Eli Lilly’s pipeline sprung a surprise on the Street Tuesday with Phase III results showing that experimental oncology drug necitumumab, aka Neci, increased overall survival rates among patients with a virulent form of lung cancer, stage-IV metastatic squamous non-small cell lung cancer (NSCLC). The benefit was seen when the drug was used as a first-line treatment with gemcitabine and cisplatin as opposed to a chemo-only approach.

Analysts expected Neci to be dust-binned when Bristol-Myers Squibb handed over its share of the drug’s rights earlier this year. Tim Anderson, of Bernstein Research, and Leerink Swann’s Seamus Fernandez also pointed out in Tuesday research notes that their corporate forecasts initially had put no money behind the drug when assessing Lilly’s corporate potential.

Now, that’s changed. Fernandez’s revised estimate pegs Neci’s US market opportunity at around $1 billion, based on treatment costs of between $10,000 and $12,000.

Tuesday’s news still has some holes. Lilly has yet to put a timeframe on just how much of a survival window Neci provides, and there appears to be a clotting risk. But analysts see the news release as total upside for the company, which is struggling to balance out an onslaught of patent expirations, which includes Cymbalta (2013), Evista (2014), Alimta (2017), Cialis (2017), Strattera (2017) and Effient (2017).

Lilly said in a statement that it expects to send in its FDA filing in 2014, citing a manufacturing process issue.

The drug’s surprise potential goes beyond reversing a trend of recent pipeline disappointments. The drug was initially developed to replace BMS/Imclone cancer drug Erbitux in the metastatic colorectal cancer/head and neck setting, but got shoved aside because it failed. Meanwhile, Erbitux failed in the very space necitumumab could break into, NSCLC.

The added benefit is that this is a market with a clear need. American Cancer Society statistics indicate that a patient diagnosed with stage IV metastatic squamous non-small cell lung cancer has a 1% chance of surviving five years.