The market is pricing Ibtrozi like a category-defining oncology franchise, but the more important signal is the sequential decline in starts: that usually means the launch is converting the easy patients first and then running into a much smaller residual pool. In rare-disease/precision-oncology launches, the first 2-3 quarters often look strongest because of pent-up demand; after that, share gains tend to normalize unless the drug clearly extends duration, expands labels, or wins broad payer preference. That makes the gap between peak-sales rhetoric and current sell-through the key valuation risk, not the near-term revenue print.

Competitively, the biggest second-order effect is on the ROS1 class rather than on any single rival. If NUVB keeps taking first-line starts, competitors such as BMY’s Augtyro and Roche’s Rozlytrek will likely see pressure in their legacy lines, but the overall dollar pool is still constrained by incidence and sequencing. In other words, share can shift meaningfully without the total opportunity justifying a multi-billion-dollar peak; that is why extrapolating a launch curve into a blockbuster multiple is the main consensus error.

The contrarian setup is that the stock’s >200% rerate may have already discounted the best part of the launch. Over the next 1-3 months, the first question is whether quarterly starts re-accelerate or plateau; over 6-18 months, the real test is whether management can defend a much higher peak-sales framework with duration and persistence data. Falsifiers are straightforward: sustained growth in new starts, meaningful upward estimate revisions, or evidence that payers are accelerating formulary wins. Absent that, the downside is mostly multiple compression, not a thesis-breaking revenue collapse.