Last year saw the first two US Food and Drug Administration (FDA) approvals of oncology biosimilars: Mvasi (bevacizumab-awwb), a biosimilar to Genentech’s Avastin (bevacizumab), for treating patients diagnosed with colorectal, lung, kidney, cervical, and brain cancers; and Ogivri (trastuzumab-dkst), a biosimilar to Herceptin (trastuzumab), for treating patients with HER2-positive breast cancers or metastatic gastric or gastroesophageal junction adenocarcinomas.
But experts have voiced concerns about the emerging US biosimilars market, particularly regarding clinical uptake and uncertainty about costs. Several factors might slow widespread uptake, including regulatory and legal uncertainties, complex pricing and contracting mechanisms, and not least, patient and clinician acceptance, according to a January 2018 analysis by Trinity Partners, an industry consultancy in Waltham, Massachusetts.
Biosimilars are new and “highly similar” but not identical to branded originator biologics. They don’t yet enjoy widespread “clinical comfort” among patients and clinicians, the report’s authors noted. Currently, patients are switched to biosimilars only after brand-name drugs lose efficacy or when patients experience adverse events.
Patients and clinicians might become more confident in biosimilars if they are granted FDA “interchangeability” status rather than only biosimilarity, the report suggests. That designation would also allow automatic pharmacy substitution. But interchangeability designation would require new clinical trials, which biosimilar manufacturers have not pursued.
Despite long-anticipated cost savings, pricing is proving to be another potential barrier for biosimilars, the report’s authors cautioned. Real-world pricing isn’t a simple matter of public wholesale “list prices” because of manufacturer rebates, contracted discounts, and the addition of new agents to institutional formularies. “Biosimilar pricing is not always what it seems,” they wrote. “Contracting between drug manufacturers and providers, wholesalers, payers, and [pharmacy benefit managers] is complex and rarely transparent.”
The US Centers for Medicare & Medicaid Services analyzes manufacturer-provided average selling price data instead of wholesale list price to calculate Medicare Payment Limits for each medication.
Contracting involves another layer of complexity called performance-based pricing. Manufacturers frequently base rebates on market performance measures like market share—another source of uncertainty about real-world costs.
Meanwhile, biologics manufacturers have sought to discourage market competition for their branded products, both in the courts and through direct-to-consumer advertising.
“Many companies have spent the last decade building deep legal and promotional moats to protect their biologic cash cows,” the report states.
Roche settled a lawsuit with Mylan in March 2017 over the Herceptin biosimilar trastuzumab-dkst. Despite its December 2017 FDA approval, it remains unclear exactly when the biosimilar will become available because that information is part of a confidential settlement agreement.
Roche has also filed suit against Pfizer over its trastuzumab biosimilar.
Biosimilar manufacturers might have to offer deep discounts and pay for clinical trials to test interchangeability before they become widely accepted and used, according to the report.