Small cell lung cancer (SCLC) has long been one of the most difficult lung cancers to treat. Marked by rapid tumor growth, early metastatic spread and historically limited treatment options, the disease has posed persistent challenges for clinicians, clinical researchers and drug developers.
Vice President of Oncology Global Development
and JAPAC Development Therapeutic Area Head
Amgen
Xtalks spoke with I-Fen Chang, Vice President of Oncology Global Development and JAPAC Development Therapeutic Area Head at Amgen, to discuss the persistent challenges in SCLC and the scientific advances reshaping the field.
“Although we are making good progress, small cell lung cancer remains one of the most aggressive and challenging cancers to treat,” I-Fen Chang said.
Compared with non-small cell lung cancer (NSCLC), where molecularly defined subtypes and actionable driver mutations have reshaped treatment over the past two decades, SCLC has been slower to move into the precision oncology era.
Chang explained that SCLC has historically had “very few actionable molecular targets,” in part because of its complex genomic profile, rapid proliferation and high tumor heterogeneity.
The disease is also strongly associated with smoking, which contributes to high levels of tumor mutational burden. While this biology can make the cancer immunologically active, it also creates substantial complexity for drug development, including difficulty identifying consistent therapeutic targets across patient populations.
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A Better Understanding of SCLC Biology
Recent progress in SCLC is being driven by a deeper understanding of the disease’s biology and the emergence of new therapeutic modalities. According to Chang, “Recent momentum in small cell lung cancer is driven by a couple of factors. It’s due to our deeper understanding of the tumor biology and also advances in translational science.”
One important shift is the recognition that SCLC is not a single, uniform disease. “Molecular profiling has revealed that small cell lung cancer is more biologically heterogeneous than what we previously thought,” Chang said, adding that SCLC is now understood to include several distinct subtypes.
This expanded view of SCLC biology is helping researchers identify tumor-associated targets that may be exploitable for drug development, including DLL3, B7-H3 and other lineage-associated antigens. These discoveries are opening the door to treatment strategies that go beyond conventional chemotherapy.
As Chang put it, “The hope here is that we will see more of a precision medicine play in the future treatment of small cell lung cancer.”
T-Cell Engagers and ADCs Reshaping SCLC Drug Development
Among the most closely watched advances in SCLC are T-cell engagers, a class of targeted immunotherapies designed to redirect a patient’s T cells toward cancer cells expressing specific tumor-associated targets. Amgen’s Imdelltra (tarlatamab-dlle), for example, is a DLL3-targeting T-cell engager designed to direct T cells against DLL3-expressing SCLC cells.
DLL3 has become an important target because of its high expression in SCLC and low expression in normal tissues. “It is an important target because of the fact that it’s highly expressed in small cell lung cancer. Up to 96% of patients express this marker,” Chang explained.
Beyond T-cell engagers, antibody-drug conjugates (ADCs) are also gaining attention in SCLC drug development. ADCs are designed to deliver cytotoxic payloads selectively to tumor cells expressing specific surface markers, offering a more targeted approach than traditional chemotherapy.
“Many emerging approaches, including immunotherapy, T-cell engagers and antibody-drug conjugates, are rapidly reshaping the way we think about research, particularly in small cell lung cancer,” Chang said.
SCLC Clinical Trial Challenges Remain Significant
Despite growing scientific momentum, clinical research in SCLC remains difficult. The disease’s aggressive course can make patient enrollment and retention challenging, particularly because many patients are diagnosed at an advanced stage and may deteriorate quickly.
“Historically, when you think about clinical trials in small cell lung cancer, they have been very challenging to run,” Chang said. She noted that approximately 70% of SCLC cases are diagnosed at advanced stages, which can limit the window for clinical trial participation.
Limited tissue availability and the lack of validated biomarkers have also complicated efforts to select patients for targeted therapies. As novel modalities enter development, trial designs will need to evolve to evaluate emerging treatments while accounting for the unique biology and clinical trajectory of SCLC.
Moving Therapies Earlier and Improving the Patient Experience
A major focus for the field is understanding whether newer therapies can deliver greater benefit when used earlier in the disease course. Chang said ongoing research is examining how innovative treatments may be moved into earlier lines, including first-line and limited-stage SCLC settings.
“An area of focus is really understanding how to move these innovative therapies into earlier lines of treatment, where we may have the potential to deliver greater and more durable benefits for patients,” she said.
At the same time, researchers are paying closer attention to treatment tolerability and the patient experience. For T-cell engagers, this includes efforts to improve the cytokine release syndrome (CRS) profile through better target selection, step-up dosing strategies and alternative routes of administration.
“All of these efforts could help us enable safer outpatient administration of these agents and also reduce the treatment burden for patients in oncology centers,” Chang said.
Toward a More Precision-Driven Future in SCLC
As more active treatment classes enter SCLC research and clinical practice, the field will need to answer important questions about optimal sequencing, rational combinations and biomarker-driven patient selection. For drug developers, SCLC remains a complex but increasingly active area of oncology innovation.
For patients, the hope is that advances in tumor biology, translational science and therapeutic design will translate into more effective and better-tolerated options.
“I hope that all of these efforts collectively will enable us to offer small cell lung cancer patients a more precision-driven approach, allowing therapies to be better tailored for the patient, and ultimately, the goal is to improve the outcome for these patients,” Chang said.
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