ctDNA-based mutational landscape following anti-EGFR antibodies in metastatic colorectal cancer (mCRC) to uncover novel resistance mechanisms in the CCTG CO.26 trial.

2021 ◽  
Vol 39 (3_suppl) ◽  
pp. 117-117
Author(s):  
James T. Topham ◽  
Christopher J. O'Callaghan ◽  
Harriet Feilotter ◽  
Hagen F. Kennecke ◽  
Young S Lee ◽  
...  
Keyword(s):  
De Novo ◽  
Acquired Resistance ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Post Treatment ◽  
Resistance Mutations ◽  
Treatment Groups ◽  
Whole Exome ◽  
Mutation Burden ◽  
Pre Treatment

117 Background: Previous studies have identified MAPK and PIK3CA/AKT/mTOR pathways as common mechanisms of acquired resistance to anti-EGFR antibodies (EGFRab) in mCRC. However, such alterations do not account for all patients that become treatment resistant. Using paired whole-exome (WES; tissue) and circulating tumor DNA (ctDNA; plasma) sequencing, we performed characterization of the EGFRab resistance landscape in patients with mCRC. Methods: Post-treatment (ctDNA; plasma) sequencing was performed for 169 patients with mCRC, with 112 (66%) patients also receiving pre-treatment (WES; primary tumor) sequencing as part of the CO.26 trial. 66 (39%) patients received EGFRab previously at a median of 132.0 days prior to plasma sampling. Using bespoke bioinformatics pipelines (WES) coupled with the GuardantOMNI assay (plasma), we compared somatic mutation (SNV/indel, CNV and fusion) frequencies between pre- and post-EGFRab timepoints, and contrasted results between the two groups. Results: Significant increases in de novo acquisition of EGFR (p = 5.6e-4), KRAS (p = 0.011), ZNF217 (p = 0.0022), MAP2K1 (p = 0.0078) and LRP1B (p = 0.017) SNV/indels were unique to the EGFRab group and often occurred as multiple, low allele frequency events in the same patient. De novo copy number amplification of known resistance genes EGFR/ BRAF/ MET were observed in EGFRab-treated patients (p < 0.05), along with SMO (p = 6.8e-7), PTEN inhibitory gene PREX2 (p = 5.6e-4), FLT3 (p = 2.0e-5), NOTCH4 (p = 6.3e-5), ERBB2 (7.4e-4), KMT2A (p = 3.7e-4) and ARID1B (p = 0.0014). Genes impacted by fusion events in EGFRab-treated patients included BRAF-KIAA1549 (1 patient) and MET-CAV1 (1 patient), and these events were not detected in matched pre-treatment samples. EGFRab-treated patients were found to acquire a combination of multiple (≥5) mutation events (SNV/indel, CNV or fusion) at much higher frequency compared to non-EGFRab-treated patients (67% versus 25% of patients, p = 8.7e-8). Tumor mutation burden (TMB) was not significantly different (p = 0.71) between treatment groups prior to therapy initiation, while post-treatment TMB was significantly higher (p = 1.8e-7) in EGFRab-treated patients (median 25.4 versus 13.1 mut/mb). Conclusions: In addition to previously established resistance pathways, we identified acquired alterations in additional genes such as SMO, PREX2 and epigenetic modifiers KMT2A/ARID1B in EGFRab-treated patients . Moreover, we highlight the phenomenon by which EGFRab-treated tumors acquire multiple concurrent resistance mutations and heightened TMB. Our analysis provides novel insight into the landscape of resistance mechanisms to EGFRab in mCRC while highlighting the potential role for immunotherapy post-EGFRab. Clinical trial information: NCT02870920.

Coexistence of multiple escape mechanisms in a BRAFV600E-mutated cutaneous melanoma treated with vemurafenib.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 9014-9014 ◽  
Author(s):  
Olivier Michielin ◽  
Emanuela Romano ◽  
Solange Peters ◽  
Alexandra Paillusson ◽  
Johann Weber ◽  
...  
Keyword(s):  
Splice Variant ◽  
Acquired Resistance ◽  
Local Treatment ◽  
Resistance Mechanisms ◽  
Single Nucleotide Variants ◽  
Nras Mutation ◽  
High Coverage ◽  
Whole Exome ◽  
Pre Treatment ◽  
The Right

9014 Background: Mechanisms of acquired resistance to vemurafenib are the subject of intense research. Here we report, for the first time, two coexisting yet mutually exclusive mechanisms of escape in a melanoma patient who presented an excellent clinical response following reintroduction of vemurafenib. Methods: To investigate the mechanisms of resistance to vemurafenib, we performed whole-exome sequencing using the Illumina technology of a pre-treatment paraffin-embedded lymph node metastasis (Pre) and of two progressing subcutaneous snap-frozen metastases of the right arm (PV1 and PV2). The tumor samples, along with germline controls, were sequenced at high coverage (mean range 268x-356x). Results: We identified 107 exonic somatic Single Nucleotide Variants (SNVs) in Pre, 139 SNVs in PV1, and 127 SNVs in PV2, generating a set of 202 different SNVs, 82 of which were common to all 3 samples. The non-synonymous to synonymous ratios were higher for PV1 (1.82) than for PV2 (1.46), and lower for Pre (1.31). C>T transitions, largely predominated in the samples, indicating light-induced damage. Two independent NRAS escape mutations (Q61K and Q61R) where observed in PV1, whereas appearance of a BRAF splice variant (lack of exon 4-10) was present in PV2. Most importantly, these 2 escape mechanisms were mutually exclusive, i.e. no BRAF splice variant was observed by PCR in PV1 and no NRAS mutation found in PV2. Conclusions: Our results clearly demonstrate that multiple molecular escape mechanisms can be both coexistent and mutually exclusive. These findings have clinical implications: firstly, local treatment of isolated progressing lesions and continuation of vemurafenib could be supported by the fact that the resistance mechanisms are not necessarily shared. This approach is currently being tested within clinical trials with preliminary results that seem to support this hypothesis. Secondly, the coexistence of divergent escapes within the same patient strongly argues that single biopsy analysis at progression might not reflect the molecular complexity of tumor progression, and therefore might not be sufficient to guide selection of second-line optimal combination therapy.

Incidence and heterogeneity of C797S and other EGFR resistance mutations on routine comprehensive genomic profiling (CGP).

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 9101-9101
Author(s):  
Pasi A. Janne ◽  
Jessica Kim Lee ◽  
Russell Madison ◽  
Jeffrey Michael Venstrom ◽  
Alexa Betzig Schrock ◽  
...  
Keyword(s):  
Kinase Inhibitor ◽  
Acquired Resistance ◽  
Standard Of Care ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Braf V600e ◽  
Resistance Mutations ◽  
Line Of Therapy ◽  
Egfr Mutant ◽  
Platinum Doublet

9101 Background: The emergence of osimertinib (osi) as standard of care therapy for EGFR-mutant NSCLC has led to investigations into understanding and overcoming drug resistance. There are now a number of therapeutic approaches aimed at overcoming EGFR resistance mutations (muts). We sought to understand the biology of EGFR C797S and other EGFR resistance muts through querying our clinico-genomic database (CGDB). Methods: CGP results from tissue (n = 60,889) or circulating tumor DNA (ctDNA; [n = 9,922]) samples from 70,811 NSCLC patients (pts) were queried for known osi resistance muts in EGFR (C797, L792, G796, L718, G724). Clinical outcomes were evaluated for a cohort of NSCLC pts with osi resistance from the Flatiron Health-Foundation Medicine CGDB, a nationwide de-identified EHR-derived database linked to CGP data. Results: Between 12/2014 and 11/2020, 261 osi resistance mutations in EGFR were detected in 228 samples. The most common were C797S (66%), L718X (14%), G724S (11%), and others (9%). 173 C797S muts were detected in 155 samples (123 ex19del, 30 L858R, 2 other EGFR muts); 100 tissue, 55 ctDNA (median VAF = 7.6%). EGFR T790M co-occurred with C797S muts (96% cis, 3.7% trans) in 118 (76%) samples and decreased over time, occurring in 92% (24/26) of C797S samples tested in 2017 vs 56% (20/36) of samples tested in 2020 (p = 0.002). In 19/155 (12%) samples with C797S (14 ctDNA), multiple changes resulting in EGFR resistance muts were present: 16 samples had > 1 nucleotide changes resulting in C797S (100% trans), 3 samples had other resistance muts (L718Q/V, L792H, L792F) and 3 samples had multiple C797S changes with other resistance muts (C797G, L792H/F + G796S, L718Q + G796S+C797G). 29 pts (14 ctDNA) had C797S with potential off-target resistance (17 PIK3CA muts, 4 BRAF muts, 3 CCDC6- RET fusions, 3 KRAS muts, 2 ERBB2 amplifications (amps), 1 ERBB2 ex16 del, 1 STRN- ALK fusion, 1 FGFR3- TACC3 fusion). In the CGDB, 527 EGFR-mut NSCLC pts had documented receipt of osi. Pre and post osi-treated specimens were available for 19 of these pts (12 ex19del, 6 L858R, 1 G719A/S768I). Heterogeneous acquired resistance mechanisms were observed in the post-osi specimen, including 2 CCDC6- RET fusions, 2 MET amps, 2 BRAF fusions, BRAF V600E, and secondary EGFR muts (C797S, L704F, L718V). 161/527 pts had a documented line of therapy after osi discontinuation and most frequently received platinum doublet + immunotherapy (27%) or platinum doublet alone (23%); 17 (11%) pts received another EGFR tyrosine kinase inhibitor. 214/527 had documented osi progression and median post-progression survival was 11.8 months. Conclusions: Osi resistance in EGFR-mutant NSCLC is a poor prognosis condition. EGFR C797S is a recurring resistance mut which, in a minority of cases, can co-occur with alternate on and off target resistance muts detected with tissue and liquid biopsy.

Genomic analysis of circulating tumor DNA in 3,334 patients with advanced prostate cancer to identify targetable BRCA alterations and AR resistance mechanisms.

2021 ◽  
Vol 39 (6_suppl) ◽  
pp. 25-25
Author(s):  
Hanna Tukachinsky ◽  
Russell Madison ◽  
Jon Chung ◽  
Lucas Dennis ◽  
Bernard Fendler ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Advanced Prostate Cancer ◽  
Acquired Resistance ◽  
Genomic Analysis ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Cancer Tissue ◽  
Castration Resistant Prostate Cancer ◽  
High Level ◽  
Tumor Dna

25 Background: Comprehensive genomic profiling (CGP) by next-generation sequencing (NGS) of circulating tumor DNA (ctDNA) from plasma provides a minimally invasive method to identify targetable genomic alterations (GAs) and resistance mechanisms in patients with metastatic castration-resistant prostate cancer (mCRPC). The circulating tumor fraction in patients with mCRPC and the clinical validity of GAs detected in plasma remain unknown. We evaluated the landscape of GAs using ctDNA-based CGP and assessed concordance with tissue-based CGP. Methods: Plasma from 3,334 patients with advanced prostate cancer (including 1,674 mCRPC screening samples from the TRITON2/3 trials and 1,660 samples from routine clinical CGP) was analyzed using hybrid-capture-based gene panel NGS assays. Results were compared with CGP of 2,006 metastatic prostate cancer tissue biopsies. Concordance was evaluated in 837 patients with both tissue (archival or contemporaneous) and plasma NGS results. Results: 3,127 patients [94%] had detectable ctDNA. BRCA1/2 were mutated in 295 patients [8.8%]. In concordance analysis, 72/837 [8.6%] patients had BRCA1/2 mutations detected in tissue, 67 [93%] of whom were also identified by ctDNA, and 20 patients were identified using ctDNA but not tissue [23% of all patients identified using ctDNA]. ctDNA detected subclonal BRCA1/2 reversions in 10 of 1,660 [0.6%] routine clinical CGP samples. AR alterations, including amplifications and hotspot mutations, which were detected in 940/2,213 patients [42%]. Rare AR compound mutations, rearrangements, and novel in-frame deletions were identified. Altered pathways included PI3K/AKT/mTOR [14%], WNT/β-catenin [17%], and RAS/RAF/MEK [5%]. Microsatellite instability was detected in 31/2,213 patients [1.4%]. Conclusions: In the largest study of mCRPC plasma samples conducted to date, CGP of ctDNA recapitulated the genomic landscape detected in tissue biopsies, with a high level of agreement in detection of BRCA1/2 alterations. It also identified patients who may have gained somatic BRCA1/2 alterations since archival tissue was collected. ctDNA detected more acquired resistance GAs than tissue, including novel AR-activating variants. The large percentage of patients with rich genomic signal from ctDNA, and the sensitive, specific detection of BRCA1/2 alterations position liquid biopsy as a compelling clinical complement to tissue CGP for patients with mCRPC.

scholarly journals Detection of Multiple Recurrent Novel BCL2 Mutations Co-Occurring with BCL2 Gly101Val in Patients with Chronic Lymphocytic Leukemia on Long Term Venetoclax

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 171-171 ◽  
Author(s):  
Piers Blombery ◽  
Ella Thompson ◽  
Tamia Nguyen ◽  
Xiangting Chen ◽  
Michelle McBean ◽  
...  
Keyword(s):  
Research Funding ◽  
Acquired Resistance ◽  
Resistance Mechanisms ◽  
Drug Binding ◽  
Cellular Systems ◽  
Clinical Relapse ◽  
Resistance Mutations ◽  
Recurrent Mutations ◽  
Eliza Hall Institute ◽  
Hall Institute

The BCL2 Gly101Val mutation may be acquired in patients with chronic lymphocytic leukaemia (CLL) treated with venetoclax (VEN), leading to reduced drug binding affinity and secondary resistance. In the majority of patients, the Gly101Val mutation is subclonal within the CLL compartment consistent with the presence of alternative resistance mechanisms in CLL cells not harboring the Gly101Val mutation. To date, two Gly101Val mutated patients have been identified with co-existing candidate resistance mechanisms in Gly101Val non-mutated cells; one with BCL-XL over-expression (Blombery et al, Cancer Discov., 2019) and another with a second subclonal candidate BCL2 resistance mutation - Asp103Tyr (Tausch et al, Haematologica 2019). Given the possibility of additional resistance mechanisms, we investigated patients with progressive CLL on VEN harboring the Gly101Val mutation for the presence of additional acquired resistance mutations in BCL2. Ten patients with progressive CLL on VEN with Gly101Val mutations were identified by sensitive allele-specific droplet digital PCR. To further assess for alternative BCL2 mutations in this cohort we performed ultra-deep amplicon-based next generation sequencing (NGS) (median depth ~50,000X) targeting BCL2. An amplicon variant caller (Canary) specifically designed for low level variant calling was used (Doig et al, BMC Bioinformatics, 2017). To achieve enhanced specificity we performed digital NGS with PCR error-correction using unique molecular indexes (UMI) (QiaSEQ Targeted DNA Panel). Given the high GC content of BCL2 we also used hybridization-based NGS using a custom targeted panel (Blombery et al, BJH 2017) combined with a sensitive unpaired variant caller (GATK4/Mutect2). In 7/10 (70%) patients, BCL2 mutations in addition to the Gly101Val were detected. Recurrent mutations (detected in more than one patient) were Asp103Tyr, Asp103Glu, Arg107_Arg110dup, and Val156Asp. All additional recurrent mutations were confirmed to be absent prior to commencing VEN (sensitivity 1% variant allele frequency[VAF]). Phase-analysis of NGS reads was consistent with the presence of the additional recurrent mutations on different alleles (and therefore cells, assuming heterozygosity) to both each other and to Gly101Val. Multiple addition recurrent mutations were observed in patients in the cohort with one patient harboring three recurrent mutations in addition to the Gly101Val (Asp103Tyr, Asp103Glu, Val156Asp). In multiple patients in the cohort, the VAF of non-Gly101Val mutations exceeded that of the Gly101Val mutation. Importantly, in all patients a significant (albeit variable) proportion of CLL cells were found to be BCL2 wild-type consistent with the presence of as yet unidentified resistance mechanisms unrelated to BCL2 mutations. In one patient, two additional non-recurrent mutations were observed (Ala113Gly and Arg129Leu) in addition to Gly101Val and Val156Asp. Again, all four mutations in this patient were observed to be in mutually exclusive NGS reads. Strikingly, all of the recurrent acquired BCL2 mutated residues identified in our cohort are situated in the BCL2 binding groove that binds VEN (Figure 1). The Asp103 codon in the P4 pocket is critical for VEN binding through hydrogen bonding between its sidechain and the azaindole moiety of VEN. The Asp103Glu mutation is noteworthy given that the equivalent residue to Asp103 in BCL-XL is a Glu, which reduces VEN binding to BCL-XL. The Val156 mutation situated at the base of the P2 pocket is close to the chlorophenyl moiety of VEN and a change to Asp in this position may disrupt VEN binding. Ongoing binding experiments and modeling in cellular systems will further elucidate the mechanism and contributions of these new recurrent mutations to VEN resistance. In summary, we have extended the landscape of acquired candidate resistance mutations occurring in patients treated with VEN to include four novel recurrent BCL2 mutations. Moreover, our data are consistent with the emerging observation of multiple acquired resistance mechanisms operating in different CLL cells in a single patient contributing to an "oligoclonal" pattern of clinical relapse on VEN therapy. Figure 1 - BCL2 protein structure surface bound to venetoclax (VEN) in orange. The Asp103Tyr, Asp103Glu and Val156Asp mutation sites are shown in red and Arg107_Arg110dup region in blue Disclosures Blombery: Janssen: Honoraria; Invivoscribe: Honoraria; Novartis: Consultancy. Anderson:Walter and Eliza Hall Institute: Employment, Patents & Royalties: Institute receives royalties for venetoclax, and I receive a fraction of these.. Seymour:Acerta: Consultancy; Celgene: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; Takeda: Consultancy. Huang:Genentech: Patents & Royalties: DCSH is an employee of the Walter and Eliza Hall Institute which receives milestone and royalty payments related to venetoclax. Roberts:AbbVie: Other: Unremunerated speaker for AbbVie, Research Funding; Australasian Leukaemia and Lymphoma Group: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Walter and Eliza Hall Institute: Patents & Royalties: Institute receives royalties for venetoclax, and I receive a fraction of these.; BeiGene: Research Funding.

scholarly journals The genomic landscape of intrinsic and acquired resistance to cyclin-dependent kinase 4/6 inhibitors in patients with hormone receptor positive metastatic breast cancer

2019 ◽  
Author(s):  
Seth A. Wander ◽  
Ofir Cohen ◽  
Xueqian Gong ◽  
Gabriela N. Johnson ◽  
Jorge Buendia-Buendia ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Acquired Resistance ◽  
Metastatic Breast ◽  
Resistance Mechanisms ◽  
Akt Activation ◽  
Hormone Receptor Positive ◽  
Ras Activation ◽  
Whole Exome ◽  
Clinical Resistance

AbstractClinical resistance mechanisms to CDK4/6 inhibitors in HR+ breast cancer have not been clearly defined. Whole exome sequencing of 59 tumors with CDK4/6i exposure revealed multiple candidate resistance mechanisms including RB1 loss, activating alterations in AKT1, RAS, AURKA, CCNE2, ERBB2, and FGFR2, and loss of ER expression. In vitro experiments confirmed that these alterations conferred CDK4/6i resistance. Cancer cells cultured to resistance with CDK4/6i also acquired RB1, KRAS, AURKA, or CCNE2 alterations, which conferred sensitivity to AURKA, ERK, or CHEK1 inhibition. Besides inactivation of RB1, which accounts for ∼5% of resistance, seven of these mechanisms have not been previously identified as clinical mediators of resistance to CDK4/6 inhibitors in patients. Three of these—RAS activation, AKT activation, and AURKA activation—have not to our knowledge been previously demonstrated preclinically. Together, these eight mechanisms were present in 80% of resistant tumors profiled and may define therapeutic opportunities in patients.SignificanceWe identified eight distinct mechanisms of resistance to CDK4/6 inhibitors present in 80% of resistant tumors profiled. Most of these have a therapeutic strategy to overcome or prevent resistance in these tumors. Taken together, these findings have critical implications related to the potential utility of precision-based approaches to overcome resistance in many patients with HR+ MBC.

scholarly journals Mechanisms of Acquired Resistance to Savolitinib, a Selective MET Inhibitor in MET-Amplified Gastric Cancer

2020 ◽  
pp. 222-232 ◽  
Author(s):  
Melanie M. Frigault ◽  
Aleksandra Markovets ◽  
Barrett Nuttall ◽  
Kyoung-Mee Kim ◽  
Se Hoon Park ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cancer Progression ◽  
Tumor Tissue ◽  
Treatment Options ◽  
Acquired Resistance ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Met Inhibitor ◽  
Tumor Dna ◽  
Generation Sequencing

PURPOSE Some gastric cancers harbor MET gene amplifications that can be targeted by selective MET inhibitors to achieve tumor responses, but resistance eventually develops. Savolitinib, a selective MET inhibitor, is beneficial for treating patients with MET-driven gastric cancer. Understanding the resistance mechanisms is important for optimizing postfailure treatment options. PATIENTS AND METHODS Here, we identified the mechanisms of acquired resistance to savolitinib in 3 patients with gastric cancer and MET-amplified tumors who showed a clinical response and then cancer progression. Longitudinal circulating tumor DNA (ctDNA) is useful for monitoring resistance during treatment and progression when rebiopsy cannot be performed. RESULTS Using a next-generation sequencing 100-gene panel, we identified the target mechanisms of resistance MET D1228V/N/H and Y1230C mutations or high copy number MET gene amplifications that emerge when resistance to savolitinib develops in patients with MET-amplified gastric cancer. CONCLUSION We demonstrated the utility of ctDNA in gastric cancer and confirmed this approach using baseline tumor tissue or rebiopsy.

Anti-EGFR treatment for EGFR-amplified gastroesophageal adenocarcinoma.

2017 ◽  
Vol 35 (4_suppl) ◽  
pp. 60-60
Author(s):  
Steven Brad Maron ◽  
Lindsay Alpert ◽  
David Xu ◽  
Rachel Rendak ◽  
Emily O'Day ◽  
...  
Keyword(s):  
De Novo ◽  
Locally Advanced ◽  
Stage Iv ◽  
Response Duration ◽  
Resistance Mechanisms ◽  
Post Treatment ◽  
Phase Iii ◽  
Pathway Activation ◽  
Gastroesophageal Adenocarcinoma ◽  
Next Generation Sequencing Ngs

60 Background: Gastroesophageal cancer (GEC) is a global health problem. Multiple phase III anti-EGFR trials of unselected metastatic GEC patients (pts) were negative, yet subset analyses suggested potential benefit in pts with EGFR amplification (amp). We sought to quantify the incidence of EGFR amp in metastatic/recurrent GEC pts compared to the locally advanced TCGA rate, treat them with EGFR antagonists, quantify response/duration, and assess for mechanisms of action and resistance (MOA, MOR). Methods: 106 stage IV GEC pts in any therapy (tx) line (L) were prospectively screened for EGFR amp between 9/1/14-8/31/16 at a single site using tumor next generation sequencing (NGS). EGFR amp samples were then assessed by FISH, immunohistochemistry (IHC) and mass spectroscopy (MS) to confirm. Pts received 1L ABT-806 (1/4) or 2L+ cetux (3/4) monoclonal anti-EGFR antibodies, in combination with chemotherapy if 1L or 2L (2/4), or as monotherapy for 3L+ (2/4). Pts were followed for response (ORR) and disease control (DCR). Pre and post-treatment NGS, serial ctDNA, and EGFR/PD-L1 FISH/IHC/MS were obtained to monitor for MOA and MOR to tx. Results: Six (5.7%) pts harbored EGFR amp tumors with copies/cell ranging 54-167. Four eligible pts received >1 dose of tx with monoclonal anti-EGFR therapy: 1 FOLFOX-ABT-806 (1L), 1 FOLFIRI-cetux (2L), and 2 cetux alone (3L, 4L); ORR was 100% (4/4) by RECIST, respectively (-70%, -65%, -77%, -43%). All 3 cetux treated pts developed classic rash, which disappeared when/if progression (2/3). The 4-month DCR was 75% (3/4). No pts showed PD-L1 staining pre/post therapy. Upon progression, the 2L pt acquired de novo PTEN exon 6 deletion after 10 months, while basal NRAS mutated and HER2 amp ctDNA clones had expanded in the 4L pt after 4 months of monotherapy. Conclusions: EGFR amp incidence was similar to TCGA. Despite large negative trials with EGFR antagonists for GEC, EGFR amp predicted benefit (100%) from anti-EGFR tx, including monotherapy in 50%, albeit until various resistance mechanisms emerged, including HER2, RAS, and PTEN/AKT pathway activation. No PD-L1 expression was observed pre/post treatment, consistent with our previous data showing that EGFR-amplified cases trend towards a ‘non-T cell-inflamed’ phenotype. Clinical trial information: NCT01416714 / NCT02213289.

Non-invasive detection of acquired resistance to FGFR inhibition in patients with cholangiocarcinoma harboring FGFR2 alterations.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. 4096-4096 ◽  
Author(s):  
Anna M. Varghese ◽  
Juber Ahamad A Patel ◽  
Yelena Yuriy Janjigian ◽  
Fanli Meng ◽  
S Duygu Selcuklu ◽  
...  
Keyword(s):  
Targeted Therapy ◽  
Acquired Resistance ◽  
High Sensitivity ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Tumor Evolution ◽  
Background Error ◽  
Tumor Biopsy ◽  
Invasive Approach ◽  
Non Invasive

4096 Background: FGFR2 alterations are present in 14% of cholangiocarcinomas (CCA) and are promising targets of investigational FGFR-directed therapies. Cell-free DNA profiling has emerged as a non-invasive approach to monitor disease and longitudinally characterize tumor evolution. We describe the use of circulating tumor DNA (ctDNA) among patients (pts) with FGFR2-altered CCA receiving FGFR-targeted therapy in the identification of acquired FGFR2 mutations (mut) at resistance. Methods: Serial blood samples were collected from 8 pts with FGFR-altered CCA for ctDNA isolation and next generation sequencing. Plasma ctDNA collected at baseline and resistance to FGFR-targeted therapy were sequenced using a custom ultra-deep coverage cfDNA panel, MSK-ACCESS, incorporating dual index primers and unique molecular barcodes to enable background error suppression and high-sensitivity mut detection. The assay was enhanced to include all protein-coding exons and relevant introns of FGFR2. In 5/8 pts, genomic profiling of an initial tumor biopsy was performed. Results: 8 pts with FGFR2-altered CCA (7 gene fusions, 1 amplification) were treated with FGFR-targeted therapies. 7/8 pts exhibited stable disease or partial response. 19 total acquired mut in FGFR2 were detected at resistance in 5/8 pts (between 1-9 unique mut identified in each sample). All mut were located in the kinase domain. Conclusions: Acquired mut in FGFR2 are seen in pts who have developed resistance to targeted therapy. CtDNA can be used to identify these mut at the time of acquired resistance. The multitude of FGFR2 mut observed within individual pts suggest heterogeneity and evolutionary convergence of resistance mechanisms. Our results illustrate the utility of ctDNA as a less invasive way to monitor for signs of resistance and to identify other potential targetable alterations. [Table: see text]

KLF4 p.A472D mutation: An acquired resistant mutation to cetuximab in colorectal cancer.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e15077-e15077
Author(s):  
Liu Yang ◽  
Jiahong Jiang ◽  
Lianpeng Chang ◽  
Yaping Xu ◽  
Chao Ni ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Function Analysis ◽  
Acquired Resistance ◽  
Growth Factor Receptor ◽  
Circulating Tumor Dna ◽  
Resistance Mechanisms ◽  
Sequencing Analysis ◽  
Kras Mutations ◽  
Target Capture ◽  
Epidermal Growth

e15077 Background: With the increase of treatment course, acquired resistance of epidermal growth factor receptor (EGFR) blockade is inevitable in patients with metastatic colorectal cancer (mCRC). KRAS mutations have been considered to be primary drivers of this acquired resistance; however, the potential function of other genes has not been extensively investigated. Methods: This study included 17 mCRC patients with acquired cetuximab resistance, and mutations in circulating tumor DNA (ctDNA) from plasma samples were identified using target-capture deep sequencing. Analysis of mutational prevalence in ctDNA, three CRC tissue-based datasets and one ctDNA dataset was performed. Mutation predicted with significant effect on acquired resistance was selected and the functional analysis was validated in CRC cells. Results: The prevalence of mutations identified in ctDNA was consistent with CRC tissue-based and ctDNA datasets. Clonal analysis revealed that 41.2% of patients were positive for at least one subclonal. Multiply resistance mechanisms of cetuximab were co-existed in individual patient, with one of them even harbored nine distinct mutations. In particularly, function analysis of Krüppel-like factor 4 (KLF4) mutation p.A472D revealed increased cetuximab resistance in CRC cells, which was associated with the increased phosphorylation of downstream EGFR signaling proteins. Conclusions: The KLF4 mutation p.A472D contributes to acquired cetuximab resistance in patients with mCRC and it may serve as a new biomarker useful in clinical application. Monitoring somatic mutations related to acquired cetuximab resistance in mCRC patients through ctDNA is an appropriate means of providing real-time insights useful for clinical reference and treatment planning.

scholarly journals PSII-33 Mitigation of testicular heat stress in boars with PG600

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 380-381
Author(s):  
John J Parrish ◽  
Jodi L Berndtson
Keyword(s):  
Heat Stress ◽  
Chorionic Gonadotropin ◽  
Semen Quality ◽  
Post Treatment ◽  
Fourier Harmonic ◽  
Treatment Groups ◽  
Summer Temperatures ◽  
Pre Treatment ◽  
Equine Chorionic Gonadotropin ◽  
Scrotal Insulation

Abstract Testicular heat stress due to increasing summer temperatures negatively impacts spermatogenesis reducing semen quality in boars. Scrotal insulation (SI) can mimic summer heat stress. Our hypothesis is that PG600 can mitigate heat stress in boars. PG600 is human chorionic gonadotropin (HCG) and equine chorionic gonadotropin (ECG) which have LH- and FSH-like effects respectively. During spermatogenesis, LH impacts testosterone production by Leydig cells and FSH impacts Sertoli cells to produce androgen receptors, inhibit apoptotic signals and sustain spermatogenesis. Eight boars (8–12 months of age) were randomly assigned to two treatment groups: SI + saline or SI + PG600. The SI was applied for 48 hrs. Injections were administered 24 hrs prior to SI application and again at onset of SI. PG600 was given at a standard gilt dose to induce puberty. Semen was collected every M-W-F for two weeks prior to treatment and 44 days post-treatment. Semen was evaluated for nuclear head shape via Fourier harmonic analysis (FHA) described as Harmonic amplitudes 0–5 (HA0-5). Semen for each collection day post-treatment was compared to the average of the semen collection days pre-treatment, described as day 0. Scrotal insulation produced a 3.7°C increase in average scrotal temperature for 48 hrs. Post-SI + saline, HA0 decreased on days 21–33 (P &lt; 0.05), HA1 increased on day 30 (P &lt; 0.05), HA2 decreased on day 35 (P &lt; 0.05), HA3 increased on days 21–33 (P &lt; 0.05), HA4 increased on days 21–26 (P &lt; 0.05), and HA5 increased on days 21–30 (P &lt; 0.05). Post-SI + PG600, decreased the number of days post-SI when changes in harmonic amplitudes were seen (P &lt; 0.05) as well as the magnitude of the response (P &lt; 0.05). PG600 was for the first time shown to significantly mitigated the response of boars to SI and testicular heat stress. Increased doses of PG600 may improve results.

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