Imdelltra marks SCLC breakthrough, but Korean patients left waiting

A new drug offers the first meaningful survival improvement in decades for small-cell lung cancer (SCLC), yet Korean patients face significant barriers to access in the healthcare system.

As treatment gaps persist for this aggressive disease, there are increasing calls for timely reimbursement discussions that recognize its clinical value.

SCLC is considered the most aggressive subtype of lung cancer. It progresses rapidly—with an average survival period of just 1.5 to four months if left untreated—and tumors often grow rapidly within months.

About 60–70 percent of patients are diagnosed at an advanced stage, after the disease has already metastasized. The disease tends to spread to the brain, liver, bones, adrenal glands, and kidneys, and even patients with limited-stage disease are likely to have micrometastases, resulting in a poor overall prognosis.

Amgen’s small-cell lung cancer (SCLC) drug Imdelltra (talatamab)

The treatment landscape has also remained largely unchanged for a long time. Even with treatment, patients with advanced small-cell lung cancer have a median overall survival of six to 12 months. Chemotherapy, which has served as the standard of care for the past 30 years, shows limitations in durability of response. Most patients rapidly experience recurrence or disease progression, and the five-year relative survival rate for all small-cell lung cancer patients is only about 9 percent.

Treatment options are particularly limited for patients who relapse after first-line chemotherapy. About 90 percent of patients with metastatic SCLC experience disease progression within two years of treatment, and patients who do not respond to first-line therapy have a median survival of around four to five months.

Furthermore, in refractory patients who relapse within six months of their last chemotherapy, the response rate to conventional chemotherapy is known to drop to 10 percent or lower, highlighting the persistent need for subsequent treatment options. However, there have been virtually no treatment options available beyond third-line treatment.

In response to this ongoing treatment gap, a new immunotherapy targeting DLL3 is emerging and may shift clinical practice. Using a bispecific antibody mechanism, the novel drug simultaneously binds to the tumor antigen DLL3, which is expressed in approximately 96 percent of SCLC patients, and to T cells, prompting immune cells to directly attack cancer cells.

The drug that emerged in this context is Imdelltra (talatamab), a treatment for small-cell lung cancer. Imdelltra is a drug with a novel mechanism of action that links immune T cells to proteins on the surface of cancer cells, enabling the T cells to attack tumor cells. In particular, it has been recognized by regulatory authorities for its innovation, having received approval from the U.S. Food and Drug Administration (FDA) based on clinical results showing that it improved survival in advanced patients by about three times compared to existing standard treatments.

The clinical value of Imdelltra was confirmed in the phase 2 trial, DeLLphi-301, which enrolled patients receiving third-line or later treatment for SCLC. The objective response rate (ORR) in the 10 mg Imdelltra group was 40 percent, and a disease control rate (DCR) was observed in 70 percent of patients.

Among patients who responded, 58 percent maintained their response for six months or longer, and 25 percent sustained their response for nine months or longer. The median overall survival (mOS) was reported as 14.3 months, and the median progression-free survival (mPFS) was 4.9 months. These treatment responses were consistently observed regardless of prior treatment history, platinum-based chemotherapy sensitivity, prior immunotherapy, or DLL3 expression.

In particular, a subgroup analysis of Asian patients reported even more significant results. In the Imdelltra 10 mg group, the median overall survival was 19 months, demonstrating improved survival benefits compared to the standard of care.

Based on these clinical results, Imdelltra has been approved by the U.S. FDA as a treatment option for third-line or later-line treatment of extensive-stage small cell lung cancer. It is also recommended as a follow-up therapy in major global clinical guidelines, including ASCO and NCCN. Notably, within the NCCN guidelines, it is the only follow-up treatment option to receive a Category 1 recommendation, effectively establishing it as a standard of care in the United States.

Despite these developments, the situation in Korea remains limited. While public health insurance covers immunotherapy and targeted therapies for various cancer types, policymakers continue to underprioritize SCLC treatment.

Excluding cytotoxic anticancer drugs, the healthcare system has covered only atezolizumab combination therapy for SCLC under national health insurance in Korea since 2020. Even at the Cancer Disease Review Committee (CDRC) meeting this past January, officials did not establish coverage criteria for Imdelltra.

Given that this innovative treatment has emerged in a therapeutic landscape that has remained stagnant for nearly 30 years, the limited access faced by Korean patients goes beyond a systemic issue and is directly linked to survival.

Given that approximately 90 percent of patients with metastatic SCLC experience recurrence and that follow-up treatment options are limited, ensuring access to new treatments is inevitably a critical challenge.

“Imdelltra has demonstrated unprecedented survival benefits for the first time in 30 years in the third-line or later treatment of advanced SCLC—an area previously considered a therapeutic wasteland following chemotherapy—and is a drug that brings new hope to SCLC patients who had no further options with existing treatments,” said Professor Lee Se-hoon of the Department of Hematology and Oncology at Samsung Medical Center.

“Unlike non-small cell lung cancer (NSCLC), the fact that there are restrictions on the use of this new drug—which has emerged in a situation where there are no alternatives to chemotherapy after recurrence—is a major limitation for both patients and the clinical setting.”

He added, “Given that Imdelltra is a treatment option with significant unmet needs for both healthcare providers and patients in actual clinical practice, discussions on institutional accessibility—taking into comprehensive consideration its clinical utility, the severity of the disease, and unmet needs—must not be delayed any further.”

While Imdelltra has clearly changed the SCLC treatment landscape, persistent gaps between clinical innovation and patient access in Korea mean that improved outcomes are not yet a reality for most patients. Urgent reimbursement and policy action are needed to ensure Korean patients can benefit from this breakthrough treatment.