Humanigen, Inc. (Nasdaq: HGEN) (“Humanigen”), a clinical-stage biopharmaceutical company focused on preventing and treating an immune hyper-response called ‘cytokine storm,’ announced today a peer-reviewed publication in Leukemia, a leading oncology and hematology journal, entitled “GM-CSF disruption in CART cells modulates T cell activation and enhances CART cell anti-tumor activity.”
This publication is a significant addition to the findings from a previous article in the leading hematology journal, blood, which demonstrated that neutralization of GM-CSF with lenzilumab (LENZ®) was able to break the efficacy/toxicity linkage by reducing cytokine release syndrome (CRS) and neuroinflammation (ICANS) while enhancing CAR-T function.1
The Leukemia publication demonstrates that CRISPR/Cas9-mediated GM-CSF knockout in CAR-T cells directly ameliorates CAR-T cell early activation, reduces activation-induced cell death, and results in enhanced anti-tumor activity in vivo in a xenograft model.2
Enhancing CAR-T cell in vivo efficacy by using strategies to non-specifically stimulate CAR-T cell proliferation utilizing synthetic biology or combination therapy to edit exhaustion pathways or prevent apoptosis is an important goal and is the subject of substantial ongoing research. However, while this may improve CAR-T efficacy, it is often at the cost of an increase in important toxicities, such as CRS and ICANS. In contrast, these data published in Leukemia indicate that GM-CSFko CAR-T cells result in enhanced CAR-T cell proliferation and anti-tumor activity while being associated with a marked reduction in GM-CSF levels, which have been linked to CAR-T associated toxicities.
CAR-T therapies have resulted in significant advances for patients. However, for up to one-third of patients, toxicities such as severe ICANS and CRS occur, and tumor relapse is still a frequent occurrence.3 Currently, the widespread adoption of CAR-T therapy is limited, in part, by the requirement for treatment in centers that are experienced in managing the common toxicities of ICANS and CRS and by the financial and health burden that this creates. “CRS, ICANS, and tumor relapse remain challenges for physicians and patients treated with CAR-T therapy,” said Saad Kenderian, M.B., Ch.B., hematologist at Mayo Clinic Cancer Center, an author of the Leukemia paper and the primary investigator for the SHIELD study (Study on How to Improve Efficacy and toxicity with Lenzilumab in DLBCL and other NHL patients treated with CAR-T therapy). He added, “They result in additional morbidity for patients, as well as significantly increased costs for healthcare providers. Treatments that can prevent ICANS and CRS while potentially improving CAR-T efficacy could address a critical unmet need.”
This publication adds to the body of knowledge of GM-CSF depletion in CAR-T. The upcoming Phase 3 CAR-T study, known as SHIELD, will determine the efficacy and safety of prophylactic lenzilumab on the rates of ICANS, CRS, and CAR-T efficacy. “The SHIELD trial has been designed to build on the positive results from the ZUMA-19 study. The primary endpoint of SHIELD will focus on demonstrating a significant improvement in neurotoxicity associated with both Yescarta® and Tecartus®. We will also seek to explore the beneficial impact that lenzilumab may have CAR-T efficacy,” stated Dale Chappell, M.D., MBA, Chief Scientific Officer, Humanigen.
1. Sterner, R. et al. (2019). GM-CSF inhibition reduces cytokine release syndrome and neuroinflammation but enhances CAR-T cell function in xenografts. blood. https://doi.org/10.1182/blood-2018-10-881722
2. Cox, M. et al. (2022). GM-CSF disruption in CART cells modulates T cell activation and enhances CART cell anti-tumor activity. Leukemia. https://doi.org/10.1038/s41375-022-01572-7
3. Morris, E. et al. (2021). Cytokine release syndrome and associated neurotoxicity in cancer immunotherapy. Nature Reviews Immunology. https://doi.org/10.1038/s41577-021-00547-6
Lenzilumab is a proprietary Humaneered® first-in-class monoclonal antibody that has been proven to neutralize GM-CSF, a cytokine of critical importance in the hyperinflammatory cascade, sometimes referred to as cytokine release syndrome, or cytokine storm, associated with COVID-19 and other indications. Lenzilumab binds to and neutralizes GM-CSF, potentially improving outcomes for patients hospitalized with COVID-19. Humanigen believes that GM-CSF neutralization with lenzilumab also has the potential to reduce the hyper-inflammatory cascade known as cytokine release syndrome common to chimeric antigen receptor T-cell (CAR-T) therapy and acute Graft versus Host Disease (aGvHD).
In CAR-T, lenzilumab successfully achieved the pre-specified primary endpoint at the recommended dose in a Phase 1b study (ZUMA-19) with Yescarta® in which the overall response rate was 100% and no patient experienced severe cytokine release syndrome or severe neurotoxicity. Based on these results, Humanigen plans to test lenzilumab in a randomized, multicenter, potentially registrational, Phase 3 study (“SHIELD”) to evaluate its efficacy and safety when combined with Yescarta and Tecartus CAR-T therapies in non-Hodgkin lymphoma. Lenzilumab will also be tested to assess its ability to prevent and/or treat acute Graft versus Host Disease (aGvHD) in patients undergoing allogeneic hematopoietic stem cell transplantation.
A study of lenzilumab is also underway for patients with chronic myelomonocytic leukemia (CMML) exhibiting RAS pathway mutations. This study builds on evidence from a Phase 1 study, conducted by Humanigen, that showed RAS mutations are associated with hyper-proliferative features, which may be sensitive to GM-CSF neutralization.
Lenzilumab is an investigational product and is not approved or authorized in any country.
About Humanigen: Humanigen, Inc. (Nasdaq: HGEN) (“Humanigen”), is a clinical-stage biopharmaceutical company focused on preventing and treating an immune hyper-response called ‘cytokine storm.’ Lenzilumab is a first-in-class antibody that binds to and neutralizes granulocyte-macrophage colony-stimulating factor (GM-CSF).
Results from preclinical models indicate GM-CSF is an upstream regulator of many inflammatory cytokines and chemokines involved in the cytokine storm. Early in the COVID-19 pandemic, investigation showed high levels of GM-CSF secreting T cells were associated with disease severity and intensive care unit admission.
Humanigen’s Phase 3 LIVE-AIR study suggests early intervention with lenzilumab may prevent consequences of a full-blown cytokine storm in hospitalized patients with COVID-19. Humanigen is developing lenzilumab as a treatment for cytokine storm associated with COVID-19 and CD19-targeted CAR-T cell therapies and is also exploring the effectiveness of lenzilumab in other inflammatory conditions such as acute Graft versus Host Disease in patients undergoing allogeneic hematopoietic stem cell transplantation, eosinophilic asthma, and rheumatoid arthritis