Increased p53 expression induced by APR-246 reprograms tumor-associated macrophages to augment immune checkpoint blockade
Arnab Ghosh, … , Taha Merghoub, Jedd D. Wolchok
Arnab Ghosh, … , Taha Merghoub, Jedd D. Wolchok
Published September 15, 2022
Citation Information: J Clin Invest. 2022;132(18):e148141. https://doi.org/10.1172/JCI148141.
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Research Article Oncology

Increased p53 expression induced by APR-246 reprograms tumor-associated macrophages to augment immune checkpoint blockade

Abstract

In addition to playing a major role in tumor cell biology, p53 generates a microenvironment that promotes antitumor immune surveillance via tumor-associated macrophages. We examined whether increasing p53 signaling in the tumor microenvironment influences antitumor T cell immunity. Our findings indicate that increased p53 signaling induced either pharmacologically with APR-246 (eprenetapopt) or in p53-overexpressing transgenic mice can disinhibit antitumor T cell immunity and augment the efficacy of immune checkpoint blockade. We demonstrated that increased p53 expression in tumor-associated macrophages induces canonical p53-associated functions such as senescence and activation of a p53-dependent senescence-associated secretory phenotype. This was linked with decreased expression of proteins associated with M2 polarization by tumor-associated macrophages. Our preclinical data led to the development of a clinical trial in patients with solid tumors combining APR-246 with pembrolizumab. Biospecimens from select patients participating in this ongoing trial showed that there was a suppression of M2-polarized myeloid cells and increase in T cell proliferation with therapy in those who responded to the therapy. Our findings, based on both genetic and a small molecule–based pharmacological approach, suggest that increasing p53 expression in tumor-associated macrophages reprograms the tumor microenvironment to augment the response to immune checkpoint blockade.

Authors

Arnab Ghosh, Judith Michels, Riccardo Mezzadra, Divya Venkatesh, Lauren Dong, Ricardo Gomez, Fadi Samaan, Yu-Jui Ho, Luis Felipe Campesato, Levi Mangarin, John Fak, Nathan Suek, Aliya Holland, Cailian Liu, Mohsen Abu-Akeel, Yonina Bykov, Hong Zhong, Kelly Fitzgerald, Sadna Budhu, Andrew Chow, Roberta Zappasodi, Katherine S. Panageas, Olivier de Henau, Marcus Ruscetti, Scott W. Lowe, Taha Merghoub, Jedd D. Wolchok

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Figure 1

APR-246 augments the effects of PD-1 blockade in mouse models.

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APR-246 augments the effects of PD-1 blockade in mouse models. (A) Schem...
(A) Schematic showing analysis of the TME of B16 tumors in APR-246– versus vehicle-treated mice. Tumors were harvested on day 13. Flow cytometry was performed and frequency of p53+ events in gated immune subsets are depicted (n = 3–5/group, mean ± SEM shown). (B) Murine cytokine array for tumor lysates. Bars represent the ratio of the mean intensity of 3 biologically independent experiments with 3 technical replicates each (log2). Factors relatively increased (blue) or decreased (red) on tumors from mice treated with APR-246 versus PBS (vehicle) are shown (n = 9/group, performed in duplicate; the ratio of means shown). (C) Sorted CD11b+F4/80+ TAMs were cocultured with CTV-labeled CD8+ T cells that were magnetically sorted from non–tumor-bearing B6 mice as well as anti-CD3/anti-CD28–coated activating beads. CTV dilution was detected by flow cytometry and expansion index calculated by FlowJo. Plot is representative of 3 independent experiments. (D) Schematic of treatment, tumor growth curves, and Kaplan-Meier survival of B6 mice with B16 tumors when treated with APR-246 versus vehicle with and without anti–PD-1 antibody in B6 mice with B16 tumors (n = 10/group, representing 3 independent experiments). (E) Schematic of treatment, tumor growth curves, and Kaplan-Meier survival of B6 mice with B16 tumors when treated with APR-246 versus vehicle, with and without anti–PD-1 and anti–CTLA-4 (n = 10/group, representing 3 independent experiments). (F) Schematic of treatment, mean fold change (vs. pretreatment), and Kaplan-Meier survival in tumor growth of B16 tumors in B6 mice treated with APR-246 versus vehicle, with and without anti–PD-1 and anti–CTLA-4 (n = 10/group, representing 2 independent experiments). (G) Schematic of treatment, mean fold change (vs. pretreatment) in tumor growth, and Kaplan-Meier survival of MC38 colorectal carcinoma (CRC) tumors in B6 mice treated with APR-246 versus vehicle, with and without anti–PD-1 and anti–CTLA-4 in B6 mice with MC38 CRC tumors (n = 10/group, representing 2 independent experiments). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001 by 2-way ANOVA with multiple t tests corrected with Bonferroni’s method (A and D–G [tumor growth]), 1-way ANOVA with multiple t tests corrected with Bonferroni’s method (C), or Kaplan-Meier with results ranked by Mantel-Cox log-rank test (D–G [survival patterns]).