Multiple Solid Tumor Types Research Articles

Targeting Liver Cancer Stem Cells: An Alternative Therapeutic Approach for Liver Cancer.

Simple SummaryCancer stem cells (CSCs) are known to be highly resistant to conventional therapeutic approaches, such as chemotherapeutic drugs and radiation. Therefore, selectively targeting CSCs with specific markers or signaling pathways can be an effective therapeutic strategy for treating chemotherapy-resistant liver cancer. However, there is not enough information currently available to make a conclusive statement regarding hepatic CSC-specific signaling pathways and biomarkers. In present study, we provide an overview of the current knowledge on the specific surface markers and critical signaling pathways of hepatic CSC.The first report of cancer stem cell (CSC) from Bruce et al. has demonstrated the relatively rare population of stem-like cells in acute myeloid leukemia (AML). The discovery of leukemic CSCs prompted further identification of CSCs in multiple types of solid tumor. Recently, extensive research has attempted to identity CSCs in multiple types of solid tumors in the brain, colon, head and neck, liver, and lung. Based on these studies, we hypothesize that the initiation and progression of most malignant tumors rely largely on the CSC population. Recent studies indicated that stem cell-related markers or signaling pathways, such as aldehyde dehydrogenase (ALDH), CD133, epithelial cell adhesion molecule (EpCAM), Wnt/β-catenin signaling, and Notch signaling, contribute to the initiation and progression of various liver cancer types. Importantly, CSCs are markedly resistant to conventional therapeutic approaches and current targeted therapeutics. Therefore, it is believed that selectively targeting specific markers and/or signaling pathways of hepatic CSCs is an effective therapeutic strategy for treating chemotherapy-resistant liver cancer. Here, we provide an overview of the current knowledge on the hepatic CSC hypothesis and discuss the specific surface markers and critical signaling pathways involved in the development and maintenance of hepatic CSC subpopulations.

Therapeutic Potential of Afatinib in NRG1 Fusion-Driven Solid Tumors: A Case Series.

Neuregulin 1 (NRG1) fusions, which activate ErbB signaling, are rare oncogenic drivers in multiple tumor types. Afatinib is a pan-ErbB family inhibitor that may be an effective treatment for NRG1 fusion-driven tumors. This report summarizes pertinent details, including best tumor response to treatment, for six patients with metastatic NRG1 fusion-positive tumors treated with afatinib. The six cases include four female and two male patients who ranged in age from 34 to 69 years. Five of the cases are patients with lung cancer, including two patients with invasive mucinous adenocarcinoma and three patients with nonmucinous adenocarcinoma. The sixth case is a patient with colorectal cancer. NRG1 fusion partners for the patients with lung cancer were either CD74 or SDC4. The patient with colorectal cancer harbored a novel POMK-NRG1 fusion and a KRAS mutation. Two patients received afatinib as first- or second-line therapy, three patients received the drug as third- to fifth-line therapy, and one patient received afatinib as fifteenth-line therapy. Best response with afatinib was stable disease in two patients (duration up to 16 months when combined with local therapies) and partial response (PR) of >18 months in three patients, including one with ongoing PR after 27 months. The remaining patient had a PR of 5 months with afatinib 40 mg/day, then another 6 months after an increase to 50 mg/day. This report reviews previously published metastatic NRG1 fusion-positive tumors treated with afatinib and summarizes six previously unpublished cases. The latter include several with a prolonged response to treatment (>18 months), as well as the first report of efficacy in NRG1 fusion-positive colorectal cancer. This adds to the growing body of evidence suggesting that afatinib can be effective in patients with NRG1 fusion-positive tumors. NRG1 fusions activate ErbB signaling and have been identified as oncogenic drivers in multiple solid tumor types. Afatinib is a pan-ErbB family inhibitor authorized for the treatment of advanced non-small cell lung cancer that may be effective in NRG1 fusion-driven tumors. This report summarizes six previously unpublished cases of NRG1 fusion-driven cancers treated with afatinib, including five with metastatic lung cancer and one with metastatic colorectal cancer. Several patients showed a prolonged response of >18 months with afatinib treatment. This case series adds to the evidence suggesting a potential role for afatinib in this area of unmet medical need.

Lymph Node Ratio Is an Independent Prognostic Factor for Patients with Siewert Type II Adenocarcinoma of Esophagogastric Junction: Results from a 10-Year Follow-up Study.

Emerging evidences suggest that lymph node ratio (LNR), the number of metastatic lymph node (LN) to the total number of dissected lymph nodes (NDLN), may predict survival in multiple types of solid tumor. However, the prognostic role of LNR in adenocarcinoma of the esophagogastric junction (AEG) remains uninvestigated. The present study is intended to determine the prognostic value of LNR in the patients with Siewert type II AEG. A total of 342 patients with Siewert type II AEG who underwent R0 resection were enrolled in this study. The optimal cutoff of LNR was stratified into tertiles using X-tile software. The log-rank test was used to evaluate the survival differences, and multivariate Cox regression analyses were performed to determine the independent prognostic variables. The optimal cutoff of LNR were classified as LNR = 0, LNR between 0.01 and 0.40, and LNR > 0.41. Patients with high LNR had a shorter 5- and 10-year disease-specific survival (DSS) rate (8.5%, 1.4%) compared with those with moderate LNR (20.4%, 4.9%) and low LNR (58.0%, 27.5%) (P < 0.001). Multivariate Cox regression analysis indicated that LNR was an independent factor for DSS after adjusting for confounding variables (P < 0.05). Furthermore, after stratification by NDLN between NDLN < 15 group and NDLN ≥ 15 group, the LNR remained a significant predictor for DSS (P < 0.05). LNR is an independent predictor for DSS in patients with Siewert type II AEG regardless of NDLN. Patients with higher LNR have significantly shorter DSS.

Abstract 2661: AUTO6NG overcomes immune suppressive mechanisms in the TME and demonstrate preclinical anti-tumor activity in GD2-expressing solid tumors

Abstract Immune-checkpoint blockade therapies has had impressive results in the clinic and are approved in multiple cancer indications. However, meaningful responses remain elusive in several solid tumor types and durable responses in some of these indications, or subtypes, are rarely observed. It has been postulated that this is in part due to elaborate poorly understood immunosuppressive mechanisms that the therapeutic approach must overcome to elicit the desired durable responses. Chimeric Antigen Receptor T (CAR-T) cell therapies had been therapeutically highly successful in haematological malignancies but such successes have not been replicated yet in solid tumors, primarily due to immune suppressive mechanisms in the tumor microenvironment (TME) of these settings. To address these issues in developing our CAR-T therapeutics, we deployed tissue cytometry to conduct a multiplex analysis of 30 markers on the same tissue sections from each patient from a set of patients from various solid tumor indications expressing the antigen GD2 (e.g. SCLC, Melanoma, Neuroblastoma), a disialoganglioside to which we have developed a selective CAR. The panel aimed to characterize and phenotype key players within the TME (i.e. tumour cells, T cells, DCs, macrophages, MDSCs, CAFs, as well as endothelial cells). We then deployed machine learning analytics to assist in inferring about potential interactions the different cell types have in the 3D context of the tumor tissue which allowed the identification of therapeutically relevant elements in the TMEs of these indications. Next, we generated CAR-T cells from healthy donors targeting GD2, an antigen we validated its expression in multiple solid tumor types. A first generation GD2 CAR is currently being developed in the clinic for the treatment of Neuroblastoma. We proceeded to incorporate a CCR module (IL7R chimeric protein designed to improve cell persistence), a dnTGFβ (dominant negative TGF-βRII protein designed to block inhibitor signals from TGFβ), and other function enhancing modules into the GD2 CAR. The multi module CAR-T cells showed potent in vitro activity against human patient derived cancer cell lines as measured by both tumor lysis and cytokine secretion. These CAR-T cells also demonstrated enhanced tumor infiltration and anti-tumor activity in vivo in xenografts mouse models. Our findings suggest that GD2 targeted CAR-T cell therapy is a viable novel approach for the treatment of multiple solid tumors indications. Citation Format: Margarida Neves, Lukas Stanczuk, Alireza Alavi, Meggan Czapiga, Rebecca Moore, Frederick Vargas, Muhammad A. Al-Hajj. AUTO6NG overcomes immune suppressive mechanisms in the TME and demonstrate preclinical anti-tumor activity in GD2-expressing solid tumors [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 2661.

Abstract 5229: Discovery of novel potent allosteric inhibitors of YAP/TAZ-TEAD transcription for the treatment of multiple solid tumor types addicted to Hippo signaling

Abstract The Hippo pathway is a highly conserved signaling pathway across higher-order vertebrates and a key modulator of developmental biology. Both genetic aberrations as well as non-genetic dysregulation of the pathway lead to constitutive nuclear localization and transcriptional activity of the YAP/TAZ-TEAD complex in multiple solid tumor types, including mesothelioma, uveal melanoma, squamous cell cancer, liver cancer, lung cancer, etc. Genetic aberrations are manifested as gene amplifications and gene fusions of the core transcriptional YAP/TAZ-TEAD complex subunits, and, more commonly, as deletions or loss-of-function mutations in the upstream negative regulators of the Hippo pathway such as NF2, LATS1/2 or FAT1. More recently, constitutive activation of YAP/TAZ-TEAD has been implicated in cancer therapy resistance and in immune evasion. Multiple efforts have been devoted to identify small-molecule inhibitors of the YAP/TAZ-TEAD protein-protein interaction, yet with limited success reported to date. Based on the identification of an auto-palmitoylation pocket centrally located in TEAD, and its reported role to sustain YAP/TAZ-TEAD transcriptional activity, we set up a biophysical assay to detect selective small-molecule binding into the palmitoylation pocket of TEAD1. Based on screening a rationally designed compound collection in this assay and iterations of analoging, we identified several novel chemical series of TEAD-palmitoylation pocket binders. Hits were confirmed as specific allosteric inhibitors of YAP/TAZ-TEAD transcription in cell-based assays (Q-PCR and reporter gene assays). Soaking compounds in TEAD crystals revealed structural information enabling hit-to-lead optimization of two different chemical series. Best allosteric inhibitors in the series display single-digit nM potency in transcriptional assays, and translate to low nM inhibition of Hippo mutant (but not WT, &amp;gt;1000x selectivity window) mesothelioma proliferation. These molecules are well suited to probe for additional Hippo-dependent solid cancer types using in vitro cancer cell panels, selected based on genetics and/or a YAP/TAZ-TEAD gene signature. Furthermore, optimization towards orally bioavailable compounds is in progress and an update on in vivo efficacy in various solid tumor models will be presented. Citation Format: Matthias Versele, Aurélie Candi, Marnik Nijs, Wanda Haeck, Hugo Klaassen, Wim Smets, Stéphane Spieser, Bart Vanderhoydonck, Arnaud Marchand, Patrick Chaltin, Leticia Sansores, Georg Halder. Discovery of novel potent allosteric inhibitors of YAP/TAZ-TEAD transcription for the treatment of multiple solid tumor types addicted to Hippo signaling [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 5229.

Abstract 3443: Atlas of clinically-distinct cell states and cellular ecosystems across human solid tumors

Abstract Tumors are complex ecosystems consisting of malignant, immune, and stromal elements whose dynamic interactions drive patient survival and response to therapy. A comprehensive understanding of the diversity of cellular states within the tumor microenvironment (TME), and their patterns of co-occurrence, could provide new diagnostic tools for improved disease management and novel targets for therapeutic intervention. To address this challenge, we developed EcoTyper, a novel machine learning framework for large-scale identification of TME cell states and their co-association patterns from bulk, single-cell, and spatially resolved tumor expression data. EcoTyper starts by “purifying” cell type-specific gene expression profiles of epithelial cells, immune, and stromal cell types from bulk tissue transcriptomes using CIBERSORTx (Newman et al., Nat Biotechnol 2019). It then identifies transcriptional states for each cell type, validates them in scRNA-seq data, and uncovers co-occurrence patterns between cell states in order to define tumor cellular ecosystems. Applied to 6,475 tumor and adjacent normal samples from solid tumor types profiled by The Cancer Genome Atlas (TCGA), EcoTyper identified robust transcriptional states across 12 major cell types, including epithelial, fibroblast, endothelial, and 9 immune subsets. These states included both known and novel cellular phenotypes, nearly all of which could be validated in a compendium of scRNA-seq tumor atlases spanning ~140,000 cells. Most cell states were specific to neoplastic tissue, ubiquitous across tumor types, and significantly associated with overall survival, both in TCGA and in 9,062 held-out tumor specimens (Gentles/Newman et al., Nat Medicine 2015). We found that specific cell states co-occur in distinct cellular communities with characteristic patterns of ligand-receptor interactions, genomic features, clinical outcomes, and spatial organization. One such ecosystem defined a normal-like state that was strongly enriched in non-malignant samples. Others delineated novel pro- and anti-tumor inflammatory environments involving specific fibroblast, endothelial, and immune cell transcriptional programs. In summary, large-scale deconvolution of cell type-specific transcriptomes across thousands of solid tumors revealed a comprehensive atlas of TME cell states and cellular ecosystems. Our results provide a high-resolution portrait of cellular heterogeneity in the TME across multiple solid tumor types, with implications for novel diagnostics and immunotherapeutic targets.

Abstract 5999: The Warburg Effect suggests a palliative care approach to cancer therapy

Abstract Introduction: Otto Warburg discovered in 1924 that cancer cells needed a lot more glucose than normal cells. Today, the “Warburg Effect” is not only recognized as a “hallmark of cancer” but also served as the scientific basis for cancer detection using fluorodeoxyglucose (FDG) Positron emission tomography (PET-scans). Warburg suggested in 1927 that treating cancer patients with insulin can deprive glucose to the cancer cells by lowering the blood glucose levels and may inhibit tumor growth. Although at least six peer-reviewed publications so far have provided support for the feasibility of this approach, no clinical trial has ever been done. We have previously presented an analysis of the data from hospitals in China suggesting that insulin can be safely administered for patients receiving a small dosage of standard chemotherapy drugs as palliative treatments for late-stage cancer patients. Here, we report additional data from more patients and medical facilities. Experimental procedures: Patients diagnosed with multiple types of late-stage solid tumors were treated with regular insulin (Humulin R) administered intravenously, and small doses of standard chemotherapy drugs (approximately 10% of the standard dosages). Blood glucose levels were monitored throughout the course of treatment. Hypoglycemia was reversed by ingestion of food and drink or injection of glucose solution. Depending on how well the patients tolerated the treatments, 5-30 units of insulin were used. No permanent side effects were observed or reported. Summary of data: Over 400 treatments have been performed on over 30 patients ranging from 30 to 76 years old, and diagnosed with 14 types of cancer. The average age of the patients was 56.2 years old. Symptoms of hypoglycemia were observed in all 30+ patients, and readily reversed by intravenous infusions of glucose or ingestion of food and drink. The insulin treatments were well tolerated and no longer -term side effects were observed. Conclusions: Our analysis supports the feasibility of using regular insulin as a reproducibly safe method to achieve glucose deprivation in patients with advanced stages of multiple types of cancer receiving palliative and hospice care. These and additional future studies could form the basis for eventually conducting a clinical trial testing whether regular insulin, which is inexpensive and available over the counter, can be an alternative therapeutic option for palliative and hospice care in some patients. Citation Format: Linda C. Meade-Tollin, Tom C. Tsang. The Warburg Effect suggests a palliative care approach to cancer therapy [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 5999.

The Role of Methyltransferase NSD2 as a Potential Oncogene in Human Solid Tumors.

Malignant solid tumors are the leading cause of death in humans, and epigenetic regulation plays a significant role in studying the mechanism of human solid tumors. Recently, histone lysine methylation has been demonstrated to be involved in the development of human solid tumors due to its epigenetic stability and some other advantages. The 90-kb protein methyltransferase nuclear receptor SET domain-containing 2 (NSD2) is a member of nuclear receptor SET domain-containing (NSD) protein lysine methyltransferase (KMT) family, which can cause epigenomic aberrations via altering the methylation states. Studies have shown that NSD2 is frequently over-expressed in multiple types of aggressive solid tumors, including breast cancer, renal cancer, prostate cancer, cervical cancer, and osteosarcoma, and such up-regulation has been linked to poor prognosis and recurrence. Further studies have identified that over-expression of NSD2 promotes cell proliferation, migration, invasion, and epithelial–mesenchymal transformation (EMT), suggesting its potential oncogenic role in solid tumors. Moreover, Gene Expression Profiling Interactive Analysis (GEPIA) was searched for validation of prognostic value of NSD2 in human solid tumors. However, the underlying specific mechanism remains unclear. In our present work, we summarized the latest advances in NSD2 expression and clinical applications in solid tumors, and our findings provided valuable insights into the targeted therapeutic regimens of solid tumors.

Chimeric antigen receptor T cells targeting PD-L1 suppress tumor growth

BackgroundChimeric antigen receptor T cells (CAR-T cells) therapy has been well recognized for treating B cell-derived malignancy. However, the efficacy of CAR-T cells against solid tumors remains dissatisfactory, partially due to the heterogeneity of solid tumors and T cell exhaustion in tumor microenvironment. PD-L1 is up-regulated in multiple solid tumors, resulting in T cell exhaustion upon binding to its receptor PD-1.MethodsHere, we designed a dominant-negative form of PD-1, dPD1z, a vector containing the extracellular and transmembrane regions of human PD-1, and a CAR vector against PD-L1, CARPD-L1z, a vector employs a high-affinity single-chain variable fragment (scFv) against human PD-L1. These two vectors shared the same intracellular structure, including 4-1BB and TLR2 co-stimulatory domains, and the CD3ζ signaling domain.ResultsdPD1z T and CARPD-L1z T cells efficiently lysed PD-L1+ tumor cells and had enhanced cytokine secretion in vitro and suppressed the growth of non-small cell lung cancer (NSCLC), gastric cancer and hepatoma carcinoma in patient-derived xenograft (PDX). However, the combination of anti-mesothelin CAR-T cells (CARMSLNz T) with dPD1z T or CARPD-L1z T cells did not repress tumor growth synergistically in PDX, as CARMSLNz T cells upregulated PD-L1 expression upon activation and were subsequently attacked by dPD1z T or CARPD-L1z T cells.ConclusionsIn conclusion, we demonstrate CAR-T cells targeting PD-L1 were effective for suppressing the growth of multiple types of solid tumors in PDX models though their safety needs to be carefully examined.

Clinical activity of the RET inhibitor pralsetinib (BLU-667) in patients with RET fusion+ solid tumors.

109 Background: RET gene fusions are targetable oncogenic drivers in multiple tumor types, including up to 20% of papillary thyroid cancers (PTC). Pralsetinib is an investigational, highly potent, selective inhibitor of oncogenic RET alterations. In the registration-enabling Phase 1/2 ARROW study (NCT03037385), pralsetinib demonstrated an overall response rate (ORR; response-evaluable patients [REP], central review) of 73% (19/26) in treatment-naïve patients and 61% (49/80; 2 pending confirmation) in platinum-exposed patients with RET fusion+ non-small cell lung cancer (NSCLC) and was well tolerated (data cut-off November 18, 2019). We provide an update on the clinical activity of pralsetinib in other RET fusion+ solid tumor types. Methods: ARROW consists of a phase 1 dose escalation (30–600 mg once [QD] or twice daily) followed by a phase 2 expansion (400 mg QD) in patients with advanced RET-altered solid tumors. Primary objectives were ORR and safety. Results: As of November 18, 2019, 29 patients with metastatic solid tumor types other than NSCLC (16 PTC, 1 undifferentiated thyroid, 3 pancreatic, 3 colon, 6 other) bearing a RET fusion have received pralsetinib. Efficacy data are presented for REP enrolled by July 11, 2019. In patients with thyroid cancer that is RET fusion+, ORR (investigator assessment) was 75% (9/12; all confirmed). Median (range) duration of response (DOR) was 14.5 (3.7+, 16.8) months (mo), with 67% of responding patients continuing treatment. Two patients with stable disease were continuing treatment at 11.5+ and 19.3+ mo. In other RET fusion+ cancers, ORR was 60% (3/5; all confirmed) with partial responses in 2/2 patients with pancreatic cancer (DOR 5.5, 7.4+ mo) and 1 patient with intrahepatic bile duct carcinoma (DOR 7.5 mo). Two patients with colon cancer had stable disease for 7.3 and 9.3 mo. Responses were observed across multiple fusion genotypes. In the entire safety population (all patients treated with 400 mg QD pralsetinib, regardless of diagnosis; n = 354), most treatment-related adverse events (TRAEs) were grade 1-2, and included increased aspartate aminotransferase (31%), anemia (22%), increased alanine aminotransferase (21%), constipation (21%) and hypertension (20%). Only 4% of patients in the safety population discontinued due to TRAEs. Conclusions: Pralsetinib demonstrated broad and durable antitumor activity across multiple advanced solid tumor types, regardless of RET fusion genotype, and was well tolerated. The study is ongoing and still enrolling patients in this cohort. Clinical trial information: NCT03037385.

Sindbis Virus with Anti-OX40 Overcomes the Immunosuppressive Tumor Microenvironment of Low-Immunogenic Tumors

Despite remarkable responses to cancer immunotherapy in a subset of patients, many patients remain resistant to therapies. It is now clear that elevated levels of tumor-infiltrating T cells as well as a systemic anti-tumor immune response are requirements for successful immunotherapies. However, the tumor microenvironment imposes an additional resistance mechanism to immunotherapy. We have developed a practical and improved strategy for cancer immunotherapy using an oncolytic virus and anti-OX40. This strategy takes advantage of a preexisting T cell immune repertoire in vivo, removing the need to know about present tumor antigens. We have shown in this study that the replication-deficient oncolytic Sindbis virus vector expressing interleukin-12 (IL-12) (SV.IL12) activates immune-mediated tumor killing by inducing OX40 expression on CD4 T cells, allowing the full potential of the agonistic anti-OX40 antibody. The combination of SV.IL12 with anti-OX40 markedly changes the transcriptome signature and metabolic program of T cells, driving the development of highly activated terminally differentiated effector T cells. These metabolically reprogrammed T cells demonstrate enhanced tumor infiltration capacity as well as anti-tumor activity capable of overcoming the repressive tumor microenvironment. Our findings identify SV.IL12 in combination with anti-OX40 to be a novel and potent therapeutic strategy that can cure multiple types of low-immunogenic solid tumors.

First-in-Human, Multicenter, Phase I Dose-Escalation and Expansion Study of Anti-Mesothelin Antibody–Drug Conjugate Anetumab Ravtansine in Advanced or Metastatic Solid Tumors

PURPOSEThis phase I study, which to our knowledge is the first-in-human study of this kind, investigates the safety, tolerability, pharmacokinetics, and clinical activity of anetumab ravtansine, an antibody–drug conjugate of anti-mesothelin antibody linked to maytansinoid DM4, in patients with advanced, metastatic, or recurrent solid tumors known to express the tumor-differentiation antigen mesothelin.PATIENTS AND METHODSThis phase I, open-label, multicenter, dose-escalation and dose-expansion study of anetumab ravtansine enrolled 148 adult patients with multiple solid tumor types. Ten dose-escalation cohorts of patients with advanced or metastatic solid tumors (0.15-7.5 mg/kg) received anetumab ravtansine once every 3 weeks, and 6 expansion cohorts of patients with advanced, recurrent ovarian cancer or malignant mesothelioma received anetumab ravtansine at the maximum tolerated dose once every 3 weeks, 1.8 mg/kg once per week, and 2.2 mg/kg once per week.RESULTSForty-five patients were enrolled across the 10 dose-escalation cohorts. The maximum tolerated dose of anetumab ravtansine was 6.5 mg/kg once every 3 weeks or 2.2 mg/kg once per week. Thirty-two patients were enrolled in the 6.5 mg/kg once-every-3-weeks, 35 in the 1.8 mg/kg once-per-week, and 36 in the 2.2 mg/kg once-per-week expansion cohorts. The most common drug-related adverse events were fatigue, nausea, diarrhea, anorexia, vomiting, peripheral sensory neuropathy, and keratitis/keratopathy. There were no drug-related deaths. Anetumab ravtansine pharmacokinetics were dose proportional; the average half-life was 5.5 days. Among 148 patients with mesothelioma or ovarian, pancreatic, non–small-cell lung, and breast cancers, 1 had a complete response, 11 had partial responses, and 66 had stable disease. High levels of tumor mesothelin expression were detected in patients with clinical activity.CONCLUSIONAnetumab ravtansine exhibited a manageable safety and favorable pharmacokinetic profile with encouraging preliminary antitumor activity in heavily pretreated patients with mesothelin-expressing solid tumors. The results allowed for the determination of recommended doses, schedules, and patient populations for anetumab ravtansine in phase II studies.

Abstract OT1-07-06: Phase 1/2 first-in-human study of U3-1402, an anti-human epidermal growth factor receptor 3 (HER3) antibody-drug conjugate, in HER3-expressing advanced/unresectable or metastatic breast cancer, including those with triple negative breast cancer (TNBC) or HER3-low disease

Abstract Background: The HER3 protein is expressed in multiple solid tumor types, including breast cancer, and high expression of HER3 is associated with poor prognosis. U3-1402 is a novel HER3-targeted antibody-drug conjugate designed with a peptide-based cleavable linker and a topoisomerase I inhibitor payload. U3-1402 has a high drug-to-antibody ratio (~ 8:1), and the stable linker is selectively cleaved by lysosomal enzymes upregulated in tumor cells. In addition, high cell membrane cross-penetration allows for potential payload activity against neighboring tumor cells with antigen heterogeneity. This ongoing phase 1/2, multicenter, open-label, first-in-human study was initiated in Japan and expanded to the United States to evaluate the safety and efficacy of U3-1402 in HER2-negative (including hormone receptor [HR]-positive disease and TNBC), HER3-expressing advanced/unresectable or metastatic breast cancer (NCT02980341/JapicCTI-163401). The study comprises 3 parts: dose escalation, dose finding, and dose expansion. Preliminary results from the phase 1 dose-escalation and dose-finding parts demonstrated the recommended dose for expansion, with antitumor activity of U3-1402 in this heavily pretreated patient population (Masuda, et al. SABCS 2018). Methods: In the ongoing, phase 2, dose-expansion part of this trial, U3-1402 is administered via intravenous infusion every 3 weeks to patients with HER3-expressing advanced/unresectable or metastatic breast cancer. Approximately 110 patients will be treated in the dose-expansion part within cohorts based on breast cancer molecular subtype and HER3 protein expression: patients with HER3-high, HER2-negative, HR-positive disease will receive 4.8 or 6.4 mg/kg U3-1402; patients with HER3-low, HER2-negative, HR-positive disease will receive 6.4 mg/kg U3-1402; and patients with HER3-high, TNBC will receive 6.4 mg/kg U3-1402. Eligible patients for dose expansion are aged ≥ 18 years in the United States (≥ 20 years in Japan); have documented HER3-positive disease, as measured by immunohistochemistry; must undergo fresh tumor biopsy prior to starting treatment, if a sample has not already been submitted for assessment of HER3 expression. For all cohorts except TNBC, patients must have received ≥ 2 and ≤ 6 prior chemotherapy regimens, including ≥ 2 regimens for advanced/unresectable or metastatic disease. For the TNBC cohort, patients must have progressed after receiving 1 to 2 prior chemotherapy regimens in the advanced setting. Patients with previously treated or asymptomatic untreated brain metastases are eligible. Treatment will continue until progression, unacceptable toxicity, death, withdrawal of consent, or termination of the study. The primary objective of dose expansion is to evaluate the safety and efficacy of U3-1402; the secondary objectives are to evaluate the relationship between the efficacy of U3-1402 and HER3 expression and to assess pharmacokinetics and antidrug antibodies. Efficacy assessments include investigator-assessed objective response rate per RECIST v1.1, response duration, time to response, clinical benefit rate, progression-free survival, overall survival, and percent change in target lesion(s). Patients receiving at least 1 dose of U3-1402 with pretreatment and posttreatment tumor assessments will be evaluated for efficacy. Citation Format: Ian Krop, Norikazu Masuda, Takahiro Kogawa, Shunji Takahashi, Kan Yonemori, Kenichi Inoue, Takahiro Nakayama, Yutaka Yamamoto, Ricardo Alvarez, Tatsuya Toyama, Akihiko Osaki, Masato Takahashi, Joyce O'Shaughnessy, Yasuaki Sagara, Shigehira Saji, Virginia Kaklamani, Sun Young Oh, William Gradishar, Barbara Haley, Tsutomu Iwasa, Tiffany Traina, Naoto Ueno, Steve Isakoff, Shoichi Ohwada, Yoshimi Tanaka, Sabeen Mekan, Hiroshi Onuma, Om Sharma, Hiroji Iwata. Phase 1/2 first-in-human study of U3-1402, an anti-human epidermal growth factor receptor 3 (HER3) antibody-drug conjugate, in HER3-expressing advanced/unresectable or metastatic breast cancer, including those with triple negative breast cancer (TNBC) or HER3-low disease [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-07-06.

Tazemetostat for the treatment of multiple types of hematological malignancies and solid tumors.

Epigenetic alterations contributing to malignancy have become a more prominent field of investigation over the past several years, as several hallmarks of cancer are substantially altered by changes in the epigenome. Enhancer of zeste homologue 2 (EZH2), an enzyme involved in silencing the transcription of various genes, is overexpressed or mutated in multiple cancers and can lead to proliferation of dedifferentiated cells. Both gain-of-function and loss-of-function mutations have been noted in hematologic cancers, with gain-of-function mutations prevalent among non-Hodgkin lymphomas. Tazemetostat is a first-in-class EZH2 inhibitor developed to target this overexpression. Phase I trials have shown it is generally well tolerated and efficacious in solid tumors as well as hematological malignancies. Tazemetostat was approved by the U.S. Food and Drug Administration (FDA) for use in epithelioid sarcoma in January 2020 on the basis of the results of a recent phase II trial, but with several clinical trials ongoing, the use of tazemetostat for hematological malignancies is a promising avenue for treatment.

ATG12 deficiency leads to tumor cell oncosis owing to diminished mitochondrial biogenesis and reduced cellular bioenergetics.

In contrast to the "Warburg effect" or aerobic glycolysis earlier generalized as a phenomenon in cancer cells, more and more recent evidence indicates that functional mitochondria are pivotal for ensuring the energy supply of cancer cells. Here, we report that cancer cells with reduced autophagy-related protein 12 (ATG12) expression undergo an oncotic cell death, a phenotype distinct from that seen in ATG5-deficient cells described before. In addition, using untargeted metabolomics with ATG12-deficient cancer cells, we observed a global reduction in cellular bioenergetic pathways, such as β-oxidation (FAO), glycolysis, and tricarboxylic acid cycle activity, as well as a decrease in mitochondrial respiration as monitored with Seahorse experiments. Analyzing the biogenesis of mitochondria by quantifying mitochondrial DNA content together with several mitochondrion-localizing proteins indicated a reduction in mitochondrial biogenesis in ATG12-deficient cancer cells, which also showed reduced hexokinase II expression and the upregulation of uncoupling protein 2. ATG12, which we observed in normal cells to be partially localized in mitochondria, is upregulated in multiple types of solid tumors in comparison with normal tissues. Strikingly, mouse xenografts of ATG12-deficient cells grew significantly slower as compared with vector control cells. Collectively, our work has revealed a previously unreported role for ATG12 in regulating mitochondrial biogenesis and cellular energy metabolism and points up an essential role for mitochondria as a failsafe mechanism in the growth and survival of glycolysis-dependent cancer cells. Inducing oncosis by imposing an ATG12 deficiency in solid tumors might represent an anticancer therapy preferable to conventional caspase-dependent apoptosis that often leads to undesirable consequences, such as incomplete cancer cell killing and a silencing of the host immune system.

B7-H3 specific T cells with chimeric antigen receptor and decoy PD-1 receptors eradicate established solid human tumors in mouse models

ABSTRACT The application of chimeric antigen receptor (CAR)-T cell therapy in patients with advanced solid tumors remains a significant challenge. Simultaneously targeting antigen and the solid tumor microenvironment are two major factors that greatly impact CAR-T cell therapy outcomes. In this study, we engineered CAR-T cells to specifically target B7-H3, a protein commonly found in solid human tumors, using a single-chain variable fragment (scFv) derived from an anti-B7-H3 monoclonal antibody. We tested the antitumor activity of B7-H3 CAR-T cells in mouse models with solid human tumors and determined that B7-H3 CAR-T cells exhibited potent antitumor activity against B7-H3+ tumor cells in vitro and in vivo. In addition, PD-1 decoy receptors were engineered to include extracellular PD-1 fused to the intracellular stimulatory domain of either CD28 or IL-7 receptor, respectively, which were then introduced into B7-H3 CAR-T cells. As a result, these newly modified, superior CAR-T cells exhibited more persistent antitumor activity in B7-H3+/B7-H1+ tumors in vivo. Our findings indicate that B7-H3 specific CAR-T cells have the potential to treat multiple types of advanced solid tumors.

Enapotamab vedotin, an AXL-specific antibody-drug conjugate, shows preclinical antitumor activity in non-small cell lung cancer.

Targeted therapies and immunotherapy have shown promise in patients with non-small cell lung cancer (NSCLC). However, the majority of patients fail or become resistant to treatment, emphasizing the need for novel treatments. In this study, we confirm the prognostic value of levels of AXL, a member of the TAM receptor tyrosine kinase family, in NSCLC and demonstrate potent antitumor activity of the AXL-targeting antibody-drug conjugate enapotamab vedotin across different NSCLC subtypes in a mouse clinical trial of human NSCLC. Tumor regression or stasis was observed in 17/61 (28%) of the patient-derived xenograft (PDX) models and was associated with AXL mRNA expression levels. Significant single-agent activity of enapotamab vedotin was validated in vivo in 9 of 10 AXL-expressing NSCLC xenograft models. In a panel of EGFR-mutant NSCLC cell lines rendered resistant to EGFR inhibitors in vitro, we observed de novo or increased AXL protein expression concomitant with enapotamab vedotin-mediated cytotoxicity. Enapotamab vedotin also showed antitumor activity in vivo in 3 EGFR-mutant, EGFR inhibitor-resistant PDX models, including an osimertinib-resistant NSCLC PDX model. In summary, enapotamab vedotin has promising therapeutic potential in NSCLC. The safety and preliminary efficacy of enapotamab vedotin are currently being evaluated in the clinic across multiple solid tumor types, including NSCLC.

Genomic profiling of cell-free circulating tumor DNA in patients with colorectal cancer and its fidelity to the genomics of the tumor biopsy.

Liquid biopsy offers the ability to non-invasively analyze the genome of a tumor through circulating tumor DNA (ctDNA) to identify targetable and prognostic genomic alterations. Few studies have rigorously analyzed ctDNA results and determined the fidelity with which they recapitulate the genomics of a sequenced tissue sample obtained from the same tumor. The clinical utility study (CUS) for the FoundationACT™ ctDNA assay (Foundation Medicine, Cambridge, MA, USA; NCT02620527) is a multi-center prospective clinical study for multiple solid tumor types to compare genomic profiling of paired tissue and blood samples from the same patient. In this subset of the study, paired specimens from 96 patients with colorectal cancer (CRC) were analyzed with comprehensive genomic profiling (CGP) of the tumor tissue sample (FoundationOne®) and blood sample (FoundationACT™). Both samples underwent CGP using the hybrid capture-based Illumina Hi-Seq technology. Maximum somatic allele frequency (MSAF) was used to estimate the fraction of ctDNA in the sample. The set of genes and targeted regions common to both tumor and liquid were compared for each subject. Among these patients, 61% were male; 74% had clinical stage IV disease, 19% had clinical stage III disease, and 7% had clinical stage II disease. Time between the tissue biopsy and liquid biopsy (range, 0-709 days) had a significant impact on the positive percent agreement (PPA) between the two assays. Eighty percent of cases had evidence of ctDNA in the blood (MSAF >0). For all cases with MSAF >0, 171 base substitutions and insertions/deletions (indels) were identified in the tumor, and 79% (PPA) of these identical alterations were also identified in matched ctDNA samples; PPA increased to 87% for cases <270 days between the tissue and liquid biopsy, 95% for <90 days, and 100% PPA for <30 days. All known and likely short variants in KRAS, NRAS, and BRAF were analyzed independently as testing of these genes is recommended by the National Comprehensive Cancer Network (NCCN) for patients with CRC and have therapeutic implications. For NCCN genes, PPA was 80% for all time points for short variants; PPA increased to 90% for cases <270 days between the tissue and liquid biopsy. There was high concordance for KRAS G12X between tissue and liquid: overall percent agreement (97%), PPA (93%), negative percent agreement (NPA) (100%), positive predictive value (PPV) (100%), and negative predictive value (NPV) (96%) for the <270 day cohort. In cases where tumor tissue profiling is not possible, these results provide compelling evidence that genomic profiling of ctDNA in late stage CRC shows a high concordance with tumor tissue sequencing results and can be used to identify most clinically relevant alterations capable of guiding therapy for these patients.

GADD45G ACTS AS A NOVEL TUMOR SUPPRESSOR IN AML

State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, China (People's Republic) Acute myeloid leukaemia (AML) is an aggressive hematologic neoplasm with distinct molecular and genetic features which is characterized by differentiation blockade and uncontrolled proliferation of malignant clones of immature myeloid cells. The growth arrest and DNA-damage induced 45 (GADD45) family protein GADD45g, has been shown to mediate DNA repair, cell cycle, senescence and apoptosis in response to various physiological and environmental stressors. Altered expression of GADD45g has been observed in multiple types of solid tumors, the function of GADD45g in hematopoietic malignancies remains almost completely unknown. Here, we found that GADD45g expression was preferentially silenced in AML, especially in AML with MLL rearrangements and FLT3-ITD mutations, and reduced expression of GADD45g correlates with poor prognosis in AML patients. Ectopic expression of GADD45g suppresses leukemic growth, induced apoptosis, senescence and differentiation of AML cells in vitro and in vivo. What's more, GADD45g caused downregulation of DNA repair proteins, resulting in inhibition of DNA double-strand break repair pathways and leading to DNA damage accumulation in AML cells. Moreover, GADD45g is epigenetically silenced in AML by both promoter DNA methylation and histone deacetylation, while the HDACi is more powerful. Exogenous expression of FLT3-ITD and MLL-AF9 repress GADD45G expression in AML, and the expression of GADD45G could be significantly induced by the small-molecule inhibitors FLT3 TKI or BRD4i target FLT3 or MLL respectively. Furthermore, the combination of HDACi and FLT3 TKI or BRD4i exerted a synergistic effect against FLT3-ITD+ or MLL-rearranged AML, respectively. These findings suggest that GADD45G may act as a tumor suppressor in AML and provide a novel and promising therapeutic target for AML.

Abstract 546: Selectively targeting CD47 with bispecific antibody to efficiently eliminate mesothelin-positive solid tumors

Abstract The CD47- signal regulatory protein α (SIRPα) axis, originally discovered as a mechanism of self-recognition, has emerged as a novel innate immune check-point employed by cancer cells to escape immune surveillance. Over-expression of CD47 on a plethora of hematologic and solid cancers has been shown to be associated with poor prognosis. CD47 blockade is thus considered as an attractive strategy to retune the host immune system toward eliminating cancer cells. Clinical efficacy has been achieved in patients with Non-Hodgkin lymphoma (NHL) treated with a combination of the anti-CD20 monoclonal antibody (mAb), rituximab, and the anti-CD47 mAb, Hu5F9-G4. However, in parallel, due to the ubiquitous expression of CD47 on healthy cells, toxicity is observed limiting exposure which impairs clinical development of anti-CD47 mAbs. To harness the tumoricidal potential and avoid the liabilities of CD47 blockade, we have developed bispecific antibodies (bsAbs), co-targeting CD47 and a tumor associated antigen (TAA), for selective blockade of CD47 on malignant cells. Mesothelin (MSLN) has been selected as one of these TAAs as it is over-expressed on multiple types of solid tumors. An anti-CD47xMSLN bsAb with a fully functional IgG1 Fc domain has been generated and tested for efficacy and safety in vitro and in vivo using cell-based assays and animal models. With a panel of human MSLN+ target cells, the bsAb kills more efficiently through Ab-dependent cellular phagocytosis (ADCP) and cell-mediated cytotoxicity (ADCC) as compared to the anti-MSLN mAb, amatuximab. Efficacy of the bsAb was minimally affected by soluble MSLN as compared to amatuximab. Mechanistic studies demonstrated that the increased ADCP and ADCC were due to co-engagement-mediated blockade of both target proteins. In vivo using xenograft models, whereas amatuximab was unable, the bsAb inhibited tumor growth of OVCAR3 and MSLN-transfected HepG2 cell lines. Phenotypic analysis showed that treatment with the bsAb induced the accumulation of myeloid cells with increased F4/80 expression in the tumor microenvironment. Importantly, the bsAb was well-tolerated in an exploratory four-week repeated dose study at the highest dose tested (10 mg/kg) in cynomolgus monkeys. Conclusion: Selective CD47 targeting on tumor cells with an anti-CD47xMSLN bsAb showed efficient killing of MSLN+ tumor cells in vitro and in vivo. A study in non-human primates administered weekly a therapeutically relevant dose over 28 days was well tolerated demonstrating no adverse hematological profiles. Citation Format: Limin Shang, Vanessa Buatois, Eric Hatterer, Xavier Chauchet, Hasnaà Haddouk, Stefano Majocchi, Krzysztof Masternak, Marie H. Kosco-Vilbois, Nicolas Fischer, Walter G. Ferlin. Selectively targeting CD47 with bispecific antibody to efficiently eliminate mesothelin-positive solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 546.