Breast cancer prescription shifts: As Enhertu moves to earlier lines, how will share gains translate into revenue?
Goldman Sachs prescription tracking shows that Enhertu is changing the treatment mix in HER2-positive breast cancer, while Kisqali is expanding in adjuvant treatment. But Roche faces a lower-priced product mix and Novartis is constrained by pricing pressure, so prescription strength and revenue expectations are not moving in step.
Original source：Goldman SachsFirst published on Unhidea：Original source date：
Key takeaway
Goldman Sachs’ long-term sales expectations for Enhertu are significantly above consensus, while prescription trends for Roche and Kisqali show that revenue also depends on product mix and pricing.
How is Enhertu moving from a later-line advantage into earlier treatment?
Enhertu is expanding into earlier stages of treatment. An IQVIA BrandImpact survey as of September 2026 shows its share of adjuvant treatment for HER2-positive breast cancer rose from 6% in May to 12%; its share in second-line and later treatment was 54%, maintaining its existing lead.
Growth in earlier treatment came alongside a retreat by an older regimen: Kadcyla’s share of adjuvant treatment fell from 16% in September 2025 to 9% in September 2026. Goldman Sachs says this is consistent with Enhertu beginning, following its approval, to replace some medication used by patients with residual disease after preoperative treatment; the survey did not track individual patient switches.
This is important context for Goldman Sachs’ positive outlook on sales expansion: the bank expects global Enhertu sales to rise from 3.9 billion dollars in 2026 to 9.2 billion dollars in 2030. On a product sales and collaboration revenue basis, its forecast is 5% above company-compiled consensus in 2026 and an average of about 35% higher in 2029–2030.
Why might Roche retain volume while facing revenue pressure?
In first-line treatment of HER2-positive metastatic breast cancer, Phesgo’s share fell from 63% in September 2025 to 33% in September 2026, while “other Perjeta combinations” rose from 1% to 35% over the same period. Based on the timing of approval and the scale of growth, Goldman Sachs believes the latter primarily reflects adoption of Enhertu in combination with Perjeta, although the category does not specify the components of the combinations.
The key is that Roche can still sell Perjeta through the new combination, while the product mix changes. Phesgo contains Perjeta and Herceptin and has an annual wholesale acquisition cost of 175 thousand dollars, compared with 83 thousand dollars for Perjeta alone; assuming similar discount rates, relatively stable prescription volume could still be accompanied by revenue pressure.
Goldman Sachs expects sales of Roche’s HER2 portfolio to remain flat at 8.2 billion Swiss francs at constant exchange rates in 2026, then decline by an average of about 8% annually in 2027–2030. Its overall forecast is broadly in line with Visible Alpha consensus. Enhertu’s expansion affects Roche through both the replacement of older products and a shift in retained volume toward lower-priced combinations.
Kisqali’s share exceeds Verzenio’s: why is Goldman Sachs still below long-term consensus?
In adjuvant treatment of HR-positive, HER2-negative breast cancer, Kisqali’s share increased by about 3.5 percentage points year on year to 7% in September 2026, slightly above Verzenio’s 6%. The growth came from broader coverage: its share among patients at intermediate risk of recurrence rose from 5% a year earlier to 12%; among high-risk patients, however, Verzenio remained ahead at 24%, versus Kisqali’s 16%.
Change in the overall treatment mix remains gradual: aromatase inhibitors accounted for an average of about 62% over the past year, while chemotherapy still had a 23% share in September. The first-line metastatic market also shows different signals: although Kisqali led with 37%, it was down 8 percentage points from its March peak, while Ibrance had risen to 36%; Goldman Sachs says this category is subject to substantial monthly volatility and short-term rises or falls are insufficient to establish a structural change in the competitive landscape.
Share expansion is also constrained by pricing. Goldman Sachs expects Kisqali’s US sales to reach 4.3 billion dollars in 2026, about 1% above Visible Alpha consensus, but its forecast averages about 9% below consensus in 2027–2030; its US model incorporates IRA-related pricing pressure. For Verzenio, the bank’s US sales forecasts for the same period average about 17% below consensus, reflecting its cautious assessment of competitive pressure.
