Over the weekend, Immunomedics (NASDAQ:IMMU) presented previously undisclosed clinical trial results for Trodelvy, a recently approved cancer drug. Gilead Sciences (NASDAQ:GILD) turned a lot of heads when it offered a 108% premium in its buyout bid for Immunomedics earlier this month, but it looks like that pricey gamble is going to work out just fine.

Trodelvy earned an accelerated approval from the FDA in April because it shrank tumors for a high percentage of patients with triple-negative breast cancer (TNBC), a particularly aggressive form of the disease that doesn't respond well to any of the targeted therapies oncologists previously had in their arsenal.

Laboratory technician with pippette.

Image source: Getty Images.

In order to earn full approval from the FDA, Trodelvy needed to prove it actually improves patients' chances of long-term survival, and with this data release, it knocked that challenge out of the park. Treatment with Trodelvy reduced TNBC patients' risk of death by 52% compared to patients given a physician's choice of standard treatment options.

Trodelvy is a first-in-class antibody that delivers a miniature dose of chemotherapy to cancer cells that exhibit a protein called Trop-2 on their surface, and it probably has a future beyond TNBC. Over the weekend, Immunomedics also presented results from a phase 2 study of it as a treatment for advanced-stage bladder cancer patients who have already relapsed multiple times. Trodelvy shrank tumors for an impressive 31 patients from a group of 113, six of whom achieved complete remission.

Before the end of 2020, Immunomedics expects to submit an application to the FDA that could expand Trodelvy's addressable patient population to include people with late-stage bladder cancer.