Merck & Co.’s PD-1 superstar Keytruda has been growing exponentially thanks mainly to its lead in newly diagnosed non-small cell lung cancer. However, recent successes for immuno-oncology competitors could put some pressure on its near-term growth, one analyst says. But worry not, SVB Leerink analyst Daina Graybosch wrote in a Wednesday note to clients: The drug still has other indications to lean on. The way she sees it, Merck can compensate for Keytruda's deceleration with uptake in even earlier stages of the disease, such as before or directly after surgery. In those settings, known as neoadjuvant and adjuvant, respectively, “a potentially long duration of treatment and larger addressable population provide the largest untapped market for checkpoint inhibitors.” Keytruda arguably has an unshakeable lead in first-line NSCLC with seemingly unparalleled clinical data, but each new entry, however less meaningful, will eat away some market share. That argument led to Graybosch to project a higher probability of receding share for the Merck drug in the indication. She now projects Keytruda’s U.S. quarterly sales in NSCLC will start to decline in early 2020 from a peak of around $1.4 billion. Hurt by that slide, its overall U.S. sales will plateau next year at around $8.2 billion before ticking upward again in 2023, she estimates.