Cellectar Biosciences (NASDAQ:CLRB) reported a narrower first-quarter loss and highlighted new clinical data that management said support its plans to pursue accelerated approval for iopofosine I-131 in Waldenström’s macroglobulinemia, a rare and incurable lymphoma.
On the company’s first-quarter 2026 earnings call, President and CEO James Caruso described the quarter as “transformational,” citing updated 12-month results from the phase II-B CLOVER-WaM study and a recently completed financing package of up to $140 million.
Iopofosine Data Drives Regulatory Plans
Cellectar’s main focus remains iopofosine I-131, its radiopharmaceutical candidate being studied in heavily pretreated WM patients, including those previously exposed to and refractory to BTK inhibitors. Caruso said the study met both its primary and secondary endpoints and addressed a population with limited treatment options after BTK inhibitor therapy.
Chief Operating Officer Jarrod Longcor said patients in CLOVER-WaM had a median of four prior lines of therapy. He said refractory rates were 77%, 75% and 60% among BTK inhibitor-, rituximab- and chemotherapy-exposed patients, respectively, and that 58% of patients exposed to both BTK inhibitors and rituximab were dual-class refractory.
In the protocol study population of 55 patients, Longcor said iopofosine produced an overall response rate of 83.6% and a major response rate of 61.8%, which was the trial’s primary endpoint. The secondary endpoint, duration of response, reached a median of 17.8 months. He also reported median progression-free survival of 13.5 months, a VGPR/CR rate of 14.5% and a disease control rate of 98.2%.
Longcor said more than 30% of responders maintained responses beyond 36 months. He added that the results were consistent in both BTK inhibitor-exposed and BTK inhibitor-refractory patients and compared favorably with available therapies in the post-BTK inhibitor setting.
The company said an immediately post-BTK inhibitor subgroup analysis from CLOVER-WaM has been selected for presentation at the upcoming ASCO conference.
Phase III Trial Expected Late in 2026
Cellectar plans to begin a randomized phase III confirmatory study in late fourth quarter 2026, with progression-free survival as the primary endpoint. During the question-and-answer session, Longcor said the company has aligned with the FDA on a comparator arm of rituximab, cyclophosphamide and dexamethasone, or RCD.
In response to a question from Ladenburg Thalmann analyst Kevin DeGeeter, Longcor said RCD is commonly used in the post-BTK inhibitor population and provides a comparable outcome to other treatment scenarios. He cited published data suggesting progression-free survival with rituximab combinations or salvage therapy in post-BTK inhibitor-exposed patients ranged from about 5.8 to 8.1 months, with the lower figure in refractory patients.
Longcor said the planned confirmatory study is expected to enroll an immediately post-BTK inhibitor population following frontline therapy, and that Cellectar expects the majority of those patients to be refractory to BTK inhibitors upon entering the study. He said the company powered the study assuming an 8-month progression-free survival for the comparator arm and no greater than a 12-month progression-free survival for iopofosine. If patients behave similarly to those in CLOVER-WaM, Longcor said Cellectar would expect something closer to 15 months for the iopofosine arm.
Caruso said the company expects to submit its new drug application after the phase III study is initiated and enrolling, which he characterized as possibly “a couple, 2, 3 months” after study start. He noted that iopofosine received breakthrough therapy designation in May 2025 and said, based on the company’s expected timing, potential FDA action could occur in the second half of 2027.
First-Quarter Loss Narrows
Chief Financial Officer Chad Kolean said Cellectar ended the first quarter with cash and cash equivalents of approximately $8.3 million, compared with $13.2 million at the end of 2025. That figure did not include proceeds from the financing completed after the quarter.
Research and development expenses were approximately $3 million for the three months ended March 31, 2026, down from approximately $3.4 million in the prior-year period. Kolean said the decline reflected reduced follow-up activity for CLOVER-WaM patients and reduced preclinical product development, partially offset by higher manufacturing spending for iopofosine and CLR 125.
General and administrative expenses were $2.8 million, compared with $3 million a year earlier, with the decrease driven primarily by lower personnel costs. Net loss was $5.7 million, or $1.33 per share, compared with $6.6 million, or $4.30 per share, in the first quarter of 2025.
Financing Provides Up to $140 Million
Cellectar recently completed an oversubscribed financing for up to $140 million, including $35 million upfront and up to $105 million in milestone-based capital. Kolean said the company believes its current cash position enables it to fund operations, including the initiation of the phase III confirmatory trial in WM, into the second quarter of 2027.
The financing includes three tranches of warrants tied to specific milestones: initiation of the confirmatory study through enrollment of the first patient, FDA acceptance of an NDA submission and FDA approval of iopofosine. Each milestone could provide $35 million in additional funding if conditions are met, including the company’s common stock trading above $3.45 with daily volume exceeding $500,000 for 20 consecutive days.
Kolean said the warrants are exercisable upon stockholder approval of the transaction, which will be included on the agenda for the company’s annual stockholders meeting.
CLR 125 Trial Advances in Triple-Negative Breast Cancer
Cellectar also provided an update on CLR 125, an Auger-emitting radioconjugate being studied in relapsed or refractory triple-negative breast cancer. Longcor said the first patients have been dosed in a phase I-B open-label dose-finding study.
The trial will evaluate three dose levels and dosing regimens, with approximately 15 patients per treatment arm and an additional 15-patient expansion arm for the recommended phase II dose. Longcor said the study will use dosimetry assessments to characterize tumor uptake and distribution, with endpoints including safety, tolerability and preliminary efficacy measures such as tumor response by RECIST criteria and progression-free survival.
Caruso closed the call by saying Cellectar is entering the next phase of 2026 with “clarity of purpose,” and that the company remains focused on advancing iopofosine toward a confirmatory trial and potential accelerated approval application while continuing work on its broader radiopharmaceutical pipeline.
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.
