UMG1/CD3ε-bispecific T-cell engager redirects T-cell cytotoxicity against diffuse large B-cell lymphoma.

UMG1 is a unique epitope of CD43, not expressed by normal cells and tissues of haematopoietic and non-haematopoietic origin, except thymocytes and a minority (<5%) of peripheral blood T lymphocytes. By immunohistochemistry analysis of tissue microarray and pathology slides, we found high UMG1 expression in 20%-24% of diffuse large B-cell lymphomas (DLBCLs), including highly aggressive BCL2high and CD20low cases. UMG1 membrane expression was also found in DLBCL bone marrow-infiltrating cells and established cell lines. Targeting UMG1 with a novel asymmetric UMG1/CD3ε-bispecific T-cell engager (BTCE) induced redirected cytotoxicity against DLBCL cells and was synergistic with lenalidomide. We conclude that UMG1/CD3ε-BTCE is a promising therapeutic for DLBCLs.

A Pronectin™ AXL-targeted first-in-class bispecific T cell engager (pAXLxCD3ε) for ovarian cancer.

BACKGROUND: Pronectins™ are a new class of fibronectin-3-domain 14th-derived (14Fn3) antibody mimics that can be engineered as bispecific T cell engager (BTCE) to redirect immune effector cells against cancer. We describe here the in vitro and in vivo activity of a Pronectin™ AXL-targeted first-in-class bispecific T cell engager (pAXLxCD3ε) against Epithelial Ovarian Cancer (EOC). METHODS: pAXLxCD3ε T-cell mediated cytotoxicity was evaluated by flow cytometry and bioluminescence. pAXLxCD3ε mediated T-cell infiltration, activation and proliferation were assessed by immunofluorescence microscopy and by flow cytometry. Activity of pAXLxCD3ε was also investigated in combination with poly-ADP ribose polymerase inhibitors (PARPi). In vivo antitumor activity of pAXLxCD3ε was evaluated in immunocompromised (NSG) mice bearing intraperitoneal or subcutaneous EOC xenografts and immunologically reconstituted with human peripheral blood mononuclear cells (PBMC). RESULTS: pAXLxCD3ε induced dose-dependent cytotoxicity by activation of T lymphocytes against EOC cells, regardless of their histologic origin. The addition of PARPi to cell cultures enhanced pAXLxCD3ε cytotoxicity. Importantly, in vivo, pAXLxCD3ε was highly effective against EOC xenografts in two different NSG mouse models, by inhibiting the growth of tumor cells in ascites and subcutaneous xenografts. This effect translated into a significantly prolonged survival of treated animals. CONCLUSION: pAXLxCD3ε is an active therapeutics against EOC cells providing a rational for its development as a novel agent in this still incurable disease. The preclinical validation of a first-in-class agent opens the way to the development of a new 14Fn3-based scaffold platform for the generation of innovative immune therapeutics against cancer.

Exploiting DNA Ligase III addiction of multiple myeloma by flavonoid Rhamnetin.

BACKGROUND: DNA ligases are crucial for DNA repair and cell replication since they catalyze the final steps in which DNA breaks are joined. DNA Ligase III (LIG3) exerts a pivotal role in Alternative-Non-Homologous End Joining Repair (Alt-NHEJ), an error-prone DNA repair pathway often up-regulated in genomically unstable cancer, such as Multiple Myeloma (MM). Based on the three-dimensional (3D) LIG3 structure, we performed a computational screening to identify LIG3-targeting natural compounds as potential candidates to counteract Alt-NHEJ activity in MM. METHODS: Virtual screening was conducted by interrogating the Phenol Explorer database. Validation of binding to LIG3 recombinant protein was performed by Saturation Transfer Difference (STD)-nuclear magnetic resonance (NMR) experiments. Cell viability was analyzed by Cell Titer-Glo assay; apoptosis was evaluated by flow cytometric analysis following Annexin V-7AAD staining. Alt-NHEJ repair modulation was evaluated using plasmid re-joining assay and Cytoscan HD. DNA Damage Response protein levels were analyzed by Western blot of whole and fractionated protein extracts and immunofluorescence analysis. The mitochondrial DNA (mtDNA) copy number was determined by qPCR. In vivo activity was evaluated in NOD-SCID mice subcutaneously engrafted with MM cells. RESULTS: Here, we provide evidence that a natural flavonoid Rhamnetin (RHM), selected by a computational approach, counteracts LIG3 activity and killed Alt-NHEJ-dependent MM cells. Indeed, Nuclear Magnetic Resonance (NMR) showed binding of RHM to LIG3 protein and functional experiments revealed that RHM interferes with LIG3-driven nuclear and mitochondrial DNA repair, leading to significant anti-MM activity in vitro and in vivo. CONCLUSION: Taken together, our findings provide proof of concept that RHM targets LIG3 addiction in MM and may represent therefore a novel promising anti-tumor natural agent to be investigated in an early clinical setting.

The New Microtubule-Targeting Agent SIX2G Induces Immunogenic Cell Death in Multiple Myeloma.

Microtubule-targeting agents (MTAs) are effective drugs for cancer treatment. A novel diaryl [1,2]oxazole class of compounds binding the colchicine site was synthesized as cis-restricted-combretastatin-A-4-analogue and then chemically modified to have improved solubility and a wider therapeutic index as compared to vinca alkaloids and taxanes. On these bases, a new class of tricyclic compounds, containing the [1,2]oxazole ring and an isoindole moiety, has been synthetized, among which SIX2G emerged as improved MTA. Several findings highlighted the ability of some chemotherapeutics to induce immunogenic cell death (ICD), which is defined by the cell surface translocation of Calreticulin (CALR) via dissociation of the PP1/GADD34 complex. In this regard, we computationally predicted the ability of SIX2G to induce CALR exposure by interacting with the PP1 RVxF domain. We then assessed both the potential cytotoxic and immunogenic activity of SIX2G on in vitro models of multiple myeloma (MM), which is an incurable hematological malignancy characterized by an immunosuppressive milieu. We found that the treatment with SIX2G inhibited cell viability by inducing G2/M phase cell cycle arrest and apoptosis. Moreover, we observed the increase of hallmarks of ICD such as CALR exposure, ATP release and phospho-eIF2α protein level. Through co-culture experiments with immune cells, we demonstrated the increase of (i) CD86 maturation marker on dendritic cells, (ii) CD69 activation marker on cytotoxic T cells, and (iii) phagocytosis of tumor cells following treatment with SIX2G, confirming the onset of an immunogenic cascade. In conclusion, our findings provide a framework for further development of SIX2G as a new potential anti-MM agent.

Exploiting MYC-induced PARPness to target genomic instability in multiple myeloma.

Multiple Myeloma (MM) is a hematologic malignancy strongly characterized by genomic instability, which promotes disease progression and drug resistance. Since we previously demonstrated that LIG3-dependent repair is involved in the genomic instability, drug resistance and survival of MM cells, we here investigated the biological relevance of PARP1, a driver component of Alternative-Non Homologous End Joining (Alt-NHEJ) pathway, in MM. We found a significant correlation between higher PARP1 mRNA expression and poor prognosis of MM patients. PARP1 knockdown or its pharmacological inhibition by Olaparib impaired MM cells viability in vitro and was effective against in vivo xenografts of human MM. Anti-proliferative effects induced by PARP1-inhibition were correlated to increase of DNA double-strand breaks, activation of DNA Damage Response (DDR) and finally apoptosis. Importantly, by comparing a gene expression signature of PARP inhibitors (PARPi) sensitivity to our plasma cell dyscrasia (PC) gene expression profiling (GEP), we identified a subset of MM patients which could benefit from PARP inhibitors. In particular, Gene Set Enrichment Analysis (GSEA) suggested that high MYC expression correlates to PARPi sensitivity in MM. Indeed, we identified MYC as promoter of PARP1-mediated repair in MM and, consistently, we demonstrate that cytotoxic effects induced by PARP inhibition are mostly detectable on MYC-proficient MM cells. Taken together, our findings indicate that MYC-driven MM cells are addicted to PARP1 Alt-NHEJ repair, which represents therefore a druggable target in this still incurable disease.

Error-prone DNA repair pathways as determinants of immunotherapy activity: an emerging scenario for cancer treatment.

Defects in DNA repair machinery play a critical role in the pathogenesis and progression of human cancer. When they occur, the tumor cells activate error-prone mechanisms which lead to genomic instability and high mutation rate. These defects represent, therefore, a cancer Achilles'heel which could be therapeutically exploited by the use of DNA damage response inhibitors. Moreover, experimental and clinical evidence indicates that DNA repair deregulation has a pivotal role also in promoting immune recognition and immune destruction of cancer cells. Indeed, immune checkpoint inhibitors have received regulatory approval in tumors characterized by high genomic instability, such as melanomas and lung cancer. Here, we discuss how deregulation of DNA repair, through activation of error-prone mechanisms, increases immune activation against cancer. Finally, we address the potential strategies to use DNA repair components as biomarkers and/or therapeutic targets to empower immune-oncology treatment of human cancer.

Therapeutic vulnerability of multiple myeloma to MIR17PTi, a first-in-class inhibitor of pri-miR-17-92.

The microRNA (miRNA) cluster miR-17-92 is oncogenic and represents a valuable therapeutic target in c-MYC (MYC)-driven malignancies. Here, we developed novel LNA gapmeR antisense oligonucleotides (ASOs) to induce ribonuclease H-mediated degradation of MIR17HG primary transcripts and consequently prevent biogenesis of miR-17-92 miRNAs (miR-17-92s). The leading LNA ASO, MIR17PTi, impaired proliferation of several cancer cell lines (n = 48) established from both solid and hematologic tumors by on-target antisense activity, more effectively as compared with miR-17-92 inhibitors. By focusing on multiple myeloma (MM), we found that MIR17PTi triggers apoptosis via impairment of homeostatic MYC/miR-17-92 feed-forward loops (FFLs) in patient-derived MM cells and induces MYC-dependent synthetic lethality. We show that alteration of a BIM-centered FFL is instrumental for MIR17PTi to induce cytotoxicity in MM cells. MIR17PTi exerts strong in vivo antitumor activity in nonobese diabetic severe combined immunodeficient mice bearing clinically relevant models of MM, with advantageous safety and pharmacokinetic profiles in nonhuman primates. Altogether, MIR17PTi is a novel pharmacological tool to be tested in early-phase clinical trials against MM and other MYC-driven malignancies.

Rituximab-based pre-emptive treatment of molecular relapse in follicular and mantle cell lymphoma.

Pre-emptive rituximab (pRTX) might represent an effective approach for patients with follicular (FL) and mantle cell lymphoma (MCL) experiencing molecular relapse (M-rel). However, available experience is still limited. We retrospectively collected FL and MCL cases that underwent pRTX with four weekly rituximab infusions (375 mg/m²) due to molecular persistence or M-rel. M-rel was assessed using nested polymerase chain reaction (PCR) and real-time quantitative PCR using the Bcl-1/IGH, Bcl-2/IGH or the immunoglobulin heavy chain rearrangement. Twenty-three occurrences of M-rel or persistence were treated in 18 patients (nine MCL and nine FL). The pRTX reinduced molecular remission (MR) in 17/23 cases (7/9 FL and 10/14 MCL). The median time to MR reinduction was 4.5 months (range 3-12), and the median duration of the first MR reinduction was 34 months (range 12-72). In five MCL cases, pRTX was used to treat subsequent M-rels, with success in four cases. No clinical relapses were seen within 2 years of successful reinduction of MR. Progression-free survival after pRTX was 64 % at a median follow-up of 6 years. pRTX was feasible and safe and effectively reinduced MR in FL and MCL patients (74 %). Prospective trials are needed to verify the clinical benefit of similar approaches.

The lymphocyte to monocyte ratio improves the IPI-risk definition of diffuse large B-cell lymphoma when rituximab is added to chemotherapy.

The peripheral blood lymphocyte to monocyte ratio (LMR) at diagnosis can be clinically relevant in patients with diffuse large B-cell lymphoma (DLBCL). We reviewed the outcome of 1,057 DLBCL patients followed from 1984 to 2012 at four centers. LMR was analyzed as a clinical biomarker by receiver-operating characteristic (ROC) analysis and Harrell's C-statistics. Patients were characterized by a median age of 61 years, International Prognostic Index (IPI) score of >2 in 39%, and were treated with a rituximab-containing chemotherapy in 66%. LMR proved strongly predictive for survival in patients treated with rituximab-based programs, but not in those receiving chemotherapy alone. Additionally, an LMR value of ≤2.6 (as determined by ROC analysis) was associated with a worst performance status, a higher lactate dehydrogenase (LDH) level, an advanced clinical stage, and a higher IPI score (P = 0.000). In patients treated with rituximab-supplemented chemotherapy programs, an LMR value of <2.6 was found in most of the primary refractory patients (75%) which proved as the best cutoff to predict both response and survival (P = 0.018). Finally, multivariate analysis and Harrell's C-statistics confirmed the IPI-independent role of LMR on survival (P = 0.0000). In conclusion, LMR is a potent predictor of clinical response and survival in DLBCL treated with rituximab-containing chemotherapy.

The emerging scenario of immunotherapy for T-cell Acute Lymphoblastic Leukemia: advances, challenges and future perspectives.

T-cell acute lymphoblastic leukemia (T-ALL) is a challenging pediatric and adult haematologic disease still associated with an unsatisfactory cure rate. Unlike B-ALL, the availability of novel therapeutic options to definitively improve the life expectancy for relapsed/resistant patients is poor. Indeed, the shared expression of surface targets among normal and neoplastic T-cells still limits the efficacy and may induce fratricide effects, hampering the use of innovative immunotherapeutic strategies. However, novel monoclonal antibodies, bispecific T-cell engagers (BTCEs), and chimeric antigen receptors (CAR) T-cells recently showed encouraging results and some of them are in an advanced stage of pre-clinical development or are currently under investigation in clinical trials. Here, we review this exciting scenario focusing on most relevant advances, challenges, and perspectives of the emerging landscape of immunotherapy of T-cell malignancies.

The First-In-Class Anti-AXL×CD3ε Pronectin™-Based Bispecific T-Cell Engager Is Active in Preclinical Models of Human Soft Tissue and Bone Sarcomas.

Sarcomas are heterogeneous malignancies with limited therapeutic options and a poor prognosis. We developed an innovative immunotherapeutic agent, a first-in-class Pronectin™-based Bispecific T-Cell Engager (pAXL×CD3ε), for the targeting of AXL, a TAM family tyrosine kinase receptor highly expressed in sarcomas. AXL expression was first analyzed by flow cytometry, qRT-PCR, and Western blot on a panel of sarcoma cell lines. The T-cell-mediated pAXL×CD3ε cytotoxicity against sarcoma cells was investigated by flow cytometry, luminescence assay, and fluorescent microscopy imaging. The activation and degranulation of T cells induced by pAXL×CD3ε were evaluated by flow cytometry. The antitumor activity induced by pAXL×CD3ε in combination with trabectedin was also investigated. In vivo activity studies of pAXL×CD3ε were performed in immunocompromised mice (NSG), engrafted with human sarcoma cells and reconstituted with human peripheral blood mononuclear cells from healthy donors. Most sarcoma cells showed high expression of AXL. pAXL×CD3ε triggered T-lymphocyte activation and induced dose-dependent T-cell-mediated cytotoxicity. The combination of pAXL×CD3ε with trabectedin increased cytotoxicity. pAXL×CD3ε inhibited the in vivo growth of human sarcoma xenografts, increasing the survival of treated mice. Our data demonstrate the antitumor efficacy of pAXL×CD3ε against sarcoma cells, providing a translational framework for the clinical development of pAXL×CD3ε in the treatment of human sarcomas, aggressive and still-incurable malignancies.

TERRA G-quadruplex stabilization as a new therapeutic strategy for multiple myeloma.

BACKGROUND: Multiple myeloma (MM) is a hematologic malignancy characterized by high genomic instability, and telomere dysfunction is an important cause of acquired genomic alterations. Telomeric repeat-containing RNA (TERRA) transcripts are long non-coding RNAs involved in telomere stability through the interaction with shelterin complex. Dysregulation of TERRAs has been reported across several cancer types. We recently identified a small molecule, hit 17, which stabilizes the secondary structure of TERRA. In this study, we investigated in vitro and in vivo anti-MM activities of hit 17. METHODS: Anti-proliferative activity of hit 17 was evaluated in different MM cell lines by cell proliferation assay, and the apoptotic process was analyzed by flow cytometry. Gene and protein expressions were detected by RT-qPCR and western blotting, respectively. Microarray analysis was used to analyze the transcriptome profile. The effect of hit 17 on telomeric structure was evaluated by chromatin immunoprecipitation. Further evaluation in vivo was proceeded upon NCI-H929 and AMO-1 xenograft models. RESULTS: TERRA G4 stabilization induced in vitro dissociation of telomeric repeat-binding factor 2 (TRF2) from telomeres leading to the activation of ATM-dependent DNA damage response, cell cycle arrest, proliferation block, and apoptotic death in MM cell lines. In addition, up-regulation of TERRA transcription was observed upon DNA damage and TRF2 loss. Transcriptome analysis followed by gene set enrichment analysis (GSEA) confirmed the involvement of the above-mentioned processes and other pathways such as E2F, MYC, oxidative phosphorylation, and DNA repair genes as early events following hit 17-induced TERRA stabilization. Moreover, hit 17 exerted anti-tumor activity against MM xenograft models. CONCLUSION: Our findings provide evidence that targeting TERRA by hit 17 could represent a promising strategy for a novel therapeutic approach to MM.

Safety and activity of the first-in-class locked nucleic acid (LNA) miR-221 selective inhibitor in refractory advanced cancer patients: a first-in-human, phase 1, open-label, dose-escalation study.

BACKGROUND: We developed a 13-mer locked nucleic acid (LNA) inhibitor of miR-221 (LNA-i-miR-221) with a full phosphorothioate (PS)-modified backbone. This agent downregulated miR-221, demonstrated anti-tumor activity against human xenografts in mice, and favorable toxicokinetics in rats and monkeys. Allometric interspecies scaling allowed us to define the first-in-class LNA-i-miR-221 safe starting dose for the clinical translation. METHODS: In this first-in-human, open-label, dose-escalation phase 1 trial, we enrolled progressive cancer patients (aged ≥ 18 years) with ECOG 0-2 into 5 cohorts. The treatment cycle was based on a 30-min IV infusion of LNA-i-miR-221 on 4 consecutive days. Three patients within the first cohort were treated with 2 cycles (8 infusions), while 14 patients were treated with a single course (4 infusions); all patients were evaluated for phase 1 primary endpoint. The study was approved by the Ethics Committee and Regulatory Authorities (EudraCT 2017-002615-33). RESULTS: Seventeen patients received the investigational treatment, and 16 were evaluable for response. LNA-i-miR-221 was well tolerated, with no grade 3-4 toxicity, and the MTD was not reached. We recorded stable disease (SD) in 8 (50.0%) patients and partial response (PR) in 1 (6.3%) colorectal cancer case (total SD + PR: 56.3%). Pharmacokinetics indicated non-linear drug concentration increase across the dose range. Pharmacodynamics demonstrated concentration-dependent downregulation of miR-221 and upregulation of its CDKN1B/p27 and PTEN canonical targets. Five mg/kg was defined as the recommended phase II dose. CONCLUSIONS: The excellent safety profile, the promising bio-modulator, and the anti-tumor activity offer the rationale for further clinical investigation of LNA-i-miR-221 (ClinTrials.Gov: NCT04811898).

Tools in Pharmacogenomics Biomarker Identification for Cancer Patients.

The understanding of the biological differences which underlie the inter-individual variability in drug response improved the efficacy of cancer therapy in the era of precision medicine. In fact molecularly targeted drugs and immunotherapy represent a revolution in cancer treatment. The identification of genetic predictive and/or prognostic biomarkers linked to drug pharmacokinetics (PK) and pharmacodynamics (PD) is allowed by the development of high-throughput omics tools for detecting and understanding biological differences among individuals, in order to improve drug efficacy and minimize risk of toxicity. Personalized medicine in cancer treatment reduces costs of the healthcare system. Unfortunately, pharmacogenomics biomarkers discovery is influenced by complexity, need of high-quality evidence, and a validation process for regulatory purposes. This chapter is focused on the critic analysis of presently available pharmacogenomics tools for discovering or testing genetic polymorphic variants in drug metabolizing enzyme to be introduced in clinical practice for the prospective stratification of cancer patients.

Integration of DNA Microarray with Clinical and Genomic Data.

DNA microarrays have been widely employed to understand cancer development. This technology is able to measure expression levels of a large numbers of genes or to genotype multiple regions of a genome in a massively parallel experiment. In addition, the detection of methylation patterns and gene copy number variations are also performed. Clinicians began to apply these findings in personalized medicine for the selection of cancer therapy according to the individual's cancer genomic profile. Because cancer is a complex disease it is of great value to integrate microarray data with genomic and clinical data. Here, we presented an overview of DNA microarray technology and discuss about benefits and challenging of microarray data integration.

Risk Alleles for Multiple Myeloma Susceptibility in ADME Genes.

The cause of multiple myeloma (MM) remains largely unknown. Several pieces of evidence support the involvement of genetic and multiple environmental factors (i.e., chemical agents) in MM onset. The inter-individual variability in the bioactivation, detoxification, and clearance of chemical carcinogens such as asbestos, benzene, and pesticides might increase the MM risk. This inter-individual variability can be explained by the presence of polymorphic variants in absorption, distribution, metabolism, and excretion (ADME) genes. Despite the high relevance of this issue, few studies have focused on the inter-individual variability in ADME genes in MM risk. To identify new MM susceptibility loci, we performed an extended candidate gene approach by comparing high-throughput genotyping data of 1936 markers in 231 ADME genes on 64 MM patients and 59 controls from the CEU population. Differences in genotype and allele frequencies were validated using an internal control group of 35 non-cancer samples from the same geographic area as the patient group. We detected an association between MM risk and ADH1B rs1229984 (OR = 3.78; 95% CI, 1.18-12.13; p = 0.0282), PPARD rs6937483 (OR = 3.27; 95% CI, 1.01-10.56; p = 0.0479), SLC28A1 rs8187737 (OR = 11.33; 95% CI, 1.43-89.59; p = 0.005), SLC28A2 rs1060896 (OR = 6.58; 95% CI, 1.42-30.43; p = 0.0072), SLC29A1 rs8187630 (OR = 3.27; 95% CI, 1.01-10.56; p = 0.0479), and ALDH3A2 rs72547554 (OR = 2.46; 95% CI, 0.64-9.40; p = 0.0293). The prognostic value of these genes in MM was investigated in two public datasets showing that shorter overall survival was associated with low expression of ADH1B and SLC28A1. In conclusion, our proof-of-concept findings provide novel insights into the genetic bases of MM susceptibility.

A Novel Bispecific T-Cell Engager (CD1a x CD3ε) BTCE Is Effective against Cortical-Derived T Cell Acute Lymphoblastic Leukemia (T-ALL) Cells.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy burdened by poor prognosis. While huge progress of immunotherapy has recently improved the outcome of B-cell malignancies, the lack of tumor-restricted T-cell antigens still hampers its progress in T-ALL. Therefore, innovative immunotherapeutic agents are eagerly awaited. To this end, we generated a novel asymmetric (2 + 1) bispecific T-cell engager (BTCE) targeting CD1a and CD3ε (CD1a x CD3ε) starting from the development of a novel mAb named UMG2. UMG2 mAb reacts against CD1a, a glycoprotein highly expressed by cortical T-ALL cells. Importantly, no UMG2 binding was found on normal T-cells. CD1a x CD3ε induced high T-cell mediated cytotoxicity against CD1a+ T-ALL cells in vitro, as demonstrated by the concentration-dependent increase of T-cell proliferation, degranulation, induction of cell surface activation markers, and secretion of pro-inflammatory cytokines. Most importantly, in a PBMC-reconstituted NGS mouse model bearing human T-ALL, CD1a x CD3ε significantly inhibited the growth of human T-ALL xenografts, translating into a significant survival advantage of treated animals. In conclusion, CD1a x CD3ε is a novel BTCE highly active against CD1a-expressing cortical-derived T-ALL cells suitable for clinical development as an effective therapeutic option for this rare and aggressive disease.

miR-221/222 as biomarkers and targets for therapeutic intervention on cancer and other diseases: A systematic review.

Among deregulated microRNAs (miRs) in human malignancies, miR-221 has been widely investigated for its oncogenic role and as a promising biomarker. Moreover, recent evidence suggests miR-221 as a fine-tuner of chronic liver injury and inflammation-related events. Available information also supports the potential of miR-221 silencing as promising therapeutic intervention. In this systematic review, we selected papers from the principal databases (PubMed, MedLine, Medscape, ASCO, ESMO) between January 2012 and December 2020, using the keywords "miR-221" and the specific keywords related to the most important hematologic and solid malignancies, and some non-malignant diseases, to define and characterize deregulated miR-221 as a valuable therapeutic target in the modern vision of molecular medicine. We found a major role of miR-221 in this view.

Alternative Non-Homologous End-Joining: Error-Prone DNA Repair as Cancer's Achilles' Heel.

Error-prone DNA repair pathways promote genomic instability which leads to the onset of cancer hallmarks by progressive genetic aberrations in tumor cells. The molecular mechanisms which foster this process remain mostly undefined, and breakthrough advancements are eagerly awaited. In this context, the alternative non-homologous end joining (Alt-NHEJ) pathway is considered a leading actor. Indeed, there is experimental evidence that up-regulation of major Alt-NHEJ components, such as LIG3, PolQ, and PARP1, occurs in different tumors, where they are often associated with disease progression and drug resistance. Moreover, the Alt-NHEJ addiction of cancer cells provides a promising target to be exploited by synthetic lethality approaches for the use of DNA damage response (DDR) inhibitors and even as a sensitizer to checkpoint-inhibitors immunotherapy by increasing the mutational load. In this review, we discuss recent findings highlighting the role of Alt-NHEJ as a promoter of genomic instability and, therefore, as new cancer's Achilles' heel to be therapeutically exploited in precision oncology.