Pfizer Inc. has agreed to settle more than 10,000 cases accusing it of hiding the cancer risks of its Zantac heartburn drug, according to people familiar with the deal, the biggest of the litigation.

A boy with Duchenne muscular dystrophy died after receiving a Pfizer experimental gene therapy. The company is pausing its trial in older boys.

Pfizer has paused enrollment in a Phase III trial assessing its Duchenne muscular dystrophy (DMD) gene therapy candidate fordadistrogene movaparvovec after acknowledging the sudden death of a young boy who received the treatment last year.