Ilmars Kisis

Most neuroendocrine cancers lack caspase 8 protein expression. While this feature was thought to facilitate escape from extrinsic apoptosis, its cancer-regulatory function has remained unexplored. Here, we devise a mouse model of small cell lung cancer (SCLC) recapitulating the lack of expression of caspase 8 seen in humans and uncover an unexpected role for necroptosis-fueled pre-tumoral inflammation resulting in reprogramming towards a neuronal progenitor cell-like state and increased metastatic disease. Notably, transcriptional signatures of this cellular state are enriched in relapsed and metastatic human SCLC. Mechanistically, caspase 8 loss within the pre-tumoral niche promotes inflammation marked by increased recruitment of regulatory T cells (Tregs) which are responsible for the promotion of metastatic disease. Importantly, inactivation of the necroptosis executioner MLKL reverses pre-tumoral inflammation, decreases metastasis as well as neuronal-like reprogramming. Taken together, our findings suggest that pre-tumoral inflammatory cell death contributes to neuronal progenitor mimicry, immunosuppression and increased metastasis in SCLC.

Table S4 contains the individual mutations of PPMBC and MBC lymphomas.

Table S6 contains clinical parameters and sequencing results of human DLBCL samples.

Table S3 contains B cell receptor repertoire sequencing data and lists the individual sublcones of the dominant clones of MBC, SMBC and PPMBC lymphomas.

Table S1 contains the p values of comparisons of the V gene usage in non-malignant GC B cells between the individual genotypes. These comparisons were done on the family, gene and allele level. V usage was compared for all BCR sequences as well as for isotype subsets.

This file contains the Supplementary Figures S1 to S12.

Table S2 contains a summary of the B cell receptor sequencing data of lymphoma samples. It includes 1) an overview of the investigated samples, 2) a list of characteristics of the dominant clone of each lymphoma sample, 3) a list comparing the frequencies of V family usage in WT samples to the lymphoma frequency, 4) the frequencies of FR and CDR mutations in samples analyzed by full-length BCR sequencing.

Table S5 contains statistical values of gene set enrichment analyses of the KEGG, BIOCARTA and HALLMARK gene set collections.

Genomic profiling revealed the identity of at least 5 subtypes of diffuse large B-cell lymphoma (DLBCL), including the MCD/C5 cluster characterized by aberrations in MYD88, BCL2, PRDM1, and/or SPIB. We generated mouse models harboring B cell–specific Prdm1 or Spib aberrations on the background of oncogenic Myd88 and Bcl2 lesions. We deployed whole-exome sequencing, transcriptome, flow-cytometry, and mass cytometry analyses to demonstrate that Prdm1- or Spib-altered lymphomas display molecular features consistent with prememory B cells and light-zone B cells, whereas lymphomas lacking these alterations were enriched for late light-zone and plasmablast-associated gene sets. Consistent with the phenotypic evidence for increased B cell receptor signaling activity in Prdm1-altered lymphomas, we demonstrate that combined BTK/BCL2 inhibition displays therapeutic activity in mice and in five of six relapsed/refractory DLBCL patients. Moreover, Prdm1-altered lymphomas were immunogenic upon transplantation into immuno-competent hosts, displayed an actionable PD-L1 surface expression, and were sensitive to antimurine-CD19-CAR-T cell therapy, in vivo.Significance:Relapsed/refractory DLBCL remains a major medical challenge, and most of these patients succumb to their disease. Here, we generated mouse models, faithfully recapitulating the biology of MYD88-driven human DLBCL. These models revealed robust preclinical activity of combined BTK/BCL2 inhibition. We confirmed activity of this regimen in pretreated non–GCB-DLBCL patients.See related commentary by Leveille et al., p. 8.This article is highlighted in the In This Issue feature, p. 1