Table of Contents
- What is CLR 131?
- Target Condition: Waldenstrom Macroglobulinemia
- Study Objectives
- Eligibility Criteria
- Treatment Details
- Measuring Success: Endpoints
- Safety Considerations
What is CLR 131?
CLR 131 is an innovative medication being studied for the treatment of Waldenstrom Macroglobulinemia (WM), a rare type of blood cancer. This drug, also known by its chemical name 18-(P-IODOPHENYL)OCTADECYL PHOSPHOCHOLINE, is classified as an orphan drug, which means it’s designed to treat rare diseases[1]. CLR 131 is administered as a sterile solution through an intravenous infusion, which means it’s given directly into your bloodstream through a vein[1].
Target Condition: Waldenstrom Macroglobulinemia
Waldenstrom Macroglobulinemia is a type of cancer that affects a specific kind of white blood cell called B lymphocytes or B cells. These cells normally help your body fight infections. In WM, these cells grow out of control and produce too much of a protein called IgM, which can make your blood thicker than normal[1].
Study Objectives
The main goal of the study is to determine how well CLR 131 works in patients with Waldenstrom Macroglobulinemia who have already tried at least two other treatments. Researchers are looking at something called the major response rate (MRR), which measures how many patients show significant improvement after receiving CLR 131[1].
Additionally, the study aims to:
- Determine how many patients respond to the treatment overall (overall response rate or ORR)
- Measure how long patients can go without needing additional treatment (treatment-free survival or TFS)
- Assess how long the positive effects of the treatment last (duration of response or DOR)
- Evaluate the overall benefit of the treatment (clinical benefit rate or CBR)
- Further understand the safety and side effects of CLR 131[1]
Eligibility Criteria
To participate in this study, patients must meet certain criteria. Some key requirements include:
- Confirmed diagnosis of Waldenstrom Macroglobulinemia
- Age 18 or older
- Have received at least two prior treatments for WM
- Be in relatively good overall health (ECOG performance status of 0 to 2, which means able to carry out daily activities with minimal assistance)
- Life expectancy of at least 6 months[1]
There are also several conditions that would prevent a person from participating in the study, such as ongoing severe side effects from previous treatments, certain types of prior radiation therapy, pregnancy or breastfeeding, and active infections[1].
Treatment Details
CLR 131 is given as an intravenous infusion. The maximum daily dose is 15 millicuries (mCi), which is a unit used to measure radioactivity. The total maximum dose over the entire treatment period is 60 mCi. The treatment period can last up to 22 days[1].
Measuring Success: Endpoints
The study uses several ways to measure how well CLR 131 works:
- Major Response Rate (MRR): This is the main measure of success. It looks at how many patients have a complete response (CR), very good partial response (VGPR), or partial response (PR) to the treatment within 12 months of receiving CLR 131[1].
- Overall Response Rate (ORR): This includes patients who have any level of positive response to the treatment[1].
- Treatment Free Survival (TFS): This measures how long patients can go without needing additional treatment after receiving CLR 131[1].
- Duration of Response (DOR): This looks at how long the positive effects of the treatment last[1].
- Clinical Benefit Rate (CBR): This includes all patients who have any level of positive response or stable disease after treatment[1].
Safety Considerations
As with any medical treatment, safety is a crucial concern. The study will closely monitor patients for any side effects or adverse events. This includes tracking:
- Any adverse events (AEs) that occur
- Serious adverse events (SAEs)
- Side effects that are grade 3 or higher (which means they are severe or life-threatening)
- Changes in laboratory test results, vital signs, and heart activity (via ECG)
- Changes in overall health status (using the ECOG performance status scale)[1]
It’s important to note that CLR 131 is still an experimental treatment. While it shows promise, more research is needed to fully understand its effectiveness and safety profile for patients with Waldenstrom Macroglobulinemia.



