Kadcyla Dose Cost in the US
A single dose of Kadcyla (ado-trastuzumab emtansine), which is 3.6 mg/kg of body weight administered intravenously every 3 weeks, costs about $13,500-$15,000 for an average 70 kg patient (roughly 252 mg). This uses the wholesale acquisition cost (WAC) of $53 per mg from Roche/Genentech.[1][2]
How Pricing Varies by Patient Weight
Dosing scales with weight: a 50 kg patient pays around $9,500 per dose, while a 100 kg patient pays up to $19,000. Hospitals add markups, but net prices after discounts average 20-30% lower for eligible patients.[3]
Factors Driving High Costs
Kadcyla's price reflects manufacturing complexity as an antibody-drug conjugate, plus R&D for HER2-positive breast cancer treatment. Annual treatment (17 doses) exceeds $200,000 before insurance.[1][4] No generic exists; patents run through 2027-2032 depending on claims.[5]
Insurance Coverage and Patient Out-of-Pocket
Most commercial plans cover 80-100% after deductibles ($1,000-$5,000 typical copay per dose). Medicare Part B pays 80%, leaving patients $2,700+ per dose. Patient assistance from Genentech caps costs at $0-$5,000/year for low-income qualifiers.[2][6]
Cheaper Alternatives or Biosimilars
No US biosimilars yet due to patents, but Enhertu (trastuzumab deruxtecan) costs $13,000-$15,000 per dose with similar efficacy in some trials. Tucatinib combos run $20,000+ monthly. International prices (e.g., Canada) are 40-50% lower at $8,000-$10,000 per dose.[4][7]
When Might Prices Drop
Patent expiry starts 2027 for some formulation claims, opening biosimilar competition by 2030. Ongoing challenges from Amgen and others could accelerate this.[5]
[1]: Drugs.com - Kadcyla Pricing
[2]: GoodRx - Kadcyla
[3]: ASCO Post - ADC Pricing Analysis
[4]: ICER Report on HER2 Breast Cancer Drugs
[5]: DrugPatentWatch.com - Kadcyla Patents
[6]: Genentech Access Solutions
[7]: Canadian Agency for Drugs and Technologies in Health