CASI Pharmaceuticals' CID-103 Shows 73% Response Rate in Phase 1 Immune Thrombocytopenia Trial
Key Insights
CASI Pharmaceuticals reported promising interim results from its Phase 1 study of CID-103, an anti-CD38 (search) monoclonal antibody, achieving the primary efficacy endpoint in 73% of immune thrombocytopenia (search) patients.
The study demonstrated a manageable safety profile with only two Grade 3 treatment-related events and no dose-limiting toxicities across dose levels from 30 mg to 900 mg.
Complete response was achieved in 75% of responding patients, with platelet improvements observed as early as one week post-dose, supporting further development in autoimmune disorders.
CASI Pharmaceuticals announced encouraging interim results from its Phase 1 dose-escalation study of CID-103, a potentially best-in-class anti-CD38 (search) monoclonal antibody, in patients with immune thrombocytopenia (search) (ITP (search)) at the 67th American Society of Hematology Annual Meeting. The study achieved its primary efficacy endpoint in 8 of 11 patients (73%), demonstrating significant therapeutic potential for this autoimmune blood disorder.
Strong Efficacy Signal in Refractory Patients
The open-label Phase 1 study enrolled adult patients with primary ITP (search) who had received at least two previous lines of treatment and maintained mean platelet counts ≤ 35 x 10⁹/L. The primary efficacy endpoint was defined as achieving a platelet count ≥ 50 x 10⁹/L and ≥ 20 x 10⁹/L above baseline on at least two consecutive measurements at least seven days apart within the first twelve weeks of treatment.
Of the eight patients who achieved the primary endpoint, six (75%) demonstrated complete response with platelet improvement observed as early as one week post-dose. This rapid onset of action represents a notable clinical advantage in managing this challenging condition.
Dose Escalation and Safety Profile
The study evaluated sequential dose-escalating cohorts receiving intravenous infusions of CID-103 at 30 mg (n=1), 150 mg (n=1), 300 mg (n=3), 600 mg (n=3), and 900 mg (n=3). Each patient received a priming dose of either 30 mg or 150 mg prior to their assigned cohort dose.
CID-103 demonstrated a manageable safety profile across all dose levels, with only two Grade 3 treatment-related events and no dose-limiting toxicities observed. All infusion-related reactions occurred with the priming dose and were attributed to low-grade adverse events, suggesting the treatment regimen can be optimized for patient comfort.
Mechanism of Action Validation
The study provided important validation of CID-103's presumed mechanism of action through pharmacodynamic marker analysis. Researchers observed reduction in anti-platelet antibodies, immunoglobulins, NK cells, and plasma cells, which correlated with the observed platelet response. This mechanistic understanding supports the therapeutic rationale for targeting CD38 (search) in autoimmune conditions.
"We are pleased with the safety and tolerability of CID-103 and encouraged by the 73% of patients achieving the primary efficacy endpoint," said Alex Zukiwski, M.D., Global Chief Medical Officer of CASI. "Importantly, this study provides important clinical proof of concept supporting further development of CID-103 in autoimmune disorders, solid organ transplant rejection (search), and other CD38 (search) mediated diseases with large unmet medical need."
Study Design and Regulatory Status
The multicenter study incorporated both accelerated escalation and standard 3+3 design elements, with adaptive features including potential intra-patient dose escalation and dose expansion as determined by the Safety Monitoring Committee. The protocol allows for enrollment of up to approximately 30 adults between ages 18 and 65.
The study operates under FDA-approved IND status and a Clinical Trial Application approved by the Chinese Center for Drug Evaluation, enabling development in both U.S. and Chinese markets.
Broader Development Program
CID-103 is a fully human IgG1 monoclonal antibody that targets a unique CD38 (search) epitope and has demonstrated encouraging preclinical efficacy and clinical safety profiles compared to other anti-CD38 antibodies. CASI holds exclusive global rights to the compound and has received FDA IND clearance for a separate Phase 1 study in renal allograft antibody-mediated rejection (search).
The company is also exploring subcutaneous formulation development through assessment of multiple technologies for creating stable, high-concentration protein solutions, which could improve patient convenience and treatment accessibility.