRDN-001
	IV (n=8)		SC (n=12)	Placebo	IV (n=8)	SC (n=8)	IV (n=8)	SC (n=8)
		(n=8)
Treatment-Related AEs	--		3 (25%)	--	1 (12.5%)	--	3 (37.5%) **	3 (37.5%)
Muscle Spasms	--		--	--	--	--	1 (12.5%)	--
Headaches	--		--	--	1 (12.5%)	--	3 (37.5%)	--
Injection Site Reactions (ISRs) *	--		1 (8%)	--	--	--	--	1 (12.5%)
Hyperglycemia	--		--	--	--	--	--	1 (12.5%)
Thrombocytopenia	--		--	--	--	--	--	1 (12.5%)
Insomnia	--		1 (8%)	--	--	--	--	--
Hepatic Enzyme Increased	--		1 (8%)	--	--	--	--	--
Severe Adverse Events (SAEs)	--		--	--	--	--	--	--
Hearing Impairment *	--		--	--	--	--	--	--
Grade 3/4 Aes	--		--	--	--	--	--	--
Anti-Drug Antibodies (ADAs)							Low ADAs detected after
	None were detected		None were detected	Day 43 with no
							neutralizing antibodies

• No treatment discontinuations
• No hearing AEs
• All treatment-related AEs were grade 1 (mild) or grade 2 (moderate), no SAEs
• • VRDN-003:all grade 1
  • VRDN-002:all grade 1
  • VRDN-001:all grade 1 and grade 2
• Hyperglycemia and ISRs all resolved within the follow up period

* Injection Site Reactions and Hearing Impairment each includes multiple MedDRA terms.

9 ** One participant experienced both muscle spasm and headache and was only counted once in this row of total AEs, for the headache which was at a higher grade of 2; one additional participant experienced a grade 2 headache. AEs = Adverse Events, IV= intravenous, SAEs = serious adverse events, SC = subcutaneous.

VRDN-001 IV clinical experience informs exposures of VRDN-003 expected to lead to clinical responses

Concentration (μg/mL)

250

200

150

100

50

0

VRDN-001 IV Pharmacokinetics

20 mg/kg IV

Cmin

(20 mg/kg IV)

10 mg/kg IV

Cmin

(10 mg/kg IV)

3 mg/kg IV

Cmin

(3 mg/kg IV)

• 20 mg/kg IV exposure range (Cmin to Cavg)

• 10 mg/kg IV exposure range (Cmin to Cavg)

• THRIVE and THRIVE-2 dosing

• 3 mg/kg IV exposure range (Cmin to Cavg)

* VRDN-001 IV PK based on 5 doses and 15 weeks.

10 Source: Viridian clinical data and modeling on file. IV = intravenous.