REGN Gains 21.5% in a Month: Time to Buy, Sell or Hold the Stock?

Core Insights - Regeneron Pharmaceuticals (REGN) shares have increased by 21.5% year to date, outperforming the industry growth of 10.2% and the S&P 500 Index [1][7] - The stock's rally is attributed to positive updates regarding its pipeline and regulatory approvals, reversing its earlier performance trend [1][7] Pipeline and Regulatory Updates - The FDA approved Eylea HD (aflibercept) Injection 8 mg for treating macular edema following retinal vein occlusion (RVO), allowing dosing every eight weeks after an initial monthly period [4][5] - A monthly dosing option for Eylea has also been approved for various indications, including wet age-related macular degeneration (wAMD) and diabetic macular edema (DME) [5] - Eylea HD sales in the U.S. rose by 10% in Q3 2025 due to increased demand [6] Competitive Landscape - Eylea faces competition from Roche's Vabysmo, which has seen significant uptake [8] - Regeneron is countering Eylea's sales decline with the introduction of Eylea HD, which has shown positive sales growth [6][7] Oncology Portfolio Developments - Regeneron's oncology franchise includes Libtayo (cemiplimab-rwlc), which generated $1.03 billion in sales in the first nine months of 2025, a 21% increase year over year [10] - Recent label expansions for Libtayo have been approved by both the European Commission and the FDA, enhancing its market potential [10][11] - The FDA granted accelerated approval for linvoseltamab-gcpt for relapsed or refractory multiple myeloma, further strengthening Regeneron's oncology portfolio [12] Dupixent Sales Performance - Dupixent continues to contribute significantly to Regeneron's revenue, with recent label expansions approved for additional indications [14][15] - The collaboration with Sanofi on Dupixent has been beneficial, as solid sales have bolstered both companies' top lines [14] Financial Valuation and Estimates - Regeneron's shares are currently trading at a price/earnings ratio of 23.27X forward earnings, above the industry average of 17.26X [17] - The bottom-line estimate for 2025 has increased by $3.23 to $43.29 over the past 60 days, indicating positive revisions in earnings expectations [17][18] Overall Assessment - Regeneron is viewed as a safe haven in the biotech sector, with ongoing progress in its oncology portfolio and consistent sales growth from Dupixent [19] - However, the decline in Eylea sales poses a challenge, and regulatory setbacks could impact future performance [19][20]