Plus Therapeutics, Inc. (Nasdaq: PSTV) announced comprehensive plans to commercially launch its CNSide Cerebrospinal Fluid (CSF) Assay Platform in the second half of 2025, targeting what the company estimates to be a $6 billion underserved diagnostic market for central nervous system (CNS) cancer metastases in the United States.
The clinical-stage pharmaceutical company, which acquired CNSide Diagnostics as a wholly-owned subsidiary in 2024, has been preparing infrastructure and market access strategies to support the commercial rollout of its proprietary diagnostic platform designed for patients suspected of having CNS cancer metastases.
Addressing Critical Unmet Medical Need
CNS metastases represent a significant clinical challenge, affecting as many as 30% of adult cancer patients. According to the company, approximately half of patients with cerebrospinal fluid metastases receive only palliative care or hospice due to the difficulties in diagnosis and treatment once the CNS is affected.
The current standard of care for CNS metastases diagnosis, CSF cytology, was developed over a century ago and offers suboptimal test sensitivity, leading to missed or delayed diagnosis and treatment. Leptomeningeal metastases (LM), a rare complication where primary cancer spreads to the cerebrospinal fluid and leptomeninges, occurs in approximately 5% of people with cancer and is usually terminal with 1-year and 2-year survival rates of just 7% and 3%, respectively.
"CNS Mets are an epidemic affecting as many as 30% of adult cancer patients and affect the highly protected CNS space," said Marc H. Hedrick, M.D., Plus Therapeutics' President and Chief Executive Officer. "The developer of the CNSide technology invested over $300 million in this core technology and after a year of detailed analysis and preparation by our team and key consultants, our enthusiasm regarding the unmet clinical need and the inherent value of CNSide has only grown."
Superior Clinical Performance Demonstrated
The CNSide CSF Assay Platform has demonstrated significant advantages over current diagnostic methods. More than 11,000 CNSide tests have been performed at over 200 U.S. cancer institutions since 2020, delivering high sensitivity (92%) and specificity (95%), while influencing treatment decisions in 90% of cases. The platform's superior clinical utility has been documented in 8 peer-reviewed publications and validated through a completed clinical trial and real-world use.
The comprehensive CNSide CSF Assay is designed as a highly sensitive platform that diagnoses, monitors, and guides treatment for CNS metastases. The platform enables quantitative analysis and molecular characterization of tumor cells and circulating tumor DNA in cerebrospinal fluid, providing physicians with tools for detection, enumeration, and characterization of metastatic cancer cells in the central nervous system.
Commercial Infrastructure and Market Strategy
Since acquiring CNSide in 2024, Plus Therapeutics has established infrastructure to support a scalable and centralized testing laboratory in Houston, Texas, that will service the U.S. market. The company's commercial market access strategy includes prioritized state licensure, proprietary reimbursement codes, commercial and government payor coverage, and value-based pricing to optimize revenue.
The company plans to introduce the CNSide platform first in Texas in the second half of 2025, followed by rapid expansion into additional states in late 2025 and 2026. Additional expanded CNS testing capabilities are also expected to roll out over the next year.
When the CNSide CSF Assay Platform was previously commercially available, market acceptance and adoption were widespread, with several national and regional commercial payor agreements in place and the test in regular use at major cancer centers across the U.S. The company is now in contact with legacy payors and healthcare providers in anticipation of the planned 2025 launch.
Plus Therapeutics has hired experienced leadership with expertise in the development and commercialization of clinical diagnostic technologies, including the recent appointment of Russ Bradley as CNSide Diagnostics, LLC President and General Manager.
"We believe CNSide is uniquely differentiated by providing physicians with superior tools for the detection, enumeration, and characterization of metastatic cancer cells in the central nervous system," said Bradley. "This foundation is supported by prior market acceptance and rapid adoption of the CNSide technology by over 200 unique physician providers at more than 120 separate institutions when it was first previewed in 2020."
Financial Outlook and Revenue Projections
Andrew Sims, Plus Therapeutics' Vice President and Chief Financial Officer, indicated that while CNSide's launch is on track for 2025, the revenue contributions from the CNSide subsidiary will become meaningful to Plus Therapeutics' operations in fiscal year 2026.
"CNSide, as a laboratory-developed test widely adopted under a prior commercial program, will begin to hit the market this year under our full commercial access strategy, providing Plus with an expedited path to both revenue and corporate profitability while allowing us to continue the progress in our core CNS radiotherapeutics clinical development pipeline," Hedrick stated.
Complementary Therapeutic Development
The CNSide platform provides additional value to the company's lead developmental radiotherapeutic candidate, REYOBIQ (rhenium 186re obisbemeda), for patients with leptomeningeal metastases. REYOBIQ is a novel injectable radiotherapy specifically formulated to deliver direct targeted high dose radiation in CNS tumors and is being evaluated in the ReSPECT-GBM and ReSPECT-LM clinical trials.
The company's clinical development programs are supported by significant grant funding, including a three-year $17.6 million grant from the Cancer Prevention & Research Institute of Texas (CPRIT) for ReSPECT-LM, and awards from the National Cancer Institute and the U.S. Department of Defense's Peer Reviewed Cancer Research Program.
