Bone marrow microenvironments that contribute to patient outcomes in newly diagnosed multiple myeloma: A cohort study of patients in the Total Therapy clinical trials.

BACKGROUND: The tumor microenvironment (TME) is increasingly appreciated as an important determinant of cancer outcome, including in multiple myeloma (MM). However, most myeloma microenvironment studies have been based on bone marrow (BM) aspirates, which often do not fully reflect the cellular content of BM tissue itself. To address this limitation in myeloma research, we systematically characterized the whole bone marrow (WBM) microenvironment during premalignant, baseline, on treatment, and post-treatment phases. METHODS AND FINDINGS: Between 2004 and 2019, 998 BM samples were taken from 436 patients with newly diagnosed MM (NDMM) at the University of Arkansas for Medical Sciences in Little Rock, Arkansas, United States of America. These patients were 61% male and 39% female, 89% White, 8% Black, and 3% other/refused, with a mean age of 58 years. Using WBM and matched cluster of differentiation (CD)138-selected tumor gene expression to control for tumor burden, we identified a subgroup of patients with an adverse TME associated with 17 fewer months of progression-free survival (PFS) (95% confidence interval [CI] 5-29, 49-69 versus 70-82 months, χ2 p = 0.001) and 15 fewer months of overall survival (OS; 95% CI -1 to 31, 92-120 versus 113-129 months, χ2 p = 0.036). Using immunohistochemistry-validated computational tools that identify distinct cell types from bulk gene expression, we showed that the adverse outcome was correlated with elevated CD8+ T cell and reduced granulocytic cell proportions. This microenvironment develops during the progression of premalignant to malignant disease and becomes less prevalent after therapy, in which it is associated with improved outcomes. In patients with quantified International Staging System (ISS) stage and 70-gene Prognostic Risk Score (GEP-70) scores, taking the microenvironment into consideration would have identified an additional 40 out of 290 patients (14%, premutation p = 0.001) with significantly worse outcomes (PFS, 95% CI 6-36, 49-73 versus 74-90 months) who were not identified by existing clinical (ISS stage III) and tumor (GEP-70) criteria as high risk. The main limitations of this study are that it relies on computationally identified cell types and that patients were treated with thalidomide rather than current therapies. CONCLUSIONS: In this study, we observe that granulocyte signatures in the MM TME contribute to a more accurate prognosis. This implies that future researchers and clinicians treating patients should quantify TME components, in particular monocytes and granulocytes, which are often ignored in microenvironment studies.

Multiplex immunofluorescence staining and image analysis assay for diffuse large B cell lymphoma.

With the explosion of immuno-oncology and the approval of many immune checkpoint therapies by regulatory agencies in the last few years, understanding the tumor microenvironment (TME) in the context of patients' immune status has become essential. Among available immune profiling techniques, multiplex immunofluorescence (mIF) assays offer the unique advantage of preserving the architectural features of the tumor and revealing the spatial relationships between tumor cells and immune cells. A number of mIF and image analysis assays have been described for solid tumors but most are not sufficiently suitable in lymphoma, where the lack of clear tumor-stromal boundaries and high tumor density present significant challenges. Here we describe the development and optimization of a reliable workflow using Akoya Opal staining kits to label and analyze 6 markers per slide in diffuse large B-cell lymphoma (DLBCL) tissue sections. Five panels totaling 30 markers were developed to characterize infiltrating immune cells and relevant check-point proteins such as PD1, PD-L1, ICOS, SIRP-alpha and Lag3 on 70 DLBCL sections. Multiplexed sections were scanned using an Akoya multispectral scanner. An image analysis workflow using InForm and Matlab was developed to overcome challenges inherent to the DLBCL environment. Using the assays and workflows detailed here, we were able to quantify cell densities of subsets of infiltrating immune cells and observe their spatial patterns within the tumors. We highlight heterogeneous distribution of cytotoxic T cells across tumors with similar T cell density to underscores the importance of considering spatial context when studying the effects of immunological therapies in DLBCL.

Anti-VEGF antibody therapy does not promote metastasis in genetically engineered mouse tumour models.

Resistance to anti-angiogenic therapy can occur via several potential mechanisms. Unexpectedly, recent studies showed that short-term inhibition of either VEGF or VEGFR enhanced tumour invasiveness and metastatic spread in preclinical models. In an effort to evaluate the translational relevance of these findings, we examined the consequences of long-term anti-VEGF monoclonal antibody therapy in several well-validated genetically engineered mouse tumour models of either neuroendocrine or epithelial origin. Anti-VEGF therapy decreased tumour burden and increased overall survival, either as a single agent or in combination with chemotherapy, in all four models examined. Importantly, neither short- nor long-term exposure to anti-VEGF therapy altered the incidence of metastasis in any of these autochthonous models, consistent with retrospective analyses of clinical trials. In contrast, we observed that sunitinib treatment recapitulated previously reported effects on tumour invasiveness and metastasis in a pancreatic neuroendocrine tumour (PNET) model. Consistent with these results, sunitinib treatment resulted in an up-regulation of the hypoxia marker GLUT1 in PNETs, whereas anti-VEGF did not. These results indicate that anti-VEGF mediates anti-tumour effects and therapeutic benefits without a paradoxical increase in metastasis. Moreover, these data underscore the concept that drugs targeting VEGF ligands and receptors may affect tumour metastasis in a context-dependent manner and are mechanistically distinct from one another.

COP1 is a tumour suppressor that causes degradation of ETS transcription factors.

The proto-oncogenes ETV1, ETV4 and ETV5 encode transcription factors in the E26 transformation-specific (ETS) family, which includes the most frequently rearranged and overexpressed genes in prostate cancer. Despite being critical regulators of development, little is known about their post-translational regulation. Here we identify the ubiquitin ligase COP1 (also known as RFWD2) as a tumour suppressor that negatively regulates ETV1, ETV4 and ETV5. ETV1, which is mutated in prostate cancer more often, was degraded after being ubiquitinated by COP1. Truncated ETV1 encoded by prostate cancer translocation TMPRSS2:ETV1 lacks the critical COP1 binding motifs and was 50-fold more stable than wild-type ETV1. Almost all patient translocations render ETV1 insensitive to COP1, implying that this confers a selective advantage to prostate epithelial cells. Indeed, COP1 deficiency in mouse prostate elevated ETV1 and produced increased cell proliferation, hyperplasia, and early prostate intraepithelial neoplasia. Combined loss of COP1 and PTEN enhanced the invasiveness of mouse prostate adenocarcinomas. Finally, rare human prostate cancer samples showed hemizygous loss of the COP1 gene, loss of COP1 protein, and elevated ETV1 protein while lacking a translocation event. These findings identify COP1 as a tumour suppressor whose downregulation promotes prostatic epithelial cell proliferation and tumorigenesis.

MYC cooperates with AKT in prostate tumorigenesis and alters sensitivity to mTOR inhibitors.

MYC and phosphoinositide 3-kinase (PI3K)-pathway deregulation are common in human prostate cancer. Through examination of 194 human prostate tumors, we observed statistically significant co-occurrence of MYC amplification and PI3K-pathway alteration, raising the possibility that these two lesions cooperate in prostate cancer progression. To investigate this, we generated bigenic mice in which both activated human AKT1 and human MYC are expressed in the prostate (MPAKT/Hi-MYC model). In contrast to mice expressing AKT1 alone (MPAKT model) or MYC alone (Hi-MYC model), the bigenic phenotype demonstrates accelerated progression of mouse prostate intraepithelial neoplasia (mPIN) to microinvasive disease with disruption of basement membrane, significant stromal remodeling and infiltration of macrophages, B- and T-lymphocytes, similar to inflammation observed in human prostate tumors. In contrast to the reversibility of mPIN lesions in young MPAKT mice after treatment with mTOR inhibitors, Hi-MYC and bigenic MPAKT/Hi-MYC mice were resistant. Additionally, older MPAKT mice showed reduced sensitivity to mTOR inhibition, suggesting that additional genetic events may dampen mTOR dependence. Since increased MYC expression is an early feature of many human prostate cancers, these data have implications for treatment of human prostate cancers with PI3K-pathway alterations using mTOR inhibitors.

Cooperativity of TMPRSS2-ERG with PI3-kinase pathway activation in prostate oncogenesis.

The TMPRSS2-ERG fusion, present in approximately 50% of prostate cancers, is less common in prostatic intraepithelial neoplasia (PIN), raising questions about whether TMPRSS2-ERG contributes to disease initiation. We identified the translational start site of a common TMPRSS2-ERG fusion and showed that transgenic TMPRSS2-ERG mice develop PIN, but only in the context of PI3-kinase pathway activation. TMPRSS2-ERG-positive human tumors are also enriched for PTEN loss, suggesting cooperation in prostate tumorigenesis.

Simultaneous haploinsufficiency of Pten and Trp53 tumor suppressor genes accelerates tumorigenesis in a mouse model of prostate cancer.

Tumor suppressor gene PTEN is important in the initiation and progression of human prostate carcinoma, whereas the role of TP53 remains controversial. Since Pten/Trp53 double conditional knockout mice show earlier onset and fast progression of prostate cancer when compared to Pten knockout mice, we asked whether heterozygosity of these two tumor suppressor genes was sufficient to accelerate prostatic tumorigenesis. To answer this question we examined prostatic lesion progression of Pten/Trp53 double heterozygous mice and a series of controls such as Pten heterozygous, Pten conditional knockout, Trp53 heterozygous and Trp53 knockout mice. Tissue recombination of adult prostatic epithelium coupled with embryonic rat seminal vesicle mesenchyme was used as a tool to stimulate prostatic epithelial proliferation. In our study, high-grade prostatic intraepithelial neoplasia (PIN) was found with high frequency at 8 weeks post-tissue recombination transplantation. PIN lesions in Pten/Trp53 double heterozygous mice were more severe than those seen in Pten heterozygous alone. Furthermore, morphologic features attributable to Pten or Trp53 loss appeared to be enhanced in double heterozygous tissues. LOH analysis of Pten and Trp53 in genomic DNA collected from high-grade PIN lesions in Pten heterozygous and Pten/Trp53 double heterozygous mice showed an intact wild-type allele for both genes in all samples examined. In conclusion, simultaneous heterozygosity of Pten and Trp53 accelerates prostatic tumorigenesis in this mouse model of prostate cancer independently of loss of heterozygosity of either gene.

Chk2 suppresses the oncogenic potential of DNA replication-associated DNA damage.

The Mre11 complex (Mre11, Rad50, and Nbs1) and Chk2 have been implicated in the DNA-damage response, an inducible process required for the suppression of malignancy. The Mre11 complex is predominantly required for repair and checkpoint activation in S phase, whereas Chk2 governs apoptosis. We examined the relationship between the Mre11 complex and Chk2 in the DNA-damage response via the establishment of Nbs1(DeltaB/DeltaB) Chk2(-/-) and Mre11(ATLD1/ATLD1) Chk2(-/-) mice. Chk2 deficiency did not modify the checkpoint defects or chromosomal instability of Mre11 complex mutants; however, the double-mutant mice exhibited synergistic defects in DNA-damage-induced p53 regulation and apoptosis. Nbs1(DeltaB/DeltaB) Chk2(-/-) and Mre11(ATLD1/ATLD1) Chk2(-/-) mice were also predisposed to tumors. In contrast, DNA-PKcs-deficient mice, in which G1-specific chromosome breaks are present, did not exhibit synergy with Chk2(-/-) mutants. These data suggest that Chk2 suppresses the oncogenic potential of DNA damage arising during S and G2 phases of the cell cycle.

Engineered telomere degradation models dyskeratosis congenita.

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome characterized by cutaneous symptoms, including hyperpigmentation and nail dystrophy. Some forms of DC are caused by mutations in telomerase, the enzyme that counteracts telomere shortening, suggesting a telomere-based disease mechanism. However, mice with extensively shortened telomeres due to telomerase deficiency do not develop the characteristics of DC, raising questions about the etiology of DC and/or mouse models for human telomere dysfunction. Here we describe mice engineered to undergo telomere degradation due to the absence of the shelterin component POT1b. When combined with reduced telomerase activity, POT1b deficiency elicits several characteristics of DC, including hyperpigmentation and fatal bone marrow failure at 4-5 mo of age. These results provide experimental support for the notion that DC is caused by telomere dysfunction, and demonstrate that key aspects of a human telomere-based disease can be modeled in the mouse.

Dissociation of epithelial and neuroendocrine carcinoma lineages in the transgenic adenocarcinoma of mouse prostate model of prostate cancer.

The transgenic adenocarcinoma of mouse prostate (TRAMP) model is widely used in prostate cancer research because of rapid tumor onset and progression. The transgenic mouse is on a C57BL/6 (B6) background and expresses SV40 T-antigen under the probasin promoter. The strong genetic component of susceptibility to prostate cancer in humans prompted us to investigate the effect of mouse strain background (FVB and B6) on incidence, progression, and pathology of prostate cancer in this model. Because TRAMP lesions are unique but differ from conventional prostatic intraepithelial neoplasia because the epithelium and stroma are affected diffusely, we designated them as "atypical hyperplasia of Tag." Although the incidence and severity of atypical hyperplasia of Tag is similar, FVB-TRAMP mice live significantly shorter lives than B6-TRAMP mice because of the rapid development and progression of neuroendocrine carcinomas. This is associated with an increased frequency of neuroendocrine precursor lesions in young TRAMP mice, detectable at 4 weeks after birth. These lesions show properties of bipotential stem cells and co-express markers of epithelial (E-cadherin) and neuroendocrine (synaptophysin) lineages, as well as the transcription factors Foxa1 and Foxa2. Transplantation studies using TRAMP prostatic ducts suggested that neuroendocrine carcinomas arise independently from atypical hyperplasias or other epithelial lesions. Adenocarcinomas were not seen in our cohort. Thus, neuroendocrine carcinomas are the principal malignancy in this model and may develop from bipotential progenitor cells at an early stage of prostate tumorigenesis.

The carboxy terminus of NBS1 is required for induction of apoptosis by the MRE11 complex.

The MRE11 complex (MRE11, RAD50 and NBS1) and the ataxia-telangiectasia mutated (ATM) kinase function in the same DNA damage response pathway to effect cell cycle checkpoint activation and apoptosis. The functional interaction between the MRE11 complex and ATM has been proposed to require a conserved C-terminal domain of NBS1 for recruitment of ATM to sites of DNA damage. Human Nijmegen breakage syndrome (NBS) cells and those derived from multiple mouse models of NBS express a hypomorphic NBS1 allele that exhibits impaired ATM activity despite having an intact C-terminal domain. This indicates that the NBS1 C terminus is not sufficient for ATM function. We derived Nbs1(DeltaC/DeltaC) mice in which the C-terminal ATM interaction domain is deleted. Nbs1(DeltaC/DeltaC) cells exhibit intra-S-phase checkpoint defects, but are otherwise indistinguishable from wild-type cells with respect to other checkpoint functions, ionizing radiation sensitivity and chromosome stability. However, multiple tissues of Nbs1(DeltaC/DeltaC) mice showed a severe apoptotic defect, comparable to that of ATM- or CHK2-deficient animals. Analysis of p53 transcriptional targets and ATM substrates showed that, in contrast to the phenotype of Chk2(-/-) mice, NBS1(DeltaC) does not impair the induction of proapoptotic genes. Instead, the defects observed in Nbs1(DeltaC/DeltaC) result from impaired phosphorylation of ATM targets including SMC1 and the proapoptotic factor, BID.