Shares of Exelixis (EXEL 17.81%) were skyrocketing 18.5% higher at 11:05 a.m. ET on Wednesday. The huge gain came after the drugmaker announced its 2025 first-quarter results Tuesday evening.

Exelixis reported Q1 revenue of $555.4 million, up 30.6% year over year. This result handily topped the consensus revenue estimate of $503 million.

The company posted net income of $159.6 million, or $0.55 per diluted share, based on generally accepted accounting principles (GAAP). Non-GAAP earnings were $179.6 million, or $0.62 per diluted share. This reflected a significant improvement from non-GAAP earnings of $52 million, or $0.17 per diluted share, in the prior-year period. It also blew past Wall Street's average Q1 adjusted earnings estimate of $0.42 per share.

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What investors really loved

Investors like it anytime a company beats top- and bottom-line quarterly estimates, as Exelixis did in Q1. However, what they really loved in this case was Exelixis' full-year guidance. The company raised its full-year revenue outlook to a range of $2.25 billion to $2.35 billion from the previous forecast of between $2.15 billion and $2.25 billion. This $100 million guidance increase was the result of accelerating demand for Exelixis' flagship cancer drug, Cabometyx.

Don't be surprised by further guidance hikes later this year. CEO Michael Morrissey said in the Q1 earnings press release that the company's team quickly shifted into action to launch Cabometyx in the advanced neuroendocrine tumors (NET) indication "within hours of receiving U.S. regulatory approval in late March." He added, "We are very pleased with the initial reception and plan to provide further updates to our 2025 financial guidance as we build momentum on the NET launch and gain further clarity on additional revenue opportunities for 2025."

Is Exelixis stock a buy?

Exelixis could have more good news on the way as well. The company expects to report results from pivotal clinical studies evaluating zanzalintinib in treating colorectal cancer and non-clear cell renal cell carcinoma in the second half of 2025. With these near-term potential positive catalysts and continued strength for Cabometyx, I think Exelixis remains a good biotech stock for aggressive investors to buy.