https://www.nature.com/articles/s41598-025-21866-x
Second Life Therapeutics Presents SL-28 Complete Response Case Report at the American Thoracic Society 2026 International Conference
Novel off-the-shelf cell therapy SL-28 was associated with complete response in a patient with malignant pleural effusion under compassionate use. Data from a stage IV non-small cell lung cancer patient with malignant pleural effusion were presented at ATS 2026, one of the world’s largest respiratory medicine conferences, held May 15–20, 2026, in Orlando, Florida.
New York, NY, May 19, 2026. Second Life Therapeutics announced the publication of a case report abstract in the American Journal of Respiratory and Critical Care Medicine supplement describing a complete response in a patient with stage IV non-small cell lung cancer and malignant pleural effusion treated with SL-28, the company’s investigational allogeneic cell therapy.
The clinical case report, titled “Complete Response in a Patient With Non-Small Cell Lung Cancer and Malignant Pleural Effusion to a Novel Cell Therapy SL-28: A Case Report,” describes the treatment of an 82-year-old male patient with advanced lung cancer and persistent malignant pleural effusion who showed no tumor response after two cycles of chemotherapy.
SL-28, also known as Leukocyte-Tells, is a novel cell therapy based on allogeneic leukocytes whose anticancer activity is altered ex vivo through TezR receptors, without direct genetic modification. According to the abstract, Leukocyte-Tells are characterized by upregulated pathways associated with immune cell migration, signaling, and enhanced energy metabolism, and have demonstrated activity against multiple types of solid tumors.
The patient received SL-28 under compassionate use. Treatment was well tolerated, with no graft-versus-host disease, cytokine release syndrome, or immune effector cell-associated neurotoxicity syndrome observed.
After three weeks of SL-28 therapy, CT imaging demonstrated stable disease according to RECIST 1.1, including no growth of the S6 lesions and an approximately 80% reduction of the S3 lesion. By week eight, CT imaging showed a partial response, including complete resolution of one S6 lesion and the S3 lesion, along with a marked reduction in pleural fluid volume.
By week 22, no new nodules were observed, all S6 lesions had disappeared, and the remaining tumor in S3 was no longer visible. Fine-needle biopsy performed at the original lesion site showed no malignant cells and only fibrotic tissue. Together with CT imaging, these findings were consistent with a complete response under RECIST 1.1. The patient was monitored for an additional six months after completing SL-28 therapy, with no evidence of disease recurrence.
“This case report represents an important clinical observation for SL-28 in advanced solid tumors,” said George Tetz, MD, PhD, founder of Second Life Therapeutics and co-author of the abstract. “The complete response observed in a patient with stage IV non-small cell lung cancer and malignant pleural effusion supports further clinical evaluation of SL-28 as a potential off-the-shelf cell therapy for advanced malignancies.”
The abstract concludes that SL-28 demonstrated safety and clinical activity in this patient with stage IV lung cancer and supports its continued development for advanced malignancies.
About SL-28
SL-28, also known as Leukocyte-Tells, is an investigational allogeneic, non-genetically modified cell therapy developed by Second Life Therapeutics. SL-28 uses donor-derived leukocytes whose anticancer activity is modulated ex vivo through TezR receptors to enhance immune cell function, including migration, signaling, and energy metabolism.
Second Life Therapeutics is a biotechnology company developing novel cell-based therapies for advanced malignancies and other serious diseases. The company’s lead investigational therapy, SL-28, is being developed as an off-the-shelf cellular therapy for solid tumors.
SL-28 is an investigational therapy and has not been approved by the U.S. Food and Drug Administration or other regulatory authorities. This press release includes findings from a single-patient case report under compassionate use. Additional clinical studies are required to evaluate the safety and efficacy of SL-28.
press@secondlifegrp.com
