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Supplementary Table S5: Microscopic IHC staining for CD205 in different cynomolgus tissues after treatment with MEN1309/OBT076. Staining: 1, minimal (+, rare cells with low staining intensity); 2, slight/moderate (++, many cells with medium/high staining intensity); 3, marked (+++, significant numbers of cells with high staining intensity); 0, negative (no stained cells); -, no background present; tm, tissue missing; lp, lesion present; p, background staining present; N/A, not applicable.

Supplementary Figure S3-A. Representative image of IHC staining for CD205 in a tumor mass from HCC-70 xenograft model, 16 days far from the initial treatment with 5 mg/kg of MEN1309/OBT076. The semiquantitative IHC analysis showed a score of 1+ in 30% of cells while the remaining were scored negative (0). Supplementary Figure S3-B. Representative image of IHC staining for CD205 in a tumor mass from PDX-347 model, 16 days far from the initial treatment with 5 mg/kg of MEN1309/OBT076. The semiquantitative IHC analysis showed a score of 2+ in 100% of cells. Red and green lines represent tumor and fibrotic areas.

Supplementary Figure S2. In vitro characterization of MEN1309/OBT076. A) ELISA assay showed that both the unconjugated and DM4-conjugated antibodies were able to bind FcγRIIIA with the same affinity (n=2). B) FACS binding experiment on THP-1 cell line, performed by titrating unlabeled antibody with a constant amount of labelled antibody, showed high binding affinity of MBH1309/OBT076 to CD205 expressed on the cell surface with no affinity loss after conjugation (N=2). C) In vitro ADCC bioluminescence assay showed that, despite the ability to bind FcγRIIIA, MBH1309/OBT076 didn't induce any ADCC response. D) In vitro CDC assay on Raji cancer cell lines showed no CDC activity of MBH1309/OBT076 when incubated with purified human complement. On the contrary, Rituximab (used as positive control), showed a strong induction of CDC activity.

Supplementary Table S1. Commercial tumor TMAs representing different solid tumor types. Supplementary Table S2. Summary of CD205 expression in human solid tumor types.

CD205 is a type I transmembrane glycoprotein and is a member of the C-type lectin receptor family. Analysis by mass spectrometry revealed that CD205 was robustly expressed and highly prevalent in a variety of solid malignancies from different histotypes. IHC confirmed the increased expression of CD205 in pancreatic, bladder, and triple-negative breast cancer (TNBC) compared with that in the corresponding normal tissues. Using immunofluorescence microscopy, rapid internalization of the CD205 antigen was observed. These results supported the development of MEN1309/OBT076, a fully humanized CD205-targeting mAb conjugated to DM4, a potent maytansinoid derivate, via a cleavable N-succinimidyl-4-(2-pyridyldithio) butanoate linker. MEN1309/OBT076 was characterized in vitro for target binding affinity, mechanism of action, and cytotoxic activity against a panel of cancer cell lines. MEN1309/OBT076 displayed selective and potent cytotoxic effects against tumor cells exhibiting strong and low to moderate CD205 expression. In vivo, MEN1309/OBT076 showed potent antitumor activity resulting in durable responses and complete tumor regressions in many TNBC, pancreatic, and bladder cancer cell line–derived and patient-derived xenograft models, independent of antigen expression levels. Finally, the pharmacokinetics and pharmacodynamic profile of MEN1309/OBT076 was characterized in pancreatic tumor–bearing mice, demonstrating that the serum level of antibody–drug conjugate (ADC) achieved through dosing was consistent with the kinetics of its antitumor activity. Overall, our data demonstrate that MEN1309/OBT076 is a novel and selective ADC with potent activity against CD205-positive tumors. These data supported the clinical development of MEN1309/OBT076, and further evaluation of this ADC is currently ongoing in the first-in-human SHUTTLE clinical trial.

Supplementary Materials and Methods

Information of patients underwent the biopsy procedures.

Evaluation of RAD51 scores in CCA_PDXs and CCA patients. (A) RAD51 scores of CCA_PDXs and their matched originating biopsy samples. (B) RAD51 scores evaluated in PDX85 (IDH1mut) treated as for Figure 4C.

Purpose:Cholangiocarcinoma (CCA) is usually diagnosed at advanced stages, with limited therapeutic options. Preclinical models focused on unresectable metastatic CCA are necessary to develop rational treatments. Pathogenic mutations in IDH1/2, ARID1A/B, BAP1, and BRCA1/2 have been identified in 30%–50% of patients with CCA. Several types of tumor cells harboring these mutations exhibit homologous recombination deficiency (HRD) phenotype with enhanced sensitivity to PARP inhibitors (PARPi). However, PARPi treatment has not yet been tested for effectiveness in patient-derived models of advanced CCA.Experimental Design:We have established a collection of patient-derived xenografts from patients with unresectable metastatic CCA (CCA_PDX). The CCA_PDXs were characterized at both histopathologic and genomic levels. We optimized a protocol to generate CCA tumoroids from CCA_PDXs. We tested the effects of PARPis in both CCA tumoroids and CCA_PDXs. Finally, we used the RAD51 assay to evaluate the HRD status of CCA tissues.Results:This collection of CCA_PDXs recapitulates the histopathologic and molecular features of their original tumors. PARPi treatments inhibited the growth of CCA tumoroids and CCA_PDXs with pathogenic mutations of BRCA2, but not those with mutations of IDH1, ARID1A, or BAP1. In line with these findings, only CCA_PDX and CCA patient biopsy samples with mutations of BRCA2 showed RAD51 scores compatible with HRD.Conclusions:Our results suggest that patients with advanced CCA with pathogenic mutations of BRCA2, but not those with mutations of IDH1, ARID1A, or BAP1, are likely to benefit from PARPi therapy. This collection of CCA_PDXs provides new opportunities for evaluating drug response and prioritizing clinical trials.

Effect of doxorubicin and Cdk4/6i on cells expressing different levels of HER2.

Antibody–drug conjugates (ADC) are antineoplastic agents recently introduced into the antitumor arsenal. T-DM1, a trastuzumab-based ADC that relies on lysosomal processing to release the payload, is approved for HER2-positive breast cancer. Next-generation ADCs targeting HER2, such as [vic-]trastuzumab duocarmazine (SYD985), bear linkers cleavable by lysosomal proteases and membrane-permeable drugs, mediating a bystander effect by which neighboring antigen-negative cells are eliminated. Many antitumor therapies, like DNA-damaging agents or CDK4/6 inhibitors, can induce senescence, a cellular state characterized by stable cell-cycle arrest. Another hallmark of cellular senescence is the enlargement of the lysosomal compartment. Given the relevance of the lysosome to the mechanism of action of ADCs, we hypothesized that therapies that induce senescence would potentiate the efficacy of HER2-targeting ADCs. Treatment with the DNA-damaging agent doxorubicin and CDK4/6 inhibitor induced lysosomal enlargement and senescence in several breast cancer cell lines. While senescence-inducing drugs did not increase the cytotoxic effect of ADCs on target cells, the bystander effect was enhanced when HER2-negative cells were cocultured with HER2-low cells. Knockdown experiments demonstrated the importance of cathepsin B in the enhanced bystander effect, suggesting that cathepsin B mediates linker cleavage. In breast cancer patient-derived xenografts, a combination treatment of CDK4/6 inhibitor and SYD985 showed improved antitumor effects over either treatment alone. These data support the strategy of combining next-generation ADCs targeting HER2 with senescence-inducing therapies for tumors with heterogenous and low HER2 expression.Significance:Combining ADCs against HER2-positive breast cancers with therapies that induce cellular senescence may improve their therapeutic efficacy by facilitating a bystander effect against antigen-negative tumor cells.

Supplementary Tables

Extended Materials and Methods and Supplementary figures with legends

PDF file - 62K, The tyrosine kinase inhibitor lapatinib does not revert the cellular senescence induced by p95HER2

PDF file - 65K, Growth of a mixture 1:1 of MCF7 Tet-off / p95HER2 and MDA-MB-231 / Luc cells in the presence or absence of doxycycline

PDF file - 136K, Expression of p95HER2 leads to senescence in MCF7 cell xenografts

XLSX file - 225K, Log2FC of the 1631 gene transcripts regulated in MCF7 Tet-Off/p95HER2 60 hours after doxycycline removal and log2FC of the same transcripts in MCF7 Tet-Off/HER2 cells under the same conditions; Log2FC of the 361 genes products upregulated in the secretome of MCF7 Tet-Off / p95HER2 cells after doxycycline removal; Log2FC of the 55 gene transcripts upregulated preferetially by p95HER2 and Log2FC of the same gene products upregulated in the secretome of MCF7 Tet-Off/p95HER2 cells afer doxycycline removal

PDF file - 104K, Expression of p95HER2 in MCF10A, T47D and MDA-MB-453 cells and expression of HER2 in MCF7 cells

PDF file - 76K

Inhibition of HER2 in HER2-amplified breast cancer has been remarkably successful clinically, as demonstrated by the efficacy of HER-kinase inhibitors and HER2-antibody treatments. Whilst resistance to HER2 inhibition is common in the metastatic setting, the specific programs downstream of HER2 driving resistance are not established. Through genomic profiling of 733 HER2-amplified breast cancers, we identify enrichment of somatic alterations that promote MEK/ERK signaling in metastatic tumors with shortened progression-free survival on anti-HER2 therapy. These mutations, including NF1 loss and ERBB2 activating mutations, are sufficient to mediate resistance to FDA-approved HER2 kinase inhibitors including tucatinib and neratinib. Moreover, resistant tumors lose AKT dependence while undergoing a dramatic sensitization to MEK/ERK inhibition. Mechanistically, this driver pathway switch is a result of MEK-dependent activation of CDK2 kinase. These results establish genetic activation of MAPK as a recurrent mechanism of anti-HER2 therapy resistance that may be effectively combated with MEK/ERK inhibitors., Resistance to HER2 inhibition in HER2- amplified breast cancer is common in the metastatic setting and the underlying molecular mechanisms remain unknown. Here, the authors, perform genomic profiling of 733 HER2-amplified breast cancers and propose genetic activation of MAPK as a resistance mechanism.

Cholangiocarcinoma (CCA) is usually diagnosed at advanced stages, with limited therapeutic options. Preclinical models focused on unresectable metastatic CCA are necessary to develop rational treatments. Pathogenic mutations in IDH1/2, ARID1A/B, BAP1, and BRCA1/2 have been identified in 30\\%–50\\% of patients with CCA. Several types of tumor cells harboring these mutations exhibit homologous recombination deficiency (HRD) phenotype with enhanced sensitivity to PARP inhibitors (PARPi). However, PARPi treatment has not yet been tested for effectiveness in patient-derived models of advanced CCA.We have established a collection of patient-derived xenografts from patients with unresectable metastatic CCA (CCA\_PDX). The CCA\_PDXs were characterized at both histopathologic and genomic levels. We optimized a protocol to generate CCA tumoroids from CCA\_PDXs. We tested the effects of PARPis in both CCA tumoroids and CCA\_PDXs. Finally, we used the RAD51 assay to evaluate the HRD status of CCA tissues.This collection of CCA\_PDXs recapitulates the histopathologic and molecular features of their original tumors. PARPi treatments inhibited the growth of CCA tumoroids and CCA\_PDXs with pathogenic mutations of BRCA2, but not those with mutations of IDH1, ARID1A, or BAP1. In line with these findings, only CCA\_PDX and CCA patient biopsy samples with mutations of BRCA2 showed RAD51 scores compatible with HRD.Our results suggest that patients with advanced CCA with pathogenic mutations of BRCA2, but not those with mutations of IDH1, ARID1A, or BAP1, are likely to benefit from PARPi therapy. This collection of CCA\_PDXs provides new opportunities for evaluating drug response and prioritizing clinical trials. The authors would like to thank the patients and their families for their support. This work was supported by grants from the Fundaci o Marat o TV3 awarded to T. Macarulla, M. Mel e, and S. Peir o; BeiGene research grant awarded toT. Macarulla and S. Peir o; AECC (INVES20036TIAN), Ram on y Cajal investigator program (RYC2020-029098-I), Proyecto de IþDþi (PID2019-108008RJ-I00), and FERO Foundation grant awarded to T.V. Tian; Proyecto de Investigaci on en Salud from the Instituto de Salud Carlos III (ISCIII) (PI20/00898) awarded to T. Macarulla; FIS/FEDER from the Instituto de Salud Carlos III (ISCIII) (PI12/01250; CP08/00223; PI16/00253 and CB16/12/00449) awarded to S. Peir o; and Ram on y Cajal investigator program (RYC-2017-22249) awarded to M. Mel e. Q. Serra-Camprubí is a recipient of the Ph.D. fellowship from La Caixa Foundation (LCF/PR/PR12/51070001). A. LlopGuevara was supported by the AECC (INVES20095LLOP) and V. Serra by the ISCIII (CPII19/00033). E.J. Arenas was funded by the AECC (POSTD211413AREN).J. Arribas is funded by the Instituto de Salud Carlos III (AC15/00062, CB16/12/00449, and PI22/00001). This publication is based upon the work of COST Action CA18122, European Cholangiocarcinoma Network, supported by the COST (European Cooperation in Science and Technology, www.cost.eu), a funding agency for research and innovation networks. The authors would like to thank Dr. V.A. Raker for manuscript editing and Drs. N. Herranz and J. Mateo for scientific discussions. The authors acknowledge the infrastructure and support of the FERO Foundation, La Caixa Foundation, and the Cellex Foundation. Peer Reviewed "Article signat per 31 autors/es: Queralt Serra-Camprubí; Helena Verdaguer; Winona Oliveros; Núria Lupión-Garcia; Núria Lupión-Garcia;Alba Llop-Guevara; Cristina Molina; Maria Vila-Casadesús; Anthony Turpin; Cindy Neuzillet; Joan Frigola; Jessica Querol; Mariana Yáñez-Bartolomé; Florian Castet; Carles Fabregat-Franco; Carmen Escudero-Iriarte; Marta Escorihuela; Enrique J. Arenas; Cristina Bernadó-Morales; Noemí Haro; Francis J. Giles; Óscar J. Pozo; Josep M. Miquel ; Paolo G. Nuciforo; Ana Vivancos; Marta Melé; Violeta Serra ; Joaquín Arribas; Josep Tabernero; Sandra Peiró; Teresa Macarulla; Tian V. Tian"

CD205 is a type I transmembrane glycoprotein and is a member of the C-type lectin receptor family. Analysis by mass spectrometry revealed that CD205 was robustly expressed and highly prevalent in a variety of solid malignancies from different histotypes. IHC confirmed the increased expression of CD205 in pancreatic, bladder, and triple-negative breast cancer (TNBC) compared with that in the corresponding normal tissues. Using immunofluorescence microscopy, rapid internalization of the CD205 antigen was observed. These results supported the development of MEN1309/OBT076, a fully humanized CD205-targeting mAb conjugated to DM4, a potent maytansinoid derivate, via a cleavable N-succinimidyl-4-(2-pyridyldithio) butanoate linker. MEN1309/OBT076 was characterized in vitro for target binding affinity, mechanism of action, and cytotoxic activity against a panel of cancer cell lines. MEN1309/OBT076 displayed selective and potent cytotoxic effects against tumor cells exhibiting strong and low to moderate CD205 expression. In vivo, MEN1309/OBT076 showed potent antitumor activity resulting in durable responses and complete tumor regressions in many TNBC, pancreatic, and bladder cancer cell line–derived and patient-derived xenograft models, independent of antigen expression levels. Finally, the pharmacokinetics and pharmacodynamic profile of MEN1309/OBT076 was characterized in pancreatic tumor–bearing mice, demonstrating that the serum level of antibody–drug conjugate (ADC) achieved through dosing was consistent with the kinetics of its antitumor activity. Overall, our data demonstrate that MEN1309/OBT076 is a novel and selective ADC with potent activity against CD205-positive tumors. These data supported the clinical development of MEN1309/OBT076, and further evaluation of this ADC is currently ongoing in the first-in-human SHUTTLE clinical trial.

BACKGROUND We aim to compare the benefit of adding pertuzumab (P) to the standard neoadjuvant treatment with trastuzumab (T) in patients (pt) with early immunohistochemically (IHC) defined HER2+ breast cancer (BC) in the different intrinsic molecular subtypes defined by PAM50 gene expression analysis. METHODS Two hundred forty-four pt. with IHC HER2 positive BC, stage I-IIIC, diagnosed in 8 Spanish hospitals were consecutively treated with neoadjuvant chemotherapy (NAC) plus antitargeted HER2 therapy. Cohort A (n=128) received NAC+T and Cohort B (n=116) received NAC+T+P. All the patients were classified into intrinsic molecular subtypes based on the PAM50® signature made in the diagnostic biopsies. Rate of pathologic complete response in breast and axilla (pCR) in the different PAM50 subtypes was compared by ChiSquared and Fisher test. A multivariate logistic regression model was used to analyze the potential effects of the covariates over the pCR rates. RESULTS Characteristics of the patients and intrinsic molecular subtypes are shown in. The overall pCR rate was significantly higher in cohort B vs A (61% vs 39%,p=0,0009). The pCR rate in the HER2E was 50% for T and 75% for T+P (p=0,003) and 11% for T and 42% for T+P (p=0.004) in Luminal subtype. In the multivariate analysis, the improvement pCR rates was highly associated with type of treatment (cohort) (p=0.0015,OR:2.44) and were not related to clinicopathologic covariates (tumor stage, hystological grade, HR) (p>0.05). These results were confirmed for the HER2enriched subtype (p=0.00398,OR:2.94) and even more strongly for Luminals (p=0.0026,OR:13.41). Clinicopathologic and treatment characteristics of patients Trastuzumab+NCT ( groupA, n128)Trastuzumab+pertuzumab+NCT ( groupB, n116)Median age years (range)52 (29-83)50 (30-77)Menopausal Statusn (%)n (%)Pre-menopausal54 (42)54 (47)Post-menupausal49 (38)49 (42)Missing25 (20)13 (11)Histological graden (%)n (%)Grade 12 (2)3 (2)Grade 258 (45)30 (26)Grade 343 (34)44 (38)Grade unknown25 (19)39 834)Ki 67n (%)n (%)50%24 (19)23 (20)Unknown35 (27)3 (2)Hormone receptor statusn (%)n (%)Positive89 (70)71 (61)Negative39 (30)45 (39)Tumor stagen (%)n (%)T123 (18)13 (11)T275 (59)64 (55)T312 (9)26 (22)T410 (8)12 (11)Tx8 (6)1 (1)Clinical node statusn (%)n (%)Negative54 (42)73 (63)Positive74 (58)43 (37)Chemotherapyn (%)n (%)Taxanes9 (7)16 (14)Taxanes and anthracyclines119 (93)100 (86)PAM50 Subtypesn (%)n (%)HER2E88 (69)64 (55)Luminal A16 (12)17 (15)Luminal B19 (15)21 (18)Basal like2 (2)14 (12)Normal like3 (2)0NCT:neoadjuvant chemotherapy CONCLUSIONS: 1.The highest pCR was reached by the PAM50HER2E patients treated with T+P. 2.In Luminal subtype the improvement of pCR is strongly associated with the used of P and this association is independent of clinical covariates. Citation Format: Díaz-Redondo T, Lavado-Valenzuela R, Ribelles N, Pascual T, Galvez F, Falcón A, Alamo MC, Morales C, Amerigo M, Prat A, Alba E. Different pCR rates according PAM50 defined subtypes in HER2 positive early breast cancer treated with neoadjuvant pertuzumab and trastuzumab [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-03.

Despite advances in breast cancer (BC) treatment, its mortality remains high due to intrinsic or acquired resistance to therapy. Several ongoing efforts are being made to develop novel drugs to treat this pathology with the aim to overcome resistance, prolong patient survival and improve their quality of life. We have previously shown that the non-hypercalcemic vitamin D analogues EM1 and UVB1 display antitumor effects in preclinical studies employing conventional cell lines and animal models developed from these cells. In this work, we explored the antitumor effects of EM1 and UVB1 employing BC cells derived from patient-derived xenografts (PDXs), which are a powerful preclinical tool for testing new drugs. We demonstrated that the analogues reduced the viability of HER2-positive and Triple Negative BC-PDXs. Moreover, using an in vitro model of acquired resistance to Trastuzumab-emtansine, UVB1 displayed anti-proliferative actions under 2D and 3D culture conditions. It inhibited both formation and growth of established organoids. In addition, a direct correlation between UVB1 antitumor effects and VDR expression in PDXs was found. In conclusion, all the results reinforce the potential use of these vitamin D analogues as antitumor agents to treat HER2-positive and Triple Negative BC. Fil: Ferronato, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina Fil: Nadal, Serrano Mercedes. Universidad Autonoma de Barcelona. Hospital Vall D' Hebron. Instituto de Investigación Vall D'hebron; España Fil: Arenas Lahuerta, Enrique Javier. Universidad Autonoma de Barcelona. Hospital Vall D' Hebron. Instituto de Investigación Vall D'hebron; España Fil: Morales, Cristina Bernadó. Universidad Autónoma de Barcelona. Hospital Vall D' Hebron; España Fil: Paolillo, Giuliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina Fil: Martinez Sabadell, Aliguer Alex. Universidad Autónoma de Barcelona. Hospital Vall D' Hebron; España Fil: Mascaró, Marilina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina Fil: Vitale, Cristian Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina Fil: Fall, Yagamare. Universidad de Vigo; España Fil: Arribas, Joaquín. Universidad Autónoma de Barcelona. Hospital Vall D' Hebron; España. Universitat Autònoma de Barcelona; España. Centro de Investigación Biomédica en Red de Cáncer; España. Institució Catalana de Recerca i Estudis Avancats; España Fil: Facchinetti, María Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina Fil: Curino, Alejandro Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; Argentina

Cromosomes; Marcadors pronòstics Cromosomas; Marcadores de pronóstico Chromosomes; Prognostic markers Oxidation of H3 at lysine 4 (H3K4ox) by lysyl oxidase-like 2 (LOXL2) generates an H3 modification with an unknown physiological function. We find that LOXL2 and H3K4ox are higher in triple-negative breast cancer (TNBC) cell lines and patient-derived xenografts (PDXs) than those from other breast cancer subtypes. ChIP-seq revealed that H3K4ox is located primarily in heterochromatin, where it is involved in chromatin compaction. Knocking down LOXL2 reduces H3K4ox levels and causes chromatin decompaction, resulting in a sustained activation of the DNA damage response (DDR) and increased susceptibility to anticancer agents. This critical role that LOXL2 and oxidized H3 play in chromatin compaction and DDR suggests that functionally targeting LOXL2 could be a way to sensitize TNBC cells to conventional therapy. This work was supported by grants from Instituto de Salud Carlos III (ISCIII) FIS/FEDER (PI12/01250; CP08/00223; PI16/00253; and CB16/12/00449), MINECO (SAF2013-48849-C2-1-R) to SP, BFU2015-68354 to THS, Breast Cancer Research Foundation (BCRF-17-008) to JA, AGL2014-52395-C2-2-R to DA, Worldwide Cancer Research, Red Temática de Investigación Cooperativa en Cáncer (RD012/0036/005), Fundación Científica de la Asociación Española contra el Cáncer, and Fundació La Marató TV3. THS was supported by institutional funding (MINECO) through the Centres of Excellence Severo Ochoa award and the CERCA Programme of the Catalan Government, and SS-B, by a Fundació La Caixa fellowship. We thank La Caixa Foundation and Cellex Foundation for provide research facilities and equipment. GV has received funding from the MINECO (a “Juan de la Cierva Incorporation” fellowship; IJCI-2014-20723). SP was a recipient of a Miguel Servet contract (ISCIII/FIS), and AI, JPC-C, LP-G, and GS-B are supported by contracts from Worldwide Cancer Research, Fundació La Marató TV3, Fundació FERO, and a FI Fellowship from the Generalitat de Catalunya, respectively.

PHARMACOLOGY Correction for "Therapeutic targeting of HER2-CB2R heteromers in HER2-positive breast cancer," by Sandra Blasco-Benito, Estefania Moreno, Marta Seijo-Vila, Isabel Tundidor, Clara Andradas, Maria M. Caffarel, Miriam Caro-Villalobos, Leyre Uriguen, Rebeca Diez-Alarcia, Gema Moreno-Bueno, Lucia Hernandez, Luis Manso, Patricia Homar-Ruano, Peter J. McCormick, Lucka Bibic, Cristina Bernado-Morales, Joaquin Arribas, Meritxell Canals, Vicent Casado, Enric I. Canela, Manuel Guzman, Eduardo Perez-Gomez, and Cristina Sanchez, which was first published February 7, 2019; 10.1073/pnas.1815034116 (Proc Natl Acad Sci USA 116:3863-3872). The authors note that, due to a printer's error, the affiliation for Lucka Bibic appeared incorrectly. It should instead appear as School of Pharmacy, University of East Anglia, Norwich, Norfolk NR4 7TJ, United Kingdom. The corrected author and affiliation lines appear below. The online version has been corrected.

Erratum in: Correction for Blasco-Benito et al., Therapeutic targeting of HER2-CB2R heteromers in HER2-positive breast cancer., Although human epidermal growth factor receptor 2 (HER2)-targeted therapies have dramatically improved the clinical outcome of HER2-positive breast cancer patients, innate and acquired resistance remains an important clinical challenge. New therapeutic approaches and diagnostic tools for identification, stratification, and treatment of patients at higher risk of resistance and recurrence are therefore warranted. Here, we unveil a mechanism controlling the oncogenic activity of HER2: heteromerization with the cannabinoid receptor CB2R. We show that HER2 physically interacts with CB2R in breast cancer cells, and that the expression of these heteromers correlates with poor patient prognosis. The cannabinoid Δ9-tetrahydrocannabinol (THC) disrupts HER2-CB2R complexes by selectively binding to CB2R, which leads to (i) the inactivation of HER2 through disruption of HER2-HER2 homodimers, and (ii) the subsequent degradation of HER2 by the proteasome via the E3 ligase c-CBL. This in turn triggers antitumor responses in vitro and in vivo. Selective targeting of CB2R transmembrane region 5 mimicked THC effects. Together, these findings define HER2-CB2R heteromers as new potential targets for antitumor therapies and biomarkers with prognostic value in HER2-positive breast cancer., This work was supported by grants from the Spanish Ministry of Economy and Competitiveness [supported with European Regional Development funds: PI14/01101 and PI17/00041 (to C.S. and E.P.-G.), and PI16/00134 (to G.M.-B.); CIBERONC (CB16/12/00295, to G.M.-B.); Fundació La Marató TV3 (20140610, to E.I.C.); Fundación Asociación Española Contra el Cáncer (to E.P.-G.); Zelda Therapeutics (to C.S. and M.G.); and Fundación Mutua Madrileña (2013/0072, to L.M.)]. S.B.-B. and I.T. are recipients of a Formación de Profesorado Universitario and pFIS fellowship (from the Spanish Ministry of Economy and Competitiveness). P.J.M. would like to acknowledge funding from the Biotechnology and Biological Sciences Research Council (BBSRC) Doctoral Training Programme.

T cell bispecific antibodies (TCBs) are engineered molecules that include, within a single entity, binding sites to the T cell receptor and to tumor-associated or tumor-specific antigens. The receptor tyrosine kinase HER2 is a tumor-associated antigen in ~25% of breast cancers. TCBs targeting HER2 may result in severe toxicities, likely due to the expression of HER2 in normal epithelia. About 40% of HER2-positive tumors express p95HER2, a carboxyl-terminal fragment of HER2. Using specific antibodies, here, we show that p95HER2 is not expressed in normal tissues. We describe the development of p95HER2-TCB and show that it has a potent antitumor effect on p95HER2-expressing breast primary cancers and brain lesions. In contrast with a TCB targeting HER2, p95HER2-TCB has no effect on nontransformed cells that do not overexpress HER2. These data pave the way for the safe treatment of a subgroup of HER2-positive tumors by targeting a tumor-specific antigen.

Significance In HER2-amplified breast cancers, HER2 inhibitors have been very successful as adjuvant therapy but not as monotherapy. Here, we demonstrate that coamplification of a HER2 intronic miRNA causes intrinsic resistance to HER2 inhibitors by indirectly down-regulating the pro-apoptotic NOXA. Importantly, coinhibition with MCL-1 inhibitors overcomes this resistance., HER2 (ERBB2) amplification is a driving oncogenic event in breast cancer. Clinical trials have consistently shown the benefit of HER2 inhibitors (HER2i) in treating patients with both local and advanced HER2+ breast cancer. Despite this benefit, their efficacy as single agents is limited, unlike the robust responses to other receptor tyrosine kinase inhibitors like EGFR inhibitors in EGFR-mutant lung cancer. Interestingly, the lack of HER2i efficacy occurs despite sufficient intracellular signaling shutdown following HER2i treatment. Exploring possible intrinsic causes for this lack of response, we uncovered remarkably depressed levels of NOXA, an endogenous inhibitor of the antiapoptotic MCL-1, in HER2-amplified breast cancer. Upon investigation of the mechanism leading to low NOXA, we identified a micro-RNA encoded in an intron of HER2, termed miR-4728, that targets the mRNA of the Estrogen Receptor α (ESR1). Reduced ESR1 expression in turn prevents ERα-mediated transcription of NOXA, mitigating apoptosis following treatment with the HER2i lapatinib. Importantly, resistance can be overcome with pharmacological inhibition of MCL-1. More generally, while many cancers like EGFR-mutant lung cancer are driven by activated kinases that when drugged lead to robust monotherapeutic responses, we demonstrate that the efficacy of targeted therapies directed against oncogenes active through focal amplification may be mitigated by coamplified genes.

In HER2 -amplified breast cancers, HER2 inhibitors have been very successful as adjuvant therapy but not as monotherapy. Here, we demonstrate that coamplification of a HER2 intronic miRNA causes intrinsic resistance to HER2 inhibitors by indirectly down-regulating the pro-apoptotic NOXA. Importantly, coinhibition with MCL-1 inhibitors overcomes this resistance. HER2 (ERBB2) amplification is a driving oncogenic event in breast cancer. Clinical trials have consistently shown the benefit of HER2 inhibitors (HER2i) in treating patients with both local and advanced HER2+ breast cancer. Despite this benefit, their efficacy as single agents is limited, unlike the robust responses to other receptor tyrosine kinase inhibitors like EGFR inhibitors in EGFR -mutant lung cancer. Interestingly, the lack of HER2i efficacy occurs despite sufficient intracellular signaling shutdown following HER2i treatment. Exploring possible intrinsic causes for this lack of response, we uncovered remarkably depressed levels of NOXA, an endogenous inhibitor of the antiapoptotic MCL-1, in HER2 -amplified breast cancer. Upon investigation of the mechanism leading to low NOXA, we identified a micro-RNA encoded in an intron of HER2, termed miR-4728, that targets the mRNA of the Estrogen Receptor α (ESR1). Reduced ESR1 expression in turn prevents ERα-mediated transcription of NOXA, mitigating apoptosis following treatment with the HER2i lapatinib. Importantly, resistance can be overcome with pharmacological inhibition of MCL-1. More generally, while many cancers like EGFR -mutant lung cancer are driven by activated kinases that when drugged lead to robust monotherapeutic responses, we demonstrate that the efficacy of targeted therapies directed against oncogenes active through focal amplification may be mitigated by coamplified genes.

T cell bispecific antibodies (TCBs) are engineered molecules that include, within a single entity, binding sites to the T cell receptor and to a tumor-specific or a tumor-associated antigen. The receptor tyrosine kinase HER2 is a tumor-associated antigen in ~25% of breast cancers. Clinical evidence shows that TCBs targeting HER2 may result in severe toxicities, likely due to the physiologic levels of HER2 in normal epithelia. Approximately 40% of HER2-positive tumors express detectable levels of p95HER2, a carboxy-terminal fragment of HER2. We previously developed different antibodies that specifically recognize p95HER2 but not full-length HER2 and hypothesized that a TCB antibody recognizing p95HER2 would be exquisitely specific for tumor cells. Here, we describe the development of such p95HER2-TCB and show that it has a potent anti-tumor effect on p95HER2-expressing breast cancers. Since p95HER2 is not expressed in normal tissues, in contrast with HER2-TCB, it has no effect on non-transformed cells expressing physiological levels of HER2. These data paves the way for the safe targeting of a subtype of HER2-positive tumors with a novel tumor-specific TCB. Citation Format: Rocío Vicario, Irene Rius Ruiz, Beatriz Morancho, Cristina Bernadó Morales, Sylvia Herter, Anne Freimoser-Grundscholber, Jitka Somandin, Johannes Sam, Oliver Ast, Águeda Martinez Barriocanal, Antonio Luque, Marta Escorihuela, Ismael Varela, Paolo Nuciforo, Roberta Fasani, Vicente Peg, Isabel Rubio, Javier Cortés, Violeta Serra, Santiago Escrivá, Jeff Sperinde, Ahmed Chenna, Weidong Huang, John Winslow, Maurizio Scaltriti, Josep Baselga, Josep Tabernero, Pablo Umaña, Marina Bacac, Cristina Saura, Christian Klein, Joaquín Arribas. p95HER2-T cell bispecific antibody for breast cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-292.

Gene amplification is one of the most frequent manifestations of genomic instability in human tumors and plays an important role in tumor progression and acquisition of drug resistance. To better understand the factors involved in acquired resistance to cytotoxic drugs via gene amplification, we have analyzed the structure and dynamics of dihydrofolate reductase (DHFR) gene amplification in HT29 cells treated with methotrexate (MTX). Analysis of the DHFR gene amplification process shows that the amplicon exhibits a complex structure that is consistently reproduced in independent treatments. The cytogenetic manifestation of the amplification in advanced stages of the treatment may be in the form of double minutes or as a homogeneously stained region. To get insights into the mechanisms of resistance, we have also investigated the sensitization to MTX of MTX-resistant cells after drug withdrawal and reexposure to MTX. Passive loss of the DHFR amplicon by withdrawal of the drug results in MTX-sensitive cells exhibiting a substantial reduction of their capacity or even an incapacity to generate resistance when submitted to a second cycle of MTX treatment. On a second round of drug administration, the resistant cells generate a different amplicon structure, suggesting that the formation of the amplicon as in the first cycle of treatment is not feasible. These results indicate that DHFR gene amplification is a “wear and tear” process in HT29 cells and that MTX-resistant cells may become responsive to a second round of treatment if left untreated during a sufficient period of time. [Mol Cancer Ther 2009;8(2):424–32]

Methylation of the cytosine is the most frequent epigenetic modification of DNA in mammalian cells. In humans, most of the methylated cytosines are found in CpG-rich sequences within tandem and interspersed repeats that make up to 45% of the human genome, being Alu repeats the most common family. Demethylation of Alu elements occurs in aging and cancer processes and has been associated with gene reactivation and genomic instability. By targeting the unmethylated SmaI site within the Alu sequence as a surrogate marker, we have quantified and identified unmethylated Alu elements on the genomic scale. Normal colon epithelial cells contain in average 25 486 +/- 10 157 unmethylated Alu's per haploid genome, while in tumor cells this figure is 41 995 +/- 17 187 (P = 0.004). There is an inverse relationship in Alu families with respect to their age and methylation status: the youngest elements exhibit the highest prevalence of the SmaI site (AluY: 42%; AluS: 18%, AluJ: 5%) but the lower rates of unmethylation (AluY: 1.65%; AluS: 3.1%, AluJ: 12%). Data are consistent with a stronger silencing pressure on the youngest repetitive elements, which are closer to genes. Further insights into the functional implications of atypical unmethylation states in Alu elements will surely contribute to decipher genomic organization and gene regulation in complex organisms.

So far, CRC cell lines have contributed to descriptions of 2 patterns of genetic instability, affecting either microsatellite sequences or chromosome number and structure. Often, these patterns are mutually exclusive; while near-diploid karyotypes usually appear with MSI and chromosomal stability, near-triploid or tetraploid cells display a high degree of CIN and are stable at the microsatellite level. In the present study, we describe the genomic instability pattern of KM12 CRC cells. KM12C and derived cell lines with different metastatic properties were analyzed by conventional cytogenetics, CGH and M-FISH. Results were compared to 5 cell lines usually used as model of MSI and CIN. Concordance between our results and previously published SKY data are also reviewed. Interestingly, the poorly metastatic KM12C cell line displayed a near-diploid karyotype with high levels of structural chromosome instability and microsatellite instability. The highly metastatic KM12SM and KM12L4A cell lines showed polyploid karyotypes and maintained CIN and MSI. A comparison between karyotypes of poorly and highly metastatic KM12 cell lines allowed us to delineate a cytogenetic evolution pathway. Our results clearly demonstrated that endoreduplication was the origin of the polyploid dosages in the highly metastatic forms following the monosomic model postulated for CRC. Therefore, we demonstrate that KM12C cells and their metastatic derivates, KM12SM and KM12L4A, are a useful model of chromosomal evolution where MSI may coexist with CIN.

The cell surface antigen Lymphocyte antigen 75 (LY75, CD205, DEC-205) is over-expressed in several tumor histotypes. It is a type I C-type lectin receptor (CLR), normally expressed on various APC subsets, characterized by a cytoplasmic domain containing protein motifs crucial for endocytosis and internalization upon ligation. These features make the antigen ideal to be exploited as a target for a novel ADC. MEN1309 is a humanized IgG1 antibody directed against the cell surface antigen Ly75, conjugated through a cleavable linker to a potent maytansinoid microtubule disruptor, DM4. In this study, we evaluated the in vitro and in vivo (xenografts and PDX) efficacy of MEN1309 in different tumor histotypes. A PK/PD relationship was also investigated in tumor-bearing mice. IHC demonstrated high prevalence of Ly75 in human pancreatic, triple negative breast, and bladder cancers, as well as in diffuse large B-cell lymphoma. In vitro experiments showed that cytotoxic activity of MEN1309 was in nM/sub nM range against several lymphoma, pancreatic, bladder and triple-negative breast cancer (TNBC) cell lines. Moreover, MEN1309 exhibited high cell-killing ability against cells having either strong as well as low to moderate antigen expression. In vivo, MEN1309 at 2.5-5 mg/kg (schedule varying from single dose, q7dx3, or q21dx3) showed an impressive antitumor activity, resulting in complete and long lasting responses in most of the xenograft models representing lymphoma, TNBC, bladder and pancreatic cancers, expressing the antigen at high but also at low levels. No treatment related toxicity in terms of change of body weight and death events were detected. Moreover, the administration of (i) isotype control-DM4, (ii) the non-conjugate antibody IgG1 and (iii) the free toxin DM4 (at a dosage corresponding to the equimolar concentration linked at 10 mg/kg ADC) showed little to no therapeutic efficacy on tumor growth. In TNBC patient-derived xenograft (PDX) model (coming from a heavily pre-treated patient and expressing high level of the antigen Ly75), MEN1309 (5 mg/kg q21dx3) showed a complete tumor regression. Finally, in the pancreatic adenocarcinoma xenograft model HPAFII, the pharmacokinetics profile in serum of MEN1309 at 5 mg/kg was characterized and it was qualitatively correlated, using immunofluorescence, with the occurrence of phosphorylation of Serine 10 of H3 Histone in cancer cells, as a pharmacodynamic (PD) marker of DM4 activity on microtubules. Initial ADC exposure was noteworthy and was followed by a relatively fast decline. In parallel with the decay of the serum ADC concentrations there was a progressive increase in the number of positive cells showing the PD marker for mitotic arrest. Overall, our data suggest that MEN1309 is a selective and potent novel antitumoral ADC and it deserves to enter into aPhase I study for a variety of Ly75 positive tumor histotypes. Citation Format: Mario Bigioni, Giuseppe Merlino, Cristina Bernadó Morales, Rossana Bugianesi, Attilio Crea, Rosanna Manno, Joaquin Arribas, Rachel Dusek, Nickolas Attanasio, Keith Wilson, Christian Rohlff, Monica Binaschi. MEN1309, a novel antibody drug conjugate (ADC) targeting Ly75 antigen, induces complete responses in several xenografts of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2630. doi:10.1158/1538-7445.AM2017-2630

Senescence, a terminal cell proliferation arrest, can be triggered by oncogenes. Oncogene-induced senescence is classically considered a tumor defense barrier. However, several findings show that, under certain circumstances, senescent cells may favor tumor progression because of their secretory phenotype. Here, we show that the expression in different breast epithelial cell lines of p95HER2, a constitutively active fragment of the tyrosine kinase receptor HER2, results in either increased proliferation or senescence. In senescent cells, p95HER2 elicits a secretome enriched in proteases, cytokines, and growth factors. This secretory phenotype is not a mere consequence of the senescence status and requires continuous HER2 signaling to be maintained. Underscoring the functional relevance of the p95HER2-induced senescence secretome, we show that p95HER2-induced senescent cells promote metastasis in vivo in a non–cell-autonomous manner. Cancer Res; 73(1); 450–8. ©2012 AACR.

Background Methotrexate is one of the earliest cytotoxic drugs used in cancer therapy, and despite the isolation of multiple other folate antagonists, methotrexate maintains its significant role as a treatment for different types of cancer and other disorders. The usefulness of treatment with methotrexate is limited by the development of drug resistance, which may be acquired through different ways. To get insights into the mechanisms associated with drug resistance and sensitization we performed a functional analysis of genes deregulated in methotrexate resistant cells, either due to its co-amplification with the dhfr gene or as a result of a transcriptome screening using microarrays. Methods Gene expression levels were compared between triplicate samples from either HT29 sensitive cells and resistant to 10-5 M MTX by hybridization to the GeneChip® HG U133 PLUS 2.0 from Affymetrix. After normalization, a list of 3-fold differentially expressed genes with a p-value < 0.05 including multiple testing correction (Benjamini and Hochberg false discovery rate) was generated. RT-Real-time PCR was used to validate the expression levels of selected genes and copy-number was determined by qPCR. Functional validations were performed either by siRNAs or by transfection of an expression plasmid. Results Genes adjacent to the dhfr locus and included in the 5q14 amplicon were overexpressed in HT29 MTX-resistant cells. Treatment with siRNAs against those genes caused a slight reduction in cell viability in both HT29 sensitive and resistant cells. On the other hand, microarray analysis of HT29 and HT29 MTX resistant cells unveiled overexpression of caveolin 1, enolase 2 and PKCα genes in resistant cells without concomitant copy number gain. siRNAs against these three genes effectively reduced cell viability and caused a decreased MTX resistance capacity. Moreover, overexpression of E-cadherin, which was found underexpressed in MTX-resistant cells, also sensitized the cells toward the chemotherapeutic agent. Combined treatments targeting siRNA inhibition of caveolin 1 and overexpression of E-cadherin markedly reduced cell viability in both sensitive and MTX-resistant HT29 cells. Conclusion We provide functional evidences indicating that caveolin 1 and E-cadherin, deregulated in MTX resistant cells, may play a critical role in cell survival and may constitute potential targets for coadjuvant therapy.

DNA hypomethylation is a common trait of colorectal cancer. Studies in tumor cell lines and animal models indicate that genome-wide demethylation may cause genetic instability and hence facilitate or accelerate tumor progression. Recent studies have shown that DNA hypomethylation precedes genomic damage in human gastrointestinal cancer, but the nature of this damage has not been clearly established. Here, we show a thorough analysis of DNA methylation and genetic alterations in two series of colorectal carcinomas. The extent of DNA demethylation but not of hypermethylation (both analyzed by amplification of intermethylated sites in near 200 independent sequences arbitrarily selected) correlated with the cumulated genomic damage assessed by two different techniques (arbitrarily primed PCR and comparative genomic hybridization). DNA hypomethylation–related instability was mainly of chromosomal nature and could be explained by a genome-wide effect rather than by the concurrence of the most prevalent genetic and epigenetic alterations. Moreover, the association of p53 mutations with genomic instability was secondary to DNA hypomethylation and the correlation between DNA hypomethylation and genomic instability was observed in tumors with and without mutation in the p53 gene. Our data support a direct link between genome-wide demethylation and chromosomal instability in human colorectal carcinogenesis and are consistent with the studies in model systems demonstrating a role of DNA demethylation in inducing chromosomal instability. (Cancer Res 2006; 66(17): 8462-8)

Alternative genetic pathways characterized by specific genetic profiles and exhibiting distinctive biological and clinical features have been proposed in colorectal carcinogenesis. Methotrexate (MTX) is a potent inhibitor of the dihydrofolate reductase (DHFR) enzyme, which is essential for DNA synthesis and cell growth. We have evaluated the association between different genetic features and the capacity to develop MTX resistance in colon cancer cell lines representative of alternative genetic pathways. Three aneuploid cell lines (HT-29, SW480, and SK-CO-1) showed pre-existing amplifications, but only one (HT-29) developed MTX resistance, showing amplification of the DHFR gene at 5q12-14 (>20-fold amplification and presence of extrachromosomal double minutes). Failure to develop resistance was attributed to the absence of two complete chromosomes 5 in SW480 and SK-CO-1 cells. Four near-diploid cell lines (LoVo, HCT116, DLD-1 and KM12C) and two aneuploid KM12C-derived metastases (KM12SM and KM12L4A) developed MTX resistance but none exhibited DHFR amplification. All resistant cells without DHFR gene amplification showed microsatellite instability. We conclude that chemoresistance capacity and the mechanism of chemoresistance are related with the genetic pathway and the karyotypic features of colon cancer cells.

The pleiotropic cytokine IL-6 accelerates the progression of breast cancer in a variety of preclinical models through the activation of the STAT3 (signal transducer and activator of transcription 3) signaling pathway. However, the proportion of breast cancers sensitive to anti-IL-6 therapies is not known. This study evaluates the efficacy of anti-IL-6 therapies using breast cancer patient derived xenografts (PDXs). During the generation of our collection of PDXs, we showed that the successful engraftment of tumor tissue in immunodeficient mice correlates with bad prognosis. Four PDXs out of six were resistant to anti-IL-6 therapies and the expression of IL-6, its receptor or the levels of phospho-STAT3 (the active form of the signal transducer) did not correlate with sensitivity. Using cell cultures established from the PDXs as well as samples from in vivo treatments, we showed that only tumors in which the activation of STAT3 depends on IL-6 respond to the blocking antibodies. Our results indicate that only a fraction of breast tumors are responsive to anti-IL-6 therapies. In order to identify responsive tumors, a functional assay to determine the dependence of STAT3 activation on IL-6 should be performed.