Payers covering hormone receptor-positive, HER2-negative advanced breast cancer already face a testing problem, and the class of drugs that depends on that testing is getting larger. A new AMCP Market Insights report published in the October 2026 Journal of Managed Care & Specialty Pharmacy finds that ESR1 mutation testing practices are inconsistent across plans, benefits are misaligned between medical and pharmacy sides, and prior authorization friction delays care, all while next-generation selective estrogen receptor degraders (SERDs) move into earlier treatment lines where testing consistency matters more, not less.
The clinical case for early detection is real. ESR1 mutations drive endocrine resistance in nearly half of patients with this breast cancer subtype, yet most plans wait for radiologic progression before acting. SERENA-6 trial data, presented at ASCO 2025 and published in the New England Journal of Medicine, showed that catching an ESR1 mutation via circulating tumor DNA liquid biopsy and switching to camizestrant plus a CDK4/6 inhibitor significantly improved progression-free survival compared with waiting. The AMCP findings echo that gap: patients remain on ineffective first-line therapy until imaging confirms what a blood draw could have flagged earlier.
AMCP’s recommendations center on a structural fix. Auto-approvals for guideline-concordant ctDNA testing, extended authorization periods, and gold carding for qualifying oncologists would reduce the administrative load on community practices, which the report identifies as particularly underserved. The cost argument also runs in testing’s favor: payers evaluating ctDNA coverage by test price alone miss the savings from delayed progression. That framing matters as the treatment field grows. Eli Lilly’s Inluriyo (imlunestrant), an oral SERD approved by FDA in September 2025 for ESR1-mutated advanced or metastatic breast cancer, represents exactly the kind of targeted agent whose value depends on reliable, timely mutation detection upstream.
The AMCP program was funded by AstraZeneca, which has its own SERD program in camizestrant. That funding context does not invalidate the recommendations, but payers reading the supplement should weigh it. The more durable question the report surfaces is operational: if coverage policy for ctDNA testing remains split between medical and pharmacy benefits with no unified pathway, even a well-designed prior authorization reform will stall at the benefits-alignment problem. Watch whether large national plans move to unify ESR1 ctDNA coverage under a single benefit category in their 2027 formulary updates.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
