The CLOVER-1 clinical trial is exploring the safety and efficacy of CLR 131 in patients previously treated for B-cell malignancies.
Patients with multiple myeloma may have new hope in CLR 131, an investigational therapy that is currently being studied in clinical trial.
Unlike some other types of cancer therapies, CLR 131, which is produced by Cellectar Biosciences, Inc., is given in just two doses. The phase 2 CLOVER-1 study is still enrolling patients across 10 sites in the United States to examine how well the therapy works in those with B-cell malignancies.
In an interview with CURE®, Dr. Laura Finn, director of Bone Marrow Transplant at Ochsner Medical Center in New Orleans, Louisiana, discussed the risk versus reward and side effects of this therapy, and what it means for patients with multiple myeloma.
CURE®: What type of drug is CLR 131, and how does it work?
Finn: CLR 131 is a very unique drug. It falls into a category of radioactive substances because everything else that we have had in this arena has been antibody bound. It’s a way to deliver radiation to the cancer cells and to deliver radiation with the intent to be delivered to the cancer cell itself with very little radiation to (healthy) cells around it. This is usually done by antibodies, so CLR 131 is an investigational cancer therapy. Instead of being bound to an antibody, what it’s bound to will recognize the lipid structure that is in the membrane of cancer cells.
It has to be delivered in a treatment center and, in our center, it is done in nuclear medicine — this would be the same place patients go to get PET scans — because it has to be done by physicians who are used to handling radiation. It’s an IV infusion and patients get two doses, and that’s it. There is also an option to get a repeat dose 85 days after the first treatment if there is a good response or partial response to the first dose.
What have clinical trials shown in patients with multiple myeloma regarding response rates, progression-free survival and overall survival?
We are still investigating this. The CLOVER-1 trial is enrolling many types of B-cell malignancies, which myeloma falls into a loose category of B-cell malignancies. We are waiting for the study to accrue so we can answer these questions. The study will enroll 80 patients across all the disease types and 41 patients have been treated so far.
Who is eligible for the CLOVER-1 clinical trial?
Patients must be 18 or older. It’s for patients of different lymphoma types, so multiple myeloma, chronic lymphocytic leukemia, small lymphocytic lymphoma, lymphoplasmacytic lymphoma, marginal zone lymphoma, mantle cell lymphoma and diffuse large B-cell lymphoma. Patients should also have normal blood counts and organ function. And for most of these diagnoses, they have to have had at least two prior therapies.
Why should patients join a clinical trial?
Clinical trials are standard of care. We have guidelines, and most of us follow the National Comprehensive Cancer Network guidelines. All approved therapies to date have gone through this process. It’s a way to get patients early exposure to drugs that have potential future approval for treatment.
And it’s one of the safest ways to be treated for a malignancy. When you’re on a clinical trial, you have an investigator that’s studying an investigational agent, then you have dedicated personnel that follow you through the clinical trial with every side effect and every lab.
What is the risk versus benefit for CLR 131 compared with other treatments that may be safer or more effective?
What I like about this drug, and especially in multiple myeloma, is its safety and its very low incidence of side effects. The two main things that patients who receive this have to be aware of is there are some radiation precautions. We will educate patients when they are first treated that they must have a degree of boundary from everyone in their household because they do emit radiation for about a week.
The second thing we see is low platelet counts as a side effect of therapy, which lasts for a few weeks. Now that we are doing what we call a split dose, we have found the degree of low platelet counts to be much less. I have treated seven patients at our center and have not seen bleeding events or severe consequences as a result of low platelet counts. It’s something we are aware of and monitoring very closely.
One thing that I find with patients with myeloma is that by the time they are reaching out to us to consider a clinical trial, they have had a lot of therapy. Probably one of the greatest things we deal with is the long-term side effects of prior treatment. I find repeat treatments of all the different drugs for myeloma will often contribute to neuropathy, fatigue and nausea — all those side effects that build up from these treatments that we don’t see with CLR 131. And nor have I seen the therapy worsen these side effects.
This isn’t the last therapy to give when there is nothing left to offer. We are offering this after two prior lines of treatment, which is relatively early in the long course of regimens for patients with myeloma. I think that’s where we will see the best responses. We almost never offer radiation to patients with blood cancers because it’s their blood, so CLR 131 is a unique mechanism of action that isn’t offered in any other way.
Have there been any challenges in treating this patient population?
Not to a significant degree. CLR 131 is very well tolerated. Patients come in often for observation of blood numbers. But the biggest appeal to patients is it’s a limited treatment. They come in for two treatments and then they are done for months. They get treated twice, but this medicine is working for a very long time.