A study to assess the Efficacy and Safety of Efgartigimod IV in Adult Participants with Primary Immune Thrombocytopenia

Overview

Sponsor-declared trial summary

Key facts

Sponsor

Argenx

Participant type

Patients

Age range

18-64 years, 65+ years

Gender

Male and Female

Therapeutic area

Diseases [C] - Immune System Diseases [C20]

Trial duration

27 Feb 2025 → ongoing

Decision date (initial)

2025-01-29

Transition trial

No

Low-intervention

No

Rare-disease indication

Yes

Vulnerable population

Yes

Funding sources

argenx, BV

External identifiers

EU CT number

2024-515451-38-00

ClinicalTrials.gov

NCT06544499

Trial design

CTIS Part I — objectives, methods, condition coding

Main objective

Scope: Pharmacodynamic, Efficacy, Safety, Pharmacokinetic, Others

To evaluate the efficacy of efgartigimod IV compared with placebo IV in the extent of disease control

Secondary objectives 8

1. To evaluate the efficacy of efgartigimod IV compared with placebo IV in achieving sustained platelet count response
2. To evaluate the efficacy of efgartigimod IV compared with placebo IV in overall platelet count response
3. To evaluate the incidence and severity of bleeding in participants treated with efgartigimod IV compared with participants treated with placebo IV
4. To evaluate the use of rescue ITP therapy in participants treated with efgartigimod IV compared with participants treated with placebo IV
5. To evaluate the long-term efficacy of efgartigimod IV (including the OLTP1)
6. To evaluate the tolerability and safety of efgartigimod IV
7. To assess the immunogenicity of efgartigimod IV
8. To assess the pharmacokinetics (PK) and pharmacodynamics (PD) of efgartigimod IV

Conditions and MedDRA coding

Primary Immune thrombocytopenia (ITP)

Study design 3 periods

Regulatory references

Scientific advice from competent authorities

European Medicines Agency

Plan to share IPD

No

Eligibility criteria

Principal inclusion / exclusion criteria as submitted by sponsor

Inclusion criteria 6

1. Is at least 18 years of age and the local legal age of consent for clinical studies when signing the informed consent form (ICF).
2. Has documented baseline mean platelet count of <30 x 10^9/L before randomization
3. Has a documented duration of primary immune thrombocytopenia (ITP) of more than 12 months on the date of informed consent form (ICF) signature
4. Has documented prior ITP treatment with at least 1 of the following treatments: corticosteroids, intravenous immunoglobulin (IVIg), anti-D immunoglobulin (for participants who are nonsplenectomized and Rho(D)- positive), thrombopoietin receptor agonist (TPO-RAs), or rituximab
5. Has documented insufficient response to a prior ITP treatment with corticosteroids, IVIg, anti-D immunoglobulin (for participants who are nonsplenectomized and Rho(D)-positive), TPO-RAs, rituximab (the specific criteria can be found in the protocol).
6. Has documented prior response defined as 1 platelet count of ≥50 × 10^9/L to at least 1 of the following ITP treatments in the 3 years before the date of ICF signature: prednisone, dexamethasone, other or nonspecified corticosteroids, IVIg, or anti-D immunoglobulin (for participants who are nonsplenectomized and Rho(D)-positive).

Exclusion criteria 5

1. Other than the indication under study, known autoimmune disease or any medical condition that would interfere with an accurate assessment of clinical symptoms of ITP, confound the results of the study or put the participant at undue risk.
2. Secondary ITP
3. Nonimmune thrombocytopenia
4. Autoimmune hemolytic anemia
5. ITP-associated critical or severe bleeding

Endpoints

Primary and secondary outcome measures (English text)

Primary endpoints 1

1. Extent of disease control, defined as the number of cumulative weeks during the Double-Blinded Treatment Period with platelet counts of at least 50 × 10^9/L.

Secondary endpoints 30

1. Proportion of participants achieving platelet counts of at least 50 × 10^9/L for at least 4 of the 6 study visits between study weeks 19 and 24 of the DBTP
2. Proportion of participants achieving platelet counts of at least 50 × 10^9/L for at least 6 of the 8 study visits between study weeks 17 and 24 of the DBTP
3. Proportion of participants achieving platelet counts of at least 50 × 10^9/L for at least 8 of the 12 study visits between weeks 13 and 24 of the DBTP
4. Proportion of participants achieving a platelet count of at least 50 × 10^9/L on at least 4 occasions at any time until study week 12 during the DBTP
5. Time to response, defined as the time to achieve 2 consecutive platelet counts of at least 50 × 10^9/L at any time during the DBTP
6. Proportion of participants with an International Working Group (IWG) response during the DBTP
7. Proportion of participants with International Working Group (IWG) complete response during the DBTP
8. Proportion of participants with initial response, defined as a platelet count of at least 30 × 10^9/L and a 2-fold increase from baseline in platelet count at study week 5 of the DBTP
9. Time to achieve a platelet count of at least 30 × 10^9/L and a 2-fold increase from baseline in platelet count during the DBTP
10. Number of cumulative weeks during the DBTP with platelet counts of at least 30 × 10^9/L and ≥20 × 10^9/L above baseline
11. Number of cumulative weeks during the DBTP with platelet counts of at least 30 × 10^9/L and at least 20 × 10^9/L above baseline in participants with baseline platelet counts of <15 × 10^9/L
12. Extent of disease control, defined as the percentage of weeks with platelet counts of at least 50 × 10^9/L
13. In participants receiving placebo IV in the DBTP, the extent of disease control, defined as the number of cumulative weeks with platelet counts of at least 50 × 10^9/L, between weeks 13 and 24 of the OLTP1
14. Overall platelet count response, defined as the proportion of participants achieving a platelet count of at least 50 × 10^9/L on at least 4 occasions during the first 52 weeks of treatment with efgartigimod IV.
15. Mean change from baseline in platelet count at each study visit
16. The percentage of weeks with platelet counts of at least 30 × 10^9/L and at least 20 × 10^9/L above baseline
17. In participants with baseline platelet counts <15 × 10^9/L, the percentage of weeks with platelet counts of at least 30 × 10^9/L and at least 20 × 10^9/L above baseline
18. Proportion of participants who achieve a sustained platelet count response, defined as achieving platelet counts of at least 50 × 10^9/L for at least 4 occasions during 6-week intervals.
19. In participants receiving placebo IV in the DBTP, the proportion of participants achieving platelet counts of at least 50 × 10^9/L for at least 8 of the 12 study visits between weeks 13 and 24 of the OLTP1
20. In participants receiving placebo IV in the DBTP, the proportion of participants who achieve a sustained platelet count response, defined as achieving platelet counts of at least 50 × 10^9/L for at least 6 of the 8 study visits between weeks 17 and 24 of the OLTP1
21. In participants receiving placebo IV in the DBTP, the extent of disease control, defined as the number of cumulative weeks with platelet counts of at least 50 × 10^9/L during the first 24 weeks of treatment with efgartigimod IV
22. Occurrence rate of rescue ITP therapy
23. Proportion of participants with reduction in concurrent ITP therapy during the OLTP1
24. Incidence and severity of bleeding, assessed by the ITP Bleeding Scale (IBLS)
25. Incidence and severity of adverse events (AEs) (including AEs of clinical interest) and serious AEs.
26. Vital signs, laboratory safety measurements, physical examination
27. Incidence and prevalence of antidrug antibodies (ADA) against efgartigimod in serum over time
28. Incidence and prevalence of NAb against efgartigimod in serum over time
29. Efgartigimod Cmax and Ctrough over time
30. Percent change from baseline in total IgG levels in serum over time

Investigational products

Investigational medicinal products (IMPs), comparators, placebo, auxiliary

Test 2

Placebo 1

Sponsors and contacts

Sponsor organisations, regulatory contacts, third parties

Argenx

Sponsor organisation

Argenx

Address

Industriepark-Zwijnaarde 7

City

Gent

Postcode

9052

Country

Belgium

Scientific contact point

Organisation

Argenx

Contact name

Chief Scientific Officer

Public contact point

Organisation

Argenx

Contact name

Vice President Clinical Development

Third parties 15

Locations

14 EU/EEA countries · 57 investigational sites

By country

Investigational sites

Country notifications

Trial-start, recruitment-start, end and early-termination notifications submitted per Member State

Results and documents

Annex IV summary of results, Annex V layperson summary, and all documents registered in CTIS for this trial

Documents 206 files

Public protocol annexes, IB summaries, regulatory submissions and post-authorisation documents registered in CTIS.

Application history

30 submissions — initial application plus substantial / non-substantial modifications