New pan-ALK inhibitor-resistant EML4::ALK mutations detected by liquid biopsy in lung cancer patients

ALK and ROS1 fusions are effectively targeted by tyrosine kinase inhibitors (TKIs), however patients inevitably relapse after an initial response, often due to kinase domain mutations. We investigated circulating DNA from TKI-relapsed NSCLC patients by deep-sequencing. New EML4::ALK substitutions, L1198R, C1237Y and L1196P, were identified in the plasma of NSCLC ALK patients and characterized in a Ba/F3 cell model. Variants C1237Y and L1196P demonstrated pan-inhibitor resistance across 5 clinical and 2 investigational TKIs.

Edaravone: A Novel Possible Drug for Cancer Treatment?

Despite significant advancements in understanding the causes and progression of tumors, cancer remains one of the leading causes of death worldwide. In light of advances in cancer therapy, there has been a growing interest in drug repurposing, which involves exploring new uses for medications that are already approved for clinical use. One such medication is edaravone, which is currently used to manage patients with cerebral infarction and amyotrophic lateral sclerosis. Due to its antioxidant and anti-inflammatory properties, edaravone has also been investigated for its potential activities in treating cancer, notably as an anti-proliferative and cytoprotective drug against side effects induced by traditional cancer therapies. This comprehensive review aims to provide updates on the various applications of edaravone in cancer therapy. It explores its potential as a standalone antitumor drug, either used alone or in combination with other medications, as well as its role as an adjuvant to mitigate the side effects of conventional anticancer treatments.

Differential Expression of NOTCH-1 and Its Molecular Targets in Response to Metronomic Followed by Conventional Therapy in a Patient with Advanced Triple-Negative Breast Cancer

A group of 27 patients diagnosed with metastatic triple-negative breast cancer (mTNBC) was randomly distributed into two groups and underwent different lines of metronomic treatment (mCHT). The former group (N 14) received first-line mCHT and showed a higher overall survival rate than the second group (N 13), which underwent second-line mCHT. Analysis of one patient still alive from the first group, diagnosed with mTNBC in 2019, showed a complete metabolic response (CMR) after a composite approach implicating first-line mCHT followed by second-line epirubicin and third-line nab-paclitaxel, and was chosen for subsequent molecular characterization. We found altered expression in the cancer stemness-associated gene NOTCH-1 and its corresponding protein. Additionally, we found changes in the expression of oncogenes, such as MYC and AKT, along with their respective proteins. Overall, our data suggest that a first-line treatment with mCHT followed by MTD might be effective by negatively regulating stemness traits usually associated with the emergence of drug resistance.

TWIST1 Upregulation Is a Potential Target for Reversing Resistance to the CDK4/6 Inhibitor in Metastatic Luminal Breast Cancer Cells

Cyclin-dependent kinase (CDK) 4/6 inhibitors have significantly improved progression-free survival in hormone-receptor-positive (HR+), human-epidermal-growth-factor-receptor-type-2-negative (HER2-) metastatic luminal breast cancer (mLBC). Several studies have shown that in patients with endocrine-sensitive or endocrine-resistant LBC, the addition of CDK4/6 inhibitors to endocrine therapy significantly prolongs progression-free survival. However, the percentage of patients who are unresponsive or refractory to these therapies is as high as 40%, and no reliable and reproducible biomarkers have been validated to select a priori responders or refractory patients. The selection of mutant clones in the target oncoprotein is the main cause of resistance. Other mechanisms such as oncogene amplification/overexpression or mutations in other pathways have been described in several models. In this study, we focused on palbociclib, a selective CDK4/6 inhibitor. We generated a human MCF-7 luminal breast cancer cell line that was able to survive and proliferate at different concentrations of palbociclib and also showed cross-resistance to abemaciclib. The resistant cell line was characterized via RNA sequencing and was found to strongly activate the epithelial-to-mesenchymal transition. Among the top deregulated genes, we found a dramatic downregulation of the CDK4 inhibitor CDKN2B and an upregulation of the TWIST1 transcription factor. TWIST1 was further validated as a target for the reversal of palbociclib resistance. This study provides new relevant information about the mechanisms of resistance to CDK4/6 inhibitors and suggests potential new markers for patients' follow-up care during treatment.

An Overview of PARP Resistance in Ovarian Cancer from a Molecular and Clinical Perspective

Epithelial ovarian cancer (EOC), a primarily high-grade serous carcinoma (HGSOC), is one of the major causes of high death-to-incidence ratios of all gynecological cancers. Cytoreductive surgery and platinum-based chemotherapy represent the main treatments for this aggressive disease. Molecular characterization of HGSOC has revealed that up to 50% of cases have a deficiency in the homologous recombination repair (HRR) system, which makes these tumors sensitive to poly ADP-ribose inhibitors (PARP-is). However, drug resistance often occurs and overcoming it represents a big challenge. A number of strategies are under investigation, with the most promising being combinations of PARP-is with antiangiogenetic agents and immune checkpoint inhibitors. Moreover, new drugs targeting different pathways, including the ATR-CHK1-WEE1, the PI3K-AKT and the RAS/RAF/MEK, are under development both in phase I and II-III clinical trials. Nevertheless, there is still a long way to go, and the next few years promise to be exciting.

Conditioned Medium of Mesenchymal Stromal Cells Loaded with Paclitaxel Is Effective in Preclinical Models of Triple-Negative Breast Cancer (TNBC)

Triple-negative breast cancer (TNBC) is a very aggressive disease even in its early stages and is characterized by a severe prognosis. Neoadjuvant chemotherapy is one of the milestones of treatment, and paclitaxel (PTX) is among the most active drugs used in this setting. However, despite its efficacy, peripheral neuropathy occurs in approximately 20-25% of cases and represents the dose-limiting toxicity of this drug. New deliverable strategies to ameliorate drug delivery and reduce side effects are keenly awaited to improve patients' outcomes. Mesenchymal stromal cells (MSCs) have recently been demonstrated as promising drug delivery vectors for cancer treatment. The aim of the present preclinical study is to explore the possibility of a cell therapy approach based on the use of MSCs loaded with PTX to treat TNBC-affected patients. For this purpose, we in vitro evaluated the viability, migration and colony formation of two TNBC cell lines, namely, MDA-MB-231 and BT549, treated with MSC-PTX conditioned medium (MSC-CM PTX) in comparison with both CM of MSCs not loaded with PTX (CTRL) and free PTX. We observed stronger inhibitory effects on survival, migration and tumorigenicity for MSC-CM PTX than for CTRL and free PTX in TNBC cell lines. Further studies will provide more information about activity and potentially open the possibility of using this new drug delivery vector in the context of a clinical study.

Abstract P6-01-42: BASELINE 18FDG-PET METABOLIC TUMOUR VOLUME (MTV) AS A POTENTIAL PREDICTIVE FACTOR OF RESPONSE TO METRONOMIC CHEMOTHERAPY (mCHT) IN HR+/HER2- METASTATIC BREAST CANCER (MBC) PATIENTS (pts). PRELIMINARY RESULTS OF THE METRO-PET STUDY

Background: MBC is an incurable disease and chemotherapy (CHT) represents one option of treatment upfront, in TNBC pts, or at failure of an endocrine therapy + targeted agents in HR+ ones. mCHT was extensively studied in different types of ABC pts and is largely used in clinical practice. 18FDG-PET is often used as a tool for disease staging at baseline and for disease restaging during treatment. Different quantitative and semi-quantitative 18FDG-PET parameters have been investigated as predictive and prognostic biomarkers in NSCLC and other tumours. Aim of the present study is to evaluate the role of baseline SUVmax , global SUVmean, SUVpeak, Metabolic Tumour Volume (MTV) and Total Lesion Glycolysis (TLG) as predictive factors of response to mCHT.

Patients and Methods: We identified 36 MBC pts treated with mCHT between 2014 and 2021, with at least two separate 18FDG-PET evaluations. Patients and biological tumour characteristics, previous treatments, site of relapse as well as quantitative pre-treatment 18FDG-PET parameters have been collected. Tumour response was assessed using PERCIST Criteria. Median and mean ± SD 18FDG-PET parameters have been reported according to the type of response. Complete and Partial responses have been grouped together with Stable Disease.

Results: Median age was 69 (33-82). Luminal pts were 25 (67.6%), TNBC pts were 16.2%); most were heavily pre-treated for their metastatic disease (≥ 3 lines: 14, 37.8%) and presented ≥ 3 metastatic sites (14, 37.8%). All pts received mCHT, 26 (70.3%) as combination therapy (VRL+CAPE or VRL+CAPE+CTX), or single agent (VRL, 11). Bone was the commonest metastatic site (62.2%). ORR was 43.2%; 7 pts had SD (18.9%), the remaining developed PD (37.8%). Similar values have been observed between the 2 groups in terms of SUVmax , global SUVmean and SUVpeak,. Mean MTV was higher in responder (n=22) vs non responder (n=14) pts, as TLG. Details are reported in Table 1.

Conclusions: High mean baseline MTV and TLG seem to be related to response to mCHT in MBC pts. Our observation is in contrast to what is described for other cancer types, especially NSCLC, and for standard neoadjuvant treatment of BC. Considering the peculiar mechanisms of action of mCHT, our preliminary findings warrant further exploration in a larger series of BC pts.

Table 1 Baseline 18FDG-PET uptake values in responder and non responder patients

Citation Format: Marco Meazza Prina, Irene Gotuzzo, Marina Elena Cazzaniga, Elisabetta De Bernardi, Pietro Cafaro, Serena Capici, Viola Cogliati, Francesca Fulvia Pepe, Federica Cicchiello, Francesca Riva, Nicoletta Cordani, Maria Grazia Cerrito, Elia Anna Turolla, Claudio Landoni, Federica Elisei, Cinzia Crivellaro, Leonardo Virdone, Lavinia Monaco, Alessandro Guidi, Luca Guerra. BASELINE 18FDG-PET METABOLIC TUMOUR VOLUME (MTV) AS A POTENTIAL PREDICTIVE FACTOR OF RESPONSE TO METRONOMIC CHEMOTHERAPY (mCHT) IN HR+/HER2- METASTATIC BREAST CANCER (MBC) PATIENTS (pts). PRELIMINARY RESULTS OF THE METRO-PET STUDY [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-42.

Abstract P1-13-21: Loss of CDKN2B expression as a potential marker of resistance to CDK4/6 inhibitor in Luminal Breast Cancer cells

Background Cyclin-Dependent Kinase (CDK) 4/6 inhibitors have significantly improved progression-free survival of Hormone Receptor positive (HR+), Human Epidermal Growth Factor Receptor type 2 negative (HER2-) luminal breast cancers (LBC). Several studies demonstrated that the addition of CDK4/6 inhibitors to endocrine therapy results in a significant prolongation of progression-free survival in patients with endocrine-sensitive or endocrine-resistant LBCs. However, the percentage of patients unresponsive or refractory to these therapies is as high as 40%, and no reliable and reproducible biomarkers able to select a priori responder or resistant patients have been validated till now. The main cause of resistance is the selection of mutant clones in the target oncoprotein. Other mechanisms, like oncogene amplification/overexpression or mutations in other pathways, have been described in several models. Here, we focused on palbociclib, a selective inhibitor of CDK4/6. Methods: We generated and characterized human luminal breast cancer MCF-7 and T47D derived cell lines, able to survive and proliferate at different palbociclib concentrations, which also shows cross-resistance to abemaciclib. The resistant MCF7 cell line was characterized by RNA sequencing. Results: To confirm resistance, we performed cell viability assays in MCF-7 and T47D palbociclib sensitive cells (MCF-7pS and T47pS) versus MCF-7 and T47D palbociclib resistant cells (MCF-7pR5), showing a 10-fold increase of IC50 in MCF-7pR5 compared to parental MCF-7pS cells (16.7 vs 1.8 µM) and a 3-fold increase of IC50 in T47DpR5 vs parental T47DpS. We also confirmed a significant cross resistance using abemaciclib in MCF-7pR5 with an IC50 equal to 6.8 vs 0.35 µM and in T47DpR with an IC50 of 10.72 vs 0.5 µM. RNA sequencing, qRT-qPCR and Western blot results demonstrated a dramatic downregulation of the CDK4 inhibitor CDKN2B in both cell lines and we found upregulation of an miR-31, a putative regulator of CDKN2B. This finding was further validated in a biopsy from a patient progressing on CDK4/6 inhibitor therapy. Conclusions: This study provides new relevant information regarding the mechanism of resistance to CDK4/6 inhibitors and suggests potential new markers to follow up patients during the treatment.

Citation Format: Nicoletta Cordani, Luca Mologni, Rocco Piazza, Viola Cogliati, Francesca Pepe, Serena Capici, Camillo Di Bella, Marta Jaconi, Maria Grazia Cerrito, Matteo Villa, Pietro Tettamanti, Guido Cavaletti, Marialuisa Lavitrano, Marina Elena Cazzaniga. Loss of CDKN2B expression as a potential marker of resistance to CDK4/6 inhibitor in Luminal Breast Cancer cells [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-13-21.

Harnessing DLL3 inhibition: From old promises to new therapeutic horizons

Small-cell lung cancer (SCLC) is an aggressive neuroendocrine tumor with a high relapse rate, limited therapeutic options, and poor prognosis. The combination of chemotherapy and immune-checkpoint inhibitors brings a new therapeutic era, although the lack of predictive biomarkers of response reduces the efficacy of applying the treatment to the entire population of patients with SCLC. The lack of treatments able to bind to a specific target has always been a substantial difference to the non-small cell lung cancer (NSCLC) counterpart. Delta-like canonical Notch ligand 3 is a protein frequently overexpressed in SCLC and is therefore being explored as a potentially promising therapeutic target in high-grade neuroendocrine lung cancer. In this article, we critically review the activity and efficacy of old DLL3 inhibitors antibody-drug conjugate (ADC) and their failures through new compounds and their possible applications in clinical practice, with a focus on new molecular classification of SCLC.

Co-targeting triple-negative breast cancer cells and endothelial cells by metronomic chemotherapy inhibits cell regrowth and migration via downregulation of the FAK/VEGFR2/VEGF axis and autophagy/apoptosis activation

High-dose standard-of-care chemotherapy is the only option for triple-negative breast cancer (TNBC) patients, which eventually die due to metastatic tumors. Recently, metronomic chemotherapy (mCHT) showed advantages in treating TNBCs leading us to investigate the anti-metastatic and anti-angiogenic potential of metronomic 5-Fluorouracil plus Vinorelbine (5-FU+VNR) on endothelial cells (ECs) and TNBCs in comparison to standard treatment (STD). We found that 10-fold lower doses of 5-FU+VNR given mCHT vs. STD inhibits cell proliferation and survival of ECs and TNBC cells. Both schedules strongly affect ECs migration and invasion, but in TNBC cells mCHT is significantly more effective than STD in impairing cell migration and invasion. The two treatments disrupt FAK/VEGFR/VEGF signaling in both ECs and TNBC cells. mCHT, and to a much lesser extent STD treatment, induces apoptosis in ECs, whereas it switches the route of cell death from apoptosis (as induced by STD) to autophagy in TNBC cells. mCHT-treated TNBCs-derived conditioned medium also strongly affects ECs' migration, modulates different angiogenesis-associated proteins, and hampers angiogenesis in matrix sponge in vivo. In conclusion, mCHT administration of 5-FU+VNR is more effective than STD schedule in controlling cell proliferation/survival and migration/invasion of both ECs and TNBC cells and has a strong anti-angiogenic effect. Our data suggest that the stabilization of tumor growth observed in TNBC patients treated with mCHT therapy schedule is likely due not only to direct cytotoxic effects but also to anti-metastatic and anti-angiogenic effects.

Immunomodulatory effects of metronomic vinorelbine (mVRL), with or without metronomic capecitabine (mCAPE), in hormone receptor positive (HR+)/HER2-negative metastatic breast cancer (MBC) patients: final results of the exploratory phase 2 Victor-5 study

Tregs are able of suppressing tumor-specific effector cells, such as lymphocytes CD8+, CD4+ and Natural Killer cells. Different drugs, especially different schedules of administration, like metronomic chemotherapy (mCHT), seem to be able to increase anticancer immunity, by acting on downregulation of Tregs. Most of the data available regarding the immunomodulating effect of mCHT have been obtained with Cyclophosphamide (CTX). Aim of the present study was to explore the effects of mVRL and mCAPE administration, alone or in combination, on T cells. Observation of 13 metastatic breast cancer patients lasted controlling for 56 days, where Treg frequencies and function, spontaneous anti-tumor T-cell responses were monitored, as well as the clinical outcome. No depletion in Treg absolute numbers, or percentage of T lymphocytes, was observed. Only in 5 patients, a modest and transient depletion of Tregs was observed during the first 14 days of treatment. To better describe the effect on Tregs, we subsequently looked at the variations in Memory, Naïve and Activated Treg subpopulations: we observed a trend in reduction for memory Treg (Treg MEM) and an increase for Treg Naïve (Treg NAIVE) and Treg Activated (Treg ACT) components. We finally analyzed the average trend of Treg in the Treg depleted patients and non-depleted ones, without fiding any significant differences. The trend of the Treg MEM appeared different, showing a reduction during the first 14 days, followed by an increase at the levels before treatment at Day 56 in the group of depleted patients and a progressive substantial reduction in the group of non-depleted patients along the entire course of treatment. Opposed to the data known, treatment with mVRL w/o mCAPE did not show any effect on Tregs.

Metronomic Chemotherapy for Metastatic Breast Cancer Treatment: Clinical and Preclinical Data between Lights and Shadows

Metronomic chemotherapy (mCHT), defined as continuous administration of low-dose chemotherapeutic agents with no or short regular treatment-free intervals, was first introduced to the clinic in international guidelines in 2017, and, since then, has become one of the available strategies for the treatment of advanced breast cancer (ABC). Despite recent successes, many unsolved practical and theoretical issues remain to be addressed. The present review aims to identify the “lights and shadows” of mCHT in preclinical and clinical settings. In the preclinical setting, several findings indicate that one of the most noticeable effects of mCHT is on the tumor microenvironment, which, over the last twenty years, has been demonstrated to be pivotal in supporting tumor cell survival and proliferation. On the other hand, the direct effects on tumor cells have been less well-defined. In addition, critical items to be addressed are the lack of definition of an optimal biological dose (OBD), the method of administration of metronomic schedules, and the recognition and validation of predictive biomarkers. In the clinical context—where mCHT has mainly been used in a metastatic setting—low toxicity is the most well-recognised light of mCHT, whereas the type of study design, the absence of randomised trials and uncertainty in terms of doses and drugs remain among the shadows. In conclusion, growing evidence indicates that mCHT is a suitable treatment option for selected metastatic breast cancer (MBC) patients. Moreover, given its multimodal mechanisms of action, its addition to immunological and targeted therapies might represent a promising new approach to the treatment of MBC. More preclinical data are needed in this regard, which can only be obtained through support for translational research as the key link between basic science and patient care.

How to Treat HR+/HER2- Metastatic Breast Cancer Patients after CDK4/6 Inhibitors: An Unfinished Story

CDK4/6 inhibitors in association with endocrine therapy represent the best therapeutic choice for either endocrine-sensitive or resistant hormone-receptor-positive advanced breast cancer patients. On the contrary, the optimal therapeutic strategy after the failure of CDK4/6 inhibitors-based treatment still remains an open question worldwide. In this review, we analyze the most studied mechanisms of resistance to CDK4/6 inhibitors treatment, as well as the most significant results of retrospective and prospective trials in the setting of progression after CDK4/6 inhibitors, to provide the reader a comprehensive overview from both a preclinical and especially a clinical perspective. In our opinion, an approach based on a deeper knowledge of resistance mechanisms to CDK4/6 inhibitors, but also on a careful analysis of what is done in clinical practice, can lead to a better definition of prospective randomized trials, to implement a personalized sequence approach, based on molecular analyses.

Metronomic Chemotherapy

Simple Summary

The present article reviews the state of the art of metronomic chemotherapy use to treat the principal types of cancers, namely breast, non-small cell lung cancer and colorectal ones, and of the most recent progresses in understanding the underlying mechanisms of action. Areas of novelty, in terms of new regimens, new types of cancer suitable for Metronomic chemotherapy (mCHT) and the overview of current ongoing trials, along with a critical review of them, are also provided.

Abstract

Metronomic chemotherapy treatment (mCHT) refers to the chronic administration of low doses chemotherapy that can sustain prolonged, and active plasma levels of drugs, producing favorable tolerability and it is a new promising therapeutic approach in solid and in hematologic tumors. mCHT has not only a direct effect on tumor cells, but also an action on cell microenvironment, by inhibiting tumor angiogenesis, or promoting immune response and for these reasons can be considered a multi-target therapy itself. Here we review the state of the art of mCHT use in some classical tumour types, such as breast and no small cell lung cancer (NSCLC), see what is new regarding most recent data in different cancer types, such as glioblastoma (GBL) and acute myeloid leukemia (AML), and new drugs with potential metronomic administration. Finally, a look at the strategic use of mCHT in the context of health emergencies, or in low –and middle-income countries (LMICs), where access to adequate healthcare is often not easy, is mandatory, as we always need to bear in in mind that equity in care must be a compulsory part of our medical work and research.

Abstract 4715: Characterization of potential co-drivers of pathogenesis in ALK positive ALCL

ALK positive Anaplastic large cell lymphoma (ALCL) is an aggressive non-Hodgkin lymphoma characterized by expression of the NPM/ALK fusion tyrosine kinase essential for neoplastic cells growth. When resistant or relapsed to front-line chemotherapy, ALK+ ALCL prognosis is very poor. Although ALK+ ALCL cells are mainly driven by the constitutively active NPM/ALK kinase, presence of additional mutations might affect the disease course and response to treatment, leading to different outcomes in different patients. We employed whole exome sequencing to characterize the co-mutational burden in ALK+ ALCL samples at diagnosis. Diagnosis biopsy and matched healthy control DNA samples from 24 ALK+ ALCL patients were sequenced. Somatic variants present at high frequency within the tumor (at least 25% variant allele frequency), which can be viewed as potential co-drivers, were annotated; the identified mutations were weighed using in silico tools to predict their oncogenic potential and their effects on protein function. All identified variants were confirmed by Sanger sequencing. Gene ontology and pathway analyses identified cell adhesion and actin cytoskeleton among the most enriched biological functions. Using the above-mentioned criteria, we found recurrent somatic variants in 7 genes including PPP1R9A, RUNX1T1, FAT4 and RBBP8. Here we report the initial characterization of the role of FAT4 in ALCL cells. FAT4 is a member of the cadherin superfamily with tumor suppressor functions. In our cohort, 3/24 patients (13%) were found to carry FAT4 mutations, including nonsense mutations and missense changes predicted to be deleterious, suggesting a loss of function effect. To characterize the biological consequences of these mutations, we generated FAT4 knockdown ALCL cell lines. FAT4-silenced cells grew faster and showed increased migratory properties compared to parental cells. They also differed from parental cells in terms of morphology, having bigger size and modulated F-actin rearrangement. Tumor suppressing activity of FAT4 has been linked to Wnt/β-catenin pathway; we found that FAT4-silenced cells had decreased levels of serine/threonine phosphorylated β-catenin and higher nuclear localization, which insinuates activation of Wnt/β-catenin signalling and henceforth, increased cellular proliferation. To explore therapeutic implications of FAT4 mutations, we analyzed the sensitivity of FAT4 silenced cells to chemotherapeutic agents. FAT4 knockdown cells were less sensitive to a CHOP combination treatment as compared to parental cells. No difference was seen in terms of sensitivity to crizotinib. Finally, we investigated the effects of RUNX1T1 somatic variants found in our study. Preliminary luciferase assay results showed that the variants significantly increase the transcriptional repression ability of RUNX1T1. Altogether, our data provides information about genes other than NPM-ALK that might play a role in the pathogenesis of ALCL.

Citation Format: Luca Mologni, Geeta G. Sharma, Matteo Villa, Mario Mauri, Giulia Arosio, Cosimo Lobello, Hugo Larose, Alessandra Pirola, Silvia Bombelli, Nicoletta Cordani, Luca Massimino, Šárka Pospíšilová, Suzanne D. Turner, Giorgio Inghirami, Fabio Pagni, Rocco Piazza, Roberto Perego, Roberto Chiarle, Carlo Gambacorti-Passerini. Characterization of potential co-drivers of pathogenesis in ALK positive ALCL [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4715.

Lorlatinib Treatment Elicits Multiple On- and Off-Target Mechanisms of Resistance in ALK-Driven Cancer

: Targeted therapy changed the standard of care in ALK-dependent tumors. However, resistance remains a major challenge. Lorlatinib is a third-generation ALK inhibitor that inhibits most ALK mutants resistant to current ALK inhibitors. In this study, we utilize lorlatinib-resistant anaplastic large cell lymphoma (ALCL), non-small cell lung cancer (NSCLC), and neuroblastoma cell lines in vitro and in vivo to investigate the acquisition of resistance and its underlying mechanisms. ALCL cells acquired compound ALK mutations G1202R/G1269A and C1156F/L1198F in vitro at high drug concentrations. ALCL xenografts selected in vivo showed recurrent N1178H (5/10 mice) and G1269A (4/10 mice) mutations. Interestingly, intracellular localization of NPM/ALKN^1178H skewed toward the cytoplasm in human cells, possibly mimicking overexpression. RNA sequencing of resistant cells showed significant alteration of PI3K/AKT and RAS/MAPK pathways. Functional validation by small-molecule inhibitors confirmed the involvement of these pathways in resistance to lorlatinib. NSCLC cells exposed in vitro to lorlatinib acquired hyperactivation of EGFR, which was blocked by erlotinib to restore sensitivity to lorlatinib. In neuroblastoma, whole-exome sequencing and proteomic profiling of lorlatinib-resistant cells revealed a truncating NF1 mutation and hyperactivation of EGFR and ErbB4. These data provide an extensive characterization of resistance mechanisms that may arise in different ALK-positive cancers following lorlatinib treatment. SIGNIFICANCE: High-throughput genomic, transcriptomic, and proteomic profiling reveals various mechanisms by which multiple tumor types acquire resistance to the third-generation ALK inhibitor lorlatinib.

Cisplatin may be a Valid Alternative Approach in Ovarian Carcinoma with Carboplatin Hypersensitivity. Report of Three Cases

Platinum-based therapy is considered the standard treatment for patients with advanced ovarian cancer. Carboplatin has a more favorable toxicity profile than cisplatin; however, hypersensitivity reactions to carboplatin have been reported occasionally. We reviewed 112 cases of ovarian cancer treated with carboplatin at our institute to identify the hypersensitivity reactions to this chemotherapeutic agent. Hypersensitivity reactions were documented in nine cases (8%). No deaths occurred, but the reactions were judged severe in three of the 112 patients (2.6%). In our own experience with patients showing idiosyncrasy to carboplatin we observed successful resolution after retreatment with cisplatin. Since patients who relapse after initial treatment with carboplatin often respond to it a second time, it is important to continue this treatment.

Chronic myeloid leukemia: Second-line drugs of choice

The efficacy of second-line treatment for chronic myeloid leukemia (CML) plays an important role in allowing CML patients to enjoy a normal life expectancy. Four tyrosine kinase inhibitors (TKIs) are presently available: bosutinib, dasatinib, nilotinib, ponatinib. Each one has different safety and activity profiles, which are reviewed here. No controlled studies are available to guide treatment decision, which must be based on the characterization of leukemic cells, especially in cases of resistance to TKI, coupled with the safety profile of each TKI. Patient comorbidities also play an important role in the treatment decision, which can achieve a new durable response in over 50% of treated patients.

Nitric oxide controls fat deposition in dystrophic skeletal muscle by regulating fibro-adipogenic precursor differentiation

Duchenne muscular dystrophy (DMD) is an hereditary disease characterized by loss of muscle fibers and their progressive substitution by fat and fibrous tissue. Mesenchymal fibro-adipogenic progenitors (FAPs) expressing the platelet-derived growth factor receptor alpha (PDGFRα) are an important source of fibrosis and adipogenesis in dystrophic skeletal muscle. Among the therapies suggested for dystrophy are those based on nitric oxide (NO) donating drugs, the administration of which slows disease progression. NO has been shown to act by enhancing the regenerative potential of the diseased muscle. Whether it acts also by inhibiting fibrosis and adipogenesis was not known. Here, we show in vitro that NO regulates FAP fate through inhibition of their differentiation into adipocytes. In mdx mice, an animal model of DMD, treatment with the NO donating drug molsidomine reduced the number of PDGFRα(+) cells as well as the deposition of both skeletal muscle fat and connective tissues. Inhibition of adipogenesis was due to NO-induced increased expression of miR-27b leading to downregulation of peroxisome proliferator-activated receptors gamma (Pparγ1) expression in a pathway independent of cGMP generation. These findings reveal an additional effect of NO in dystrophic muscle that conceivably synergizes with its known effects on regeneration improvement and explain why NO-based therapies appear effective in the treatment of muscular dystrophy.

EGFR overexpression in malignant pleural mesothelioma. An immunohistochemical and molecular study with clinico-pathological correlations

The epidermal growth factor receptor (EGFR) is overexpressed in many epithelial malignancies, against which some antitumoral drugs have been developed. There is a lack of information as to EGFR expression in malignant pleural mesothelioma (MPM), an aggressive and fatal cancer poorly responsive to current oncological treatments. Our aim was to: (a) compare EGFR immunohistochemical expression with mRNA levels measured by real time PCR; (b) assess the relationships between EGFR expression and clinico-pathological data including survival; (c) analyze the EGFR mutations. We developed an immunohistochemical method of EGFR evaluation based on the number of immunoreactive cells and staining intensity in 61 MPMs. EGFR immunoreactivity was documented in 34/61 (55.7%) cases. A significant correlation between EGFR protein and mRNA levels (p = 0.0077) was found, demonstrating the reliability of our quantification method of EGFR membrane expression. Radically resected patients (p = 0.005) and those with epithelial histotype (p = 0.048) showed an increased survival. No statistical correlation between EGFR immunoreactivity and patients survival was observed. No EGFR mutation was documented. This study documents EGFR overexpression in MPM at the protein and the transcriptional levels; it proposes a reliable method for EGFR expression evaluation in MPM. EGFR levels are not associated with clinico-pathological features of patients, including survival.

Primary Cell Cultures Arising from Normal Kidney and Renal Cell Carcinoma Retain the Proteomic Profile of Corresponding Tissues

Renal cell carcinoma (RCC) tissue is composed of a mixture of neoplastic and normal cells, which complicate proteome analysis. The aim of our study was to investigate whether it is feasible to establish primary cell cultures of RCC and of renal cortex maintaining the tissue phenotype along with a more homogeneous and enriched cytological material. Fourteen (82.3%) primary cultures from 17 surgical cases were established and characterized by morphology, growth rate, immunocytochemistry, and molecular analysis performed by Real-time PCR, Western blotting, two-dimensional electrophoresis (2-DE), and mass spectrometry. Cultures showed >90% cytokeratine-positive epithelial cells. In primary tumor cultures, the molecular phenotype of manganese superoxide dismutase and heat shock protein 27 was the same as that found in tumor tissues with overexpression and increased number of isoforms. Moreover, 27 out 28 specific proteins and their isoforms, present in spots excised from 2-DE gel of cortex or RCC cultures, corresponded to those identified on the 2-DE tissue cortex reference map, suggesting that these primary cultures retain the proteomic profile of the corresponding tissues.

Characterization of heat shock protein 27 phosphorylation sites in renal cell carcinoma

The phosphorylation of heat shock protein 27 (HSP27) occurs differently in human renal cell carcinoma (RCC) compared to homologous normal kidney tissue. Two-dimensional electrophoresis was used to separate and visualize HSP27, via immunostaining with anti-HSP27 antibody, in tumor and normal renal samples, obtained after surgery resection from patients with RCC. The mean number of protein species was 21 in RCC and 15 in normal tissues. Selected spots were in-gel digested with trypsin, extracted and analyzed by microcapillary liquid chromatography (LC) electrospray ionization tandem mass spectrometry to confirm HSP27 protein identity and reveal phosphorylation sites. Loss of phosphopeptides due to extensive plumbing and/or metal components in automated LC-systems was limited by manual loading of samples directly onto the LC system using a homemade pressure vessel. Mass spectrometry (MS) analysis revealed that in three of the HSP27 protein species phosphorylation occurred at Serine 15 and in five at Serine 82 in a different pattern. The phosphorylation of Serine 15 and 82 was also investigated by immunohistochemistry on tissue sections. The data obtained using anti-HSP27Serine82phos-antibody are consistent with MS results, while the variance between results achieved by anti-HSP27Serine15phos-antibody and by MS is probably due to the low specificity of the antibody. Knowledge of the diversity and modulation of HSP27 phosphorylation protein species might represent useful markers involved in the differentiation of RCC.

The relative endogenous expression levels of the IFNAR2 isoforms influence the cytostatic and pro-apoptotic effect of IFNalpha on pleomorphic sarcoma cells

Based on our previous studies where we found that IFNAR2-1, the short IFNalpha/beta receptor variant, was expressed in pleomorphic sarcoma cells, we decided to determine the relative levels of expression of IFNAR2.1 versus the longer form, named IFNAR2.2, in different pleomorphic sarcoma cells in relation to their response to interferon alpha treatment. When examining a panel of PS cells isolated from surgical specimens, we found that IFNAR2.1 prevailed in 6 out 7 lines analysed and that these generally showed cell cycle arrest and low levels of apoptosis upon IFNalpha treatment. The reverse ratio, i.e. higher constitutive levels of IFNAR2.2 than IFNAR2.1, was associated with an irreversible inhibition of cell growth and pronounced apoptosis. Impairment of tumour growth by low- and high-dose IFNalpha treatment of nude mice inoculated with PS cells expressing predominantly IFNAR2.1 further asserted the effect of the cytokine also in vivo. A proteomic analysis of 120 signalling components in growth arrested, apoptotic PS cells harbouring higher levels of IFNAR2.2 revealed engagement of the canonical Jak/Stat/ISGF3-pathway, the activation of the mitochodrial apoptotic pathway and a potentially novel mechanism of cell cycle blockade unrelated to down-regulation of cyclin A/B and their interacting/regulating kinases. Our results confirm the dominant negative role of IFNAR2.1, but also suggest that the relative endogenous levels of the two IFNalpha/beta receptor isoforms may dictate the signalling pathways triggered by the ligand, such as to cause exclusively cell cycle arrest or induce programmed cell death. This parameter may be of importance for the clinical outcome of IFNalpha treatment of PS.

Expression of heat shock protein 27 in human renal cell carcinoma

Heat shock protein 27 (HSP27, Swiss-Prot accession number P04792) is a component of the large and heterogeneous group of chaperone proteins, and its main functions are inhibition of apoptosis and prevention of aggregation of actin intermediate filament. Modified expression of HSP27 has been described in several cancers including testis, breast, and ovaric cancer. In the present work, 18 renal cell carcinoma (RCC) tissues and homologous normal kidney tissues have been investigated for HSP27 expression by combination of two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) separation and Western blotting immunodetection. The results showed significant differences either in expression and in HSP27 isoform numbers in RCC compared to normal kidney. The average number of isoforms was 21 in RCC and 15 in normal tissues with 4.5-5.9 pI range and 18-29 kDa M(r) range. The overexpression was also observed by immunohistochemistry on tissue sections. Only two of RCC samples showed less isoforms than homologous normal samples. Two isoforms were not detected using anti-Ser82 phosphorylated HSP27 antibody, neither in normal nor in RCC samples. Five of all the immunodetected isoforms were confirmed by mass spectrometry as HSP27, but no evidence of post-translational modifications was pointed out. The numerous isoforms observed in RCC are not consistent with data reported in the literature so far, and they might be due to different post-translational modifications such as phosphorylation and S-thiolation. Since activation of HSP27 seems to be involved in tumor proliferation and drug resistance, it would be crucial to correlate the severity of disease with the different isoforms from RCC samples to generate diagnostic and prognostic markers.

Expression of endothelial protein C receptor and thrombomodulin in the intestinal tissue of patients with inflammatory bowel disease

OBJECTIVE

Inflammatory bowel diseases are characterized by disorders of immunity, thrombosis of large vessels, and microthrombosis of mucosal vessels. The expression of endothelial protein C receptor (EPCR) and thrombomodulin-two receptors of the protein C pathway involved in thrombin scavenging and inflammation-was studied in intestinal resection specimens or mucosal biopsies from patients with inflammatory bowel disease and from controls. The soluble forms of the receptors in plasma were measured.

DATA SOURCE

This study involved patients from two large university hospitals. After surgery or biopsy, tissue samples were either frozen or fixed in formalin and embedded in paraffin. Sections for immunohistochemistry examination were cut and tested with the specific antibodies to EPCR and thrombomodulin. RNA was extracted from frozen tissue for amplification via reverse-transcriptase polymerase chain reaction. Normal intestinal and diverticulitis tissue was used as a control. Resection samples from 36 patients with ulcerative colitis, 38 with Crohn's disease, 38 with colonic cancer, and 32 with diverticulitis were studied by immunohistochemistry, and frozen sections from the same patients were studied by immunofluorescence. Twelve biopsy specimens of adjacent intestinal areas from six patients with inflammatory bowel disease were included in the study for reverse-transcriptase polymerase chain reaction. Soluble receptors were measured in the plasma of 52 inflammatory bowel disease patients and 52 controls.

DATA SUMMARY

EPCR and thrombomodulin were expressed on the mucosal endothelium of controls, and the intensity of the signal decreased in inflammatory bowel disease patients. EPCR was expressed by dendritic-like cells in controls, which also stained positive for CD21. The EPCR/CD21 dendritic-like cells were not as commonly observed in sections from ulcerative colitis patients as they were in sections from control patients (12.0 +/- 3.6 cells per high-power field vs. 23.8 +/- 10.4 cells per high-power field, p =.03), and this decrease was less evident in sections from Crohn's disease patients. Levels of messenger RNA for EPCR paralleled protein expression. Soluble thrombomodulin and EPCR levels were both higher in patients than in controls: 41.5 vs. 26.0 ng/mL (p <.0001) and 141 vs. 130 ng/mL (p <.05), respectively.

CONCLUSIONS

EPCR expression on dendritic-like cells that bear the key complement receptor CD21 suggests a role for EPCR in innate immunity. The reduced expression of thrombomodulin and EPCR in the mucosal vessels in inflammatory bowel disease impairs protein C activation, favoring microthrombosis.

Malignant fibrous histiocytoma: a proposed cellular origin and identification of its characterizing gene transcripts

Although malignant fibrous histiocytoma (MFH) is one of the most diffuse and highly aggressive tumors among soft tissue sarcomas in adults, it is poorly characterized from the molecular point of view. The overt lack of expression of phenotypic markers in MFH cells and the hypothesis that MFH may originate from transformed multipotent stem/progenitor cells with mesenchymal features has led us to investigate this notion and search for 'MFH-specific' genes. To address this problem, we have undertaken a differential display-based three-pair comparative mRNA profiling of bone-marrow derived mesenchymal stem cells (MSC) and cells isolated by primary MFH, leiomyosarcoma and smooth muscle cells, fibrosarcoma and dermal fibroblasts. This approach highlighted pair-wise analogies in gene expression patterns between matched tumor and healthy cells and yielded direct access to 43 genes differentially expressed between MSC and MFH cells. Eleven of the identified genes were selected for comparative evaluation of their expression levels in other sarcoma types, as well as potential markers for the detection of circulating tumor cells. Several of these genes defined the stem/progenitor versus MFH cell and some of them have the potential to be exploited for disclosure of circulating sarcoma cells. The striking similarity in the gene expression patterns observed in the two cell types was further corroborated by a remarkable similarity in the cell phenotypic markers that these cells expressed ex vivo. The findings open now the possibility to examine, also functionally, genes not previously known to be implicated in MFH development and strengthen the hypothesis that MFH originates from a mesenchymal progenitor cell.