The following article features coverage from the AACR Annual Meeting 2022. Click here to read more of Cancer Therapy Advisor’s conference coverage.

Adebrelimab plus chemotherapy improved survival outcomes over chemotherapy alone in patients with extensive-stage small cell lung cancer (ES-SCLC), according to results from a phase 3 trial presented at the AACR Annual Meeting 2022. 

Adebrelimab nearly doubled the 2-year overall survival (OS) rate and more than tripled the 1-year progression-free survival (PFS) rate, the study showed.

The phase 3 CAPSTONE-1 study ( Identifier: NCT03711305) was designed to compare adebrelimab and placebo, each in combination with carboplatin plus etoposide, as first-line treatment for ES-SCLC. 

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The researchers randomly assigned 462 patients to adebrelimab (n=230) or placebo (n=232) plus chemotherapy every 3 weeks for 4 to 6 cycles. This was followed by adebrelimab or placebo maintenance therapy every 3 weeks until disease progression, unacceptable toxicity, or the 2-year mark.

Baseline characteristics were similar between the treatment arms. The median age was 62 years (overall range, 30-74 years) in both arms, and roughly 80% of patients were men. About 97% of patients in each arm had stage IV disease, 32% had liver metastasis, and 2% had brain metastasis. 

With a median follow-up of 13.5 months, the median OS was 15.3 months with adebrelimab and 12.8 months with placebo (hazard ratio [HR], 0.72; 95% CI, 0.58-0.90; P =.0017). At 1 year, the OS rate was 62.9% with adebrelimab and 52.0% with placebo. At 2 years, the OS rate was 31.3% and 17.2%, respectively. 

The median PFS was 5.8 months with adebrelimab and 5.6 months with placebo (HR, 0.67; 95% CI, 0.54-0.83; P <.0001). At 6 months, the PFS rate was 49.4% with adebrelimab and 37.3% with placebo. At 1 year, the PFS rate was 19.7% and 5.9%, respectively. 

The overall response rate was 70.4% with adebrelimab and 65.9% with placebo. The complete response rate was 3.0% and 1.7%, respectively. The median duration of response was 5.6 months and 4.6 months, respectively.  

The most common treatment-related adverse events (TRAEs) of any grade in both treatment arms were hematologic events, alopecia, ALT/AST increase, and gastrointestinal events. 

Grade 3/4 TRAEs occurred in 84.8% of patients in the adebrelimab arm and 84.1% of those in the placebo arm. Immune-mediated events occurred in 27.8% and 17.2%, respectively. There were 2 fatal TRAEs in each arm.  

Disclosures: This research was supported by Jiangsu Hengrui Pharmaceuticals Co. Ltd. Some study authors are employed by the company. Please see the original reference for a full list of disclosures.  

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Cheng Y, Wang J, Zhou C, et al. Adebrelimab or placebo plus carboplatin and etoposide as first-line treatment for extensive-stage SCLC: A phase 3 trial. Presented at AACR 2022; April 8-13, 2022. Abstract CT038.