Cellectar Biosciences, Inc. (CLRB) Earnings

Management highlights

- Clinical Development for Lead Asset (Iopopacin I-131 for Relapsed/Refractory Waldenstrom's Macroglobulinemia (WM)) • Reported full 12-month follow-up data from the Clover-WHAM study, which met all primary and secondary endpoints, confirming deep and durable response, with a median duration of response of 17.8 months and a 62% major response rate across all patients. • Presented new ASCO 2026 data for patients treated immediately after BTK inhibitor therapy, showing a 79.2% major response rate, 87.5% overall response rate, 100% clinical benefit rate, and a 16-month median duration of response in this high-unmet-need patient population. • Initiated site activation activities for the planned confirmatory Phase 3 trial, the critical next step toward regulatory submission. • Published peer-reviewed data supporting Iopopacin I-131's differentiated mechanism of action across additional B-cell malignancies, including multiple myeloma and diffuse large B-cell lymphoma. - Pipeline and Platform Advancement • The proprietary Phospholipid Drug Conjugate (PDC) platform is a versatile, antigen-independent cancer targeting technology compatible with beta, gamma, Auger, and alpha-emitting radiotherapeutic payloads, validated by Iopopacin I-131's clinical success. • Enrolled and dosed the first patients in the Phase 1b trial of CLR125, an Auger-emitting radiotherapeutic candidate for triple negative breast cancer, with initial data expected in late 2026 or early 2027. • CLR225, an alpha-emitting candidate for solid tumors, is in earlier development, supported by the PDC platform. - Corporate and Financial Updates • Completed an oversubscribed milestone-linked financing in May 2026, providing $35 million in gross upfront proceeds ($31.7 million net) and up to an additional $105 million in milestone-linked capital, strengthening the balance sheet to fund all near-term execution goals. • Pre-commercial supply infrastructure for Iopopacin I-131 is already built out, with existing commercial-scale production capacity for the targeting ligand (with >5 years of demonstrated stability) and scalable finished production capacity of ~100 patients per week, well in excess of near-term demand projections. • An educational webinar on the PDC platform and pipeline is scheduled for August 18, 2026.

Guidance

- First patient dosing in the Iopopacin I-131 confirmatory Phase 3 trial is expected in late 2026 or early 2027, with first sites opening in the coming months after site activation. • New Drug Application (NDA) submission for Iopopacin I-131 under the FDA accelerated approval pathway remains on track for mid-2027 (March-April 2027 timeframe). • An approximately 6-month FDA review period is anticipated after NDA submission, based on the program's existing breakthrough therapy designation. • Initial dosimetry, safety, and efficacy data from the CLR125 Phase 1b trial in triple negative breast cancer is expected in late 2026 or early 2027, with potential presentation at the 2026 San Antonio Breast Cancer Conference. • The May 2026 financing structure is projected to cover capital needs through Iopopacin I-131 initial commercialization if milestones are achieved as planned.

Segment performance

Selectar Biosciences is a clinical-stage radiopharmaceutical company with only pipeline development activity in Q2 2026, no commercial product segments generating revenue. For operating performance: Research and development (R&D) expenses were $4.6 million for Q2 2026, an increase of $2.2 million from $2.4 million in Q2 2025, driven by expanded clinical activity for CLR125 in triple negative breast cancer and initiation of the Iopopacin I-131 confirmatory Phase 3 study. General and administrative (G&A) expenses were $2.6 million for Q2 2026, a decrease of $1.0 million from $3.6 million in Q2 2025, driven by reduced professional fees, pre-commercialization costs, and personnel expenses. Net loss for Q2 2026 was $6.9 million. Cash and cash equivalents as of June 30, 2026 were $34.0 million, up from $13.2 million as of December 31, 2025, reflecting proceeds from the May 2026 financing.

Risks & headwinds

- Forward-looking statements regarding clinical trial timelines, regulatory outcomes, financing milestones, and supply availability are subject to inherent uncertainties, and actual results could differ materially from projections. • Site activation and IRB approval timelines for the Phase 3 trial can vary, with academic centers requiring additional local IRB and internal review that could delay first patient enrollment. • The FDA does not provide explicit guidance on the required trial progress for accelerated approval acceptance, so the company's interpretation of requirements may not align with FDA expectations. • Actinium-225 supply for the CLR225 alpha-emitting program still faces potential long-term supply chain constraints, even with recent improvements and multi-sourcing agreements. The isotope cannot be produced far in advance due to its half-life, requiring just-in-time production that introduces supply uncertainty. • There is no guarantee that Iopopacin I-131 will receive FDA approval, or that clinical trial results will match the positive data seen in earlier studies.

Analyst Q&A

• Q: What are the key limiting steps for first patient enrollment in the Phase 3 WM trial, and what criteria trigger NDA submission for accelerated approval? /

  A: The trial startup process proceeds through CRO contracting, site identification, feasibility assessment, site qualification (verifying appropriate infrastructure for I-131 handling), IRB review, contracting, staff training, and final site initiation. Community sites can use a central IRB for faster approval, but academic centers often require additional local IRB and internal committee review that adds time. The company remains on track for first patient dosing in late 2026 or early 2027. For the NDA, the FDA only requires the confirmatory study to be initiated and ongoing at submission, with active continuation through regulatory review. Selectar's plan is to have 10-20 sites open and a small number of patients enrolled by the mid-2027 submission, with at least 5% of total patients enrolled by the time of regulatory action.

• Q: What is the timeline for initial data readout from the CLR125 Phase 1b trial, and what early observations have been made? /

  A: Initial data, including dosimetry, safety, and preliminary efficacy, is expected to be reported in late 2026 or early 2027, with the San Antonio Breast Cancer Conference identified as a potential presentation venue. Early observed tumor uptake and biodistribution match predictions based on the PDC platform's established performance from the Iopopacin program, and the team is now conducting dose optimization for the trial.

• Q: What is the current status of commercial manufacturing preparations for Iopopacin I-131, and how quickly could the company launch after approval? /

  A: The targeting ligand, which has >5 years of demonstrated stability, is already produced at commercial scale, and commercial production and logistics infrastructure is fully built out. Current scalable capacity can support approximately 100 patients per week of finished product, which far exceeds projected initial demand. Full commercial mobilization would take a minimum of 12 months after approval. The company is evaluating all commercial options: independent commercialization (made feasible by the small, concentrated WM patient population and low required marketing spend), or partnership with a larger commercial organization, and can scale launch activities relatively quickly regardless of the path chosen.

• Q: How has the Actinium-225 supply chain changed over the past year, and how is Selectar addressing supply risk? /

  A: A year ago, widespread supply concerns existed for Actinium-225. While issues have not been fully resolved, multiple new suppliers have come online recently, opening the supply chain compared to 12 months ago. To mitigate ongoing long-term supply risk as programs scale, Selectar has a strategy of multi-sourcing all key components, and currently has Actinium-225 supply agreements with four separate suppliers to support near-term and long-term program needs.