Boryung Pharmaceutical has begun a phase 3 clinical trial for its small cell lung cancer (SCLC) treatment, Zepzelca (lurbinectedin), in Korea. Industry watchers pay attention to its result, as it will decide whether the drug maintains its product permit.

Last Thursday, the Ministry of Food and Drug Safety approved Zepzelca’s IND application for the domestic phase 3 clinical trial.

The phase 3 clinical trial will target adult patients with recurrent SCLC after failing in platinum-included chemotherapies as the primary treatment by administering Zepzelca alone or Zepzelca + irinotecan combined therapy in one group and investigator-selected therapy of topotecan or irinotecan.

Several large hospitals will be the trial sites for two years from June.

The primary endpoint is overall survival (OS), and the secondary endpoint is progression-free survival (PFS) and overall response rate (ORR).

Zepzelca is the new SCLC treatment developed by Spanish-based PharmaMar, and Boryung has the exclusive right to its sales and distribution in Korea. The Korean company obtained Zepzelca’s approval last September and began to market it this past March without insurance benefits.

The upcoming trial is aimed at maintaining Zepzelca’s product permit. The drug received conditional approval in the United States and Korea based on the result of its phase 2 clinical trials. Its original developer PharmaMar began global phase 3 trials, the LAGOON study, with its North American partner Jazz Pharmaceutical in December 2021.

Through the global trials, PharmaMar and Jazz Pharmaceuticals plan to win official approval from the U.S. Food and Drug Administration and plans to do so from the European Medicine Agency, too.

It can acquire formal approval in Korea after Boryung submits phase 3 trial results to the regulator. Global clinical trials will be conducted on 705 subjects, including 19 in Korea. Syneos Health, a contract research organization, will conduct the Korean trial.

Before granting conditional approval last July, experts at the screening committee judged it appropriate to approve Zepzelca with conditions for patients with only a few treatment options. However, they agreed on the need to prove clinical usefulness and safety in phase 3 trials compared to existing treatments.

“Based on data, we cannot think it superior to the existing secondary treatments aside from adding one more option, and so, we can confirm it only after phase 3 trials,” a participant said, according to the meeting’s minutes.

Another expert said, “We cannot be 100 percent certain about the success of clinical trials only by phase 2 clinical trials, which will depend on how they design future trials.”

Others expressed expectations about the new SCLC treatment for the first time in 20 years.

“There have been little changes in treating SCLC with short survival and relatively smaller share of 15-20 percent,” one of such the experts said. “If we can add drugs with a different mechanism, it will help patients by expanding their scope of choices.”

Another participant said, “Unlike non-small cell lung cancer (NSCLC), SCLC occurs in the neuroendocrine system. The weaker the efficacy of drugs that inhibit the cell proliferation, the smaller its side effects, including blood toxicity, might be.”