Rituximab Clinical Trials

What Is Rituximab?

Rituximab is an FDA-approved medication for the treatment of certain B-cell non-Hodgkin's lymphomas, rheumatoid arthritis, Pemphigus Vulgaris, and Granulomatosis with polyangiitis/microscopic polyangiitis.

This drug is a genetically engineered chimeric murine/human monoclonal antibody. It works by targeting the CD20 antigen found on the surface of both normal and malignant B-lymphocytes. By binding to CD20, rituximab helps the immune system destroy these B cells, leading to their depletion.

In addition to its approved uses, rituximab is being investigated in clinical trials for a wide range of other conditions. These include various types of leukemia and lymphoma, Neuromyelitis Optica Spectrum Disorder (NMOSD), Post-transplant lymphoproliferative disorder (PTLD), Waldenström's macroglobulinemia (WM), and several autoimmune and inflammatory diseases.

Uses and Conditions Under Study

Rituximab is extensively studied for its role in treating various conditions, primarily those involving B-cells.

• Cancers of the Blood and Lymphatic System: Rituximab is a key treatment for many B-cell related cancers. It is being studied in 284 trials for Lymphoma, 106 trials for Chronic Lymphocytic Leukemia, 90 trials for Leukemia, 82 trials for Follicular Lymphoma, 80 trials for Mantle Cell Lymphoma, 76 trials for Non-Hodgkin's Lymphoma, 66 trials for Diffuse Large B-Cell Lymphoma, and 44 trials for Small Lymphocytic Lymphoma. Its mechanism of depleting CD20-positive B-cells is central to its effectiveness in these malignancies.
• Autoimmune and Inflammatory Conditions: The drug's ability to reduce B-cell populations makes it valuable in diseases where B-cells produce harmful autoantibodies. This includes 69 trials for Rheumatoid Arthritis, and studies for Neuromyelitis Optica Spectrum Disorder (NMOSD), Multiple Sclerosis (MS), Systemic Lupus Erythematosus (SLE), Myasthenia gravis, and Anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis. Other conditions under investigation include Chronic cold agglutinin disease, Autoimmune retinopathy, Atopic Dermatitis, Sjögren's Syndrome, Opsoclonus-myoclonus syndrome, Chronic Focal Encephalitis, and Idiopathic pulmonary fibrosis.
• Transplant-Related Complications: Rituximab is explored for preventing or treating complications after organ and stem cell transplants. This includes Post-transplant lymphoproliferative disorder (PTLD), Chronic Graft-versus-Host Disease (GVHD), and reducing the risk of organ rejection by targeting alloantibodies.
• Kidney Disorders: Studies are also evaluating rituximab for various kidney conditions, such as Nephrotic syndrome (including steroid-dependent, frequently relapsing, idiopathic membranous nephropathy, and recurrent focal segmental glomerulosclerosis).
• Other Blood Disorders: Rituximab is also studied for Hairy Cell Leukemia, Waldenström's macroglobulinemia, Aplastic anemia, Pure red cell aplasia, Diamond Blackfan anemia, Common Variable Immunodeficiency, Sickle Cell Disease, and β-Thalassemia.
• Other Conditions: Research is ongoing for its use in Acute myocardial infarction (MI), Hypersensitivity pneumonitis, and Hepatitis C associated cryoglobulinemic vasculitis.

Dosing

Rituximab is primarily administered as an intravenous infusion. The specific dose and frequency can vary depending on the condition being treated and whether it is an approved or investigational use.

A commonly studied dose is 375 mg/m^2 (milligrams per square meter of body surface area), often given weekly for several weeks or as a single dose. Other intravenous doses investigated include 1000 mg, sometimes administered in two doses, or 100 mg weekly for four consecutive weeks. Some studies explore higher or lower doses, such as 500 mg, 1 g/6 months, or 200 mg/6 months.

In addition to intravenous administration, subcutaneous forms of rituximab have also been studied, with doses like 1400 mg, 375 mg/m^2, 625 mg/m^2, and 800 mg/m^2. These are typically given in combination with chemotherapy regimens.

Rituximab is also being investigated for use in pediatric participants for conditions such as nephrotic syndrome and other lymphomas, with specific dosing regimens tailored for children.

Side Effects

The most commonly reported side effect for Rituximab was diarrhea, experienced by 24.2% of patients taking Rituximab, compared to 18.1% on placebo. Other common side effects reported in clinical trials include:

• Pyrexia (fever): 19.9% of patients on Rituximab experienced this, compared to 15.5% on placebo.
• Upper respiratory tract infection: This occurred in 18.5% of patients taking Rituximab, versus 10.9% on placebo.
• Rash: 14.9% of patients on Rituximab developed a rash, compared to 10.0% on placebo.
• Cough: 14.7% of patients taking Rituximab reported a cough, compared to 14.2% on placebo.
• Nasopharyngitis (common cold): This was observed in 13.7% of patients on Rituximab, versus 9.9% on placebo.
• Headache: 12.6% of patients taking Rituximab experienced headaches, compared to 11.3% on placebo.

Some events such as neutropenia, nausea, fatigue, anemia, and constipation were reported with similar or lower frequency in patients taking Rituximab compared to placebo, suggesting they may not be directly caused by the drug itself.

Clinical Trial Results

Non-Hodgkin's Lymphoma

A study (NCT00001337) investigated Rituximab in combination with EPOCH chemotherapy (EPOCH-R) for previously untreated aggressive Non-Hodgkin's Lymphoma, comparing it to EPOCH chemotherapy alone. In this trial, 235 participants received EPOCH-R, and 112 participants received EPOCH alone.

• Overall Response: The overall response rate (complete response plus partial response) was 91.9% for patients treated with EPOCH-R, compared to 83.9% for those receiving EPOCH alone.
• Progression-Free Survival (PFS): Progression-free survival was observed in 31.1% of patients treated with EPOCH-R, while 36.6% of patients on EPOCH alone experienced progression-free survival.
• Discontinuation Due to Adverse Events: The proportion of participants who discontinued therapy due to adverse events was 3% in the EPOCH-R group, compared to 4% in the EPOCH alone group.

Another study (NCT00004031) evaluated different regimens including CHOP/CHOP-R for Non-Hodgkin's Lymphoma. This trial compared a regimen of CHOP/CHOP-R followed by a single autologous stem cell transplant to three cycles of CHOP/CHOP-R chemotherapy.

• 2-Year Overall Survival Rates: Patients receiving CHOP/CHOP-R with one autologous stem cell transplant had a 2-year overall survival rate of 73.7%. For those receiving three cycles of CHOP/CHOP-R, the 2-year overall survival rate was 71.1%.
• 2-Year Progression-Free Survival: The 2-year progression-free survival rate was 69.1% for the CHOP/CHOP-R with one autologous stem cell transplant group, compared to 55.4% for the group receiving three cycles of CHOP/CHOP-R.

Currently Recruiting Trials

Rituximab is an established therapy, and research continues to explore its potential in new combinations and conditions. Currently, there are 264 trials actively recruiting patients to investigate Rituximab, either alone or in combination with other treatments.

• One Phase 1/2 trial, NCT06965114, is testing the combination of tovorafenib plus Rituximab in patients with recurrent or refractory hairy cell leukemia. This study, sponsored by the National Cancer Institute, aims to enroll 84 participants.
• For relapsed or refractory primary central nervous system lymphoma (PCNSL), a Phase 3 study, NCT07104032, is comparing tirabrutinib alone against a combination of Rituximab and temozolomide. This trial, sponsored by Ono Pharmaceutical Co., Ltd., plans to enroll 132 participants.
• In pediatric patients with immune thrombocytopenia (ITP), two Phase 2 trials are underway. NCT07362238 compares daratumumab with Rituximab, targeting 122 participants. Another study, NCT07234019, evaluates Rituximab combined with an anti-CD38 monoclonal antibody versus Rituximab alone, aiming for 160 patients. Both are sponsored by the Institute of Hematology & Blood Diseases Hospital, China.
• A Phase 2 trial, NCT07365306, is investigating epcoritamab in combination with Rituximab, gemcitabine, and oxaliplatin (R-GemOx) as salvage therapy before autologous stem cell transplant for relapsed/refractory diffuse large B-cell lymphoma. City of Hope Medical Center is sponsoring this study, with an enrollment target of 43 patients.
• For patients with rheumatoid arthritis, a Phase 4 study, NCT06906549, is evaluating 200 mg of Rituximab every 6 months as maintenance treatment compared to 1g every 6 months. This trial, sponsored by University Hospital, Strasbourg, France, seeks to enroll 260 participants.
• A Phase 2 study, NCT05099471, is assessing the efficacy of venetoclax in combination with Rituximab for Waldenström's macroglobulinemia, with an enrollment target of 80 patients.

Where to Participate

Clinical trials involving Rituximab are being conducted across a wide geographical area, with 1331 sites in 546 cities and 51 states. This broad reach ensures that many patients have access to potential new treatments.

The top recruiting locations include:

• Boston, Massachusetts (44 sites)
• New York, New York (44 sites)
• Las Vegas, Nevada (34 sites)
• Houston, Texas (29 sites)
• St Louis, Missouri (26 sites)
• Columbus, Ohio (26 sites)
• Seattle, Washington (24 sites)
• Des Moines, Iowa (21 sites)
• Portland, Oregon (19 sites)
• Chicago, Illinois (18 sites)

Eligibility for these studies is broad, accepting participants aged 0-130 years, of all genders, including healthy volunteers and children.

Development Timeline

The journey of Rituximab in clinical research began on November 4, 1999, with the first trial. Since then, a robust pipeline of research has led to a total of 2053 trials, enrolling over 253,277 participants.

Initial investigations explored Rituximab for conditions like IBS-C and hyperphosphatemia, but its development quickly expanded to target a wide array of B-cell related malignancies and autoimmune diseases. The largest number of studies, 950, have been conducted in Phase 2, focusing on efficacy and safety, followed by 367 Phase 3 trials, which compare new treatments to existing standards.

Leading the charge in Rituximab research are key sponsors such as M.D. Anderson Cancer Center with 136 trials, Hoffmann-La Roche with 114, and the National Cancer Institute (NCI) with 83 studies. The drug's therapeutic scope has significantly broadened over time, now encompassing conditions like various lymphomas (Follicular Lymphoma, Mantle Cell Lymphoma, Diffuse Large B-Cell Lymphoma), leukemias (Acute Lymphoblastic Leukemia, Chronic Lymphocytic Leukemia), and autoimmune disorders such as Rheumatoid Arthritis, Systemic Lupus Erythematosus, and Immune Thrombocytopenia. The latest recorded trial is set to conclude on May 29, 2026, highlighting ongoing commitment to advancing Rituximab's therapeutic applications.