AUTHORS
Morgane Denis, Chloé Grasselly, Pierre-Antoine Choffour, Anne Wierinckx, Doriane Mathé, Kamel Chettab, Anne Tourette, Nolan Talhi, Fabian Birzele, Elsa Kress, Lars Petter Jordheim, Christian Klein, Eva-Laure Matera, Charles Dumontet
INTRODUCTION
Immune checkpoint inhibitors, such as antibodies directed against PD1 and PDL1 have been shown to produce durable responses in a subset of patients However, many patients either are refractory or ultimately relapse due to acquired PD1/PDL1 resistance. As the underlying mechanisms of this secondary resistance are not well understood, we developed five syngeneic murine tumor models to characterize in vivo variants with acquired resistance to PD 1 and/or PD L 1 antibodies. PD1/PDL1 resistant in vivo models were obtained by serial treatment/ reimplantation cycles in immunocompetent mice bearing MC 38 MB 49 MBT 2 TyrNRas or RENCA tumors.
RESULTS
We analyzed the tumor immune microenvironment in sensitive and PD1/PDL1 resistance models by spectral flow cytometry. A panel of 29 markers was applied Each resistant model displayed multiple modifications in the tumor immune infiltrate in comparison to the sensitive model, involving selected lymphoid and/or myeloid subpopulations Moreover, we performed an RNAseq analysis for all models We observed alterations of the pathways already described as being modified in patients with disease progressing under ICI therapy, such as PTEN INFy, PI 3 K AKT or JAK 1 JAK 2 However, this appears to be highly model dependent, reflecting the heterogeneity observed in patient.
In accordance with the up or down regulation of immune cells we tested therapeutic combination to overcome PD1/PDL1 resistance. All combinations allowed to reverse PD1/PDL1 resistance through immune checkpoint inhibitor and induced a significant delay in tumor growth
CONCLUSION
Acquired in vivo PD1/PDL1 resistant models displayed strong diversity, both in terms of alterations of the tumor immune microenvironment and tumor gene expression profile. These variants may be used to probe the heterogeneity of resistance mechanisms observed in the clinic and contribute to the preclinical evaluation of combination regimens.
PERSPECTIVES
Our model library, which may be enriched in the future with several other variants developed using the same methodology, provides an innovative tool to better apprehend the complexity and diversity of resistance to ICI and test resistance reversal strategies
FIGURE LEGENDS
Figure 1: Wild-type sensitive models acquired PD1/PDL1 resistance in vivo process.
For all models when tumors reached 150 mm 3 mice were randomized and treated with aPD1 BioXCell 12 5 mg/kg per week, IP) or aPDL1 BioXCell 12 5 mg/kg per week, IP)
Figure 2: Immunophenotyping at basal state of tumor immune infiltrate in all models. Sunburst plots showing the proportion of CD 45 immune infiltration
Figure 3: Heatmap displaying the prediction of deregulated pathways due to the acquisition of PD1/PDL1 resistance. Top five up and down-regulated pathways for each model 5 fold z score change and significant pvalue<0 05.
Figure 4: Efficacy of therapeutic combinations in vivo in preclinical PD1/PDL1 resistance models. When tumors reached 150 mm 3 mice were randomized and treated for each treatment in IP by anti TNFa BioXCell 10 mg/kg per week), anti CD 47 BioXCell 20 mg/kg per week), anti Ly 6 G BioXCell 2 5 mg/kg once a day), anti LAG 3 BioXCell 10 mg/kg twice a week), anti CTLA 4 BioXCell 5 mg/kg twice a week), anti TIM 3 BioXCell 12 5 mg/kg twice a week)
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Download the poster here: Poster MD V3 4961_26072022
