US Biopharma New Drug Launch Tracking: Early Prescription Volumes for Cobenfy, Yeztugo, Journavx Fall Short of Consensus Expectations

Key Conclusions

As of mid-May 2026, weekly total US prescription volume grew only 1.4% year-over-year, below the 1.9% pace recorded in the same period last year. Four highly anticipated new drugs—Bristol-Myers Squibb's Cobenfy, Gilead's Yeztugo, Vertex's Journavx, and Johnson & Johnson's Icotyde—all show early prescription volumes significantly lagging the trajectory needed to achieve consensus revenue estimates for 2026. Meanwhile, biosimilars to Stelara and Prolia are rapidly eroding originator market share, and net prices in immunology remain under pressure from high gross-to-net (GTN) discounts (e.g., Journavx GTN at 65-75%). For specialist investors, the thesis relying on new drug launch ramp-ups to support valuations faces a correction, while defensive value is rising for companies with strong moats in mature product lines (e.g., AbbVie's Skyrizi, Eli Lilly's GLP-1 franchise).

Multiple New Drugs Show Prescription Trajectories Well Below Consensus-Paced Launch Curves

Conclusion: Weekly prescription volumes for Cobenfy, Yeztugo, Journavx, and Icotyde have not demonstrated the growth momentum needed to support 2026 consensus revenue estimates. Consensus may be overly reliant on optimistic linear extrapolation.

Evidence:

• Cobenfy's latest weekly prescriptions stand at approximately 3,110, flat sequentially. To reach the 2026 US consensus revenue of $296 million (MS estimate: ~197,000 cumulative prescriptions needed), its ramp-up speed would need to be 2-5 times that of the most successful new antipsychotic launches (Rexulti, Caplyta) at comparable stages—currently, the gap is enormous.
• Yeztugo (oral + injectable) posts weekly total prescriptions of about 1,720. While Gilead's own 2026 US PrEP revenue guidance is around $1 billion, the core driver remains Descovy (market share >45%). Yeztugo requires only "moderate" growth to hit the consensus 2Q26 US revenue of $222 million, but early GTN and prescription capture rates are highly uncertain, making linear assumptions risky.
• Journavx weekly prescriptions are around 20,380, up approximately 3.7% week-over-week. However, IQVIA data exclude hospital channels (45% of volume in 2025), and GTN is extremely high (65-75%). MS estimates that under a 50% GTN assumption, approximately 1.2 million total prescriptions would be needed to reach 2026 consensus revenue of $240 million. Current annualized retail prescriptions are only ~1.06 million, and after GTN erosion, actual net revenue is far below the trajectory required.
• Icotyde's 8th week prescriptions are only about 200 (7th week ~140). Despite JNJ reporting positive feedback from 1,500 patients and 1,000 physicians, prescription growth is slow. To reach US consensus revenue of $288 million, its launch curve would need to mirror early momentum of Otezla or Rinvoq—still an order of magnitude away.

Investment Implications: Revenue expectations for the above companies in 2026 face downward revision risk, especially for BMY and VRTX, where new drug contributions are most fragile. GILD's total PrEP revenue is relatively protected due to Descovy's resilience.

Biosimilar Penetration Accelerates, Reshaping Competitive Dynamics

Conclusion: Biosimilar market share for Stelara and Prolia is climbing faster than expected, rapidly dismantling originator brand revenue and barriers.

Evidence:

• For Stelara, Biocon's Yesintek has reached approximately 35% of weekly TRx share, far outpacing Amgen's Wezlana (12%). Stelara originator prescriptions are down about 50% year-over-year.
• For Prolia, Sandoz's Jubbonti has captured approximately 31% of TRx share, making it the second-largest player in the market.
• Historical comparison: Remicade biosimilars saw low adoption due to pricing not below net brand prices; Humira biosimilars ramped quickly due to aggressive discounts (80%). Current Stelara and Prolia biosimilar pricing strategies are closer to the latter, driving faster penetration.

Investment Implications: JNJ's Stelara revenue will decline faster than market expectations, partially offsetting new drug growth. Companies with biosimilar portfolios (e.g., Biocon, Sandoz) benefit structurally, but are outside our primary coverage.

Net Pricing in Immunology Continues to Decline; High GTN Erodes New Drug Leverage

Conclusion: The extremely high gross-to-net discounts during early new drug launches mean prescription volume growth is poorly translating into revenue growth. The pricing environment remains challenging.

Evidence:

• Journavx's GTN has averaged 65-75% over recent quarters, implying net revenue of only $25-35 per $100 of list price. To reach $240 million consensus, even at 70% GTN, total prescriptions of approximately 2.1 million would be needed—far above the annualized retail channel run rate.
• Overall market extended-unit TRx growth (+1.2%) is below total TRx growth (+1.4%), suggesting a decline in the proportion of 90-day prescriptions, potentially reflecting higher patient out-of-pocket costs or shorter treatment cycles, further depressing actual revenue.
• The report estimates immunology drug net price per prescription by dividing quarterly revenue by quarterly TRx. This metric has continued to decline since Stelara biosimilars launched.

Investment Implications: Investors evaluating new drug revenue should focus on net price, not prescription volume. High GTN means revenue elasticity is far lower than prescription elasticity, making linear extrapolation dangerous. For all new drugs—especially those with post-payment pricing (e.g., via PBMs)—the risk of overestimation is acute.