/ Published Nov 24, 2025

How Is Treatment For Small Cell Lung Cancer Changing? The Era Of Immunotherapy

Creator: Dr. Kaique Filardi
Published: 2025-11-24T18:44:16-05:00

: Dr. James Taylor Medical Source: Dr. Marissa Rybstein
NYU Langone Written by: Dr. Kaique Filardi
University of São Paulo

Details
Transcript
Save This Video

Small Cell Lung Cancer: Slow But Steady Progress

For small cell lung cancer (SCLC), treatment progress has been slow but promising recently. First-line therapy now routinely includes immunotherapy + chemotherapy, offering longer survival and better quality of life for some patients than chemotherapy alone, which was previously used.
Treatment involves infusions every 3 weeks, typically over several months, followed by maintenance immunotherapy to help extend control of the disease.
Unfortunately, SCLC almost always finds a way to return. When that happens, doctors reassess: if the relapse occurs months after finishing therapy, a second course of chemotherapy may be repeated. If it happens sooner, newer drugs like lurbinectedin (Zepzelca) or clinical trial options are discussed.

For decades, small cell lung cancer (SCLC) treatment has relied on the same formula: platinum-based chemotherapy for four to six cycles. The regimen works fast and, in many cases, dramatically. Tumors often shrink within weeks, symptoms improve, and scans can look clear again. But that relief is almost always temporary. The challenge of treating this rare and fast-growing disease has been keeping the cancer at bay for longer once it is detected and treated — and new developments are slowly rising to that challenge.

“In the era before immunotherapy or before some of our more modern treatments, unfortunately the outcome for small cell lung cancer was very poor,” Dr. Marissa Rybstein, a thoracic medical oncologist at NYU Langone’s Perlmutter Cancer Center, tells SurvivorNet. “The majority of the patients did not live even more than a year or so with our best standard of treatments. Thankfully now we’ve come a long way with that.”

The Era of Immunotherapy

In 2019, results from two major studies, called IMpower133 and CASPIAN, ushered in the first real advance in SCLC treatment in more than 20 years. Both added immunotherapy to the standard platinum-etoposide chemotherapy backbone in newly diagnosed extensive-stage SCLC, where the cancer has already spread beyond one lung.

In IMpower133, adding atezolizumab (Tecentriq) extended median survival to 12.3 months compared to 10.3 months with chemotherapy alone. At two years, 22% of patients on the immunotherapy combination were still alive versus 14% with chemo alone.
In CASPIAN, adding durvalumab (Imfinzi) to the same chemotherapy improved median overall survival to 13 months, with 17.6% of patients alive at three years — an outcome once considered extraordinary for SCLC.

These results/gains may sound modest, but in a disease where outcomes had barely budged for decades, they represent real progress and hope for many patients. Both regimens, carboplatin/etoposide with either atezolizumab or durvalumab, are now considered the standard first-line therapy for extensive-stage small cell lung cancer.

“The standard of care first-line treatments are a combination of two chemotherapies, one drug called carboplatin and a second drug called etoposide,” Dr. Rybstein explains. “Then we combine those with a third drug, which we call a checkpoint inhibitor, which is a type of immunotherapy.”

Changing The Standard Treatment

For most patients, treatment begins with chemotherapy given intravenously (IV) in an outpatient infusion center, meaning patients come in for a few hours and go home the same day.

Each treatment cycle lasts roughly 3 weeks, and patients receive etoposide and a platinum drug (carboplatin or cisplatin) once per day. Each infusion lasts about 2 to 4 hours, depending on the drug combination.

Immunotherapy (atezolizumab or durvalumab) is usually given on the first day of each cycle as an IV infusion, alongside the chemotherapy. After completing 4 to 6 cycles (about 12 to 18 weeks total), chemotherapy stops, and immunotherapy continues alone as “maintenance” every 3 or 4 weeks for as long as it’s working and side effects remain manageable.

This schedule allows many patients to maintain a fairly normal daily routine between treatment days. Most report feeling tired for a few days after each infusion but are able to continue with light activities, walks, or work if energy allows.

Options When Cancer Returns

“Often we are able to get patients to have their disease kind of shrink down initially. But then what happens is unfortunately the disease also is very quick to come back or start growing again, which is a part of its unfortunately aggressive nature,” Dr. Rybstein explains. Once small cell lung cancer relapses after initial chemo-immunotherapy, treatment options become more limited

Traditional second-line chemotherapy, such as topotecan, provides only modest benefit, with response rates around 15 to 25% and median survival of six months or less. Many patients are also too frail from the first-line treatment to tolerate aggressive chemotherapy again.

This is where lurbinectedin (Zepzelca), an intravenous drug approved in 2020, has become an pivotal new tool. “It was found to be effective in small cell lung cancer patients with extensive stage disease who had already progressed on that first-line treatment with the platinum-based chemotherapy,” Dr. Rybstein says of the anticancer drug.

Derived from a sea-sponge compound, lurbinectedin works by binding to DNA and blocking the machinery that allows cancer cells to replicate. In a phase II trial published in The Lancet Oncology, it achieved an overall response rate of 35%, with median survival without disease of 3.5 months and overall survival of 9.3 months among previously treated SCLC patients.

Those numbers may not sound revolutionary, but compared with older second-line regimens, they represent a significant step forward, particularly because responses tend to be more durable and side effects generally milder (mainly fatigue and manageable bone marrow suppression).

For patients whose disease relapses after 90 days or more, lurbinectedin is now the preferred standard second-line therapy, according to National Comprehensive Cancer Network Guidelines.