Development of an Immunohistochemical Assay to Detect the Ataxia-Telangiectasia Mutated (ATM) Protein in Gastric Carcinoma

Miller, Rachel M.; Nworu, Chinedu; McKee, L. Clifford; Balcerzak, Denis; Pham, Linh; Pugh, Judith; Liu, Yuzhen; Gustafson, Heather L.; Marwah, Ekta; Lamb, Tiffany; Clements, June

doi:10.1097/pai.0000000000000786

Cited by 10 publications

(6 citation statements)

References 14 publications

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“…Here the challenge is to confirm loss or reduction of ATM in tumor samples. Immunohistochemistry remains to be routinely applied in the clinic and scoring ATM mutations is made difficult by the large size of the ATM gene and difficulties of predicting whether a certain mutation is deleterious or a variant without functional significance [ 67 , 92 , 112 ].…”

Section: Targeting the Repstress Response With Replication Checkpoint Inhibitorsmentioning

confidence: 99%

Precision Oncology with Drugs Targeting the Replication Stress, ATR, and Schlafen 11

Murai

Takebe

et al. 2021

Cancers

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Precision medicine aims to implement strategies based on the molecular features of tumors and optimized drug delivery to improve cancer diagnosis and treatment. DNA replication is a logical approach because it can be targeted by a broad range of anticancer drugs that are both clinically approved and in development. These drugs increase deleterious replication stress (RepStress); however, how to selectively target and identify the tumors with specific molecular characteristics are unmet clinical needs. Here, we provide background information on the molecular processes of DNA replication and its checkpoints, and discuss how to target replication, checkpoint, and repair pathways with ATR inhibitors and exploit Schlafen 11 (SLFN11) as a predictive biomarker.

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Section: Targeting the Repstress Response With Replication Checkpoint Inhibitorsmentioning

confidence: 99%

Precision Oncology with Drugs Targeting the Replication Stress, ATR, and Schlafen 11

Murai

Takebe

et al. 2021

Cancers

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“…ATM protein IHC was performed using the Y170 rabbit monoclonal antibody (Abcam, 32420) on the Ventana Discovery XT Autostaining System (Roche/Ventana Medical Systems). The ATM Y170 clone was used to develop a similar IHC diagnostic assay (35) and was deployed in the phase III GOLD study, which looked at combination of olaparib and paclitaxel in patients with advanced gastric cancer who have progressed following first-line therapy (36). Slides were incubated with primary antibody (1:100 dilution) after antigen retrieval in CC1 buffer, and primary antibody incubation was followed by detection with the OptiView HQ System (Roche/Ventana Medical Systems).…”

Section: Ihcmentioning

confidence: 99%

Genomic and Clinicopathologic Characterization ofATM-deficient Prostate Cancer

Kaur¹,

Salles²,

Murali³

et al. 2020

Clinical Cancer Research

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Purpose: The ATM (ataxia telangiectasia mutated) gene is mutated in a subset of prostate cancers, and ATM mutation may confer specific therapeutic vulnerabilities, although ATM-deficient prostate cancers have not been well-characterized.Experimental Design: We genetically validated a clinical grade IHC assay to detect ATM protein loss and examined the frequency of ATM loss among tumors with pathogenic germline ATM mutations and genetically unselected primary prostate carcinomas using tissue microarrays (TMAs). Immunostaining results were correlated with targeted somatic genomic sequencing and clinical outcomes.Results: ATM protein loss was found in 13% (7/52) of primary Gleason pattern 5 cancers with available sequencing data and was 100% sensitive for biallelic ATM inactivation. In a separate cohort with pathogenic germline ATM mutations, 74% (14/19) had ATM protein loss of which 70% (7/10) of evaluable cases had genomic evidence of biallelic inactivation, compared with zero of four of cases with intact ATM expression. By TMA screening, ATM loss was identified in 3% (25/831) of evaluable primary tumors, more commonly in grade group 5 (17/181; 9%) compared with all other grades (8/650; 1%; P < 0.0001). Of those with available sequencing, 80% (4/5) with homogeneous ATM protein loss and 50% (6/12) with heterogeneous ATM protein loss had detectable pathogenic ATM alterations. In surgically treated patients, ATM loss was not significantly associated with clinical outcomes in random-effects Cox models after adjusting for clinicopathologic variables.Conclusions: ATM loss is enriched among high-grade prostate cancers. Optimal evaluation of ATM status requires both genomic and IHC studies and will guide development of molecularly targeted therapies.

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“…In the follow-up phase III GOLD trial (NCT01924533), a new IHC reporter assay was developed that used the same antibody clone but with different assay configurations and reagents. 41 The cut-off for "ATM-low" tumours was redefined as <25% of ATM tumour cell nuclear staining (to account for increased sensitivity of new assay); however, this trial failed to meet its primary endpoint and failed to confirm the survival benefit in "ATM-low" patients that had been observed previously. 42 It remains unclear whether redefining the cut-off to a lower threshold would bring a different result.…”

Section: Discussionmentioning

confidence: 99%

Complete loss of ATM function augments replication catastrophe induced by ATR inhibition and gemcitabine in pancreatic cancer models

et al. 2020

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Background Personalised medicine strategies may improve outcomes in pancreatic ductal adenocarcinoma (PDAC), but validation of predictive biomarkers is required. Having developed a clinical trial to assess the ATR inhibitor, AZD6738, in combination with gemcitabine (ATRi/gem), we investigated ATM loss as a predictive biomarker of response to ATRi/gem in PDAC. Methods Through kinase inhibition, siRNA depletion and CRISPR knockout of ATM, we assessed how ATM targeting affected the sensitivity of PDAC cells to ATRi/gem. Using flow cytometry, immunofluorescence and immunoblotting, we investigated how ATRi/gem synergise in ATM-proficient and ATM-deficient cells, before assessing the impact of ATM loss on ATRi/gem sensitivity in vivo. Results Complete loss of ATM function (through pharmacological inhibition or CRISPR knockout), but not siRNA depletion, sensitised to ATRi/gem. In ATM-deficient cells, ATRi/gem-induced replication catastrophe was augmented, while phospho-Chk2-T68 and phospho-KAP1-S824 persisted via DNA-PK activity. ATRi/gem caused growth delay in ATM-WT xenografts in NSG mice and induced regression in ATM-KO xenografts. Conclusions ATM loss augments replication catastrophe-mediated cell death induced by ATRi/gem and may predict clinical responsiveness to this combination. ATM status should be carefully assessed in tumours from patients with PDAC, since distinction between ATM-low and ATM-null could be critical in maximising the success of clinical trials using ATM expression as a predictive biomarker.

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Development of an Immunohistochemical Assay to Detect the Ataxia-Telangiectasia Mutated (ATM) Protein in Gastric Carcinoma

Cited by 10 publications

References 14 publications

Precision Oncology with Drugs Targeting the Replication Stress, ATR, and Schlafen 11

Precision Oncology with Drugs Targeting the Replication Stress, ATR, and Schlafen 11

Genomic and Clinicopathologic Characterization ofATM-deficient Prostate Cancer

Complete loss of ATM function augments replication catastrophe induced by ATR inhibition and gemcitabine in pancreatic cancer models

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