In oncology, prior authorization for a targeted therapy often depends on a companion diagnostic result — a biomarker test that identifies whether the patient's tumor carries the genetic variant the drug targets. But in many payer workflows, the diagnostic test itself requires prior authorization. When the diagnostic PA is denied, the drug PA cannot be submitted. The result is a sequencing deadlock: the patient cannot get the drug without the test result, and the payer will not approve the test.
A study published by the American Society for Radiation Oncology (ASTRO) in 2025 found that over 90% of surveyed radiation oncologists reported treatment delays attributed to prior authorization, with more than half lasting five days or longer. In precision oncology, the delay is often longer because the diagnostic step adds its own PA cycle. An American Society of Clinical Oncology (ASCO) survey found that 30% of oncologists reported major complications from PA-related delays, and 7% linked PA delays to patient deaths.
This article maps the companion diagnostic sequencing problem, explains the coverage landscape for biomarker testing, and provides a structured workflow for oncology access teams. It is written for oncology practice access coordinators, manufacturer hub teams, specialty pharmacy reimbursement staff, and market access professionals who manage oncology drug and diagnostic PA in parallel.
The diagnostic-first sequencing trap
The core problem is a two-step PA dependency:
| Step | What is needed | PA required? | What happens if denied |
|---|---|---|---|
| 1. Companion diagnostic test | Tissue biopsy, liquid biopsy, or surgical specimen sent to a reference lab for NGS, IHC, FISH, or PCR testing | Yes, for most commercial payers and some Medicare Advantage plans | Drug PA cannot be submitted without test result |
| 2. Drug prior authorization | Test result showing qualifying biomarker (e.g., EGFR mutation, ALK rearrangement, HER2 amplification, PD-L1 expression) submitted with drug PA | Yes, for nearly all targeted therapies | Drug not approved without biomarker confirmation |
When Step 1 is denied, Step 2 is blocked. The patient and the treating oncologist are caught in a loop where neither the test nor the drug moves forward. This is not a rare edge case. A large retrospective study found that multigene next-generation sequencing panel biomarker testing rates in advanced cancers ranged from 27% to 56%, meaning that a significant proportion of patients who should receive comprehensive testing do not — and coverage denials are a primary barrier.
Why companion diagnostic PA is denied
Companion diagnostic denials fall into five categories:
1. "Not medically necessary" for the cancer type
Payers may cover NGS testing for advanced non-small cell lung cancer (where the evidence base and NCCN guideline recommendations are strongest) but deny it for less common tumor types where the guideline support is more recent or the payer's clinical policy has not been updated. This is a particular problem for rare tumor types and for newly approved biomarker-drug pairs where the payer policy lags behind FDA label changes and NCCN guideline updates.
2. "Experimental or investigational"
Some payers classify comprehensive genomic profiling (CGP) or liquid biopsy as experimental, even when the test includes FDA-approved companion diagnostic claims. The FDA has approved dozens of companion diagnostic tests — including FoundationOne CDx, Guardant360 CDx, Oncomine Dx Target Test, and Tempus xT CDx — but payer coverage policies do not always align with the FDA's determination.
3. "Insufficient clinical information"
The PA submission did not include the cancer type, stage, line of therapy, prior treatment history, or specimen type. Without this context, the payer cannot determine whether the test meets its coverage criteria.
4. Tissue insufficiency or specimen quality
The biopsy specimen is inadequate for the requested test (insufficient tumor cellularity, poor DNA quality, or no tissue available after pathology processing). The payer may deny the test because the specimen does not meet the lab's acceptance criteria, even though the ordering oncologist has no control over specimen quality at the time of PA submission.
5. "Already tested" or duplicate testing denial
If a prior test was performed — even a limited panel — the payer may deny a more comprehensive test as duplicative, even when the initial panel did not include the biomarker relevant to the current treatment decision.
CMS coverage: National Coverage Determination 90.2
Medicare covers FDA-approved next-generation sequencing (NGS) companion diagnostic tests for patients with advanced cancer (recurrent, metastatic, relapsed, refractory, or Stage III/IV) under National Coverage Determination (NCD) 90.2. This is the baseline coverage standard:
| Requirement | NCD 90.2 criteria |
|---|---|
| Patient has advanced cancer | Recurrent, metastatic, relapsed, refractory, or Stage III/IV |
| Test is FDA-approved companion diagnostic | Must have FDA approval or clearance |
| Test results are used for clinical decision-making | Must guide treatment with an FDA-approved or NCCN-recommended therapy |
| Patient has not been previously tested with the same test | Avoids duplicate testing |
| Test is ordered by a treating physician | Not a screening test in asymptomatic patients |
NCD 90.2 provides a strong coverage foundation for Medicare and Medicare Advantage beneficiaries. However, the criteria are specific: the patient must have advanced cancer, and the test must be FDA-approved. If the patient has early-stage cancer, or the test is a lab-developed test (LDT) without FDA approval, coverage is not guaranteed by NCD 90.2 and falls to Local Coverage Determinations (LCDs) or individual payer policies.
MolDx and DEX Z-Codes
For Medicare Administrative Contractors (MACs) using the MolDx program (Palmetto GBA), molecular diagnostic tests must have a registered DEX Z-Code to be considered for coverage. This adds an administrative layer: if the test laboratory has not registered the test with MolDx and obtained a Z-Code, the claim may be denied even when NCD 90.2 criteria are met.
State biomarker testing mandates
As of 2026, approximately 20 U.S. states have enacted biomarker testing coverage mandates for state-regulated insurance plans. These laws vary in scope:
| State mandate scope | Examples |
|---|---|
| Coverage for all state-regulated plans across cancer types | AZ, CA, CT, GA, IL, IN, IA, KY, MD, NJ, NM, NY, OK, PA, RI, TX |
| Coverage for Medicaid beneficiaries | 16 states have Medicaid-specific biomarker mandates |
| Limited disease list | NE (limited list of diseases) |
| Recently enacted | MS (Jill's Law, HB 565, March 2026, effective for plans renewed on or after July 1, 2026) |
Key limitations of state mandates:
- They do not apply to Medicare or self-funded ERISA plans. Federal preemption means state insurance mandates only govern fully insured commercial plans and Medicaid. For Medicare beneficiaries, NCD 90.2 applies. For self-funded employer plans, the employer's plan document governs.
- They vary in what tests are covered. Some states mandate coverage for FDA-approved companion diagnostics only. Others include lab-developed tests and comprehensive genomic profiling.
- Prior authorization may still be required. Even in mandate states, payers may impose PA requirements, though the grounds for denial are narrower.
The EviCore/Cigna Special Circumstances guideline (effective January 2026) lists state biomarker bills and their impact on PA requirements. California's SB 535, for example, prohibits commercial insurers from requiring prior authorization for biomarker testing for enrollees with advanced or metastatic stage 3 or 4 cancer — but only for biomarker testing necessary for an FDA-approved therapy.
The FDA reclassification proposal
On November 25, 2025, the FDA proposed an order to reclassify certain oncology nucleic acid-based companion diagnostic tests from Class III to Class II. If finalized, this would:
- Reduce the regulatory burden on test manufacturers by allowing 510(k) submissions instead of Premarket Approval (PMA) applications.
- Shorten premarket review timelines.
- Enable more manufacturers to develop companion diagnostic tests, potentially increasing test availability.
- Still require compliance with special controls including performance standards, postmarket surveillance, and patient registries.
The public comment period closed January 26, 2026. If finalized, the order would take effect 30 days after publication in the Federal Register. From an access perspective, reclassification could increase the number of FDA-approved companion diagnostics available, which would strengthen NCD 90.2 coverage arguments for Medicare patients and make it harder for commercial payers to classify tests as "experimental."
Structuring the diagnostic-drug PA workflow
Oncology access teams should structure their PA process to minimize the diagnostic-first bottleneck:
Step 1: Submit diagnostic PA simultaneously with tissue acquisition
Do not wait for pathology confirmation before submitting the diagnostic PA. Submit the PA at the time the biopsy is ordered, including the cancer type, stage, line of therapy, and clinical rationale for comprehensive testing. If tissue proves insufficient, the test can be converted to a liquid biopsy, but the PA will already be in process.
Step 2: Check state biomarker mandate applicability
Before submitting, check whether the patient's state has a biomarker testing mandate that applies to their insurance type. If the mandate prohibits PA for the patient's situation, the payer should not be requiring PA at all — but the practice may need to cite the statute in the PA submission cover letter.
Step 3: Match the test to the payer's published criteria
Review the payer's clinical policy for molecular oncology testing before selecting the test. UnitedHealthcare's policy (effective January 2026) lists specific FDA-approved companion diagnostic tests and the indication-drug pairs they cover. If the payer's policy lists a specific test, order that test. If the policy allows "any FDA-approved companion diagnostic," select the test with the broadest coverage.
Step 4: Submit the drug PA as soon as the test result is available
Do not wait for the next office visit. When the biomarker result comes back positive for the target variant, submit the drug PA immediately, including the test result as supporting documentation. Some access teams pre-populate the drug PA form so it is ready to submit the moment the test result arrives.
Step 5: Prepare for the tissue-insufficiency fallback
If tissue biopsy is insufficient, have a liquid biopsy PA prepared. Liquid biopsy (ctDNA-based testing) is covered under NCD 90.2 when tissue is unavailable or inadequate, but the payer may require documentation of the tissue-insufficiency issue. The FoundationOne Liquid CDx and Guardant360 CDx tests both have FDA approval for liquid biopsy companion diagnostic use in multiple cancer types.
Appeal strategies for diagnostic denials
Peer-to-peer review
For guideline-concordant precision oncology testing, prior authorization denials are frequently overturned through peer-to-peer review. The Binaytara Cancer News investigation found that "prior authorization denials for guideline-recommended testing are frequently overturned on appeal to the specialty lab company or through a peer-to-peer review between your oncologist and the insurer's medical director." Practices should build administrative infrastructure to support P2P scheduling, or partner with specialty laboratories that offer PA appeal assistance.
Cite NCCN guidelines
NCCN guidelines recommend comprehensive genomic profiling for most advanced solid tumors. When a payer denies testing, citing the specific NCCN guideline version and recommendation category can shift the reviewer's assessment. NCCN recommendations carry significant weight in PA adjudication, particularly when the guideline category is 1 (based on high-level evidence) or 2A (based on lower-level evidence with uniform NCCN consensus).
Patient assistance programs
Most major reference laboratories (Foundation Medicine, Guardant Health, Tempus, Caris Life Sciences) offer patient assistance programs based on financial need. When coverage is denied and appeal options are exhausted, these programs can provide testing at reduced or no cost. The test result then supports the drug PA submission.
External review
For fully insured commercial plans, the Affordable Care Act guarantees the right to external review of coverage denials. The external reviewer is an independent medical reviewer who is not employed by the insurer. External reviewers overturn a significant proportion of initial denials, particularly when the denial was based on outdated clinical criteria.
What to monitor
- FDA reclassification finalization. If the FDA's proposed reclassification of oncology companion diagnostics from Class III to Class II is finalized, the number of FDA-approved tests will likely increase, strengthening NCD 90.2 coverage arguments.
- State biomarker mandate expansion. Additional states are likely to enact biomarker testing coverage legislation in 2026–2027. Each new mandate changes the PA landscape for practices in that state.
- CMS-0062-P proposed rule. Published April 14, 2026, this proposed rule would require state Medicaid FFS programs, Medicaid managed care plans, and CHIP plans to incorporate drugs covered under a medical benefit into the Prior Authorization API — including companion diagnostic tests — with a proposed October 1, 2027 compliance date.
- NCCN guideline updates. NCCN updates its guidelines continuously. Practices should verify they are citing the most current version in PA submissions, as payers may reject appeals citing outdated guidelines.
- New companion diagnostic approvals. FDA approved several new companion diagnostics in 2025, including the c-MET CDx Assay (NeoGenomics, May 2025) and xT CDx (Tempus, January 2025). Each new approval potentially adds coverage pathways.
Sources
- CMS. "National Coverage Determination (NCD) 90.2: Next Generation Sequencing (NGS) for Medicare Beneficiaries with Advanced Cancer." https://www.cms.gov/medicare-coverage-database/details/ncd-details.aspx?NCDId=372
- FDA. "List of Cleared or Approved Companion Diagnostic Devices (In Vitro and Imaging Tools)." https://www.fda.gov/medical-devices/in-vitro-diagnostics/list-cleared-or-approved-companion-diagnostic-devices-in-vitro-and-imaging-tools
- Federal Register. "Immunology and Microbiology Devices; Reclassification of Nucleic Acid-Based Test Systems for Use With a Corresponding Approved Oncology Therapeutic Product." November 25, 2025. https://www.federalregister.gov/documents/2025/11/25/2025-21071
- Federal Register. "Medicare and Medicaid Programs; Interoperability Standards and Prior Authorization for Drugs." CMS-0062-P, April 14, 2026. https://www.federalregister.gov/documents/2026/04/14/2026-07205
- Kang SL, Kim S. "Milestone to Ensure Safety and Efficacy of Companion Diagnostic (CDx) That Support Treatment Decisions in Cancer Patients." Diagnostics. 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC12785362
- ASCO. "Prior Authorization Often Places Burden on Patients With Cancer, Delays Care." October 6, 2025. https://www.asco.org/about-asco/press-center/news-releases/prior-authorization-often-places-burden-patients-with-cancer-delays-care
- Binaytara Foundation. "The Hidden Barrier to Precision Oncology: How Insurance Policies Delay Access to Genomic Testing." Cancer News, 2026. https://binaytara.org/cancernews/article/the-hidden-barrier-to-precision-oncology-how-insurance-policies-delay-access-to-genomic-testing
- IntuitionLabs. "Biomarker Testing Coordination Services: An Oncology Guide." 2026. https://intuitionlabs.ai/articles/biomarker-testing-coordination
- Exponent. "FDA Proposes Down-Classifying Companion Diagnostics." December 15, 2025. https://www.exponent.com/article/fda-proposes-down-classifying-companion-diagnostics
- UnitedHealthcare. "FDA Cleared or Approved Companion Diagnostic Testing." Commercial Medical Policy, effective January 1, 2026. https://www.uhcprovider.com/content/dam/provider/docs/public/policies/index/commercial/molecular-oncology-companion-diagnostic-testing-01012026.pdf
- LUGPA. "Expanding Coverage of Biomarker Testing in 2025." Policy Brief. https://www.lugpa.org/expanding-coverage-of-biomarker-testing-in-2025
Last updated May 31, 2026. This article is for informational purposes only and does not constitute medical advice, reimbursement guidance, or legal counsel. Coverage criteria and appeal processes vary by payer, plan, and state.
