By Counterforce Health Team in Enhertu (fam-trastuzumab deruxtecan-nxki) — 04 Oct 2025

How to Get Enhertu (fam-trastuzumab deruxtecan-nxki) Covered by Humana in Washington: Appeals, Forms & Approval Timeline

Answer Box: Getting Enhertu Covered by Humana in Washington

Fast track to approval: Enhertu requires prior authorization from Humana, typically placed on Specialty Tier 4. Your oncologist must submit HER2 testing results and clinical documentation through Humana's provider portal. If denied, you have 65 days to appeal and can access Washington's external review process. Start today: Have your clinic verify your specialty pharmacy network (likely Accredo) and gather HER2 pathology reports.

Timeline: PA decision in 7 days for standard requests; appeals take 30 days internally, then external review if needed.

Coverage at a Glance
Plan Types & Network Requirements
Formulary Status & Tier Placement
Prior Authorization Requirements
Specialty Pharmacy Setup
Step-by-Step: Fastest Path to Approval
Common Denial Reasons & Fixes
Appeals Process for Washington Residents
Cost-Share Considerations
When to Escalate
FAQ

Coverage at a Glance

Requirement	What it means	Where to find it	Source
Prior Authorization	Required before dispensing	Provider portal or PA forms	Humana PA Resources
Formulary Tier	Tier 4 (Specialty)	Plan formulary document	Humana Drug Lists
HER2 Testing	IHC/ISH results required	Pathology report	FDA Label Requirements
Specialty Pharmacy	Network restriction applies	Member services verification	Humana Specialty Rx
Appeals Deadline	65 days from denial notice	Denial letter instructions	Humana Appeals Process

Plan Types & Network Requirements

Humana offers multiple plan types in Washington, each with different implications for Enhertu coverage:

Medicare Advantage plans represent Humana's largest presence in Washington. These plans typically require you to use network providers and may need referrals for specialist care. For Enhertu, this means your oncologist must be in-network, and the infusion center must accept your specific Humana plan.

Medicare Part D plans focus solely on prescription drug coverage. If you have Original Medicare plus a Humana Part D plan, the drug coverage rules still apply, but you have more flexibility in choosing your oncologist and treatment facility.

Note: Humana's Medicare Advantage denial rate is approximately 3.5%—among the lowest of major insurers—but denials that do occur often involve documentation gaps or formulary placement issues.

Network restrictions are particularly important for specialty drugs like Enhertu. Your treatment team must verify that both the prescribing oncologist and the infusion facility accept your specific Humana plan before starting the prior authorization process.

Formulary Status & Tier Placement

Enhertu is placed on Tier 4 (Specialty) in Humana's 2025 Medicare formularies. This tier includes high-cost injectable oncology medications and typically results in the highest member cost-sharing.

Key formulary facts:

No tier exceptions available for specialty tier drugs
Quantity limits typically restrict fills to 30-day supplies
Step therapy may apply, requiring trial of alternative HER2-targeted therapies first
Site of care restrictions may limit where the drug can be administered

The specialty tier placement means you cannot request to move Enhertu to a lower-cost tier, but you can still appeal if the drug is denied for medical necessity reasons.

Prior Authorization Requirements

All Humana plans require prior authorization for Enhertu. The approval process centers on demonstrating medical necessity through specific clinical criteria:

Required Documentation:

HER2 testing results: For breast cancer, this includes IHC scores (0, 1+, 2+, 3+) and ISH results if applicable. Enhertu is now approved for HER2-low breast cancer (IHC 1+ or 2+ with negative ISH).
Previous treatment history: Documentation of prior therapies tried and outcomes
Diagnosis confirmation: ICD-10 codes and pathology reports
Clinical notes: Justification for why Enhertu is medically necessary

Biomarker Requirements by Cancer Type:

Breast Cancer: HER2-positive (IHC 3+ or ISH amplified) OR HER2-low (IHC 1+ or 2+ with negative ISH)
NSCLC: HER2 (ERBB2) mutations confirmed by molecular testing
Gastric Cancer: HER2-positive status with progression on prior trastuzumab therapy

Clinician Corner: Medical necessity letters should reference the specific FDA indication, include precise HER2 testing methodology and results, document contraindications to alternative therapies, and cite relevant treatment guidelines. The FDA prescribing information provides the foundation for all coverage criteria.

Specialty Pharmacy Setup

Enhertu must be dispensed through Humana's network specialty pharmacies. Accredo Specialty Pharmacy is typically the designated provider for oncology medications under Humana plans.

Setup Process:

Verify network status: Confirm Accredo is your plan's preferred specialty pharmacy
Provider enrollment: Your oncologist completes Accredo's enrollment forms
Insurance verification: Accredo confirms benefits and obtains prior authorization
Patient coordination: Accredo contacts you to arrange delivery and support services

The specialty pharmacy handles medication delivery to your infusion center and provides ongoing support including adherence monitoring and side effect management. This coordination is essential since Enhertu requires careful monitoring for interstitial lung disease (ILD) and other serious adverse effects.

Step-by-Step: Fastest Path to Approval

Gather HER2 testing documentation (Patient/Clinic)
- Obtain complete pathology report with IHC scores and ISH results
- Ensure testing was performed in CLIA-certified laboratory
- Timeline: Same day if records are available
Verify specialty pharmacy network (Clinic)
- Call Humana member services to confirm Accredo or alternative
- Document: Network pharmacy contact information
- Timeline: 1 business day
Submit prior authorization request (Prescriber)
- Use Humana's provider portal or PA forms
- Include: Clinical notes, HER2 testing, prior treatment history
- Timeline: Same day submission
Coordinate with specialty pharmacy (Clinic)
- Complete Accredo enrollment while PA is pending
- Submit: Patient demographics, insurance information, prescription
- Timeline: 1-2 business days
Monitor PA status (Patient/Clinic)
- Check provider portal or call Humana directly
- Standard timeline: 7 calendar days for decision
- Expedited: 72 hours if urgent clinical need
If approved, schedule treatment (Patient/Clinic)
- Coordinate delivery to infusion center
- Schedule baseline monitoring (chest imaging, labs)
- Timeline: 3-5 business days for first delivery
If denied, file appeal immediately (Patient/Prescriber)
- Submit within 65 days using denial letter instructions
- Include: Additional clinical documentation, peer-reviewed literature
- Timeline: 30 days for internal appeal decision

Common Denial Reasons & Fixes

Denial Reason	How to Overturn	Required Documents
Missing HER2 testing	Submit complete pathology report	IHC/ISH results from CLIA lab
Incorrect line of therapy	Document prior treatments and failures	Treatment history with dates/outcomes
Site of care restriction	Request exception with clinical justification	Oncologist letter explaining medical necessity
Step therapy not met	Provide contraindication documentation	Clinical notes showing why alternatives failed
"Not medically necessary"	Submit comprehensive appeal with literature	Peer-reviewed studies, treatment guidelines

Most Effective Appeal Strategies:

Include specific citations from FDA labeling and NCCN guidelines
Document why alternative therapies are inappropriate or have failed
Request peer-to-peer review with Humana's medical director
Submit supporting letters from specialists (pulmonologist for ILD monitoring)

Appeals Process for Washington Residents

If Humana denies your Enhertu request, Washington residents have robust appeal rights:

Internal Appeals (Humana):

Timeline: 65 days from denial notice to file
Decision time: 7 days for Part D drug appeals
How to file: Online portal, phone, or written request per denial letter

External Review (After Internal Appeals):

For Medicare Part D: Federal Independent Review Entity (IRE), not state IRO
For non-Medicare plans: Washington State certified IRO through Office of Insurance Commissioner
Timeline: 180 days from final internal denial to request external review

Washington-Specific Resources:

Office of Insurance Commissioner: 1-800-562-6900 for guidance
SHIP (State Health Insurance Assistance Program): Free personalized help with Medicare appeals
External review request: Can be filed online or by mail with OIC

From our advocates: We've seen several Enhertu appeals succeed when patients included detailed documentation of HER2-low testing methodology and cited the DESTINY-Breast04 trial data. The key is demonstrating that standard HER2-negative classifications may miss patients who could benefit from this therapy. Success often comes down to having the right pathology interpretation and clinical context.

Counterforce Health helps patients and clinicians navigate these complex appeals by analyzing denial letters, identifying specific policy requirements, and drafting evidence-backed rebuttals that address payer concerns directly. Our platform streamlines the process of gathering the right clinical documentation and regulatory citations needed for successful appeals.

Specialty tier placement means Enhertu will have significant cost-sharing, but several options can help:

Potential Cost-Sharing:

Specialty tier copays typically range from $100-400+ per fill
Coinsurance may be 25-40% of drug cost after deductible
Annual out-of-pocket maximums provide eventual protection

Financial Assistance Options:

ENHERTU Co-pay Program: May reduce out-of-pocket costs (verify eligibility)
Patient assistance foundations: Cancer-specific organizations offer grants
State pharmaceutical assistance programs: Washington may offer additional support

Always verify current assistance program availability and eligibility requirements, as these change frequently.

When to Escalate

Contact Washington's Office of Insurance Commissioner if:

Humana fails to respond within required timelines
You believe the denial violates state or federal law
The appeals process isn't followed properly
You need help understanding your rights

OIC Contact Information:

Phone: 1-800-562-6900
Online: Submit complaint through OIC website
Mail: Office of the Insurance Commissioner, PO Box 40255, Olympia, WA 98504-0255

The OIC can investigate complaints, help resolve disputes, and provide guidance on the external review process.

FAQ

How long does Humana prior authorization take for Enhertu in Washington? Standard PA requests receive decisions within 7 calendar days. Expedited requests (for urgent clinical situations) are decided within 72 hours.

What if Enhertu is not on Humana's formulary? Enhertu is typically on Tier 4 (Specialty) of Humana formularies. If it's not covered, you can request a formulary exception with clinical justification from your oncologist.

Can I get an expedited appeal if my cancer is progressing? Yes. Both Humana and Washington's external review process offer expedited timelines for urgent medical situations where delays could harm your health.

Does step therapy apply if I've already tried other HER2 therapies? Document all prior HER2-targeted treatments and their outcomes. If you've already failed standard therapies, step therapy requirements may be waived.

What happens if I move from Washington to another state during treatment? Your Humana coverage continues, but state-specific appeal rights may change. Contact member services immediately to understand how the move affects your coverage.

Can my family member help with the appeals process? Yes, but you'll need to complete an authorized representative form allowing them to act on your behalf with Humana.

This information is for educational purposes only and does not constitute medical or legal advice. Coverage policies change frequently—always verify current requirements with Humana directly. For personalized assistance with insurance appeals and prior authorization requirements, Counterforce Health provides specialized support for patients and clinicians navigating complex coverage decisions.

Sources & Further Reading

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