Merck & Co. reported first-quarter financial results that surpassed analyst estimates, driven by strong performance from its blockbuster cancer immunotherapy Keytruda and contributions from newer products.

The pharmaceutical giant posted quarterly sales of $16.29 billion, representing a 5% increase compared to the same period last year. The growth was primarily attributed to Keytruda, which saw sales rise 12% during the quarter.

Keytruda, Merck's flagship cancer treatment, continues to be a major revenue driver for the company. The drug is approved for treating various types of cancer and has become one of the world's best-selling oncology medications.

In addition to Keytruda's strong performance, Merck cited contributions from its portfolio of newer products as factors supporting the quarterly beat. The company's diversified product lineup helped sustain overall growth momentum.

Following the strong quarterly results, Merck has narrowed its full-year financial outlook, providing investors with updated guidance based on current business performance and market conditions.