Few companies in the biotech industry have performed better in the past two years than Summit Therapeutics (SMMT -2.71%). The drugmaker's shares are up by nearly 540%, thanks to excellent clinical progress for its leading pipeline candidate, ivonescimab, a cancer treatment in development.

The drug's prospects look so attractive that, despite Summit's $15 billion market cap -- an exceedingly rare feat for a drugmaker without a single product on the market -- some investors and analysts think it has substantial upside left.

With that as a backdrop, let's find out whether Summit Therapeutics could deliver life-changing returns and help investors become millionaires.

SMMT data by YCharts.

A shrewd management team

One of the most important factors in a company's long-term success is the team leading it. Summit's management team looks somewhat clever, given how it landed ivonescimab. This medicine was initially created by Akeso Biopharma, a company based in China, and ivonescimab is already approved in the country. The two companies signed a deal that granted Summit the right to develop and commercialize the drug in Canada, the U.S., the Caribbean, Central and South America, Europe, the Middle East, Africa, and Japan.

Licensing deals happen all the time in the biotech industry, but few involve medicines that could challenge the world's best-selling medicine, Keytruda, in its most important market. That's what Summit's management team pulled off. Last year, ivonescimab performed better than Keytruda in a phase 3 study in patients with non-small cell lung cancer (NSCLC) and PD-L1 protein overexpression.

The deal with Akeso cost Summit Therapeutics an up-front payment of about $500 million, with up to $4.5 billion in potential milestones (not including future royalties). That price looks more than fair for the first medicine to beat Keytruda in a late-stage trial in NSCLC. Many biotech giants would have made that deal in a heartbeat, but none of them did. That says something about those at the helm of the company.

Beyond ivonescimab's potential

Keytruda is expected to hit peak sales of $34.3 billion (according to some estimates) before it runs out of patent exclusivity in 2028. It's unclear how much of that will be from the NSCLC market that ivonescimab could soon enter. However, the investigational medicine is targeting many other indications: the drug is being tested as a potential therapy for breast cancer, ovarian cancer, colorectal cancer, and others. It might not hit $30 billion in peak sales, but if it can earn indications across the board, it should easily become a blockbuster.

Some analysts project that ivonescimab's revenue will be $1.7 billion by 2030. It should grow its sales well into the next decade and allow Summit Therapeutics to turn a profit, eventually. However, the commercial life of the drug almost certainly won't give enough time for Summit to become a millionaire maker. Returns of this kind don't happen overnight. They're made over many years -- typically decades -- by patient, dedicated investors willing to hold shares of companies through market volatility.

If you invested $50,000 in a stock today, it would take a compound annual growth rate of 16.2% to turn into $1,000,000 in 20 years. That initial investment of $50,000 would be challenging for average investors, and achieving a CAGR of more than 16% would be unusual. Even assuming that ivonescimab performs about as well as expected, I think returns of these kinds will be beyond Summit's reach, given that some of the drug's success is already baked into its stock price (again, clinical-stage biotechs worth $15 billion are rare).

Furthermore, the patent for the cancer medicine will expire by 2042. To become a millionaire maker, Summit Therapeutics will have to rely on more than ivonescimab, by internally developing novel products or striking more attractive licensing deals. Considering there's little to be said for Summit's work outside of ivonescimab, it's hard to bet on the stock to turn average investors into millionaires.

Summit Therapeutics could (and should) still deliver strong returns in the next five years. So I'd recommend the stock, even if it's too soon to call it a millionaire maker.