Convection-enhanced delivery of [177Lu]Lu-labeled gold nanoparticles combined with anti-PD1 checkpoint immunotherapy improves the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors

Constantine J Georgiou; Madeline K Brown; Zhongli Cai; Laila Alshafai; Andrew Gao; James T Rutka; Mitchell A Winnik; Raymond M Reilly

doi:10.1016/j.nucmedbio.2024.108970

Convection-enhanced delivery of [¹⁷⁷Lu]Lu-labeled gold nanoparticles combined with anti-PD1 checkpoint immunotherapy improves the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors

Nucl Med Biol. 2024 Nov 9:140-141:108970. doi: 10.1016/j.nucmedbio.2024.108970. Online ahead of print.

Authors

Constantine J Georgiou¹, Madeline K Brown¹, Zhongli Cai¹, Laila Alshafai², Andrew Gao³, James T Rutka⁴, Mitchell A Winnik⁵, Raymond M Reilly⁶

Affiliations

¹ Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada.
² Department of Medical Imaging, University of Toronto, Toronto, ON, Canada; Joint Department of Medical Imaging, Division of Neuroradiology, Mount Sinai Hospital and University Health Network, Toronto, ON, Canada.
³ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; Laboratory Medicine Program, University Health Network, Toronto, ON, Canada.
⁴ Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada; The Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON, Canada; Division of Neurosurgery, The Hospital for Sick Children, Toronto, ON, Canada.
⁵ Department of Chemistry, University of Toronto, Toronto, ON, Canada.
⁶ Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada; Department of Medical Imaging, University of Toronto, Toronto, ON, Canada; Laboratory Medicine Program, University Health Network, Toronto, ON, Canada. Electronic address: raymond.reilly@utoronto.ca.

PMID: 39571483
DOI: 10.1016/j.nucmedbio.2024.108970

Abstract

Introduction: Our objective was to study convection enhanced delivery (CED) of ¹⁷⁷Lu-labeled metal chelating polymer (MCP) conjugated to gold nanoparticles ([¹⁷⁷Lu]Lu-MCP-AuNP) alone or combined with anti-PD1 immune checkpoint inhibition (ICI) for improving the survival of immunocompetent C57BL/6J mice with orthotopic GL261 murine glioma tumors.

Methods: C57BL/6J mice with GL261 tumors were treated with [¹⁷⁷Lu]Lu-MCP-AuNP (0.8 or 2.7 MBq; 4 × 10¹¹ AuNP) alone or combined with anti-PD1 antibodies (200 μg i.p. every 2 d × 3 doses). Control mice received normal saline, non-radioactive MCP-AuNP or anti-PD1 antibodies. Kaplan-Meier median survival was estimated. T-cell infiltration into the brain was probed by flow cytometry. Toxicity was assessed by monitoring body weight and cognitive function tests [Object Location Test (OLT) and Novel Object Recognition Test (NORT)] and T2-weighted MRI of the brain, overall health and ex vivo histopathological examination of the brain.

Results: Treatment with [¹⁷⁷Lu]Lu-MCP-AuNP (0.8 MBq) significantly increased median survival compared to MCP-AuNP (29 vs. 25 d; P = 0.007) or normal saline-treated mice (24 d; P < 0.001). Combining [¹⁷⁷Lu]Lu-MCP-AuNP (0.8 MBq) with anti-PD1 antibodies increased median survival to 32 d (P < 0.0001 vs. normal saline). Increasing the mean amount of [¹⁷⁷Lu]Lu-MCP-AuNP to 2.7 MBq and combining with anti-PD1 antibodies extended survival to at least 218 d in 5/9 mice. Increased CD8⁺ cytotoxic T-cells and decreased CD4⁺ helper T-cells were found in the brain vs. normal saline-treated mice. No weight loss (>20 %) was observed for treated or control mice. There was no change in cognitive function in mice treated with [¹⁷⁷Lu]Lu-MCP-AuNP (0.8 MBq) alone or combined with anti-PD1 antibodies assessed by the OLT or NORT. T2-weighted MRI in mice treated with 2.7 MBq [¹⁷⁷Lu]Lu-MCP-AuNP combined with anti-PD1 antibodies revealed edema, gliosis and ex vacuo dilatation of the ventricle proximal to the site of infusion. Histopathological examination of the brain revealed dilatation of the ventricle and gliosis proximal to the site of infusion but no radiation necrosis. MRI and histological analysis did not reveal tumor in the brain of these mice. Mice treated with 2.7 MBq [¹⁷⁷Lu]Lu-MCP-AuNP combined with anti-PD1 antibodies did not demonstrate overall deleterious health effects.

Conclusions: We conclude that CED of [¹⁷⁷Lu]Lu-MCP-AuNP combined with anti-PD1 checkpoint immunotherapy improved the survival of immunocompetent C67BL/6J mice with GL261 glioma tumors in the brain. Higher administered amounts of [¹⁷⁷Lu]Lu-MCP-AuNP (2.7 MBq vs. 0.8 MBq) were most effective and yielded long-term survival.

Advances in knowledge and implications for patient care: This study demonstrates that combining a locally-infused radiation nanomedicine, [¹⁷⁷Lu]Lu-MCP-AuNP and anti-PD1 checkpoint immunotherapy improved the survival of mice with glioma tumors in the brain. In the future, this treatment may be useful to treat residual tumor at the surgical margins in patients with GBM to prevent local recurrence and improve survival.

Keywords: Convection-enhanced delivery; Glioma; Gold nanoparticles; Immunotherapy; Lutetium-177; Protein death ligand-1 (PD1); Radiotherapy.