BMI1 is a core protein of the polycomb repressive complex 1 (PRC1) that is overexpressed in several cancer types, making it a promising target for cancer therapies. However, the underlying mechanisms and interactions associated with BMI1-induced tumorigenesis are often context-dependent and complex. Here, we performed a drug resistance screen on mutagenized human haploid HAP1 cells treated with BMI1 inhibitor PTC-318 to find new genetic and mechanistic features associated with BMI1-dependent cancer cell proliferation. Our screen identified NUMA1-mutations as the most significant inducer of PTC-318 cell death resistance. Independent validations on NUMA1-proficient HAP1 and non-small cell lung cancer cell lines exposed to BMI1 inhibition by PTC-318 or BMI1 knockdown resulted in cell death following mitotic arrest. Interestingly, cells with CRISPR-Cas9 derived NUMA1 knockout also showed a mitotic arrest phenotype following BMI1 inhibition but, contrary to cells with wildtype NUMA1, these cells were resistant to BMI1-dependent cell death. The current study brings new insights to BMI1 inhibition-induced mitotic lethality in cancer cells and presents a previously unknown role of NUMA1 in this process.
Abstract Introduction. Neoadjuvant chemotherapy (NACT) is the standard of care in aggressive breast cancer, including triple negative breast cancer (TNBC). Cytotoxic drugs specifically target proliferating cells, however, patient outcome is variable. Tumor physiology and response to therapy are orchestrated by an intricate interplay between cancer, stromal and immune cells collectively forming the tumor microenvironment. We have recently uncovered a feedback mechanism of tumor cells and fibroblasts, involving IFNB1 signaling, that supports tumor cells in the recovery from chemotherapy-induced stress. Here, we wanted to assess whether targets of IFNB1 signaling in fibroblasts and tumor cells would qualify as predictive markers of pathological complete response (pCR) after neoadjuvant therapy (NACT) as prognostic markers for the course of the disease. Methods and Patients. RNA-sequencing data from in vitro experiments found the GO-term GO:0051607 ‘defense response to virus’ significantly enriched. Twentyfour genes intersected between differentially expressed genes and the genes of this GO-term. We selected three of the encoded proteins a) interferon induced with helicase C domain 1 IFIH1, b) interferon alpha-inducible protein ISG15, c) 2'-5'-oligoadenylate synthetase OAS1 to test their expression in human specimens of TNBCs after NACT by immunohistochemistry (IHC). None of the respective genes correlated with recurrence free survival when tested in treatment-naïve tumor biopsies (KM Plotter). A prospective consecutively enrolled cohort (2000 - 2021) was available with an overall pCR rate of 46%. pCR was defined by no invasive cancer cell in breast or axilla (ypT0 N0). The median follow-up for iDFS was 36.2 months (6-154) and for OS 39.3 months (6-214).Primary objective was the correlation between IFIH1, ISG15 and OAS1 protein expression in the residual tumor by non-pCR or in the tumor bed by pCR. Second objective was the association of IFIH1, ISG15 and OAS1 protein expression to invasive disease-free survival (iDFS) and overall survival (OS). Results. To date, IHC staining has been established for IFIH1, ISG15 and OAS1. In representative stainings of FFPE tissue samples with pCR we did not detect any positive signal for IFIH1 and ISG15 in stromal cells like fibroblast or lymphocytes. Slight to strong protein expression was detected by non-pCR in cancer cells, stromal cells and tumour infiltrating lymphocytes. In contrast OAS1 was expressed especially strong in lymphocytes by pCR or non-pCR. Cancer cell showed moderate OAS1 expression. IHC analysis and of the entire cohort is in progress including the analyses of the association of these markers to pCR, non-pCR and iDFS/OS. Conclusion. Using samples from our consecutive, multicentre enrolled cohort, an association between the expression of markers of an IFNB1-triggered antiviral response and pCR and survival was demonstrated in patients of the TNBC subgroup. Analysis of the entire cohort is necessary to potentially demonstrate applicability of an interferon-response as predictor of survival. Citation Format: Marcus Bauer, Martina Vetter, Ana Maia, Efstathios Vlachavas, Brigitta Michels, Mireia Berdiel-Acer, Kathleen Schüler, Alessandra Morselli, Manio Skarlatou, Christoph Thomssen, Stefan Wiemann. Communication between tumor cells and fibroblasts as a prognostic factor of NACT in TNBC [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-08-15.
Tumour cells do not exist as an isolated entity. Instead, they are surrounded by and closely interact with cells of the environment they are emerged in. The tumour microenvironment (TME) is not static and several factors, including cancer cells and therapies, have been described to modulate several of its components. Fibroblasts are key elements of the TME with the capacity to influence tumour progression, invasion and response to therapy, which makes them attractive targets in cancer treatment. In this review, we focus on fibroblasts and their numerous roles in the TME with a special attention to recent findings describing their heterogeneity and role in therapy response. Furthermore, we explore how different therapies can impact these cells and their communication with cancer cells. Finally, we highlight potential strategies targeting this cell type that can be employed for improving patient outcome.
Chromosomal instability (CIN) is a common trait of cancer characterised by the continuous gain and loss of chromosomes during mitosis. Excessive levels of CIN can suppress tumour growth, providing a possible therapeutic strategy. The Mps1/TTK kinase has been one of the prime targets to explore this concept, and indeed Mps1 inhibitors synergise with the spindle poison docetaxel in inhibiting the growth of tumours in mice.To investigate how the combination of docetaxel and a Mps1 inhibitor (Cpd-5) promote tumour cell death, we treated mice transplanted with BRCA1-/-;TP53-/- mammary tumours with docetaxel and/or Cpd-5. The tumours were analysed regarding their histopathology, chromosome segregation errors, copy number variations and cell death to understand the mechanism of action of the drug combination.The enhanced efficacy of combining an Mps1 inhibitor with clinically relevant doses of docetaxel is associated with an increase in multipolar anaphases, aberrant nuclear morphologies and cell death. Tumours treated with docetaxel and Cpd-5 displayed more genomic deviations, indicating that chromosome stability is affected mostly in the combinatorial treatment.Our study shows that the synergy between taxanes and Mps1 inhibitors depends on increased errors in cell division, allowing further optimisation of this treatment regimen for cancer therapy.
Efficacy demonstration of a unique peptide-based immunotherapy as potent approach for cancer treatment. This strategy relies on the activation of commensal-specific T cells which cross-react against peptides derived from Tumor-Associated Antigens (TAAps) found in various solid tumors, including glioblastoma, adrenocortical carcinoma and colorectal cancer. The same strategy is also used to target lineage-specific markers in hematologic cancers such as B cell malignancies.
Methods
The gut microbiota has the outstanding ability of regulating the human immune system through commensal antigens. Since specific microbiota peptides exhibit significant homology with particular TAAs, the full potential of cross-reactive CD8+ T cells that recognize both commensal peptides and poorly immunogenic tumor antigens can thus be harnessed against tumor cells. We identified a specific set of commensal derived peptides, referred to as OncoMimics™ (OMP) peptides, which elicit cross-reactive cytotoxic CD8+ T cell responses against TAAps owing to their strong sequence homology. The capacity of these OMPs to induce TAAps-specific cross-reactive CD8+ T cell responses in humans is evaluated through peptide-MHC multimer staining and flow cytometry-based cytotoxic assays.
Results
Experiments conducted on human peripheral blood mononuclear cells (PBMCs) demonstrate that OMPs can be recognized by CD8 T cells in a significant proportion of healthy individuals. Upon in vitro stimulation, OMPs induce the expansion of CD8+ T cells that recognize homologous peptides derived from tumor antigen targets. Importantly, these T cells display cytotoxic capabilities against tumor cells presenting the corresponding TAAps on their surface. Further support for this approach comes from ongoing clinical trials, since we displayed that CD8+ T cells from indolent Non-Hodgkin Lymphoma (iNHL) patients treated with EO2463 immunotherapy (SIDNEY, EONHL1–20 phase 1/2 trial) are cytotoxic against TAA protein-expressing tumor cell lines.1
Conclusions
These data provide compelling evidence that OncoMimic peptides sharing a high degree of homology with TAAps can be utilized to generate an effective anti-tumor immune response.
Reference
https://www.enterome.com/clinical-trials/
Ethics Approval
Buffy coats from healthy donors were provided from the Blood Bank (Etablissement français du sang (EFS)) of Rungis. This study was performed according to established ethical guidelines, and all blood donors gave informed consent. Patient cells are coming from the ongoing EONHL1–20 phase 1/2 trial.
Abstract EO2401 expands existing memory T cells recognizing protein sequences from gut bacteria, which cross-react with tumor associated antigens (TAAs). EO2401 contains three CD8 HLA-A2 epitopes with mimicry to glioblastoma-TAAs (IL13Rα2, BIRC5, and FOXM1) and the CD4 epitope UCP2. Patients received EO2401 (300μg/peptide, q2weeks x4, then every 4weeks) with nivolumab (3mg/kg, q2weeks) in cohorts: C1a (n = 21, Ex2→EN; option for symptom directed low-dose bevacizumab [sLDB; 5mg/kg, q2weeks] as anti-edema treatment); C2a/1 (n = 23, EN); C2a/2 (n = 15, EN+sLDB); C2b (n = 6, adjuvant EN+sLDB); C2c (n = 9, neoadjuvant ENx2→surgery→adjuvant EN+sLDB); C3 (n = 26, EN+bevacizumab, q2weeks, 10mg/kg). EO2401/nivolumab+/-bevacizumab safety profile consistent with profile of nivolumab, and when applicable bevacizumab, except the addition of local administration site reactions which occurred in 39% of patients; 96% of events Grade 1/2 and 4% Grade 3. Immune monitoring (peripheral blood, ELISPOT, tetramer assessments) demonstrated expanded mimic specific CD8 T cells with cross-reactivity against the targeted human TAAs. In C2a/1 (83% tested) and in C3 (81% tested), 89% and 95% of tested patients showed expansion. Expansions were early (week 2 after starting EO2401), durable (up to 23 months), and robust (approximately 30% of all peripheral CD8 T cells were mimic specific in 3 clinical responders). In C2c, surgery specimens after two EO2401/nivolumab doses showed increased tumor T cell infiltration versus pre-treatment tumor in 5 of 6 patients. Addition of sLDB to EO2401/nivolumab prolonged treatment duration vs EO2401/nivolumab alone by reducing edema likely worsened by study therapy induced immune cell infiltration. Integration of bevacizumab with EO2401/nivolumab in C3 further increased efficacy in C3. C2a/1vsC2a/2vsC3: median treatment duration 1.4vs3.2vs4.8 months, disease control rate 22%vs40%vs88%, median PFS 1.6vs3.6vs5.5 months; median survival 9.0vs12.6vstoo early (C3 median FU 8.3 mo, survival ongoing up to 2 years). Further follow-up will be presented.
Cancer remains one of the diseases with the highest worldwide incidence. Several cytotoxic approaches have been used over the years to overcome this public health threat, such as chemotherapy, radiotherapy, and photodynamic therapy (PDT). Cyanine dyes are a class of compounds that have been extensively studied as PDT sensitisers; nevertheless, their antiproliferative potential in the absence of a light source has been scarcely explored. Herein, the synthesis of eighteen symmetric mono-, tri-, and heptamethine cyanine dyes and their evaluation as potential anticancer agents is described. The influences of the heterocyclic nature, counterion, and methine chain length on the antiproliferative effects and selectivities were analysed, and relevant structure-activity relationship data were gathered. The impact of light on the cytotoxic activity of the most promising dye was also assessed and discussed. Most of the monomethine and trimethine cyanine dyes under study demonstrated a high antiproliferative effect on human tumour cell lines of colorectal (Caco-2), breast (MCF-7), and prostate (PC-3) cancer at the initial screening (10 µM). However, concentration-viability curves showed higher potency and selectivity for the Caco-2 cell line. A monomethine cyanine dye derived from benzoxazole was the most promising compound (IC50 for Caco-2 = 0.67 µM and a selectivity index of 20.9 for Caco-2 versus normal human dermal fibroblasts (NHDF)) and led to Caco-2 cell cycle arrest at the G0/G1 phase. Complementary in silico studies predicted good intestinal absorption and oral bioavailability for this cyanine dye.
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