KRAS amplification and mutation are independent events in gastroesophageal adenocarcinomas (GEA).

2019 ◽  
Vol 37 (4_suppl) ◽  
pp. 70-70
Author(s):  
Russell Madison ◽  
Joseph Chao ◽  
Jeffrey S. Ross ◽  
Vincent A. Miller ◽  
Siraj Mahamed Ali ◽  
...  
Keyword(s):  
Kras Mutation ◽  
Checkpoint Inhibitors ◽  
Treatment Strategies ◽  
Older Patient ◽  
Kras Mutations ◽  
Independent Events ◽  
Comprehensive Genomic Profiling ◽  
Tumor Mutational Burden ◽  
Tissue Specimens ◽  
Kras Codon

70 Background: KRAS mutations are common oncogenic events across cancers, but effective RAS-directed therapies are lacking. However, recent studies support use of PD-1 blockade in most subsets of lung cancer with KRAS short variant mutations (KRASSV) (PMID: 28039262), and preclinical data supports combined MEK and SHP2 inhibition in KRAS amplified ( KRASa) GEA (PMID: 30093730). We sought to explore the landscape of KRAS altered GEA and compare genomic profiles of KRAS-altered and KRAS wild-type (WT) cases for biomarkers of response to targeted therapies and immune checkpoint inhibitors. Methods: 6,667 tissue specimens from patients with advanced GEA were assayed using hybrid capture-based comprehensive genomic profiling. Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 95 or 114 loci. Descriptive statistics were used to compare among subgroups. Results: KRASSV and KRASa were identified in 11% and 5.8% of gastric adenocarcinoma (GA), respectively, and in 7.2% and 17% of esophageal adenocarcinoma (EA), respectively. KRASa and KRASSV were nearly mutually exclusive, co-occurring in only 4.4% of KRAS altered cases. ERBB2 alterations were less common in KRASSV and KRASa GEA (both 9%) as compared with KRAS WT GEA (19%) (p = 1.9E-16). EGFRa was less common in KRASSV versus KRASa GEA (1.9% vs. 9.3%, p = 2.6E-8), whereas PIK3CASV was more common in KRASSV versus KRASa (16% vs 5.0%, p = 1.5E-11). Median TMB for all groups was similar; however, KRASSV GEA had a higher mean TMB (9.7 mut/Mb) as compared to KRASa (5.1 mut/Mb, p = 5.0E-12) and KRAS WT cases (5.8 mut/Mb, p = 2.2E-07). KRAS codon 12/13 accounted for > 80% of predicted pathogenic mutations. MSI-high was also more prevalent in KRASSV (11.4%) versus KRASa (0.9%, p = 4.8E-15) and KRAS WT GEA (3.0%, p = 1.8E-25). MSI-high KRASSV GEA was associated with older patient age (median 72 years) and with high TMB (median 40.9 mut/mb). Conclusions: GA was enriched for KRAS mutation whereas EA was enriched for KRAS amplification. KRAS WT versus KRASSV versus KRASa each presented distinct genomic profiles. KRASa in the absence of KRAS mutation exists in 11% of GEA and warrants further exploration to inform combination treatment strategies.

KRAS amplification and mutation as independent events in gastroesophageal adenocarcinomas (GEA).

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e15565-e15565
Author(s):  
Joseph Chao ◽  
Russell Madison ◽  
Jeffrey S. Ross ◽  
Vincent A. Miller ◽  
Siraj Mahamed Ali ◽  
...  
Keyword(s):  
Kras Mutation ◽  
Checkpoint Inhibitors ◽  
Treatment Strategies ◽  
Older Patient ◽  
Kras Mutations ◽  
Independent Events ◽  
Comprehensive Genomic Profiling ◽  
Tumor Mutational Burden ◽  
Tissue Specimens ◽  
Kras Codon

e15565 Background: KRAS mutations are common oncogenic events across cancers, but effective RAS-directed therapies are lacking. However, recent studies support use of PD-1 blockade in most subsets of lung cancer with KRAS short variant mutations (KRASSV) (PMID: 28039262), and preclinical data supports combined MEK and SHP2 inhibition in KRAS amplified ( KRASa) GEA (PMID: 30093730). We sought to explore the landscape of KRAS altered GEA and compare genomic profiles of KRAS-altered and KRAS wild-type (WT) cases for biomarkers of response to targeted therapies and immune checkpoint inhibitors. Methods: 6,667 tissue specimens from patients with advanced GEA were assayed using hybrid capture-based comprehensive genomic profiling. Tumor mutational burden (TMB) was determined on up to 1.1 Mbp of sequenced DNA and microsatellite instability (MSI) was determined on 95 or 114 loci. Descriptive statistics were used to compare among subgroups. Results: KRASSV and KRASa were identified in 11% and 5.8% of gastric adenocarcinoma (GA), respectively, and in 7.2% and 17% of esophageal adenocarcinoma (EA), respectively. KRASa and KRASSV were nearly mutually exclusive, co-occurring in only 4.4% of KRAS altered cases. ERBB2 alterations were less common in KRASSV and KRASa GEA (both 9%) as compared with KRAS WT GEA (19%) (p = 1.9E-16). EGFRa was less common in KRASSV vs KRASa GEA (1.9% vs 9.3%, p = 2.6E-8), whereas PIK3CASV was more common in KRASSV vs KRASa (16% vs 5.0%, p = 1.5E-11). Median TMB for all groups was similar; however, KRASSV GEA had a higher mean TMB (9.7 mut/Mb) as compared to KRASa (5.1 mut/Mb, p = 5.0E-12) and KRAS WT cases (5.8 mut/Mb, p = 2.2E-07). KRAS codon 12/13 accounted for > 80% of predicted pathogenic mutations. MSI-high was also more prevalent in KRASSV (11.3%) vs KRASa (0.9%, p = 4.8E-15) and KRAS WT GEA (2.4%, p = 1.8E-25). MSI-high KRASSV GEA was associated with older patient age (median 72 years) and with high TMB (median 40.9 mut/mb). Conclusions: GA was enriched for KRAS mutation whereas EA was enriched for KRAS amplification. KRAS WT vs KRASSV vs KRASa each presented distinct genomic profiles. KRASa in the absence of KRAS mutation exists in 11% of GEA and warrants further exploration to inform combination treatment strategies.

scholarly journals Unique Genomic Landscape of High-Grade Neuroendocrine Cervical Carcinoma: Implications for Rethinking Current Treatment Paradigms

2020 ◽  
pp. 972-987
Author(s):  
Ramez N. Eskander ◽  
Julia Elvin ◽  
Laurie Gay ◽  
Jeffrey S. Ross ◽  
Vincent A. Miller ◽  
...  
Keyword(s):  
Treatment Strategies ◽  
Current Treatment ◽  
High Grade ◽  
Novel Treatment ◽  
Sample Average ◽  
Genomic Landscape ◽  
Comprehensive Genomic Profiling ◽  
Tumor Mutational Burden ◽  
Sample Range ◽  
Novel Treatment Strategies

PURPOSE High-grade neuroendocrine cervical cancer (HGNECC) is an uncommon malignancy with limited therapeutic options; treatment is patterned after the histologically similar small-cell lung cancer (SCLC). To better understand HGNECC biology, we report its genomic landscape. PATIENTS AND METHODS Ninety-seven patients with HGNECC underwent comprehensive genomic profiling (182-315 genes). These results were subsequently compared with a cohort of 1,800 SCLCs. RESULTS The median age of patients with HGNECC was 40.5 years; 83 patients (85.6%) harbored high-risk human papillomavirus (HPV). Overall, 294 genomic alterations (GAs) were identified (median, 2 GAs/sample; average, 3.0 GAs/sample, range, 0-25 GAs/sample) in 109 distinct genes. The most frequently altered genes were PIK3CA (19.6% of cohort), MYC (15.5%), TP53 (15.5%), and PTEN (14.4%). RB1 GAs occurred in 4% versus 32% of HPV-positive versus HPV-negative tumors ( P < .0001). GAs in HGNECC involved the following pathways: PI3K/AKT/mTOR (41.2%); RAS/MEK (11.3%); homologous recombination (9.3%); and ERBB (7.2%). Two tumors (2.1%) had high tumor mutational burden (TMB; both with MSH2 alterations); 16 (16.5%) had intermediate TMB. Seventy-one patients (73%) had ≥ 1 alteration that was theoretically druggable. Comparing HGNECC with SCLC, significant differences in TMB, microsatellite instability, HPV-positive status, and in PIK3CA, MYC, PTEN, TP53, ARID1A, and RB1 alteration rates were found. CONCLUSION This large cohort of patients with HGNECC demonstrated a genomic landscape distinct from SCLC, calling into question the biologic and therapeutic relevance of the histologic similarities between the entities. Furthermore, 73% of HGNECC tumors had potentially actionable alterations, suggesting novel treatment strategies for this aggressive malignancy.

Genomic landscape of non-small cell lung cancer (NSCLC) with methylthioadenosine phosphorylase (MTAP) deletion.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. 9116-9116
Author(s):  
Stephen L. Graziano ◽  
Dean C. Pavlick ◽  
Ethan Sokol ◽  
Shakti H. Ramkissoon ◽  
Eric Allan Severson ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Synthetic Lethality ◽  
Checkpoint Inhibitors ◽  
Large Cell ◽  
Combination Strategies ◽  
Genomic Landscape ◽  
Comprehensive Genomic Profiling ◽  
Tumor Mutational Burden ◽  
Cell Expression ◽  
The Impact

9116 Background: NSCLC remains a major cause of cancer-associated mortality despite major advancements in treatments. In addition to immune checkpoint inhibitors (ICPI), new strategies for clinically advanced NSCLC now include the development of new synthetic lethality targets focused on protein arginine methyl transferases such as PRMT5 that exploit the impact of tumor cell genomic loss of MTAP. Methods: 29,379 advanced/metastatic NSCLC cases underwent hybrid-capture based comprehensive genomic profiling to evaluate all classes of genomic alterations (GA). Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA and microsatellite instability (MSI) was determined on up to 114 loci. PD-L1 tumor cell expression was determined by DAKO 22C3 immunohistochemistry (IHC); low positive was a tumor proportion score (TPS) 1-49% and high positive was a TPS ≥50%. Results: 3,928 NSCLC exhibited MTAP homozygous loss. Cases had the following subtypes: adenocarcinoma (59%), squamous cell ca (22%), NSCLC NOS (16%), and large cell neuroendocrine, sarcomatoid, adenosquamous ca (all 1%). GA/tumor were similar when CDKN2A/B losses associated with 9p21 co-deletion with MTAP loss are excluded. Significant differences in currently targetable GA included KRAS G12C higher in MTAP-intact NSCLC (P =.0003) and EGFR short variant mutations higher in MTAP-deleted NSCLC (P <.0001). MTAP-intact NSCLC had higher frequencies of GAs in TP53 (P <.0001) and RB1 and a lower frequency of SMARCA4 (P <.0001). GAs frequencies in ERBB2, MET, ALK, ROS1 and NTRK1 were similar. Biomarkers for potential ICPI efficacy were higher in MTAP-intact including TMB ≥10mut/Mb (P =.0002) and low and high PD-L1 IHC staining (P =.01). Biomarkers potentially predictive of ICPI resistance ( STK11 and KEAP1) were similar in both groups. Conclusions: MTAP loss occurs in 13% of NSCLC, supporting the development of novel targeted therapies designed to exploit PRMT5 hyper-dependence in these tumors. MTAP loss in NSCLC is accompanied by differences in targeted and ICPI options for these patients which may impact future combination strategies. Further study of anti-PRMT5 drugs that are enabled by MTAP loss in NSCLC appears warranted.[Table: see text]

Differential responses to therapy in Hispanic NSCLC patients with EGFR, KRAS, or TP53 mutations.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e21027-e21027
Author(s):  
Fahmin Basher ◽  
Diana Saravia ◽  
Gilberto Lopes
Keyword(s):  
Checkpoint Inhibitors ◽  
Egfr Mutations ◽  
Comprehensive Cancer Center ◽  
Cancer Center ◽  
Kras Mutations ◽  
Tp53 Mutations ◽  
Hispanic Patients ◽  
Tumor Mutational Burden ◽  
Receive Treatment ◽  
Nsclc Patients

e21027 Background: Hispanic (H) patients with non-small cell lung cancer (NSCLC) tend to have more advanced disease at time of diagnosis and less likely to receive treatment compared to non-Hispanic white (NHW) Americans. While survival outcomes do not differ greatly, Hispanic patients tend to have lower response rates to immunotherapy and to targeted therapy with known EGFR mutations. We sought to determine if Hispanic patients with other common mutations present in NSCLC also demonstrate suboptimal responses to therapy compared to NHW patients. Methods: We performed a retrospective review of 468 patients with advanced stage NSCLC at the University of Miami / Sylvester Comprehensive Cancer Center who underwent next-generation sequencing (NGS) for whom treatment outcomes could be identified. Genomic results were obtained from Guardant360 and Foundation One testing in blood or tissue, respectively. Results: In our cohort, 154 patients (33%) were of Hispanic ethnicity, while 279 patients (60%) were NHW. Median age at time of diagnosis was 59, and 50% were male. PD-L1 status was known for 217 patients, with 110 expressing some level of PD-L1. EGFR mutations were present in 25% of all patients, KRAS mutations in 25%, and TP53 mutations in 61%. Average tumor mutational burden was 4.0 in Hispanic patients and 3.6 in NHW patients. We compared outcomes in patients receiving any therapy as well as those specifically receiving immune checkpoint inhibitors (ICI). No differences in OS were observed in our overall patient cohort between H and NHW patients. However, when stratifying patients with EGFR or KRAS mutations, Hispanic patients exhibit significantly shorter OS than their NHW counterparts. In patients with TP53 mutations, we observed no differences between H and NHW outcomes considering all therapy, but Hispanic patients exhibited improved OS with the use of ICI. Conclusions: Our data suggest that the presence of certain mutations in Hispanic patients with advanced NSCLC may serve some prognostic value in predicting responses to therapy, specifically the use of ICI. Further investigation is indicated to determine mechanisms leading to inferior responses after ICI therapy in Hispanic patients.[Table: see text]

Tumor mutational burden (TMB) and co-existing actionable mutations in biliary tract cancers (BTC).

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. 4086-4086 ◽  
Author(s):  
Apurva Jain ◽  
Rachna T. Shroff ◽  
Mingxin Zuo ◽  
Jacqueline Weatherly ◽  
Funda Meric-Bernstam ◽  
...  
Keyword(s):  
Dna Repair ◽  
Biliary Tract ◽  
Checkpoint Inhibitors ◽  
Repair Pathway ◽  
Biliary Tract Cancers ◽  
Mutational Burden ◽  
Study Results ◽  
Comprehensive Genomic Profiling ◽  
Tumor Mutational Burden ◽  
Brca1 Brca2

4086 Background: Mutations in DNA repair pathway were identified in 13% of Biliary Tract Cancers (BTC) [ Cancer2016;122:3838–3847]. High TMB tumors including melanoma, lung cancer and those with microsatellite instability (MSI-H) are associated with susceptibility to immune blockade using checkpoint inhibitors. TMB data in BTC is limited and its association with actionable somatic mutation (mut) profiles in BTC is unknown. Methods: Comprehensive genomic profiling (CGP) of 309 FFPE tissue blocks of BTC pts with a hybrid capture of all coding exons of 236 cancer-related genes and 47 introns of 19 genes rearranged in cancer was done using FoundationOne. Base substitutions, indels, gene fusion/rearrangements, TMB, and MSI status were assessed. TMB was calculated by counting mutations across a 1.25Mb region and classified into high (TMBH; ≥20 mut/Mb), intermediate (TMBI; 6 - 19mut/Mb) and low (TMBL; < 6mut/Mb). MSI high (MSIH) and Stable (MSS) status was assigned by a computational algorithm examining 114 intronic homopolymer loci. Patients with TMB ≥6 mut/Mb (N = 60) were included in the clinical correlative portion of this study. Results: Sixty patients with TMB ≥6 mut were identified out of 309 pts of which 9 (15%) were TMBH and 51 (85%) were TMBI. These included 3 (5%) MSIH and 18 (30 %) MSS. The median age was 59 years (range: 29-86), 35 (58%) were females, majority were intrahepatic cholangiocarcinoma (n = 31; 52%) and 28 (47%) presented with advanced disease at diagnosis. Twenty three (38%) pts had received radiation therapy, 28 (47%) surgery and 3 (5%) received immunotherapy. Most frequent co-existing mut seen was TP53 (N = 35; 58%). APC mut was seen in 7 (12%) pts. DNA repair pathway muts ( MSH6, BRCA1, BRCA2, ATM, MLH1, or MSH2 genes) were identified in 78% of TMBH versus 16% in TMBI cases (p < 0.0001). Frequency of PIK3CA mut differed significantly between TMBH and TMBI (44% vs 10%, p < 0.0001). Pts with TMBI had a significantly better median OS (110 weeks) as compared to TMBH (43 weeks) (p = 0.003). Conclusions: DNA repair pathway and PIK3CA mut maybe associated with TMBH in BTC. A better understanding of TMB and associated actionable mutations in BTC may be of value for the management of BTC patients with targeted agents and immunotherapy.

Impact of age on genomic alterations associated with pancreatic ductal adenocarcinoma (PDAC).

2017 ◽  
Vol 35 (4_suppl) ◽  
pp. 282-282
Author(s):  
Ben George ◽  
Mark Bailey ◽  
Alexa Betzig Schrock ◽  
Lauren Thorpe ◽  
Laurie M. Gay ◽  
...  
Keyword(s):  
Large Scale ◽  
Kinase Domain ◽  
Ductal Adenocarcinoma ◽  
Genomic Alterations ◽  
Kras Mutations ◽  
Entire Study ◽  
Formalin Fixed Paraffin Embedded ◽  
Comprehensive Genomic Profiling ◽  
Tumor Mutational Burden ◽  
Metastatic Sites

282 Background: Large scale, retrospective, sequencing projects have identified well-defined subtypes of PDAC, but therapeutic paradigms remain unchanged. We hypothesized that genomic alterations associated with PDAC in young adults (YA, age < 50) are distinctly different from that of older adults (OA, age > 50) to identify an enrichment of targetable alterations. Methods: DNA was extracted from formalin fixed paraffin embedded (FFPE) PDAC clinical specimens and comprehensive genomic profiling (CGP) was performed on hybrid-capture, adaptor ligation based libraries to a mean coverage depth of > 600 for up to 315 genes plus 47 introns from 19 genes frequently rearranged in cancer. Results: CGP was performed on 1533 FFPE PDAC specimens, 566 (36.9%) were from the primary tumor, 967 (63.1%) from metastatic sites. Median age at diagnosis was 63 years (yrs), 180 (11.7%) were YA. KRAS mutations were identified in 78.7 of YA and 87.7% of OA. The differentially altered genes between the two groups were KRAS (p = 0.004), TP53 (p = 0.04), BRCA2 (p = 0.02), AKT2 (p = 0.03), MAP2K4 (P = 0.003) and DNMT3A (p = 0.0002). The median tumor mutational burden (TMB) for the entire study set was 2.7 (YA – 2.5, OA –2.7). BRAF kinase domain deletion was observed in 1 patient (OA). ALK fusions were present in 2 patients (1 YA & 1 OA) and these patients had durable responses to specific ALK inhibitors. Conclusions: The majority of the genomic alterations identified were not significantly different on the basis of age. However, identification of subpopulations, such as ALK kinase fusions and BRAF kinase domain deletions that can translate into sustained clinical benefit from matched targeted therapy is promising. This underscores the importance of CGP in PDAC to investigate other targetable genomic alterations.

Mutation Analysis of Braf Exon 15 and Kras Codons 12 and 13 in Moroccan Patients with Colorectal Cancer

2010 ◽  
Vol 25 (4) ◽  
pp. 179-184 ◽  
Author(s):  
Bahia Bennani ◽  
Sophie Gilles ◽  
Frederic Fina ◽  
Isabelle Nanni ◽  
Sidi Adil Ibrahimi ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Direct Sequencing ◽  
Braf Mutations ◽  
Kras Mutations ◽  
Two Samples ◽  
Microenvironmental Factors ◽  
Tissue Specimens ◽  
Moroccan Patients ◽  
Codon 12 And 13 ◽  
Kras Codon

Background The RAS/RAF/MEK/MAP kinase cascade transduces signals from the cell surface to the nucleus in order to control cellular responses including proliferation, differentiation and survival. We investigated the occurrence of BRAF exon 15 and KRAS codon 12 and 13 mutations in Moroccan patients with colorectal cancer. Methods Sixty-two samples from patients with sporadic colorectal adenocarcinomas were studied for BRAF exon 15 and KRAS codon 12 and 13 mutations. DNA from paraffin-embedded tissue specimens was analyzed by a combination of polymerase chain reaction–high resolution melting and direct sequencing. Results Of the analyzed specimens, 29% exhibited KRAS codon 12 or 13 mutations and only 1.6% carried a BRAF codon 600 mutation. KRAS mutations were more often observed in women (35.5%) than in men (22.6%). Patients in the age range between 41 and 60 years were more likely to be carriers of this mutation. No KRAS mutations were detected in patients aged >60 years. Conclusion Despite the limited study sample, our data suggest that KRAS mutations arise more frequently than BRAF mutations in Moroccan patients with colorectal carcinomas. The KRAS mutation status must be assessed in a large cohort of Moroccan patients to confirm these findings and to determine whether this mutation in combination with extrinsic, environmental or microenvironmental factors might be involved in the high frequency of colorectal cancer in middle-aged Moroccans.

scholarly journals BRAF Mutation as a Potential Therapeutic Target for Checkpoint Inhibitors: A Comprehensive Analysis of Immune Microenvironment in BRAF Mutated Colon Cancer

2021 ◽  
Vol 9 ◽  
Author(s):  
Shuyi Cen ◽  
Kun Liu ◽  
Yu Zheng ◽  
Jianzhen Shan ◽  
Chao Jing ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Braf Mutation ◽  
Plasma Cells ◽  
Immune Cell ◽  
Checkpoint Inhibitors ◽  
Treatment Strategies ◽  
Gene Expression Omnibus ◽  
The Cancer Genome Atlas ◽  
Immune Microenvironment ◽  
Tissue Specimens

BRAF mutated colon cancer presents with poor survival, and the treatment strategies are controversial. The tumor microenvironment, which plays a key role in tumorigenesis as well as responses to treatments, of this subtype is largely unknown. In the present study, we analyzed the differences of immune microenvironments between BRAF mutated and BRAF wild-type colon cancer utilizing datasets from The Cancer Genome Atlas and Gene Expression Omnibus and confirmed the findings by tissue specimens of patients. We found that BRAF mutated colon cancer had more stromal cells, more immune cell infiltration, and lower tumor purity. Many immunotherapeutic targets, including PD-1, PD-L1, CTLA-4, LAG-3, and TIM-3, were highly expressed in BRAF mutated patients. BRAF mutation was also correlated with higher proportions of neutrophils and macrophages M1, and lower proportions of plasma cells, dendritic cells resting, and T cells CD4 naïve. In conclusion, our study demonstrates a different pattern of the immune microenvironment in BRAF mutated colon cancer and provides insights into the future use of checkpoint inhibitors in this subgroup of patients.

KRAS mutation analysis in patients (pts) with locally advanced pancreatic cancer (LAPC) treated with gefitinib and chemoradiation therapy (CT-RT) in a phase I trial

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 4106-4106 ◽  
Author(s):  
H. Chen ◽  
D. Raben ◽  
T. Schefter ◽  
M. Kane ◽  
M. McCarter ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Overall Survival ◽  
Phase I ◽  
Kras Mutation ◽  
Phase I Trial ◽  
Locally Advanced ◽  
Advanced Pancreatic Cancer ◽  
Kras Mutations ◽  
Direct Dna Sequencing ◽  
Kras Codon

4106 Background: Correlative studies that incorporate biomarkers to rapidly analyze response to new agents are needed. Unique to pancreatic cancer is the high incidence of KRAS mutations (over 90%). This pilot study evaluated plasma KRAS mutations for disease monitoring in LAPC pts treated on a Phase I trial combining CT-RT with the EGFR inhibitor, gefitinib. Methods: DNA was extracted from plasma of 11 pts collected at 3 timepoints: pre-gefitinib, pre-CT-RT, and post-gefitinib+CT-RT. Matched tissue DNA was obtained from 4 pts with available paraffin blocks. KRAS codon 12 mutations were detected using a two-stage RFLP-PCR assay. Cell line controls: Calu-1 (mutant KRAS) and LNCaP (wild-type KRAS). Mutations were confirmed by direct DNA sequencing. Results were related to pt clinical data. Results: KRAS mutations were detected in the pre-gefitinib plasma of 5/11 pts, and in the matched tumor tissue of 3/4 pts. Of the 5 pts with plasma KRAS mutations, 2 pts with no detectable mutant KRAS in the plasma post-gefitinib+CT-RT had overall survival of 8 and 21 months, whereas 2 pts who retained mutant KRAS had overall survival of only 2 and 5 months, and one pt withdrew early. Of the 3 tumor tissues containing mutant KRAS, the mutations were also detectable in the matched plasma in 2 pts (67%). KRAS codon 12 mutations spectrum: 4 GGT→GAT, 2 GGT→GTT and 1 GGT→AGT. Conclusions: Plasma KRAS mutations are readily detectable in LAPC pts, and the clearance or persistence of plasma KRAS mutations after treatments reflected the clinical course in some cases. The use of plasma KRAS mutation as a marker of survival and response will be further assessed in a recently approved phase I trial using a proteasome inhibitor with chemoradiation at the University of Colorado. No significant financial relationships to disclose.

The role of the KRAS G13D mutation in patients with metastatic colorectal cancer (mCRC) treated with first-line chemotherapy plus cetuximab.

2011 ◽  
Vol 29 (4_suppl) ◽  
pp. 630-630 ◽  
Author(s):  
S. Tejpar ◽  
C. Bokemeyer ◽  
I. Celik ◽  
M. Schlichting ◽  
E. Van Cutsem
Keyword(s):  
Kras Mutation ◽  
Melting Curve ◽  
First Line ◽  
Kras Mutations ◽  
Biologic Effects ◽  
Disease Stabilization ◽  
Table Data ◽  
Kras Codon ◽  
Line Chemotherapy

630 Background: The CRYSTAL and OPUS studies showed that adding cetuximab (cet) to first-line chemotherapy (CT) significantly improved clinical benefit in patients (pts) with KRAS wild-type (wt) mCRC. Pts with KRAS codon 12 or 13 mutations are excluded from cet treatment. Studies suggest that not all KRAS mutations are equivalent in their biologic effects. Occasional responses and prolonged disease stabilization have been recorded following cet treatment of tumors with mainly KRAS codon 13 mutations. We investigated the influence of the most common KRAS codon 13 mutation (G13D) on clinical outcome compared with pts with other KRAS mutations or wt tumors in the CRYSTAL and OPUS trials. Methods: KRAS mutations were detected in tumor DNA from archival material using a PCR clamping and melting curve technique. Treatment arms were compared by KRAS mutation status for progression-free (PFS) and overall survival (OS). Results: In the CRYSTAL study of 1,063 evaluable pts 63% were KRAS wt, 6% were G13D mutant (mt) and 32% had other mutations. In the OPUS study of 315 evaluable pts, 57% were KRAS wt, 7% were G13D mt, and 36% had other mutations. Compared with KRAS wt pts those with G13D mutations did not benefit from the addition of cet to CT (Table). Data of comparisons of the G13D mutation with other KRAS mutations in these studies will be presented. Conclusions: Patients with KRAS G13D mt tumors did not appear to benefit from the addition of cet to first-line CT for mCRC. This analysis confirms the current practice of KRAS mutation testing as the standard diagnostic tool for determining first-line treatment of mCRC pts. [Table: see text] [Table: see text]

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