Plus Therapeutics Secures Highmark Coverage for CNSide® CSF Assay, Expanding Reimbursement to ~75 Million Covered Lives

Plus Therapeutics (Nasdaq: PSTV) announced Highmark coverage for its CNSide® CSF Tumor Cell Enumeration (TCE) assay, effective April 1, 2026, expanding total covered lives from ~67 million to ~75 million.

Rhea-AI Summary

Plus Therapeutics (Nasdaq: PSTV) announced Highmark coverage for its CNSide® CSF Tumor Cell Enumeration (TCE) assay, effective April 1, 2026, expanding total covered lives from ~67 million to ~75 million.

The agreement supports patient access, may accelerate clinical adoption, and advances the company toward its 2026 objective of 150 million covered lives.

Positive

• Highmark coverage effective April 1, 2026
• Total covered lives increased to ~75 million
• 11,000 CNSide tests performed since 2020
• Reported 92% sensitivity and 95% specificity
• Health economic analyses show ~40% cost reduction

Negative

• Coverage still below the 150 million 2026 objective

Argus Apr 2 session

-8.60% close to close Open Argus

Details

News Market Reaction – PSTV

In the Apr 2 session, PSTV declined 8.60%, reflecting a notable negative market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

The stock moved -8.6% in the session following this news. A negative reaction despite expanded cover...

Analysis

The stock moved -8.6% in the session following this news. A negative reaction despite expanded coverage to 75 million lives would fit a recent pattern where even constructive milestones, such as CNSide health-economic data and corporate updates, sometimes coincided with weakness. Persistent concerns from the recent reverse split and wider losses could overshadow strategic wins. Future trading could hinge on clearer evidence of revenue traction from CNSide and progress toward the 150 million coverage goal.

Key Figures

New covered lives: 75 million Prior covered lives: 67 million Coverage objective: 150 million +5 more

New covered lives

75 million

Total CNSide covered lives after adding Highmark

Prior covered lives

67 million

CNSide covered lives before Highmark agreement

Coverage objective

150 million

Company’s 2026 target for CNSide covered lives

Cost reduction

~40%

Health economic analyses of LM-related healthcare costs with CNSide

CNSide tests performed

more than 11,000

Commercial use since 2020 at U.S. cancer institutions

Institutions using CNSide

over 120

Number of U.S. cancer institutions since 2020

Sensitivity

92%

CNSide test performance for detecting leptomeningeal metastases

Specificity

95%

CNSide test performance for ruling out leptomeningeal metastases

Historical Context

5 past events · Latest: Mar 31

5 events

1. Mar 31

   Inducement equity grants

   24h Move

   -4.2%

   New employee stock options and RSUs granted under incentive plan.

2. Mar 31

   Reverse stock split

   24h Move

   -24.2%

   1-for-25 reverse split to regain Nasdaq minimum bid compliance.

3. Mar 26

   Board appointment

   24h Move

   -1.2%

   Diagnostics industry veteran added to board to support CNSide strategy.

4. Mar 19

   Health economics data

   24h Move

   +2.2%

   ISPOR analysis showing CNSide may cut LM healthcare costs by ~40%.

5. Mar 12

   Earnings and outlook

   24h Move

   -15.2%

   2025 results with wider loss but capital raise and CNSide rollout milestones.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

cerebrospinal fluid, csf assay, leptomeningeal metastases, csf cytology, +2 more

6 terms

cerebrospinal fluid medical

"providing reimbursement for its CNSide® Cerebrospinal Fluid (CSF) Tumor Cell Enumeration"

A clear fluid that surrounds and cushions the brain and spinal cord, acting like a protective bath and cleanup system that removes waste and helps circulate nutrients. For investors, cerebrospinal fluid matters because it is a common source of diagnostic markers and a route for delivering or testing neurological drugs; changes in its composition can signal disease or affect a therapy’s development, approval prospects, and market value.

csf assay medical

"The CNSide® CSF Assay Platform enables earlier, and more accurate detection"

A CSF assay is a laboratory test that examines cerebrospinal fluid—the clear liquid around the brain and spinal cord—for chemicals, proteins, or germs that signal neurological disease or treatment effects. For investors, results from these tests can influence drug development decisions, clinical trial success, diagnostic product value and regulatory approval, acting like a water-quality test that reveals whether a treatment is working or a condition is present.

leptomeningeal metastases medical

"earlier, and more accurate detection and monitoring of leptomeningeal metastases compared"

Leptomeningeal metastases occur when cancer cells spread to the thin layers of tissue covering the brain and spinal cord, similar to how weeds can invade the surface layer of soil. This condition often indicates advanced disease and can lead to serious neurological problems. For investors, the presence of such metastases may signal challenges in treatment options and can impact the outlook for related healthcare companies or research developments.

csf cytology medical

"more accurate detection and monitoring of leptomeningeal metastases compared to conventional CSF cytology"

CSF cytology is the laboratory examination of the clear fluid that surrounds the brain and spine to look for abnormal or disease-related cells, such as cancer cells, infectious organisms, or signs of inflammation. For investors, results can affect clinical trial enrollment, safety monitoring, regulatory decisions and market expectations for therapies targeting neurological or cancerous conditions—think of it as testing the water around a ship to spot early signs of damage.

health economic analyses medical

"Earlier detection enabled by CNSide has been shown in health economic analyses to reduce"

Health economic analyses are studies that compare the costs and benefits of medical treatments, tests or programs to show which options deliver the most health for the money spent. Think of it as an ROI calculator for healthcare that looks at both expenses and patient outcomes; investors use these analyses to predict pricing, insurance coverage, market uptake and long‑term revenue potential for therapies or devices.

specificity medical

"delivering high sensitivity (92%) and specificity (95%), while influencing treatment"

Specificity measures how well a diagnostic test or screening correctly identifies people who do not have a condition — the percentage of healthy cases the test labels as negative. Think of it as a smoke alarm that stays quiet when there’s no fire; high specificity means fewer false alarms. For investors, specificity affects regulatory approval, clinical adoption, follow-up costs, and the perceived reliability and market potential of medical products.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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HOUSTON, April 02, 2026 (GLOBE NEWSWIRE) -- CNSide Diagnostics, LLC, a wholly-owned subsidiary of Plus Therapeutics, Inc. (Nasdaq: PSTV) (“Plus” or the “Company”), today announces a new payer coverage agreement with Highmark, effective April 1, 2026, providing reimbursement for its CNSide® Cerebrospinal Fluid (CSF) Tumor Cell Enumeration (TCE) assay for patients with metastatic central nervous system cancers. Highmark joins a growing list of national and regional payers, including United Healthcare and Humana, that provide coverage for CNSide.

The addition of Highmark expands CNSide’s total covered lives from approximately 67 million to 75 million, representing continued progress toward the Company’s 2026 objective of 150 million covered lives, while expanding patient access across the U.S. The agreement is expected to further accelerate adoption of CNSide across oncology centers by reducing reimbursement barriers for ordering physicians.

“Securing coverage with Highmark, a leading Blue Cross Blue Shield-affiliated payer, marks another important milestone in expanding patient access to CNSide and reinforces the growing recognition among payers of its clinical and economic value,” said Russ Havranek, EVP Corporate and Commercial Strategy at Plus Therapeutics. “We continue to make progress toward broad national coverage and expanded adoption.”

The CNSide® CSF Assay Platform enables earlier, and more accurate detection and monitoring of leptomeningeal metastases compared to conventional CSF cytology, supporting rapid diagnosis, treatment monitoring, and treatment guidance. The superior clinical utility of CNSide® over standard of care has been demonstrated in 9 peer-reviewed publications, the FORESEE clinical trial, and demonstrated in real-world practice. Earlier detection enabled by CNSide has been shown in health economic analyses to reduce overall leptomeningeal metastases-related healthcare costs by ~40%, driven by earlier detection and treatment optimization.

Since its commercial launch, more than 11,000 CNSide tests have been performed at over 120 U.S. cancer institutions since 2020, delivering high sensitivity (92%) and specificity (95%), while influencing treatment decisions in 90% of cases.

This test is available exclusively through CNSide Diagnostics, LLC as a testing service provided to health care professionals in the U.S.

About CNSide Diagnostics, LLC 
CNSide Diagnostics, LLC is a wholly owned subsidiary of Plus Therapeutics, Inc. that develops and commercializes proprietary laboratory-developed tests, such as CNSide®, designed to identify tumor cells that have metastasized to the central nervous system in patients with carcinomas and melanomas. The CNSide® CSF Assay Platform enables quantitative analysis of the cerebrospinal fluid that informs and improves the management of patients with leptomeningeal metastases. For more information, visit https://www.cnside-dx.com/.

About Plus Therapeutics
Headquartered in Houston, Texas, Plus Therapeutics, Inc. is a clinical-stage pharmaceutical company developing targeted radiotherapeutics for difficult-to-treat cancers of the central nervous system with the potential to enhance clinical outcomes. Combining image-guided local beta radiation and targeted drug delivery approaches, the Company is advancing a pipeline of product candidates with lead programs in leptomeningeal metastases (LM) and recurrent glioblastoma (GBM). The Company has built a supply chain through strategic partnerships that enable the development, manufacturing, and future potential commercialization of its products. For more information, visit https://www.plustherapeutics.com.

About Highmark

An independent licensee of the Blue Cross Blue Shield Association, Highmark Inc., together with its Blue-branded affiliates, collectively comprise the fifth largest overall Blue Cross Blue Shield-affiliated organization in the country with nearly 8 million members nationwide. Its diversified businesses serve group customer and individual needs across the United States through dental insurance and other related businesses. For more information, visit www.highmark.com.

Forward-Looking Statements
This press release contains statements that may be deemed “forward-looking statements” within the meaning of U.S. securities laws, including statements regarding clinical trials, expected operations and upcoming developments. All statements in this press release other than statements of historical fact are forward-looking statements. These forward-looking statements may be identified by future verbs, as well as terms such as “expect,” “potential,” “anticipating,” “planning” and similar expressions or the negatives thereof. Such statements are based upon certain assumptions and assessments made by management in light of their experience and their perception of historical trends, current conditions, expected future developments and other factors they believe to be appropriate. These statements include, without limitation, statements regarding the potential market for the CNSide CSF Assay, the timing in which the CNSide CSF Assay is commercially launched and commercialization is expanded, revenue and corporate profitability expectations including support reimbursements and payments for the CNSide CSF Assay, the development and utility of the CNSide CSF Assay and expectations as to the Company’s future performance, including the next steps in developing the Company’s product candidates.

Investor Contact
CORE IR
investor@plustherapeutics.com

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does Highmark coverage mean for PSTV investors after April 1, 2026?

Direct answer: Highmark coverage expands CNSide reimbursement to new patient populations, potentially increasing test volume and revenue. According to the company, the agreement increases total covered lives to approximately 75 million, which may reduce ordering barriers and support wider adoption across oncology centers.

How many lives does PSTV say are covered for the CNSide test after the Highmark agreement?

Direct answer: Plus Therapeutics reports total covered lives of about 75 million after Highmark joins payers. According to the company, this rises from ~67 million and is positioned as progress toward the company’s 2026 objective of 150 million covered lives.

What clinical performance metrics for the CNSide CSF assay does PSTV disclose?

Direct answer: The company reports high diagnostic accuracy with 92% sensitivity and 95% specificity for CNSide. According to the company, these metrics come from peer-reviewed studies and real-world use that influenced treatment decisions in 90% of cases.

How widely has the CNSide test been used in the U.S. according to Plus Therapeutics?

Direct answer: Plus Therapeutics reports that more than 11,000 CNSide tests have been performed at over 120 U.S. cancer institutions since 2020. According to the company, the test is offered exclusively through CNSide Diagnostics as a U.S. testing service.

What economic impact does Plus Therapeutics claim CNSide delivers for leptomeningeal metastases care?

Direct answer: The company cites health economic analyses showing roughly a 40% reduction in leptomeningeal metastases–related healthcare costs. According to the company, earlier detection and treatment optimization drive the stated cost savings in published analyses.