The U.S. Food and Drug Administration is reviewing Kadcyla (trastuzumab emtansine) as a post-surgery treatment for early-stage breast cancer patients whose tumors produce the HER2 factor, Roche announced.

The supplemental biologics license application — which is for patients who had residual disease after their pre-surgery treatment — is being reviewed under the FDA’s real-time oncology review and assessment aid pilot programs, meant to explore a more efficient review process, so patients can more quickly gain access to treatments found safe and effective.

For the same indication, Kadcyla was also granted breakthrough therapy designation, intended to accelerate the development and review of medicines that may treat serious or life-threatening diseases.

“Kadcyla was granted Breakthrough Therapy Designation and is also the first Roche medicine to be reviewed under the FDA’s Real-Time Oncology Review pilot programme; both FDA initiatives aim to expedite reviews and bring medicines to patients sooner,” Sandra Horning, MD, Roche’s chief medical officer and head of global product development, said in a press release.

“We are working closely with the FDA to bring Kadcyla to people with HER2-positive early breast cancer who have residual disease after neoadjuvant therapy as early as possible,” she added.

Kadcyla, marketed by Genentech, is an antibody-drug conjugate that uses the trastuzumab antibody (the active ingredient in Herceptin) to deliver a cytotoxic agent to cancer cells. Kadcyla delivers the cytotoxic agent directly into HER2-positive cancer cells, in this way limiting damage to healthy tissues.

The FDA’s decision was based on results from the Phase 3 KATHERINE trial (NCT01772472), where Kadcyla cut in half the risk of invasive disease or death, compared with Genentech’s Herceptin (trastuzumab).

KATHERINE enrolled 1,486 HER2-positive, early-stage breast cancer patients found to have residual cancer cells — detected in the breast or axilla during surgery — after receiving treatment with taxane-based chemotherapy and Herceptin.

Patients were randomized to Kadcyla or Herceptin, delivered into the blood every three weeks for 14 cycles. The trial’s primary objective was invasive disease-free survival, defined as the time without breast cancer recurrence or death from any cause.

Secondary measures included time to a second, non-breast cancer, overall survival, time to metastasis, and safety.

In addition to the 50% lower risk of invasive disease or death, Kadcyla also decreased the risk of metastatic disease by 40%, researchers found. After a median follow-up of 41.4 months, 10.5% of patients on Kadcyla had died or seen their disease spread, compared with 15.9% for those on Herceptin.

Kadcyla’s safety profile was consistent with other trials, with the most common serious adverse effects in the Kadcyla group being low platelet counts, high blood pressure, and radiation-induced skin injury. However, more patients on Kadcycla discontinued treatment due to adverse events.

Kadcyla is already approved as a single agent for HER2-positive breast cancer patients whose cancer has metastasized, or spread to other parts of the body, after unsuccessful treatment with Herceptin and a taxane. The treatment is also recommended for patients whose cancer returned less than six months after receiving post-surgery therapy.