By Counterforce Health Team in Strimvelis (autologous CD34+ ADA-SCID gene therapy) —

How to Get Strimvelis Gene Therapy Covered by Humana in Michigan: Coding, Appeals, and Authorization Guide

Answer Box: Getting Strimvelis Covered by Humana in Michigan

Strimvelis requires prior authorization from Humana using ICD-10 code D81.1 (ADA-deficient SCID) and unclassified HCPCS codes C9399 or J3590 since it lacks a specific J-code. Submit PA requests to Humana National Transplant Network at 866-421-5663 or fax 502-508-9300. If denied, appeals follow federal Medicare processes (not Michigan DIFS) for Medicare Advantage plans. Start today: Call Humana to confirm your plan's gene therapy coverage and request PA forms.

Table of Contents

  1. Coding Basics: Medical vs. Pharmacy Benefit Paths
  2. ICD-10 Mapping for ADA-SCID
  3. Product Coding: HCPCS, J-Codes, and NDC
  4. Clean Request Anatomy
  5. Frequent Coding Pitfalls
  6. Verification with Humana Resources
  7. Quick Audit Checklist
  8. Appeals Process in Michigan
  9. Common Denial Reasons & Fixes
  10. FAQ

Coding Basics: Medical vs. Pharmacy Benefit Paths

Strimvelis (autologous CD34+ ADA-SCID gene therapy) presents unique billing challenges because it's manufactured patient-specifically at SR-TIGET in Milan, Italy and lacks standard U.S. coding. Understanding which benefit pathway applies is crucial for approval.

Medical Benefit (Part B/C) Path

  • When it applies: Gene therapy administered in hospital/outpatient infusion centers
  • Coding: Use facility HCPCS codes (C9399) with detailed descriptions
  • Authorization: Medical prior authorization through Humana's provider portal
  • Timeline: 30 days for pre-service decisions under Medicare Advantage

Pharmacy Benefit (Part D) Path

  • When it applies: Rarely for Strimvelis due to manufacturing location and administration requirements
  • Coding: J3590 (unclassified biologicals) if processed as pharmacy benefit
  • Authorization: Formulary exception required since not on standard Part D formularies
  • Timeline: 72 hours for coverage determinations once prescriber statement received
Tip: Most Strimvelis cases will follow the medical benefit path due to the complex manufacturing and administration requirements at SR-TIGET.

ICD-10 Mapping for ADA-SCID

Accurate diagnosis coding is essential for Humana's prior authorization review. The primary code for ADA-SCID is straightforward, but supporting codes strengthen your case.

Primary Diagnosis Code

  • D81.1: Severe combined immunodeficiency [SCID] with low or normal B-cell numbers
  • Specificity: This covers ADA-deficient SCID specifically
  • Documentation requirements: Genetic testing confirming bi-allelic ADA mutations, enzyme activity <1% of normal

Supporting Diagnosis Codes

  • D84.9: Immunodeficiency, unspecified (for complications)
  • Z87.891: Personal history of nicotine dependence (if applicable)
  • Z51.11: Encounter for antineoplastic chemotherapy (for conditioning regimen)

Documentation Language That Supports Coding

When submitting clinical notes, include these specific phrases that align with ICD-10 criteria:

  • "Severe combined immunodeficiency with adenosine deaminase deficiency"
  • "Bi-allelic ADA gene mutations confirmed by genetic testing"
  • "ADA enzyme activity less than 1% of normal range"
  • "Recurrent severe infections consistent with SCID"
  • "Failed or contraindicated for PEG-ADA enzyme replacement therapy"

Product Coding: HCPCS, J-Codes, and NDC

Strimvelis lacks FDA approval in the U.S., creating coding complexity that requires careful coordination with Humana.

HCPCS/J-Code Overview

No specific J-code exists for Strimvelis as of 2024. Use these unclassified codes:

Code Description Use Case Units
C9399 Unclassified drugs or biologicals Hospital outpatient 1 per treatment
J3590 Unclassified biologicals Physician/other outpatient 1 per treatment

NDC Coding Challenges

  • No U.S. NDC assigned to Strimvelis
  • Patient-specific manufacturing means no standard product identifier
  • Workaround: Coordinate with Humana claims team for internal surrogate code or leave NDC field blank

Units and Billing Math

  • Standard billing: 1 unit = 1 complete gene therapy treatment
  • No weight-based or dose-based calculations required
  • One-time treatment: Single claim submission post-infusion
Note: Because Strimvelis is manufactured on-site at SR-TIGET, traditional pharmaceutical supply chain coding doesn't apply.

Clean Request Anatomy

A successful prior authorization request includes specific elements that address Humana's gene therapy review criteria.

Essential Components

Patient Information Block:

  • Humana member ID and plan details
  • Patient demographics (age, weight for dosing calculations)
  • Treating physician and facility information
  • ICD-10: D81.1 with supporting documentation

Clinical Justification Section:

  • Confirmed ADA-SCID diagnosis with genetic testing results
  • ADA enzyme activity levels (<1% of normal)
  • Documentation of failed/contraindicated PEG-ADA therapy
  • HLA typing showing no suitable matched related donor
  • Bone marrow biopsy confirming adequate CD34+ cells

Treatment Plan Details:

  • HCPCS Code: C9399 or J3590 with detailed description
  • Facility: SR-TIGET, Milan, Italy (include facility credentials)
  • Administration timeline: Apheresis, conditioning, infusion schedule
  • Cost estimate: Comprehensive breakdown including travel logistics

Required Attachments

  • Genetic testing confirming bi-allelic ADA mutations
  • Immunologic workup (lymphocyte subsets, immunoglobulin levels)
  • Documentation of PEG-ADA failure or contraindications
  • HLA typing and donor search documentation
  • Bone marrow biopsy results

Frequent Coding Pitfalls

Avoid these common errors that lead to automatic denials:

Unit Conversion Errors

  • Mistake: Trying to calculate units based on cell count or weight
  • Fix: Always use 1 unit for the complete gene therapy treatment

Mismatched Code Categories

  • Mistake: Using standard oncology J-codes for gene therapy
  • Fix: Stick to unclassified codes (C9399/J3590) with detailed descriptions

Missing Geographic Specificity

  • Mistake: Not clearly identifying SR-TIGET as the only treatment facility
  • Fix: Include facility name, address, and rationale for international treatment

Incomplete Cost Documentation

  • Mistake: Submitting partial cost estimates
  • Fix: Provide comprehensive breakdown including product, facility, travel, and follow-up costs

Verification with Humana Resources

Before submission, verify your approach using Humana's official channels:

Provider Portal Verification

  1. Log into Humana provider portal
  2. Navigate to "Prior Authorization" section
  3. Search for gene therapy or cellular therapy requirements
  4. Confirm current PA forms and submission methods

Direct Contact Verification

  • Humana National Transplant Network: 866-421-5663
  • Fax: 502-508-9300
  • Questions to ask:
    • Current gene therapy PA requirements
    • Preferred HCPCS codes for unlisted gene therapies
    • International facility authorization process
    • Required clinical documentation

Cross-Check with Current Policies

  • Review Humana's Prior Authorization Lists
  • Confirm genetic therapy is listed under transplant/cellular therapy services
  • Verify submission deadlines and review timelines

Quick Audit Checklist

Use this pre-submission checklist to ensure completeness:

□ Patient Information Complete

  • Member ID verified
  • Current insurance card copied
  • Demographics accurate

□ Diagnosis Documentation

  • ICD-10 D81.1 confirmed
  • Genetic testing results attached
  • ADA enzyme levels documented

□ Coding Accuracy

  • C9399 or J3590 selected appropriately
  • Detailed description included
  • Units set to 1

□ Clinical Justification Strong

  • PEG-ADA failure documented
  • No suitable HLA donor confirmed
  • Medical necessity clearly stated

□ Administrative Requirements Met

  • PA form completed fully
  • All attachments included
  • Submission method confirmed

□ Cost Information Comprehensive

  • SR-TIGET estimate included
  • Travel costs outlined
  • Payment method discussed

Appeals Process in Michigan

If Humana denies your Strimvelis request, Michigan DIFS external review does not apply to Medicare Advantage plans. Follow federal Medicare appeal processes instead.

Internal Appeal (Level 1)

  • Timeline: File within 65 days of denial notice
  • Method: Humana member portal, phone, or mail
  • Decision timeframe: 7 days for Part D appeals, 30 days for Part C
  • Required: Copy of denial letter, additional clinical documentation

Federal External Review (Level 2)

  • Entity: Maximus Federal Services (Medicare IRE)
  • Timeline: 65 days after Humana's internal appeal decision
  • Process: Submit external review form to Medicare IRE
  • Decision: Binding on Humana, 60 days standard (72 hours expedited)

Expedited Appeals

Available when delay could "seriously jeopardize life, health, or ability to regain maximum function":

  • Provider certification required stating urgency
  • Timeline: 24-72 hours for decision
  • Submission: Directly to IRE with provider letter
Important: Unlike commercial plans, Medicare Advantage appeals bypass Michigan DIFS and follow federal processes exclusively.

Common Denial Reasons & Fixes

Denial Reason How to Overturn Required Documentation
Experimental/Investigational Cite EU approval, peer-reviewed efficacy data FDA orphan drug status, NICE evaluation, clinical trial results
Not medically necessary Demonstrate PEG-ADA failure, infection history Detailed treatment timeline, hospitalization records
Out-of-network facility Request gap exception for unavailable service Documentation that no U.S. facility offers Strimvelis
Lack of genetic confirmation Provide comprehensive genetic testing Bi-allelic ADA mutation analysis, enzyme activity levels
Inadequate prior therapy trial Document PEG-ADA treatment and outcomes Therapy logs, response measurements, adverse events

FAQ

How long does Humana prior authorization take for gene therapy? Standard requests: 30 days for medical benefits, 72 hours for Part D coverage determinations. Expedited requests: 24-72 hours with provider certification of urgency.

What if Strimvelis is not on Humana's formulary? Submit a formulary exception request with prescriber supporting statement explaining why formulary alternatives are inadequate or would cause adverse effects.

Can I request an expedited appeal in Michigan? Yes, but through federal Medicare processes, not Michigan DIFS. Provider must certify that delay would jeopardize health.

Does step therapy apply to gene therapy? Typically yes - you must document failure or contraindications to standard treatments like PEG-ADA before gene therapy approval.

What counts as medical necessity for Strimvelis? Confirmed ADA-SCID diagnosis, failed/contraindicated PEG-ADA therapy, no suitable HLA-matched donor, and adequate CD34+ cell count for harvest.

How much does Strimvelis cost? Public list price is approximately €594,000 ($650,000) per patient for the single treatment, plus facility and travel costs.

Where can I get help with appeals in Michigan? Contact 1-800-MEDICARE for federal appeals assistance. Michigan DIFS (877-999-6442) can confirm they don't handle Medicare Advantage appeals.

Counterforce Health specializes in turning insurance denials into targeted, evidence-backed appeals. Our platform helps patients, clinicians, and specialty pharmacies navigate complex prior authorization requirements for high-cost therapies like gene treatments. We analyze denial letters, identify specific coverage criteria, and draft point-by-point rebuttals using the right clinical evidence and regulatory citations. For families facing Strimvelis denials, Counterforce Health provides the specialized expertise needed to build compelling medical necessity cases that meet payer requirements.

When dealing with international gene therapy like Strimvelis, having expert support can make the difference between approval and denial. Counterforce Health's team understands the unique challenges of coding unlisted biologicals, documenting medical necessity for rare diseases, and navigating federal appeal processes for Medicare Advantage plans.

Sources & Further Reading

Disclaimer: This guide provides general information about insurance processes and is not medical advice. Coverage decisions depend on individual plan terms and clinical circumstances. Always consult with your healthcare provider about treatment options and verify current requirements with your insurance plan. For specific legal or regulatory questions, consult appropriate professionals.

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