While the trial (NCT02278315) is still ongoing, and new updates might show an even higher overall survival, the treatment already shows significant benefits over most FDA-approved third-line therapies, which have reached overall survival rates ranging only from 11.9 months to 18.6 months. Of note, patients on this treatment group had received a median of 5.8 prior therapies.
CLR 131 is a phospholipid drug conjugate (PDC) being developed for the treatment of several blood cancers. The drug delivers a radioactive, toxic compound directly to cancer cells by targeting specific lipid molecules in their membrane.
A dose-escalating Phase 1 trial is investigating CLR 131 in heavily treated multiple myeloma patients. Study participants were included in one of five groups to determine the best and safest dosing regimen. In groups 1 to 4, patients received a single dose of CLR 131, while group 5 is dosing participants with two doses, with a combined dose corresponding to the dose of the fourth group.
Preliminary data from the first group of patients, who received a single infusion of 12.5mCi/m2 CLR131, had reported a median overall survival of 22 months, already suggesting that a single dose of the treatment could improve survival. Now, updated results show that these patients lived for a median of 26.2 months.
In addition, patients treated in groups 2 and 3 – a single dose of 18.75 mCi/m2 or 25 mCi/m2, respectively – lived for a median of 15.4 months or 10 months.
The trial is still ongoing, and median overall survivals might continue to increase over time, the researchers said. However, these interim data are very promising, as CLR 131 is already showing better results than drugs approved for third-line treatments.
“The ongoing median overall survival from the first cohort exceeding two years, and the second cohort’s mOS surpassing 15 months underscore the clinical potential of our CLR 131 program in multiple myeloma,” Jim Caruso, president and CEO of Cellectar Biosciences, said in a press release. “These observations taken together with the recently reported partial response from Cohort 3 leave us very optimistic with regard to advancing this compound through the clinic.”
CLR 131 also is being tested in combination with dexamethasone in a Phase 2 trial (NCT02952508) in patients with relapsed or refractory multiple myeloma and lymphoma. The trial is currently recruiting participants across the United States in seven clinical sites. CLR 131 will be tested as a single 25.0 mCi/m2 dose, but patients may be eligible to receive a second infusion.
CLR 131 has received orphan drug designation by the FDA for the treatment of multiple myeloma.