Abstract Background SL-28 (Leukocyte-Tells) is a novel cell therapy that uses allogeneic leukocytes whose anticancer activity is altered ex vivo through the recently discovered TezR receptors. We developed a method using TezR receptors, without direct genetic modification, to orchestrate leukocyte activity and generate so-called Leukocyte-Tells. Leukocyte-Tells are characterized by upregulated key pathways associated with immune cell function: migration, signaling, and enhanced energy metabolism, and demonstrate activity against various types of solid tumors (pancreatic cancer, prostate cancer, neuroblastoma). This study, for the first time, reports a complete response in a patient with stage IV-lung cancer with malignant pleural effusion treated with SL-28 (compassionate use NCT06872489). Case Presentation An 82-year-old male showed CT findings of a tumor in the right lower hilum with lesions measuring 18.3 × 16.7mm and 11.9 × 8.2mm; a 6.5 × 5.1mm lesion in the S3 segment of the right lung; and pleural effusion (2,700 mL). The patient received two cycles of chemotherapy (etoposide 100 mg/m², days 1-3, intravenously). A chest CT after two cycles showed no tumor response, with persistent pleural effusion exceeding 2,000 mL. SL-28 was cryopreserved and administered immediately after thawing at a dose of 1E7 to 1E8 cells/ injection once or twice-daily, five times/week. SL-28 therapy was well tolerated, with no graft-versus-host disease, cytokine-release-syndrome, or immune effector cell-associated neurotoxicity syndrome observed. After the first 3 weeks of therapy, CT demonstrated stable disease per RECIST1.1, with no growth of the S6 lesions and an 80% reduction of the S3 lesion (from 6.5 × 5.1mm to 4 × 2mm). At week 8, CT demonstrated a partial response per RECIST1.1: one lesion in S6 had completely resolved, the second showed a slight reduction (12 × 8mm to 11 × 7mm), and the lesion in S3 had completely resolved. The volume of pleural fluid gradually decreased to 50-100 mL. By week 22, no new nodules were observed, all S6 lesions had disappeared, and the remaining tumor in S3 was no longer visible. A fine-needle biopsy was performed at the original lesion site in S6, revealing no malignant cells, only fibrotic tissue. These findings, together with CT imaging, were consistent with a complete response per RECIST 1.1. The patient was monitored for an additional 6 months following completion of SL-28 therapy, with no evidence of disease recurrence. Conclusion SL-28 has demonstrated efficacy and safety in patient with stage IV lung cancer, supporting its potential as an “off-the-shelf” cell therapy for advanced malignancies. Similar results were obtained for patients with other solid tumors. This abstract is funded by: None
Tetz et al. (2026) studied this question.