Cancer Research: SL-28 and Leukocyte-Tells
Cancer remains one of the most difficult challenges in medicine, particularly for patients with advanced solid tumors that have progressed after surgery, chemotherapy, radiation therapy, targeted therapy, or immunotherapy. Despite decades of progress, many advanced solid tumors remain resistant to existing treatment approaches, creating an urgent need for new therapeutic strategies.
The Human Microbiology Institute’s cancer research is focused on discovering and developing new biological approaches that may help overcome the limitations of current cancer therapies. A major direction of this work is connected to the development of SL-28, also known as Leukocyte-Tells — a novel investigational cell therapy platform being advanced by Second Life Therapeutics.
Second Life Therapeutics describes SL-28 as a first-in-class, allogeneic, non-genetically modified cell therapy designed for advanced solid tumors. The company’s public materials state that SL-28 is based on donor-derived immune cells that are transformed into Leukocyte-Tells through modulation of the Universal Receptive System and its Teazeled receptors, or TezRs.
SL-28: A New Direction in Cell Therapy
SL-28 represents a new approach to anticancer cell therapy. Unlike autologous therapies that require cells to be collected from each individual patient, SL-28 is being developed as an off-the-shelf, allogeneic therapy derived from healthy donor leukocytes. This approach may allow treatment to begin without the long manufacturing delays associated with patient-specific cell therapies.
SL-28 is also non-genetically modified, distinguishing it from many existing cell therapy platforms. Instead of relying on genetic engineering against a single tumor-associated antigen, Leukocyte-Tells are designed to activate multiple anticancer mechanisms through regulation of immune cell activity and cellular memory.
The Science Behind Leukocyte-Tells
The scientific foundation of SL-28 is based on the discovery of the Universal Receptive System, a newly described regulatory system involving surface-associated nucleic acid-based receptors known as Teazeled receptors, or TezRs. By modulating these receptors, researchers generated Leukocyte-Tells with enhanced immune-cell functions.
Published research reports that Leukocyte-Tells demonstrated increased activity in pathways related to immune cell signaling, migration, endocytosis, phagocytosis, and energy metabolism. In vitro studies also showed enhanced antimicrobial and anticancer activity compared with control leukocytes.
This research suggests that Leukocyte-Tells may represent a new class of immune cells whose anticancer properties are not limited to a single tumor antigen or cancer type.
Focus on Advanced Solid Tumors
Advanced solid tumors are often diagnosed late, may spread to distant organs, and frequently become resistant to available therapies. Second Life Therapeutics is currently developing SL-28 for a broad range of advanced solid tumors, including tumor types in head and neck, thoracic, gastrointestinal, genitourinary, gynecologic, breast, and skin cancers.
The company is conducting a Phase 1/2a clinical trial evaluating the safety, pharmacokinetics, and anti-tumor activity of SL-28 as a monotherapy in patients with advanced solid tumors, including patients who have failed prior chemotherapy or immunotherapy.
Clinical and Translational Research
Early clinical observations under expanded access have provided encouraging signals in patients with advanced solid tumors. For example, a published case report described a partial response in a patient with metastatic pancreatic cancer treated with SL-28, including reductions in liver and bone metastases, with no serious adverse effects reported in that case.
These early observations require further evaluation in controlled clinical studies. SL-28 remains an investigational therapy, and its safety and effectiveness have not yet been fully established or approved by regulatory authorities.
HMI’s Research Direction
HMI’s cancer research is dedicated to understanding the biological mechanisms that regulate immune cell activity, cellular memory, tumor recognition, and resistance to therapy. Through this work, HMI aims to contribute to the development of novel therapeutic strategies for patients with advanced cancers, especially those with limited treatment options.
The institute’s research interests include:
- Universal Receptive System biology — Studying how TezRs and related mechanisms regulate cellular memory, immune-cell activity, and interactions between host cells, microorganisms, and cancer cells.
- Leukocyte-Tells and immune-cell modulation — Investigating how donor-derived leukocytes can be transformed into highly active immune cells with enhanced anticancer functions.
- Advanced solid tumors — Exploring new therapeutic approaches for treatment-resistant solid tumors, including pancreatic, prostate, lung, colorectal, liver, ovarian, breast, melanoma, head and neck, and other cancers.
- Cancer resistance and tumor microenvironment — Studying mechanisms that allow tumors to evade immune responses and resist conventional and advanced therapies.
- Translational development — Supporting the movement of basic scientific discoveries into clinical-stage therapeutic programs.
Commitment to Collaboration
The Human Microbiology Institute is committed to advancing cancer research through collaboration with scientific, clinical, and biotechnology partners. HMI’s goal is to help translate discoveries in microbiology, immunology, and cellular regulation into new therapeutic approaches for patients with difficult-to-treat cancers.
Disclaimer: SL-28 / Leukocyte-Tells is an investigational therapy. It has not been approved by any regulatory authority, and its safety and effectiveness have not yet been fully established
Publications:
- Regulating white blood cell activity through the novel universal receptive system
Scientific Reports (2025) - The Universal Receptive System acts as a novel regulator in the production of antimicrobial and anticancer bioactive compounds by white blood cells
Journal of Leukocyte Biology (2025) - Dramatic Clinical Response to a Novel Form of Cell Therapy SL-28 in a Patient With Advanced Prostate Cancer: A Case Report
ImmunoTargets and Therapy (2025) - Partial response in a patient with skeletal and hepatic metastases following resected pancreatic cancer to the novel cell therapy SL-28: a case report
Frontiers in Oncology (2025)