Marker Of Treatment Resistance Research Articles

Expression and Therapeutic Targeting of TROP-2 in Treatment-Resistant Prostate Cancer.

Men with metastatic castration-resistant prostate cancer (mCRPC) frequently develop resistance to androgen receptor signaling inhibitor (ARSI) treatment; therefore, new therapies are needed. Trophoblastic cell-surface antigen (TROP-2) is a transmembrane protein identified in prostate cancer and overexpressed in multiple malignancies. TROP-2 is a therapeutic target for antibody-drug conjugates (ADC). TROP-2 gene (TACSTD2) expression and markers of treatment resistance from prostate biopsies were analyzed using data from four previously curated cohorts of mCRPC (n = 634) and the PROMOTE study (dbGaP accession phs001141.v1.p1, n = 88). EPCAM or TROP-2-positive circulating tumor cells (CTC) were captured from peripheral blood for comparison of protein (n = 15) and gene expression signatures of treatment resistance (n = 40). We assessed the efficacy of TROP-2-targeting agents in a mouse xenograft model generated from prostate cancer cell lines. We demonstrated that TACSTD2 is expressed in mCRPC from luminal and basal tumors but at lower levels in patients with neuroendocrine prostate cancer. Patients previously treated with ARSI showed no significant difference in TACSTD2 expression, whereas patients with detectable AR-V7 expression showed increased expression. We observed that TROP-2 can serve as a cell surface target for isolating CTCs, which may serve as a predictive biomarker for ADCs. We also demonstrated that prostate cancer cell line xenografts can be targeted specifically by labeled anti-TROP-2 agents in vivo. These results support further studies on TROP-2 as a therapeutic and diagnostic target for mCRPC.

Electroencephalographic study of the Error Related Negativity in patients suffering from treatment-resistant obsessive-compulsive disorder

IntroductionThe physiopathology of patients with treatment-resistant obsessive-compulsive disorder (OCD) may differ from that of treatment-responsive patients. Cognitive evoked potentials may be one of the ways to detect these differences. The error-related negativity (ERN) is an electrophysiological correlate of error detection during the execution of a motor task, which is larger in patients with OCD than in typical people. According to the literature, the ERN could vary according the patients’ treatment-resistance.ObjectivesThe main goal of this study was to assess whether the ERN, which begins 20 ms before the motor response and reaches its maximum 80 ms later, was different between non-resistant and highly resistant OCD patients.MethodsForty-seven OCD patients and their age- and gender-matched controls were asked to perform a flanker task while the potentials evoked by their motor responses were recorded. For each participant, the difficulty of the task was adjusted to get an error rate of about 20%. Treatment-resistance was evaluated using Pallanti and Quercioli’s (Prog Neuropsychopharmacol Biol Psychiatry 2006; 30 400-412) resistance scales.ResultsIn all participants, response errors evoked an ERN at fronto-central electrodes [Fz, FCz, red and green lines on the figure], whereas the negativity was absent or smaller for correct responses (black and blue lines on the figure, both ps < .01). As expected, the ERN of OCD patients was consistently larger and of longer duration than that of control participants (compare the green and blue lines with the red and black ones, respectively). Interestingly, the amplitude of the potentials evoked by correct responses at central and centro-parietal electrodes on the left side of the brain [C5, C3, CP5] was significantly less negative in treatment-resistant patients (all ps < .05). In control participants, the ERN recorded at fronto-central electrodes were followed by a positive wave which reached its maximum between 170 and 270 ms after the response, and was larger after errors than after correct response. In OCD patients in contrast, this positive wave was absent whether the response was correct or not.Image:ConclusionsThe significant correlation observed between OCD patients’ treatment resistance and the potential evoked by correct responses on the left side of the brain suggest that this potential could be used as a marker of treatment-resistance. The absence in OCD patients of the positive wave that follows the ERN in control participants suggests that OCD patients were not fully aware of whether or not their response was correct.Disclosure of InterestNone Declared

IKZF1 Deletions Are Markers of Treatment Resistance in Adult Ph-Negative B-Cell Acute Lymphoblastic Leukemia Patients Treated within the Ongoing Risk-Adapted Pethema LAL19 Trial

Introduction IKZF1 (Ikaros) deletion has been related with poor outcome in pediatric B-cell precursor acute lymphoblastic leukemia (BCP ALL). However, its impact in adult patients (pts) treated with MRD-oriented trials has not been fully established. This study aimed to assess if IKZF1 deletions are markers of poor prognosis in adults with Ph-negative BCP ALL treated within the ongoing risk-adapted PETHEMA LAL19 trial (NCT04179929). The impact of IKZF1 loss in these pts and those from the EWALL Group (European Working group on ALL) is being evaluated in a HARMONY (Healthcare Alliance for Resourceful Medicine Offensive against Neoplasms in Hematology) project (Project Ref ALL2). Methods In the PETHEMA LAL19 trial, pts with poor end-induction MRD clearance (MRD>0.01%) or high-risk genetics (low-hypodiploid, KMT2Ar, TP53 biallelic alteration or IKZF1+CDKN2A/B deletion) are assigned to allogeneic stem cell transplantation, the remaining pts receive maintenance chemotherapy. All pts are analyzed by G-banding, FISH, NGS (DNA gene panel) and SNP array. Next generation flow cytometry is used for MRD assessment. Main outcome measures: i) Complete Remission (CR): absence of extramedullary disease, neutrophil level >1x109/L, platelet level >100x109/L, and bone marrow blast level < 5%; ii) Cumulative Incidence of Relapse (CIR) and non-relapse mortality (NRM): calculated using cumulative incidence rates to accommodate competing risks and compared by Gray's test; iii) Overall survival (OS): measured from the time of protocol entry to the time of death or last contact. Results 147pts were analyzed. Mean age 40y [range 18-60], 56% males, 10% CNS involvement, 78% common B, 15% pro-B and 7% pre-B ALL. Ph-like (12%) was the most common genetic subtype followed by KMT2Ar (11%), PAX5 P80R (8%), low-hypodiploid (7%), TCF3::PBX1 and high-hyperdiploid (6% each), iAMP21 and ETV6::RUNX1 (2% each). More uncommon biological entities such as ZNF384r, MEF2Dr, MYCr, IDH1 R132C and IDH2 R140Q were seen in single pts (<1% each).The remaining patients (41%) were B-other,no growth or normal karyotype. IKZF1 deletion (IK DEL) was observed in 66/147(45%) pts. Deletions involved the whole gene (37/66, 56%) or a subset of exons (partial gene deletions). The most recurrent partial gene deletions (n=29) were: loss of exons 4-7 (n=6, 21%), 4-8 (n=5, 17%), 2-8 and 1-7 (n=4, 14% each), 1-3 (n=3, 10%), 2&3 and 2-7 (n=2, 7% each). The IKZF1plus profile was observed in 37/147 (25%) pts. IK DEL were more frequent in low-hypodiploid (100%) and Ph-like ALL (88%), and less prevalent in KMT2Ar (19%), PAX5 P80R (18%) and TCF3::PBX1 ALL (11%), p<0.001. Median follow up was 11.4 months. IKDEL pts showed lower CR rate than pts without Ikaros loss (75% vs. 91%, p=0.027). The IKZF1plus signature showed similar CR rate to IK DEL without IKZF1plus profile (IKZF1not plus) (73% vs. 78%, p=ns). IKDEL pts showed poorer MRD clearance than WT individuals. Interestingly, this fact was mainly attributable to partial gene deletions (MRD≥0.01% partial 79% vs. whole 42% vs. WT 29%, p=0.003). IKZF1plus was also correlated with positive MRD, however IKZF1not plus pts showed higher frequency of MRD positivity than IKZF1plus pts (MRD≥0.01% plus 47% vs. not plus 71% vs. WT 29%, p=0.012). Pts with whole gene loss showed lower OS than pts with partial gene losses or IKZF1 WT (1y-OS 62% vs. 88% vs. 89%, p=0.012)(Figure 1A). Of note, relapse was not the main cause of death of IK DEL whole gene pts (n=26) as only 1 patient died due to disease progression. Instead, NRM was the main cause of death in whole gene-deleted pts (4 died in Ind-1, 3 in Ind-2, 1 due to TRM and 1 due to Covid19 infection). Accordingly, the 1y-CIR of IK DEL whole pts was lower than that of IKZF1 WT individuals, who showed similar CIR to IK DEL partial ones (1y-CIR whole 7% vs. WT 30% vs. partial 32%, p=0.059) (Figure 1B). Pts with IKZF1plus signature did not show differences in OS and CIR compared to IKZF1 WT or IKZF1not plus individuals (data not shown). Conclusions This preliminary data suggest that IK DEL may be marker of poor treatment response in adult Ph-negative BCP ALL. Further analyses including all patients of the HARMONY project may identify which isoforms or in which genetic ALL subtypes IKZF1 DEL are particularly deleterious. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Abstract P3-08-07: Comparison of the genomic alterations in metastatic inflammatory and non-inflammatory breast cancer

Abstract Background:. Inflammatory breast cancer (IBC) represents a rare (~1-5% of all breast cancers, BC) and particularly aggressive type of BC, accounting for roughly 10% of BC-related mortality annually. So far IBC has been mainly characterized at the genomic level using samples from the primary tumor. Here, using publicly available data from two large cohorts, we compared the genomic alterations in primary and metastatic samples from patients with metastatic IBC to alterations in samples of patients with metastatic non-IBC. Patients and methods:. We retrieved publicly available clinical and genomic data from primary (P) and metastatic (M) samples from MSK-IMPACT (MSK) and the Metastatic Breast Cancer project (MBC) from cbioportal. IBC was defined as cT4d. We considered female metastatic patients with invasive BC of no special type (commonly referred to as invasive ductal BC): 34 patients with IBC and 602 with non-IBC. To focus on alterations with potential clinical relevance, we only retained the genomic alterations annotated as oncogenic by OncoKB. We applied Firth logistic regression adjusted for hormonal receptor status (positive vs negative), HER2 status (positive vs negative) stage (II vs I, III vs I, IV vs I) and cohort (MSK vs MBC) with genomic alterations or metastatic sites as outcome variables and IBC status as independent variable (yes vs no). A minimum of 5 patients harboring the alterations were required to perform the analysis. Chromosomal instability (CIN) score and Tumor Mutational Burden (TMB) were investigated by linear regression and quantile regression respectively, adjusted as described above and considering the median for the latest. P and M samples were analyzed separately, a patient was considered as ‘having’ the alteration if at least one of her samples was altered. All analyses were performed in R 4.0.2. Results:. Metastatic samples from chest wall and skin metastases were significantly more represented in patients with IBC as compared to patients with non-IBC (Adjusted Odds Ratio (ORadj): 6.16, 95% confidence interval (95CI): [1.94-18.38], p-value: .003 and ORadj: 7.60, 95CI: [1.66-30.05], p-value: .012 respectively), which is in line with the course of the IBC disease. Several studies have suggested IBC to have a higher TMB than non-IBC. Here we confirmed an increase in TMB in P and M IBC (Adjusted coefficient (coefadj): 3.00, 95CI: [1.60-4.20], p-value: .003 and coefadj: 4.00, 95CI: [0.85-4.15], p-value&amp;lt;.001). On the contrary, we did not observe an increase in CIN score in patient with IBC as compared to patient with non-IBC, both when considering P and M samples (coefadj: -.001, 95CI: [-0.10;0.09], p-value: .877 and coefadj: -.05, 95CI: [-0.16;0.05], p-value: .330 respectively). With regard to the genomic alterations, we observed an increased frequency of TP53 mutations as well as amplifications of AURKA and FGFR1 in patients with IBC versus patient with non-IBC both considering P and M samples (Table 1). We also observed an increased prevalence of PIK3CA and GATA3 mutations in patients with IBC versus non-IBC in the M samples only. Conclusion:. While the results need to be validated in additional patient series, these could be of potential clinical relevance given the higher incidence of treatment targets (AURKA amplifications, PIK3CA mutations) and markers of treatment resistance (FGFR1 amplifications) present in IBC versus non-IBC in patients with metastatic disease. Table 1.Patients with primary samples. (279 patients with clinical information available - 279 samples)Patients with metastatic samples. (311 patients with clinical information available - 339 samples)AlterationAlteration countOR [95CI]p-valueAlteration countOR [95CI]p-valueTP53 mutation4120.18 [4.95-96.38]&amp;lt;.0013511.30 [3.68 - 37.05]&amp;lt;.001PIK3CA mutation106.00 [0.76-40.27].085156.35 [1.58-22.61].011GATA3 mutation85.10 [0.49-30.63].147610.95 [1.59 - 62.80].018AURKA amplification539.33 [5.26-490.37]&amp;lt;.001517.28 [2.76-119.06]&amp;lt;.001FGFR1 amplification98.99 [1.81-40.52].009714.08 [2.63-71.46]&amp;lt;.001 Citation Format: François Richard, Maxim De Schepper, Marion Maetens, Sophia Leduc, Edoardo Isnaldi, Tatjana Geukens, Karen Van Baelen, Ha-Linh Nguyen, Peter Vermeulen, Steven Van Laere, Luc Dirix, Giuseppe Floris, Elia Biganzoli, Christine Desmedt. Comparison of the genomic alterations in metastatic inflammatory and non-inflammatory breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-08-07.

Using data from schizophrenia outcome study to estimate the time to treatment outcome and the early-response cut-off score that predicts outcome at week 16

Background Being able to make an estimation of the time to clinical outcome, and making predictions early during treatment about the possibility of later response/non-response to treatment, is an important asset that can help to guide treatment strategies and counsel patients and caregivers about treatment expectations. Objectives The study aimed to determine the time course to treatment outcome and the psychopathological cut-off score at week 4 that predicts outcome at week 16. Methods This was a naturalistic follow-up study of 160 incident cases of schizophrenia over 16 weeks. Four intervals of follow-up clinical assessments were done. Standard criteria for response and remission were applied. Results The mean (median) times, in weeks, to response and remission using Brief Psychiatric Rating Scale (BPRS) data were 8.1(8.0); 8.4(8.0); and 10.9 (12.0), respectively. The Areas Under the Curves were high, for response (0.909; 95% C.I., 0.85-0.97) and remission (0.86; 95% C.I., 0.81 -0.94) at week 16. A cut-off score of 20.7% reduction in the total BPRS score at week 4, predicted response status (79.5% sensitivity, 84.2% specificity) and remission status (77.6% sensitivity, 73.3% specificity) at week 16. In addition, a cut-off of 10.21% reduction in the total Scale for Assessment of Negative Symptoms (SANS) score at week 4, predicted response (70.8% sensitivity, 95.5% specificity) at week 16. Discussion The results are in line with the general clinical impression that, by 2 months, most acutely ill inpatients are fit for discharge; and introduced for further investigation 10.21% reduction in SANS Score as a marker of treatment resistance in schizophrenia.

The cytokine IL-17A as a marker of treatment resistance in major depressive disorder?

Major depression is a complex disease and-among others, inflammation appears to play an important role in its pathophysiology. In this study, we investigated a broad range of cytokines in depressed patients. Plasma levels of interleukin (IL)-12/ IL-23p40, IL-15, IL-16, IL-17A, IL-1α, IL-7, tumor necrosis factorβ and vascular endothelial growth factor were compared in 48 patients suffering from major depression before, after one and after six weeks of antidepressive treatment in relation to therapy response. Interestingly, the level of IL-17A turned out to rise significantly in the non-responder group compared to responder during antidepressive treatment. IL-17A is a pro-inflammatory cytokine that initiates the production of other cytokines, thereby inducing and mediating immune response. It is also involved in allergic and autoimmune-related diseases. The database investigating the role of IL-17A in major depressive disorder has grown within the last few years comparing levels of this cytokine in depressed patients versus healthy subjects. However, little is known about the expression of IL-17A during the course of antidepressive treatment. In summary, our study provides valuable evidence that this cytokine might serve as a marker of therapy resistance to antidepressants.

Lack of an Association between a Polymorphism in the KRAS 3′ Untranslated Region (rs61764370) and Endometriosis in a Large European Case-Control Study

Background: Endometriosis is a common disorder that affects 6–10% of reproductive age women. In a previous study, we demonstrated that a polymorphism in let-7 microRNA-binding site in the 3' untranslated region of the KRAS gene was found in 31% of subjects with endometriosis resistant to medical therapy. This polymorphism was now tested in a large, case-control study. Methods: Peripheral blood or peritoneal biopsies from 2,077 European subjects with or without endometriosis and known infertility were tested for the presence of the variant allele using polymerase chain reaction. Results: Histologically proven endometriosis was found in 1,140 subjects, while 937 subjects were disease free. Variant allele carrier rates in subjects with and without endometriosis were 15.7 and 15.1%, respectively. No association between the variant KRAS allele and stage of the disease, age at surgery, body mass index, or type of infertility was identified. Conclusion: A germ-line single-nucleotide polymorphism in the let-7 microRNA-binding site of the KRAS gene was not associated with sporadic endometriosis in an infertile Caucasian population in this large case-control study. However, it remains possible that this gene variant may be a marker of treatment resistance. Further studies on the role of this polymorphism in endometriosis are needed.

Advancing evidence-based decisions in the management of EGFR-mutated metastatic NSCLC.

e20663 Background: In patients diagnosed with metastatic NSCLC it is now essential to identify targetable mutations and markers of treatment resistance in order to determine the appropriate therapy. A study was conducted to determine if simulation-based educational interventions to address clinical practice gaps could improve decisions of oncologists in the management of EGFR-mutated metastatic NSCLC. Methods: A cohort of US-oncologists who participated in a virtual patient simulation (VPS)-based education was evaluated. The VPS consisted of 2 cases that allowed oncologists to assess the patient and choose from a database of diagnostic possibilities matching the scope and depth of practice. Clinical decisions were analyzed using a decision engine, and instantaneous clinical guidance (CG) employing current evidence-based and expert faculty recommendations was provided after each decision. Oncologists were allowed a second chance at each decision point and decisions before and after CG were compared using a 2-tailed paired T-test to determine differences from pre- to post CG. P values are shown as a measure of significance; with P &lt; .05 statistically significant. Results: 197 oncologists made clinical decisions within the simulation. As a result of CG, significant improvements were observed in: Ordering EGFR mutational testing (16%, P= 0.008) and making an accurate diagnosis (36%) Selecting an EGFR TKI in the first-line setting (24%, P&lt; 0.001) Ordering a PET scan to assess disease progression (10%) and in diagnosing patients with EGFR T790M disease that is resistant (29% , P&lt; 0.001) Evidence-based treatment selection for individuals whose disease progressed on first-line therapy (19%, P= .003) Number of oncologists who ordered adverse event education and counseling (23%, P&lt; .001) Conclusions: This study showed improvements in evidence-based practices of oncologists in the diagnosis and management of EGFR-mutated NSCLC; demonstrating that VPS-based instruction that immerses and engages oncologists for an authentic, practical and16. consequence-free learning experience can result in an increase in appropriate clinical decisions. Therefore, VPS may have a role in improving the quality of patient care.

CD38 as a novel immune checkpoint and a mechanism of resistance to the blockade of the PD-1/PD-L1 axis.

79 Background: Although immune checkpoint inhibitors including PD-L1 blockade provide significant clinical benefit for patients with lung cancer, barriers to immunotherapy clinical successes have been due to a high rate of resistance. The therapeutic improvement requires a thorough understanding of the biological process of resistance. Until recently, there have been only a few studies reporting the mechanisms of resistance to PD-L1 blockade. The mechanistic basis remains poorly defined. Methods: In multiple immunocompetent syngeneic and K-rasLA1/+p53R172H?g/+ spontaneous animal models of lung cancer, we have explored the resistance mechanisms using pharmacological and genetic approaches (monoclonal antibody treatment and CRISPR/Cas9-mediated editing). The molecular and immune profiles of the tumor microenvironment were evaluated. More importantly, to determine the applicability to patients with lung cancer, we analyzed 259 patients’ specimens with IHC staining and mined many immune markers in TCGA adeno and squamous datasets. Results: We identified the up-regulation of CD38 on tumor cells as well as enrichment of CD38highTregs and CD38highMDSCs in tumor as the markers of treatment resistance. We observed the same resistance mechanism caused by CD38 in PD-L1 KO mice bearing PD-L1 KO Lewis lung tumors edited with the CRISPR/Cas9 system. Furthermore, by manipulating CD38 on a panel of lung cancer cell lines, in vitro and in vivo data demonstrates that CD38 inhibits CD8+ T cell proliferation, antitumor cytokine secretion, and tumor cell killing capability. To test whether CD38 blockade might be therapeutically efficacious to anti-PD-L1 resistance, we applied the combination therapy of anti-CD38 and anti-PD-L1 and demonstrated dramatic therapeutic benefit on primary tumor growth and metastasis. Additionally, in 259 lung patients, 18.5% of cases exhibited positive staining for CD38 on tumor cells, showing a great potential benefit for treating lung patients. Conclusions: CD38 is defined as a novel immune checkpoint and acts as a mechanism of resistance in the context of PD-L1 therapy. Targeting this novel immune checkpoint may broaden the benefit of PD-L1/PD-1 axis blockade for lung cancer treatment.

Abstract B38: Quiescence as a marker of treatment resistance and malignancy in GBM

Abstract Glioblastoma multiforme (GBM) is a World Health Organization grade IV astrocytic tumor, and is the most common primary brain malignancy. GBM is characterized as being highly malignant and rapidly progressive with a high mitotic index, diffuse invasion, microvascular proliferation and pseudopalisading necrosis. Current best treatment for GBM involves maximal safe surgical resection, with radiotherapy (XRT) and temozolomide (TMZ), but even with this regime patients survive for an average of only ~15 months. GBM’s position within the brain and diffuse progression profile prevents a surgical cure, and the cells left behind following surgery contain a quiescent, treatment-resistant subpopulation of cells with a stem-like capacity for self-renewal which survive chemoradiotherapy and cause relapse. These resistant cells have been referred to as cancer stem cells, but while stem cell markers have been useful in enriching stem populations in some cancers, a marker that reliably defines the glioma stem cell has remained elusive. The critical feature that allows these resistant cells to survive treatment is their slow division rate, which helps them to avoid chemoradiotherapy-induced cell death by virtue of their condensed chromatin and reduced requirement for DNA replication. In the present study we use a pulse-chase assay to ubiquitously label glioma cell lines with the fluorescent dye Oregon Green and observe the label dilution as an indicator of cell division. Based on their slower division rates, quiescent cells retain the dye longer than rapidly-dividing cells and are easily identified by fluorescence imaging and FACS analysis. Once such a population is isolated it can then be compared to a rapidly-dividing (Oregon Green-diluting) subpopulation of cells to analyze differences in treatment resistance, migration, invasion, and gene expression between the two populations. It is hoped that by elucidating the molecular mechanisms that drive treatment resistance and migration/invasion we will be able to inform novel GBM treatments that improve patient outcomes. We have shown that quiescent cells are innately resistant to the current gold standard GBM treatments and display more malignant features in vitro than rapidly dividing cells. We have developed a platform for quick, easy, and reliable isolation of this quiescent fraction of cells to facilitate its interrogation. This method has the potential to identify future treatment targets, and could, in principle, be extended to other malignancies. Citation Format: Ryan J. Atkins, Stanley S. Stylli, Rodney B. Luwor, Thomas MB Ware, Andrew H. Kaye, Christopher M. Hovens. Quiescence as a marker of treatment resistance and malignancy in GBM. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr B38.

Abstract B96: Adaptive resistance to therapeutic PD-1:PD-L1 blockade is mediated by upregulation of the TIM-3 immune checkpoint

Abstract Introduction: Programmed death 1 (PD-1): Programmed death ligand 1 (PD-L1) immune checkpoint blockade has been demonstrated to be efficacious in a number of cancer types, including melanoma, renal cell carcinoma, bladder cancer, hematologic malignancies and non-small cell lung cancer (NSCLC) and anti-PD-1 antibodies have recently been approved for use in the United States and Asia. Anti-PD-1 therapeutic antibodies function through binding to PD-1 on tumor-reactive T cells and inhibiting the PD-1:PD-L1 interaction, thereby reinvigorating the anti-tumor T cell response. Expression of PDL1 in tumor cells and infiltrating immune cells and PD-1 in T cells has been associated with responsiveness to blockade of this immune checkpoint; however, mechanisms of both de novo and adaptive resistance to therapy are unclear. Methods: We used two genetically engineered mouse models of lung adenocarcinomas corresponding to the two most common oncogene drivers in human lung adenocarcinoma, Kirsten rat sarcoma viral oncogene homolog (KRAS) and EGFR. The EGFR and Kras models were treated with a therapeutic anti-PD-1 antibody until tumors demonstrated progression by MRI and evaluated immune profiles. To confirm the applicability of these findings in patients, we also analyzed immune cells from patients who showed an initial response to PD-1 blockade but developed progressive disease several months after the initiation of treatment. Results: We identified upregulation of Tim-3 checkpoint receptor on therapeutic antibody-bound T cells as a marker of treatment resistance in mouse tumors. To determine whether blockade of Tim-3 at the time of resistance might be therapeutically efficacious, we performed Tim-3 blocking treatment in these mice and demonstrated a clinical benefit. Specimens from the two patients who developed progressive disease after an initial response to anti-PD1 treatments also exhibited similar upregulation of TIM-3 on therapeutic antibody-bound T cells, further supporting TIM-3 as a marker of treatment resistance. Conclusions: TIM-3 is upregulated in anti-PD-1 antibody bound T cells at the time of tumor regrowth in both genetically engineered mouse models and non-small cell lung cancer patients who initially responded to PD-1 blocking treatment. Targeting TIM-3 could be a promising option to reinitiate tumor-reactive T cell activation in patients who have developed adaptive resistance to anti-PD-1 treatment. Citation Format: Esra A. Akbay, Shohei Koyama, Yvonne Y. Li, Grit S. Herter-Sprie, Kevin A. Buczkowski, William G. Richards, Leena Gandhi, Amanda J. Redig, Scott J. Rodig, Hajime Asahina, Robert E. Jones, Meghana M. Kulkarni, Peter E. Fecci, Bruce E. Johnson, Pasi A. Janne, Jeffrey A. Engelman, Sidharta P. Gangadharan, Daniel B. Costa, Gordon J. Freeman, Raphael Bueno, F. Stephen Hodi, Glenn Dranoff, Kwok-Kin Wong, Peter S. Hammerman. Adaptive resistance to therapeutic PD-1:PD-L1 blockade is mediated by upregulation of the TIM-3 immune checkpoint. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B96.

Abstract P4-07-15: Prognostic impact of miR-18a expression in residual tumor after neoadjuvant chemotherapy for locally advanced breast cancer

Abstract Background: microRNAs (miRNAs) are small ribonucleic acids that regulate protein expression through gene silencing mechanisms and show differential expression between cancer subtypes. Several studies have demonstrated that over- or under-expression of miRNA levels in tumors can modulate the expression levels of their gene/protein targets and thus their behavior. In breast cancer, the members of cluster miR-17-92 increase their expression levels as the histological grade increases, behaving like an oncogene, and are preferentially expressed in basal-like carcinomas. Moreover, mature components of this cluster are involved in estrogen receptor pathways and epithelial-mesenchymal transition, which suggest their implication in resistance to chemotherapy. The aim of this study was to determine the prognostic impact of miR-18a expression in the residual (resistant-to-treatment) tumor after neoadjuvant chemotherapy (nQT) in patients with locally advanced breast cancer (BC). Methods: Small RNA was isolated from FFPE samples of post-chemotherapy residual tumor in patients without pathological complete response (pCR). Quantification of miR-18a was performed by RT-qPCR. Expression levels were determined by 2-DDCt method using snRNAU6 as endogenous control. We used the quartiles of expression as cutoff point. Association of miR-18a levels with clinical and pathological characteristics was evaluated with non-parametric tests. Kaplan-Meier curves, log-rank test and Cox proportional hazard regression multivariate models were used for disease free (DFS) and overall (OS) survival analysis. Statistical analysis was performed with SPSS 18.0 software. Results: 121 consecutive women with invasive BC were included, mostly with stages IIB (28%) or IIIA-C (56.4%). Patients were immunohistochemically (IHC) classified as Her2- hormone-sensitive (HS) in 50.4% of cases; other phenotypes: Her2+ HS, 13.2%; Her2+ non-HS, 10.7%; triple negative, 21.5%. Treatment included sequential anthracyclines and taxanes (80.4% docetaxel) and a pCR was obtained in 17.4% of patients. Median overall survival (OS) and disease free survival (DFS) were not reached after a median follow-up of 60 months. High (above the median) expression levels of miR-18a in post-chemotherapy residual tumor were associated with pre-treatment grade 3 (p = 0.008), cN2-3 (p = 0.004), non-HS (p = 0.006) and triple negative phenotype (p = 0.01). No other associations with clinical or pathologic tumor characteristics (stage, HER2NEU overexpression) were found. High expression levels of miR-18a in residual tumors were also associated with reduced DFS and OS (log-rank test; p = 0.004 and p = 0.041 respectively). This negative prognostic impact was also confirmed for DFS in a multivariate analysis that included IHC phenotype and ypN+ (Table 1). Table 1 OR95%CIPPhenotype1.571.11-2.230.010ypN+7.291.67-31.800.008miR-18a high3.091.01-9.410.047 Conclusion: High expression levels of miR-18a in chemotherapy-resistant residual breast cancer associates with pre-treatment aggressive biological characteristics and independently predicts disease recurrence. Our results suggest that post-treatment miR-18a might serve as a marker of treatment resistance and as a new target for BC treatment. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-07-15.