DARZALEX + DARZALEX FASPRO - Use in Immune Thrombocytopenia

SUMMARY

• DARZALEX for intravenous (IV) use and DARZALEX FASPRO for subcutaneous (SC) use are not approved by the regulatory agencies for the treatment of patients with immune thrombocytopenia (ITP). Johnson & Johnson does not recommend the use of DARZALEX or DARZALEX FASPRO in a manner that is inconsistent with the approved labeling.
• DART is a phase 2 study evaluating the efficacy and safety of DARZALEX FASPRO in adult patients with ITP who have not responded adequately or relapsed after corticosteroids and at least one second-line therapy including rituximab and/or thrombopoietin receptor agonist (TPO-RA).^1,2 
  • Tsykunova et al (2026)¹ reported the updated safety and efficacy results of the study at a median follow-up of 10.4 months. Response to treatment was achieved in 48% of patients (95% confidence interval [CI], 25.7-70.2). The most common treatment-related adverse event was infusion-related reaction (IRR; 14.3%) and the most common treatment-emergent adverse event (TEAE) was infection (38%).
• Chen et al (2026)³ reported the results of a phase 2 study evaluating the efficacy and safety of DARZALEX in patients with persistent or chronic ITP. The primary endpoint was achieved by 82.5% of patients. The most common adverse events (AEs) were IRR (32%) and infection (32%).
• Strüßmann et al (2024)⁴ reported a case series of 7 patients with refractory ITP treated with DARZALEX FASPRO. A total of 4 patients showed complete remission, 2 patients showed no sustained response, and 1 patient showed no response.
• Strüßmann et al (2024)⁵ reported a retrospective case series of 6 consecutive patients with primary or secondary ITP who received DARZALEX between 2020 and 2024. Four patients responded to treatment, whereas 1 patient did not respond to 4 applications and withdrew from the study. One patient is still under treatment.
• Several case reports and analyses of patients with ITP who received DARZALEX or DARZALEX FASPRO are referenced below.^6-19
• Retrospective cases evaluating the use of DARZALEX or DARZALEX FASPRO for autoimmune cytopenias, refractory ITP, or warm autoimmune hemolytic anemia and refractory autoimmunity before or after allogeneic hematopoietic stem cell transplantation are referenced below.^20-23
• A study exploring high-affinity autoreactive plasma cells in patients with ITP treated with DARZALEX is referenced below.²⁴

CLINICAL DATA

DART (NCT04703621) is a phase 2, open-label, multicenter study evaluating the efficacy and safety of DARZALEX FASPRO in adult ITP patients who have not responded adequately or relapsed after corticosteroids and at least one second-line therapy including rituximab and/or TPO-RA.^1,2

Study Design/Methods

• Key inclusion criteria: age ≥18 years, primary ITP, platelet count ≤30 x 10⁹/L, failed corticosteroid therapy and at least 1 second-line therapy including rituximab and/or TPO-RA; for the safety run-in phase, platelet count of 15-30 x 10⁹/L was required.¹
• In the safety run-in phase, DARZALEX FASPRO 1800 mg SC was administered weekly (QW) for 4 weeks.¹
• In the dose-increasing phase of the study, patients received the following treatment¹:
  • Cohort 1: DARZALEX FASPRO 1800 mg SC QW for 8 weeks.
  • Cohort 2: DARZALEX FASPRO 1800 SC QW for 8 weeks, then every 2 weeks (Q2W) at weeks 10 and 12.
• Premedications included diphenhydramine 50 mg or equivalent, acetaminophen 1000 mg, methylprednisolone 100 mg or equivalent (before first injection; decreased to 60 mg for subsequent injections), and montelukast 10 mg (before first injection). Methylprednisolone 20 mg or equivalent was administered for 2 consecutive days as a post-medication after the first 3 doses of DARZALEX FASPRO.¹
• Primary endpoint: response (2 consecutive platelet counts of ≥50 x 10⁹/L measured ≥24 hours apart, assessed at least 4 weeks after the last dose of DARZALEX FASPRO).¹
• Secondary endpoints: sustained response, duration of response, time to treatment failure, number of bleeding episodes per patient.¹

Updated Efficacy and Safety Analysis of the DART Study

Tsykunova et al (2026)¹ reported the updated safety and efficacy results of the study at a median follow-up of 10.4 months (range, 5.3-34.8).

Results

Patient Characteristics

• The median follow-up for cohort 1 was 15.4 months (range, 5.5-29.2) and for cohort 2 was 8.0 months (range, 5.3-15.2).¹
• A total of 21 patients were enrolled between January 2021 and September 2023. Baseline characteristics are summarized in Table: Select Patient Characteristics.¹

Efficacy

• The primary endpoint was met in 10/21 patients (48%; 95% CI, 25.7-70.2) as summarized in Table: Treatment Responses.¹

• Eighteen patients (86%) achieved a platelet count of ≥50 x 10⁹/L at least once; the median time to first platelet count ≥50 x 10⁹/L was 7 days (range, 6-10).¹
• Sustained response (2 consecutive platelet counts of ≥50 x 10⁹/L measured ≥24 hours apart at week 24) was achieved in 8 patients (38%; 95% CI, 18.1-61.6).¹
• At the end of the study, 6 patients (29%) maintained response without additional ITP-directed treatments.¹

Safety

• At least 1 treatment-related AE occurred in 9 patients (43%) as summarized in Table: Treatment-Related Adverse Events.¹

• The most common treatment-related AE was IRR (14%); all were related to the first injection and resolved within 24 hours.¹
• The most common TEAE was infection (38%).¹
• No patients discontinued study treatment.¹

Phase 2 Study of DARZALEX in Patients with Persistent or Chronic ITP

Chen et al (2026)³ reported the results of a phase 2, open-label, single-arm study evaluating the efficacy and safety of DARZALEX in patients with persistent or chronic ITP.

Study Design/Methods

• Key inclusion criteria: age ≥18 years, diagnosis of chronic or persistent ITP, platelet count <30 x 10⁹/L, documented failure of first-line glucocorticoid therapy and at least 1 second-line therapy (including thrombopoietic agents or anti-CD20 monoclonal antibodies), completion of previous therapy ≥2 weeks before DARZALEX initiation.³
• Key exclusion criteria: secondary forms of ITP, history of venous/arterial thromboembolism within 12 months, clinically significant organ dysfunction.³
• DARZALEX 16 mg/kg IV was administered QW for 8 weeks.³
• Prophylactic medications included glucocorticoids (methylprednisolone 100mg or equivalent after first and second infusions; 60mg or equivalent for subsequent infusions; 20 mg for the 2 consecutive days after the first and second infusions), antihistamines, acetaminophen, and antiviral prophylaxis.³
• Rescue therapies were permitted if patients had inadequate response or clinically significant bleeding.³
• Primary endpoints: proportion of patients with ≥2 consecutive platelet counts of ≥50 x 10⁹/L separated by at least 1 day, within 8 weeks of initiating DARZALEX; incidence and severity of AEs.³
• Key secondary endpoints: overall response, complete response (CR), partial response (PR), durable sustained platelet response.³

Results

Patient Characteristics

• A total of 63 patients were enrolled between December 2022 and August 2024. Baseline characteristics are summarized in Table: Select Baseline Characteristics.³

Efficacy

• The primary efficacy endpoint was achieved by 52 patients (63%) as summarized in Table: Treatment Responses.³

• The median platelet count was 135.5 x 10⁹/L (interquartile range [IQR], 63.5-195.8) at week 8 and 101 x 10⁹/L (IQR, 52-159) at week 24.³
• By week 24, 52 patients (83%) remained free of bleeding events and 11 patients (17%) had a World Health Organization (WHO) bleeding score of 1.³
• During the study, 22 patients (35%) required rescue interventions.³

Safety

• The most common AE was IRR (32% [n=20]), which occurred most frequently during the first DARZALEX administration.³
• Infection was reported in 20 patients (32%), most commonly upper respiratory tract infection (24% [n=15]).³
• There were 5 grade 3 events in 4 patients (pulmonary infection [n=2], urinary tract infection [n=1], gastrointestinal bleeding [n=1], and right subclavian vein thrombosis [n=1]).³
• No grade 4 or 5 events occurred.³

Case Series of Patients with Refractory ITP Treated with DARZALEX FASPRO

Strüßmann et al (2024)⁴ reported the largest case series with the longest patient follow-up of 7 patients with refractory ITP treated with DARZALEX FASPRO.

• DARZALEX FASPRO was administered at a dose of 1800 mg SC QW.⁴
• One patient had 4 lines of prior therapy, all others had ≥5 lines of prior therapy. The patient characteristics and outcomes are presented in Table: Patient Characteristics and Outcomes.⁴

Case Series of Patients with ITP Treated with DARZALEX FASPRO

Strüßmann et al (2024)⁵ retrospectively evaluated a case series of 6 consecutive patients with ITP who received DARZALEX FASPRO between 2020 and 2024.

• Of these 6 patients, 4 patients had primary ITP and 2 patients had secondary ITP.⁵
  • One patient with mantle cell lymphoma and 1 patient with hairy cell leukemia, both were in complete remission of the hematological disease with persistent, refractory ITP.
• The median age of the patients was 61 years (range, 32-87).⁵
• One patient had 4 prior lines of therapy (LOT), with the other 5 patients receiving ≥5 LOT. All patients had rituximab exposure.⁵
• DARZALEX FASPRO was administered at a dose of 1800 mg SC, and the application varied between 4 to 12 times.⁵
• Four patients responded to treatment, whereas 1 patient did not respond to 4 administrations and withdrew from the study.⁵
  • Of the 4 patients who responded, time to response (platelet count >50.000/μl) was 1, 3, 4 and 10 weeks after treatment onset.
• One patient is still under treatment.⁵
• The duration of responses are 36, 19, 18 and 9 months. All responses are ongoing with no further treatment.⁵

Literature Search

A literature search of MEDLINE^®, Embase^®, BIOSIS Previews^®, Derwent Drug File (and/or other resources, including internal/external databases) was conducted on 16 June 2026.