TransCon CNP ACcomplisH Trial Topline Results

TransCon CNP ACcomplisH Trial Topline Results November 14, 2022 TransCon CNP is an investigational

product candidate. For investor communication only. Not for use in product promotion. Not for further distribution.

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purposes for which they are being investigated. Ascendis, Ascendis Pharma, the Ascendis Pharma logo, the company logo, and TransCon are trademarks owned by the Ascendis Pharma group. November 2022 Ascendis Pharma A/S. TransCon CNP is an

investigational product candidate. 2 For investor communication only. Not for use in product promotion. Not for further distribution.

Executive Summary In the Phase 2 ACcomplisH Trial in children with achondroplasia aged 2-10, once-weekly TransCon CNP demonstrated the potential to meet patient and caregiver needs for a safe, effective, tolerable, and convenient treatment The primary endpoint, annualized height velocity (AHV)

at Week 52, demonstrated superiority of TransCon CNP at 100 g/kg/week compared to placebo (p=0.0218) TransCon CNP was generally well tolerated with low frequency of injection site reactions; all 57 randomized children continued, with

the longest treatment duration beyond two years Data showed robust and consistent results in prespecified analyses across age groups and dose levels, supporting continued development at the selected dose of 100 g/kg/week ANCOVA model.

Data on file, Ascendis Pharma 2022. 3 TransCon CNP is an investigational product candidate. For investor communication only. Not for use in product promotion. Not for further distribution.

TransCon CNP: Phase 2 Trial Design Key Secondary/Additional Endpoints Change in body proportionality

Patient reported outcome (PRO) measures Exploratory biomarkers evaluated TransCon CNP is an investigational product candidate. For investor communication only. Not for use in product promotion. Not for further

Demographics and Baseline Characteristics TransCon CNP TransCon CNP TransCon CNP TransCon CNP Total Total 6

g/kg/week 20 g/kg/week 50 g/kg/week 100 g/kg/week TransCon CNP Placebo n=10 n=11 n=10 n=11 n=42 n=15 Age (years) Mean (SD) 6.5 (2.6) 6.3 (2.9) 5.2 (3.0) 5.8 (2.6) 6.0 (2.7) 5.9 (3.1) Median 6.8 7.3 4.7 5.4 5.6 4.9 (Min,

Max) (2.3, 10.7) (2.7, 11.0) (2.1, 10.1) (2.1, 9.9) (2.1, 11.0) (2.4, 11.0) Age Group (years) n (%) < 5 years 3 (30.0) 5 (45.5) 5 (50.0) 3 (27.3) 16 (38.1) 8 (53.3) 5 years 7 (70.0) 6 (54.5) 5 (50.0) 8 (72.7) 26 (61.9) 7 (46.7) Sex

n (%) Female 7 (70.0) 3 (27.3) 3 (30.0) 6 (54.5) 19 (45.2) 5 (33.3) Male 3 (30.0) 8 (72.7) 7 (70.0) 5 (45.5) 23 (54.8) 10 (66.7) Race n (%) White 8 (80.0) 10 (90.9) 8 (80.0) 10 (90.9) 36 (85.7) 12 (80.0) Other 2 (20.0) 1 (9.1) 2 (20.0)

1 (9.1) 6 (14.3) 3 (20.0) TransCon CNP is an investigational product candidate. 5 Data on file, Ascendis Pharma 2022. For investor communication only. Not for use in product promotion. Not for further distribution.

Demographics and Baseline Characteristics (continued) TransCon CNP TransCon CNP TransCon CNP TransCon CNP Total

Total 6 g/kg/week 20 g/kg/week 50 g/kg/week 100 g/kg/week TransCon CNP Placebo n=10 n=11 n=10 n=11 n=42 n=15 Height (cm) Mean (SD) 90.63 (8.97) 92.29 (12.10) 86.61 (12.97) 89.23 (12.82) 89.74 (11.61) 90.85 (14.92)

Median 90.25 93.70 84.70 90.23 90.08 89.70 (Min, Max) (73.70, 101.77) (78.20, 111.17) (72.10, 105.87) (69.40, 111.53) (69.40, 111.53) (70.47, 113.37) Height SDS* Mean (SD) -5.45 (1.05) -4.87 (0.67) -4.85 (0.80) -4.92 (0.83) -5.02 (0.85)

-4.85 (0.96) Median -5.80 -4.66 -5.14 -4.64 -5.12 -4.69 (Min, Max) (-6.56, -3.92) (-6.15, -4.10) (-6.03, -3.66) (-6.16, -3.74) (-6.56, -3.66) (-6.73, -3.32) Height SDS,

ACH-Specific** Mean (SD) -0.20 (0.70) 0.28 (0.68) 0.21 (0.67) 0.11 (0.77) 0.11 (0.70) 0.43 (0.91) Median -0.36 0.28 0.09 0.02

0.02 0.65 (Min, Max) (-1.31, 0.66) (-0.89, 1.21) (-0.55, 1.46) (-1.16, 1.33) (-1.31, 1.46) (-1.18, 2.08) * CDC 2000 Stature-for-Age Charts,

https://www.cdc.gov/growthcharts/data_tables.htm, accessed 13 Nov 2022. ** Hoover-Fong JE, Schulze KJ, Alade AY, et al. Growth in achondroplasia including stature, weight,

weight-for-height and head circumference from CLARITY. Orphanet J Rare Dis. 2021;16(1):522. TransCon CNP is an investigational product candidate. 6 Data on file,

Ascendis Pharma 2022. For investor communication only. Not for use in product promotion. Not for further distribution.

TransCon CNP 100 g/kg/week Demonstrated Superiority in AHV Compared to Placebo Treatment Group p-value TransCon CNP Placebo (TransCon CNP AHV (cm/year), n (TransCon CNP vs. Dose Levels LS Mean [95% CI] Pooled Placebo) or Placebo) 4.09, n=10 6 g/kg/week 0.6004 AHV [3.34, 4.84] (cm/year) 4.52, n=11 20

g/kg/week 0.7022 [3.82, 5.22] 5.16, n=10 50 g/kg/week 0.0849 [4.43, 5.90] 5.42, n=11 100 g/kg/week 0.0218 [4.74, 6.11] 4.35, n=15 Pooled Placebo NA [3.75, 4.94] TransCon CNP demonstrated a dose-response in AHV across the four

dose groups ANCOVA model. TransCon CNP is an investigational product candidate. 7 Data on file, Ascendis Pharma 2022. For investor communication only. Not for use in product promotion. Not for further distribution.

Comparable AHV Across Age Groups Age <5 years old Age 5 years old Treatment Group (TransCon CNP Dose

Levels AHV (cm/year), n AHV (cm/year), n or Placebo) LS Mean, [95% CI] LS Mean, [95% CI] 4.31, n=3 3.79, n=7 6 g/kg/week [2.52, 6.10] [2.87, 4.71] 4.72, n=5 4.29, n=6 20 g/kg/week [3.30, 6.15] [3.43, 5.15] 5.07, n=5 5.33, n=5 50

g/kg/week [3.62, 6.52] [4.39, 6.26] 5.95, n=3 5.12, n=8 100 g/kg/week [4.03, 7.87] [4.35, 5.90] 4.53, n=8 4.29, n=7 Pooled Placebo [3.43, 5.63] [3.44, 5.14] Consistent dose-dependent treatment effect across age groups ANCOVA

model. TransCon CNP is an investigational product candidate. . For investor communication only. Not for use in product promotion. 8 Data on file, Ascendis Pharma 2022 Not for further distribution.

TransCon CNP 100 g/kg/week Demonstrated Superiority in Change in

ACH-Specific Height SDS Compared to Placebo p-value TransCon CNP Placebo Treatment Group Height SDS*, n (TransCon CNP (TransCon CNP Dose LS Mean

[95% CI] vs. Pooled Levels or Placebo) Placebo) Height -0.04, n=10 6 g/kg/week 0.8207 SDS [-0.26, 0.17] 0.03, n=11 20 g/kg/week

0.4107 [-0.17, 0.23] 0.11, n=10 50 g/kg/week 0.1660 [-0.10, 0.32] 0.22, n=11 100 g/kg/week 0.0283 [0.02, 0.41]

-0.08, n=15 Pooled Placebo NA [-0.25, 0.10] TransCon CNP demonstrated a dose-dependent improvement in ACH-specific height SDS

across all dose groups * Hoover-Fong JE, Schulze KJ, Alade AY, et al. Growth in achondroplasia including stature, weight, weight-for-height and head circumference from

CLARITY. Orphanet J Rare Dis. 2021;16(1):522. ANCOVA model TransCon CNP is an investigational product candidate. 9 Data on file, Ascendis Pharma 2022. For investor communication only. Not for use in product promotion. Not for further distribution.

Safety Results Summary (Double-Blind Period) TransCon CNP was generally well tolerated, with no

discontinuations Frequency of TEAEs in each dose group was similar to placebo No serious AEs (SAEs) related to treatment were reported Two unrelated SAEs were reported (febrile convulsion and viral infection) 95% of

TransCon CNP patients and 93% of placebo patients reported TEAEs 95% of TransCon CNP TEAEs were assessed as mild (Grade 1) in severity Injections were generally well tolerated with low frequency of injection site reactions No

reported events of symptomatic hypotension For body proportionality, induced growth was proportional across all groups at Week 52 Observed safety results support continued development of TransCon CNP for children with achondroplasia TEAE :

Treatment emergent adverse event TransCon CNP is an investigational product candidate. 10 Data on file, Ascendis Pharma 2022. For investor communication only. Not for use in product promotion. Not for further distribution.

Overview of TEAEs (Double-Blind Period) TransCon CNP TransCon CNP TransCon CNP TransCon CNP Total 6

g/kg/week 20 g/kg/week 50 g/kg/week 100 g/kg/week Placebo (n=10) (n=11) (n=10) (n=11) (n=15) Subjects with TEAEs* 9 (90.0) 11 (100.0) 10 (100.0) 10 (90.9) 14 (93.3) Grade 1 (mild) 9 (90.0) 11 (100.0) 10 (100.0) 9 (81.8)

14 (93.3) Grade 2 (moderate) 3 (30.0) 3 (27.3) 3 (30.0) 1 (9.1) 5 (33.3) Serious TEAEs 1 (10.0) 0 1 (10.0) 0 0 Treatment-Related TEAEs 3 (30.0) 2 (18.2) 3 (30.0) 2 (18.2) 5 (33.3) Achondroplasia-Related TEAEs** 3 (30.0) 4 (36.4) 5 (50.0) 1 (9.1) 9

(60.0) * No reported Grade 3 (severe) or Grade 4 (life-threatening) TEAEs. **Adverse events reported by investigator as related to underlying disease. TransCon CNP is an investigational product candidate. 11 Data on file, Ascendis Pharma 2022. For

investor communication only. Not for use in product promotion. Not for further distribution.

Treatment-Related Adverse Events (Double-Blind Period) TransCon CNP TransCon CNP TransCon CNP TransCon CNP

Total 6 g/kg/week 20 g/kg/week 50 g/kg/week 100 g/kg/week Placebo (n=10) (n=11) (n=10) (n=11) (n=15) Subjects with at Least One 3 (30.0) 2 (18.2) 3 (30.0) 2 (18.2) 5 (33.3) Treatment-Related TEAE Injection site reactions

(ISRs)* 2 (20.0) 1 (9.1) 3 (30.0) 2 (18.2) 2 (13.3) Abdominal pain upper 0 1 (9.1) 0 0 0 Overdose 0 0 0 0 1 (6.7) Dizziness 0 0 0 0 1 (6.7) Sleep terror 0 0 0 0 1 (6.7) Urticaria 1 (10.0) 0 0 0 0 Injections were generally well tolerated with low

frequency of injection site reactions 11 mild ISRs (in 8 patients) out of >2,000 injections * Injection site reactions includes preferred terms of Injection site reaction, Injection site pain, TransCon CNP is an investigational product candidate.

Injection site erythema, Injection site discolouration, Injection site haemorrhage, and Injection site swelling. For investor communication only. Not for use in product promotion. 12 Data on file, Ascendis Pharma 2022. Not for further distribution.

Open Label Extension (OLE) Efficacy and Safety Results* 57 of 57 patients completed the blinded period

of ACcomplisH and continued in the OLE on 100 g/kg/week with 100% retention Patients treated 6 months at 100 g/kg/week in the blinded or OLE period demonstrated a consistent and sustained response with mean AHV of 5.39

cm/year (n=40) TransCon CNP continued to be well tolerated in the OLE period with safety results consistent with those observed in the blinded period for all patients Open-label extension data confirms target product profile for once-weekly

TransCon CNP 100 g/kg/week * Preliminary ACcomplisH Trial live database snapshot as of October 27, 2022. TransCon CNP is an investigational product candidate. 13 Data on file, Ascendis Pharma 2022. For investor communication only. Not

for use in product promotion. Not for further distribution.

Next Steps IND submitted for ApproaCH, a global Phase 2b trial in 80 children with achondroplasia aged 2-11; enrollment targeted for completion in early 2023 TransCon CNP 100 g/kg/week vs. Placebo (2:1) End of Phase 2 meetings with FDA and EMA planned Plan to file IND or similar for

TransCon CNP in infants (age 0-2) Plan to file IND or similar for a combination trial with TransCon hGH and TransCon CNP Expand global reach with finalizing trial in China* and initiating trial

in Japan TransCon CNP and TransCon hGH are investigational product candidates. 14 * Conducted by VISEN Pharmaceuticals. For investor communication only. Not for use in product promotion. Not for further distribution.

Thank you Company contact: Tim Lee Senior Director, Investor Relations tle@ascendispharma.com (650) 374-6343 TransCon CNP is an investigational product candidate. For investor communication only. Not for use in product promotion. Not for further distribution.