Cellectar Biosciences (NASDAQ:CLRB) said its second-quarter efforts centered on advancing iopofosine I-131 toward a potential accelerated approval filing for relapsed or refractory Waldenström macroglobulinemia, while also progressing its broader radiopharmaceutical pipeline and strengthening its cash position through a May financing.
President and CEO James Caruso said the company has begun site-activation activities for a planned confirmatory Phase III study of iopofosine I-131 in Waldenström macroglobulinemia, or WM. The company expects initial study sites to open in the coming months and said it could enroll the first patient late in 2026 or early in 2027.
WM Data and Regulatory Plans
At ASCO 2026, Cellectar presented data from patients treated immediately after BTK inhibitor therapy. Caruso said the analysis showed a 79.2% major response rate, an 87.5% overall response rate, a 100% clinical benefit rate and a median duration of response of 16 months.
Chief Operating Officer Jarrod Longcor said the full study population produced a median response durability of 17.8 months, with approximately 62% of patients achieving a major response. The rate of very good partial responses and complete responses increased to 14.5% over time, according to Longcor.
The company said its planned Phase III confirmatory trial is intended to support long-term registration requirements and a U.S. accelerated approval filing. Management expects to submit a new drug application in mid-2027, subject to the study being initiated and ongoing. Caruso later described a March-April timeframe for the anticipated accelerated approval submission.
Longcor said the FDA has not provided a precise definition of what it considers an “ongoing” confirmatory study for an accelerated approval application. Cellectar’s working assumption is to have roughly 10 to 20 sites open and several patients enrolled at submission, followed by enrollment of at least about 5% of planned patients by the time of regulatory action, which management said could occur six to eight months after filing.
Financing Bolsters Cash Position
Chief Financial Officer Chad Kolean said Cellectar completed an oversubscribed financing in May that could provide up to $140 million, including $35 million in gross upfront proceeds and up to $105 million linked to future milestones. The company received approximately $31.7 million in net upfront proceeds through the issuance of common shares and pre-funded warrants.
The financing also included three tranches of approximately 13.2 million warrants, each with a $2.65 exercise price. The first tranche is tied to enrollment of the first patient in the confirmatory WM study; the second is tied to FDA acceptance of an iopofosine new drug application; and the third is tied to FDA marketing approval.
For the quarter ended June 30, Cellectar reported cash and cash equivalents of approximately $34 million, compared with $13.2 million at the end of 2025.
- Research and development expense was $4.6 million, compared with $2.4 million a year earlier, reflecting clinical activity for CLR 125 in triple-negative breast cancer and initiation of the iopofosine confirmatory study.
- General and administrative expense declined to $2.6 million from $3.6 million, driven by lower professional fees, pre-commercialization costs and personnel expenses.
- Net loss was $6.9 million, or $0.57 per share, compared with a net loss of $5.4 million, or $3.39 per share, in the prior-year quarter.
Pipeline Programs and Manufacturing
Beyond WM, Cellectar is advancing CLR 125, an Auger-emitting radiotherapeutic being studied in a Phase Ib trial in triple-negative breast cancer. Longcor said the company has enrolled and dosed its first patients and expects to report initial dosimetry, safety and efficacy data later in 2026 or early in 2027. He said the company has observed tumor uptake and distribution that appear consistent with expectations, while emphasizing that the study remains a dose-finding program.
The company’s pipeline is based on its phospholipid drug conjugate, or PDC, platform, which management said is designed to target cancer cells without relying on specific tumor mutations or surface antigens. Cellectar said the platform supports beta-emitting, Auger-emitting and alpha-emitting payloads, including its CLR 125 and CLR 225 programs.
In response to an analyst question about commercial readiness for iopofosine, Longcor said Cellectar has produced its targeting ligand at commercial scale for several years and has more than five years of stability data for that component. He said the company’s commercial infrastructure and logistics chain are in place, though radioisotope and finished-product production would be handled on a near-just-in-time basis.
Management said its existing manufacturing setup could support roughly 100 patients per week. Caruso added that the timing of a full commercial launch would depend on investment decisions and whether the company commercializes independently or partners with a third party.
Cellectar also said it has supply arrangements with multiple parties for actinium-225, an isotope associated with its alpha-emitting program. Longcor said the supply chain has improved from a year ago as additional suppliers have entered the market, though he expects supply constraints could reappear as demand increases.
About Cellectar Biosciences (NASDAQ:CLRB)
Cellectar Biosciences, Inc is a clinical‐stage biopharmaceutical company focused on the development of targeted cancer therapies and imaging agents. The company’s proprietary phospholipid drug conjugate (PDC) technology platform is designed to selectively deliver therapeutic and diagnostic payloads to malignant cells while sparing healthy tissue. Through its PDC approach, Cellectar aims to improve the efficacy and safety profile of traditional treatments like chemotherapy and radiotherapy.
Its lead therapeutic candidate, CLR 131, is a radioisotope‐labeled PDC being evaluated in Phase II clinical trials for relapsed or refractory B‐cell malignancies, including multiple myeloma and non‐Hodgkin lymphoma.
