Cellectar Biosciences (CLRB) announced on Tuesday a financing package worth up to $140 million, providing a critical cash infusion as the company advances its lead drug candidate, iopofosine I 131, toward a potential FDA submission. The news comes alongside updated 12-month data from the Phase 2b CLOVER WaM trial in Waldenström macroglobulinemia (WM), a rare blood cancer.
The financing includes approximately $35 million in immediate proceeds, with an additional $105 million tied to the achievement of specific milestones. Cellectar stated it will use the capital to fund a randomized confirmatory trial and prepare a New Drug Application (NDA) seeking accelerated approval for iopofosine. The company aims to initiate the confirmatory study in the fourth quarter of 2026.
Strong Clinical Data Supporting Iopofosine
In the CLOVER WaM trial, Cellectar reported an 83.6% overall response rate among 55 evaluable patients. The major response rate, a more stringent measure of clinical benefit, stood at 61.8%. Median duration of response was 17.8 months, while median progression-free survival reached 13.5 months. The company noted that all patients now have at least one year of follow-up data, fulfilling a request from the FDA.
Jarrod Longcor, Chief Operating Officer, highlighted the "depth, durability, and consistency of responses" as evidence of iopofosine's potential in WM. CEO James Caruso added that durability of response continues to improve over time.
Addressing Unmet Need in BTK Inhibitor-Exposed Patients
Cellectar is targeting patients who have previously received Bruton tyrosine kinase (BTK) inhibitors, such as Brukinsa (zanubrutinib) or Imbruvica (ibrutinib), which are current standards of care for WM. In the trial, iopofosine achieved a 64.1% major response rate in BTK inhibitor-exposed patients and a 63.6% rate in those refractory to the entire drug class. This represents a significant opportunity in a patient population with limited remaining treatment options.
Financial Position and Dilution Concerns
As of the end of 2025, Cellectar held only $13.2 million in cash, raising substantial doubt about its ability to continue as a going concern. The new financing alleviates near-term liquidity pressures, though it comes with significant dilution. Investors received common stock and pre-funded warrants for approximately 13.2 million shares, more than triple the 4.24 million shares outstanding as of late April. Additional milestone warrants could further dilute existing shareholders.
The company's stock experienced heavy trading volume of 53.78 million shares, far exceeding its average of 34,900, with shares ranging from $3.11 to $4.70. Market capitalization stood at roughly $12 million.
Regulatory Path and Market Context
The FDA's accelerated approval pathway allows for earlier approval based on surrogate endpoints, but requires confirmatory trials to verify clinical benefit. Cellectar acknowledges in its filings that there is no guarantee of approval or commercial success. The next key data readout will occur at the American Society of Clinical Oncology (ASCO) annual meeting, scheduled from May 29 to June 2 in Chicago, where results for iopofosine in relapsed or refractory WM patients after BTK inhibitor therapy will be presented.
Analyst Jonathan Aschoff of Roth Capital maintained a Buy rating on Cellectar, though he lowered his price target from $14 to $11, citing the 12-month data as supportive of an accelerated approval filing before the Phase 3 trial begins.
The financing was led by Nantahala Capital, with participation from Balyasny Asset Management, Caligan Partners, Janus Henderson Investors, SilverArc Capital Management, Stonepine Capital Management, StemPoint Capital, Empery Asset Management, and other healthcare-focused funds. Andrew Gu of Nantahala, set to join the board after closing, cited Cellectar's "meaningful body of clinical evidence" in WM.