Expanded RAS and BRAF V600 testing as predictive biomarkers for single agent cetuximab in the randomized phase III CO.17 trial.

2019 ◽  
Vol 37 (4_suppl) ◽  
pp. 537-537 ◽  
Author(s):  
Jonathan M. Loree ◽  
Anthony Dowers ◽  
Dongsheng Tu ◽  
Christopher J. O'Callaghan ◽  
Dan Edelstein ◽  
...  
Keyword(s):  
Single Agent ◽  
Predictive Biomarkers ◽  
Digital Pcr ◽  
Phase Iii ◽  
Molecular Profile ◽  
Braf Mutations ◽  
Exon 2 ◽  
Archival Tissue ◽  
Frequency Detection ◽  
Kras Exon

537 Background: KRAS/NRAS ( RAS) testing of exons 2, 3 and 4 is standard prior to anti-EGFR treatment in metastatic colorectal cancer and many consider BRAFV600 ( BRAF) mutations predictive. CO.17 was a randomized phase III trial comparing cetuximab vs best supportive care (BSC) in unselected patients (pts). Re-analysis tested only KRAS exon 2, thus the benefit of cetuximab in RAS/BRAF wild type (WT) pts is unclear. Methods: We retrospectively performed expanded RAS/BRAF testing using a highly sensitive digital PCR method (BEAMing; 1% allele frequency detection limit) on micro-dissected archival tissue from 248 CO.17 pts. Additional pts without available archival tissue, with prior Sanger sequencing or therascreen results were included in analyses if mutations were previously detected (n = 77). Overall survival (OS), progression free survival (PFS), and response rates (RR) were compared by molecular profile. Results: Of 248 sequenced pts, 139 (56%) were RAS mutant, with 112 (45%) exon 2, 11 (4%) exon 3 and 6 (2%) exon 4 KRAS mutant, and 10 (4%) NRAS mutant pts. Seven (3%) BRAF mutant, and 97 (30%) confirmed RAS/BRAF WT pts were identified. Results are summarized below. A test of interaction indicated RAS status was predictive for PFS (p = 0.0001) and OS (p = 0.037) and BRAF status neared significance as a predictive marker for PFS (p = 0.089) but not OS (p = 0.24). Conclusions: These updated results demonstrate an improved PFS (HR 0.25 vs 0.40 previously) and OS (HR 0.51 vs 0.55 previously) for cetuximab in RAS/BRAF WT pts compared to prior analyses that included only KRAS exon 2 mutation status. We provide an estimate of single agent cetuximab efficacy for future anti-EGFR re-challenge studies and demonstrate further support that BRAF mutations may predict lack of benefit from anti-EGFR therapy. Clinical trial information: NCT00079066. [Table: see text]

Comprehensive analysis of KRAS and NRAS mutations as predictive biomarkers for single agent panitumumab (pmab) response in a randomized, phase III metastatic colorectal cancer (mCRC) study (20020408).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3617-3617 ◽  
Author(s):  
Scott D. Patterson ◽  
Marc Peeters ◽  
Salvatore Siena ◽  
Eric Van Cutsem ◽  
Yves Humblet ◽  
...  
Keyword(s):  
Single Agent ◽  
Objective Response ◽  
Predictive Biomarkers ◽  
Progression Free Survival ◽  
Best Supportive Care ◽  
Phase Iii ◽  
Exon 2 ◽  
Biomarker Analysis ◽  
Exon 4 ◽  
Kras Exon

3617 Background: An exploratory biomarker analysis of the randomized, phase 3 monotherapy 20020408 study of pmab vs best supportive care (BSC) demonstrated that mutations in KRAS exon 3 and NRAS exons 2 and 3 appeared to be predictive of pmab response (Peeters et al, 2013). We expanded these results to determine whether mutations in exon 4 of the KRAS and NRAS genes are predictive for pmab treatment and to determine the treatment effect in the overall wild-type (WT) KRAS and NRAS population. Methods: Using a combination of Next Generation Sequencing, Sanger Sequencing, and WAVE-based SURVEYOR Scan Kits from Transgenomic, archival patient tumors were examined for mutations in KRAS and NRAS exon 4. These data were combined with previously presented data from KRAS and NRAS exon 2 and 3 analyses for evaluation of the comprehensive WT KRAS and NRAS subgroup. Results: 9/243 (3.7%) and 2/243 (0.8%) patient tumors with WT KRAS exon 2 status harbored a mutation in KRAS or NRAS exon 4, respectively. One tumor had mutations in both KRAS and NRAS exon 4. In the pmab arm, patients with WT KRAS and WT NRAS tumor status had an objective response rate (ORR) of 15% (11/72) whereas patients with mutant (MT) KRAS or MT NRAS tumor status had an ORR of 1% (1/95; 1 patient with MT KRAS exon 4 had a partial response). There were no responses in the BSC arm regardless of the tumor status. In this analysis set, the treatment hazard ratio (HR; pmab:BSC) for progression-free survival (PFS) in the WT KRAS and WT NRAS subgroup was 0.38 (95% CI: 0.27 - 0.56), and in the MT KRAS or MT NRAS subgroup was 0.98 (95% CI: 0.73 - 1.31). The original WT KRAS exon 2 subgroup PFS HR was 0.45 (95% CI: 0.34 - 0.59) (Amado et al, 2007). Conclusions: This exploratory analysis suggests that mutations in KRAS and NRAS exon 4 occur in a small, but meaningful percentage of patients with mCRC. Extending previous findings from this study in patients with MT KRAS and/or MT NRAS exon 2 and/or 3 tumors, patients with MT KRAS and/or MT NRAS exon 4 tumors do not appear to benefit from pmab therapy. Clinical trial information: NCT00113763.

Analysis of KRAS/NRAS, PI3CA, and BRAF mutations in the phase II KSCC0901 study of cetuximab plus S-1 as third-line treatment for metastatic colorectal cancer in Japanese patients.

2014 ◽  
Vol 32 (3_suppl) ◽  
pp. 587-587
Author(s):  
Yasunori Emi ◽  
Eiji Oki ◽  
Hiroshi Saeki ◽  
Hiroyuki Kitao ◽  
Hironori Samura ◽  
...  
Keyword(s):  
Direct Sequencing ◽  
Treatment Protocol ◽  
Progression Free Survival ◽  
Japanese Patients ◽  
Phase Iii ◽  
Braf Mutations ◽  
Full Spectrum ◽  
Exon 2 ◽  
Third Line ◽  
Kras Exon

587 Background: Exploratory biomarker studies in the randomized phase III PRIME study suggested that patients with mCRC tumors harboring a mutation (MT) in KRAS or NRAS (beyond KRAS exon 2) do not respond to panitumumab-FOLFOX4 (2013 ASCO, JCO 31, #3511). We reported the efficacy and safety of S-1+. Cetuximab (Cmab) in wild-type (WT)-KRAS (exon 2) mCRC patients (pts) as third-line therapy (KSCC0901) (2012 ASCO, JCO 30, s3558). The full spectrum of characterized RAS (KRAS and NRAS), PI3CA, and BRAFMTs may affect efficacy in S-1+Cmab therapy in Japanese patients. Methods: An analysis was conducted to assess the treatment effect of S-1+Cmab, according to RAS (KRAS and NRAS), PI3CA, and BRAF MTs. The treatment protocol of KSCC0901 was as follows: weekly intravenous Cmab administration of 400 mg/m2 (day 1), 250 mg/m2/week (following day 1) and oral administration of 80 mg/m2/day S-1 on days 1–28 of each 42-day cycle. MTs in KRAS codons 12 and 13 (exon 2) were detected using direct sequencing according to the manufacturer’s instructions. MTs in KRAS codons 61 and 146, NRAS codons 12, 13 and 61, BRAF codon 600 and PIK3CA codons 542, 545, 546, and 1047 were detected using the multiplex PCR-Luminex method-based MEBGEN MT Kit (Medical and Biological Laboratories, Nagoya, Japan). Results: 35 pts were eligible for the analysis. Number of MT cases of KRAS, NRAS, BRAF, and PIK3CA were 4, 2, 2, and 5, respectively. One case had MTs of NRAS and PIK3CA. In 37 cases with WT KRASexon2 pts, median progression-free survival (mPFS) was 5.6 [95% CI: 4.4 – 5.7] months; median overall survival (mOS), 13.5 [8.5-16.5] months; and best overall response (ORR), 37.8%. In the all-WT subgroup 23 cases, mPFS was 5.6 [5.1-7.1] months; mOS, 13.5 [9.3-21.2] months; and best ORR, 47.8%. In 12 patients with any MT, mPFS was 4.0 [2.7-7.5] months; mOS, 5.5[2.9- ] months; and best ORR, 16.7%. Conclusions: These results suggest that also in Japanese patients receiving a Cmab containing regimen, RAS, BRAF and PIK3CA MT status beyond KRAS exon2 might predict non-responders to treatment. Clinical trial information: UMIN000002475.

Analysis of KRAS/NRAS and BRAF mutations in the phase III PRIME study of panitumumab (pmab) plus FOLFOX versus FOLFOX as first-line treatment (tx) for metastatic colorectal cancer (mCRC).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3511-3511 ◽  
Author(s):  
Kelly S. Oliner ◽  
Jean-Yves Douillard ◽  
Salvatore Siena ◽  
Josep Tabernero ◽  
Ronald L. Burkes ◽  
...  
Keyword(s):  
Braf Mutation ◽  
Predictive Biomarker ◽  
Primary Objective ◽  
Phase Iii ◽  
Braf Mutations ◽  
Exon 2 ◽  
Mutation Status ◽  
Exon 4 ◽  
Kras Exon ◽  
Clinical Trial Information

3511 Background: Analysis of a phase III pmab monotherapy study indicated that KRAS and NRAS mutations beyond KRAS exon 2 may be predictive of pmab efficacy (Peeters et al, 2013). Methods: The primary objective of this prospectively defined retrospective analysis of PRIME was to assess the effect of pmab + FOLFOX vs FOLFOX on overall survival (OS) in pts with mCRC based on RAS (KRAS or NRAS) or BRAF mutation status. "Gold standard" bidirectional Sanger sequencing and WAVE-based SURVEYOR Scan Kits from Transgenomic (conducted independently) were used to detect mutations in KRAS exon 3, exon 4; NRAS exon 2, exon 3, exon 4; and BRAF exon 15. Results: RAS ascertainment rate was 90%. Tx HRs for pts with WT RAS were 0.78 (95% CI, 0.62 - 0.99; p = 0.04) for OS (median gain of 5.8 months in the pmab arm) and 0.72 (95% CI, 0.58 - 0.90; p = < 0.01) for PFS. Tx HRs for WT KRAS exon 2/mutant (MT) other RAS were 1.29 (95% CI, 0.79 - 2.10; p = 0.31) for OS and 1.28 (95% CI, 0.79 - 2.07; p = 0.32) for PFS. Tx HRs for pts with WT or MT BRAF were inconsistent with a predictive biomarker (Table). Prognostic effects of the tested biomarkers will be presented. Conclusions: A statistically significant OS benefit was observed in pts with WT RAS mCRC treated with pmab + FOLFOX vs FOLFOX. Pmab is unlikely to benefit pts with any RAS mutations. In this analysis, BRAF mutation had no predictive value. Clinical trial information: NCT00364013. [Table: see text]

Randomized phase III study of panitumumab (pmab) vs. cetuximab (cmab) in chemorefractory wild-type (WT) KRAS exon 2 metastatic colorectal cancer (mCRC): Outcomes by hypomagnesemia (hypomag) in ASPECCT.

2015 ◽  
Vol 33 (3_suppl) ◽  
pp. 705-705
Author(s):  
Timothy Jay Price ◽  
Marc Peeters ◽  
Tae Won Kim ◽  
Jin Li ◽  
Stefano Cascinu ◽  
...  
Keyword(s):  
Primary Endpoint ◽  
Objective Response ◽  
Progression Free Survival ◽  
Phase Iii ◽  
Exon 2 ◽  
Secondary Endpoints ◽  
Phase Iii Study ◽  
Grade 3 ◽  
Dose Modifications ◽  
Kras Exon

705 Background: ASPECCT met its primary endpoint of non-inferiority of overall survival (OS) of pmab vs. cmab. We evaluate outcomes by hypomag, an on-treatment, anti-EGFR related adverse event that develops due to the inhibition of EGFR function. Conflicting reports have suggested hypomag is associated with survival. Methods: Patients with previously treated WT KRAS exon 2 mCRC were randomized 1:1 to receive pmab or cmab. The primary endpoint was non-inferiority of OS. Progression-free survival (PFS) and objective response rate (ORR) were secondary endpoints. Patients were categorized ± any grade hypomag during the study and data analyzed by treatment arm. Analysis of Mg supplementation during hypomag was not conducted. Results: 999 patients were randomized and treated: 499 pmab, 500 cmab. Any grade hypomag was 28.8% and grade ≥3 was 7.3% in the pmab arm vs. 18.9% and 2.6% in the cmab arm, respectively. Median time to first hypomag onset was 82 days in the pmab arm and 57 days in the cmab arm. In the pmab arm, 1.0% of patients discontinued treatment and 5% of patients had dose modifications due to hypomag vs. <0.5% and 3% in the cmab arm, respectively. Results are shown (Table). Conclusions: In ASPECCT, rates of hypomag were higher in the pmab vs. the cmab arm. Patients who developed any grade hypomag with pmab or cmab had higher ORR, PFS, and OS compared with those patients who did not. Clinical trial information: NCT00788957. [Table: see text]

An open label, randomized phase III trial evaluating the treatment (tx) effects of panitumumab (pmab) + best supportive care (BSC) versus BSC in chemorefractory wild-type (WT) KRAS exon 2 metastatic colorectal cancer (mCRC) and in WT RAS mCRC.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 642-642 ◽  
Author(s):  
Tae Won Kim ◽  
Anneli Elme ◽  
Zvonko Kusic ◽  
Joon Oh Park ◽  
Anghel Adrian Udrea ◽  
...  
Keyword(s):  
Objective Response ◽  
Progression Free Survival ◽  
Best Supportive Care ◽  
Phase Iii ◽  
Open Label ◽  
Exon 2 ◽  
Ras Mutation ◽  
Secondary Endpoints ◽  
To Receive ◽  
Kras Exon

642 Background: An overall survival (OS) benefit in WT KRAS exon 2 mCRC was not seen with pmab monotherapy in study 20020408 possibly due to crossover of patients (pts) in the BSC arm. Retrospective analyses have indicated that other KRAS and NRAS mutations beyond KRAS exon 2 are predictive of anti-EGFR tx effects. Study 20100007 assesses the OS benefit of pmab in chemorefractory WT KRAS exon 2 mCRC and is the first phase 3 trial to prospectively evaluate pmab tx effects in WT RAS (exons 2, 3, and 4 of KRAS and NRAS) mCRC. Methods: Anti-EGFR naive pts were randomized 1:1 to receive pmab (6 mg/kg Q2W) + BSC or BSC. KRAS exon 2 and RAS mutation status of tumors were determined centrally. The primary endpoint was OS in WT KRAS exon 2 mCRC. Secondary endpoints were OS in WT RAS mCRC and progression-free survival (PFS), objective response rate (ORR), and safety in both WT KRAS exon 2 and WT RAS groups. Crossover was not permitted. Results: 377 pts with WT KRAS exon 2 mCRC were enrolled. RAS ascertainment rate was 86%. OS was significantly improved with pmab + BSC vs BSC in both WT KRAS exon 2 (HR=0.73, 95% CI=0.57-0.93, P=0.0096) and WT RAS (HR=0.70, 95% CI=0.53-0.93, P=0.0135) mCRC (results in table). Pts with mutant RAS mCRC did not benefit from pmab tx (OS HR=0.99, 95% CI=0.49-2.00). No new safety signals were seen. Conclusions: Pmabsignificantly improved OS in chemorefractory WT KRAS exon 2 mCRC. The tx effects in OS and PFS were more pronounced in those with WT RAS mCRC, further substantiating the importance of RAS testing at diagnosis to best inform the use of pmab to treat mCRC. Clinical trial information: NCT01412957. [Table: see text]

Monitoring tumor specific mutations in plasma during systemic treatment of biliary tract cancer.

2017 ◽  
Vol 35 (4_suppl) ◽  
pp. 318-318
Author(s):  
Lars Henrik Jensen ◽  
Rikke Fredslund Andersen ◽  
Anders Kristian Moeller Jakobsen
Keyword(s):  
Biliary Tract ◽  
Biliary Tract Cancer ◽  
Digital Pcr ◽  
Braf V600e ◽  
Wild Type ◽  
Liquid Biopsies ◽  
Exon 2 ◽  
Tract Cancer ◽  
Initial Drop ◽  
Kras Exon

318 Background: We have previously reported a rate of 23% RAS/RAF mutations in plasma from patients with KRAS exon 2 and 3 wild-type, non-resectable biliary tract tumors. We wanted to explore the changes in circulating tumor specific DNA (ctDNA) during systemic chemotherapy in these patients. Methods: Patients with non-resectable biliary tract cancer treated within a phase II trial were included if they had KRAS exon 2 and 3 wild-type tumor tissue, had quantifiable levels of tumor specific DNA in plasma and progressive disease on imaging. They received gemcitabine, oxaliplatin and capecitabine with either bevacizumab or panitumumab. Treatment continued for up to six months until progression. Blood sampling and evaluation according to RECIST 1.1 were done every 12 weeks. Droplet Digital PCR was performed on DNA isolated from 4 ml plasma. A pre-amplification step was done and adequate positive and negative controls were included. The extended RAS and BRAF mutation analysis covered 20 mutations in KRAS exons 3/4, NRAS exon 2/3, PIK3CA and BRAF V600E. The percentage of tumor specific DNA relative to total DNA was reported. Results: The inclusion criteria were met by 13 patients, 10 women and three men. The typical pattern was seen in eight cases, where the percentage of tumor specific DNA dropped at least half during therapy and rose at least two-fold at progression. In three patients, a baseline sample was not available or there was not an initial drop, but the ctDNA rose at progression. One patient had an initial drop, but not a rise a progression based on imaging. The last patient progressed rapidly. Conclusions: This exploratory analysis pointed toward changes in percentage of tumor specific mutations in plasma as a marker of effect and progression. Dynamics of liquid biopsies is a promising tool in monitoring biliary tract cancer patients during systemic therapy. Clinical trial information: NCT01206049.

Overall survival (OS) analysis from PRIME: Randomized phase III study of panitumumab (pmab) with FOLFOX4 for first-line metastatic colorectal cancer (mCRC).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3620-3620 ◽  
Author(s):  
Jean-Yves Douillard ◽  
Salvatore Siena ◽  
Josep Tabernero ◽  
Ronald L. Burkes ◽  
Mario Edmundo Barugel ◽  
...  
Keyword(s):  
Performance Status ◽  
Objective Response ◽  
Progression Free Survival ◽  
Final Analysis ◽  
Phase Iii ◽  
First Line ◽  
Primary Analysis ◽  
Ecog Performance Status ◽  
Exon 2 ◽  
Kras Exon

3620 Background: The primary and final analyses of PRIME demonstrated that pmab + FOLFOX4 significantly improved progression-free survival (PFS) vs FOLFOX4 alone for first-line treatment of patients (pts) with wild-type (WT) KRAS exon 2 mCRC. Methods: Pts were randomized 1:1 to pmab 6.0 mg/kg every 2 weeks + FOLFOX4 or FOLFOX4 alone and had no prior chemotherapy for mCRC, ECOG performance status ≤ 2, and tumor tissue for biomarker testing. The primary endpoint was PFS by central assessment. Secondary endpoints included OS, objective response rate, and safety. KRAS exon 2 tumor status was determined by a blinded central lab prior to the primary analysis. This exploratory analysis of updated survival (>80% OS events) estimated the treatment effect of pmab + FOLFOX4 compared with FOLFOX4 alone on OS by KRAS exon 2 status. Previous analyses in pts with WT KRAS exon 2 tumor status reported OS with an event rate of 54% of pts in the primary analysis and 68% of pts in the final analysis. Results: 1183 pts were randomized and received treatment: 593 pts in the pmab + FOLFOX4 arm and 590 pts in the FOLFOX4 alone arm. The KRAS exon 2 ascertainment rate was 93%, consistent with the primary analysis. 535/656 pts (82%) with WT KRAS exon 2 mCRC had an OS event at the time of this analysis. Results are shown (Table). Conclusions: In this updated analysis, an improvement in OS was observed in pts with WT KRAS exon 2 mCRC treated with pmab + FOLFOX4 vs FOLFOX4 alone (p = 0.03). Median OS was reduced in pts with mutant (MT) KRAS mCRC (p = 0.16) and is consistent with previous analyses. Updated efficacy and safety results will be presented. KRAS testing is critical to select appropriate pts with mCRC for treatment with pmab. Clinical trial information: NCT00364013. [Table: see text]

Mutations within the EGFR signaling pathway: Influence on efficacy in FIRE-3—A randomized phase III study of FOLFIRI plus cetuximab or bevacizumab as first-line treatment for wild-type (WT) KRAS (exon 2) metastatic colorectal cancer (mCRC) patients.

2014 ◽  
Vol 32 (3_suppl) ◽  
pp. 445-445 ◽  
Author(s):  
Sebastian Stintzing ◽  
Andreas Jung ◽  
Lisa Rossius ◽  
Dominik Paul Modest ◽  
Ludwig Fischer von Weikersthal ◽  
...  
Keyword(s):  
Pik3ca Mutation ◽  
Braf V600e ◽  
Phase Iii ◽  
Line Treatment ◽  
First Line ◽  
Exon 2 ◽  
Ras Mutations ◽  
Egfr Signaling Pathway ◽  
Kras Exon ◽  
First Line Treatment

445 Background: The FIRE-3 study (AIO KRK-0306) was designed as a randomized multicenter trial to compare the efficacy of FOLFIRI plus cetuximab (cet) to FOLFIRI plus bevacizumab (bev) as first-line treatment in KRAS WT mCRC patients. FOLFIRI plus cet as first-line treatment of KRAS WT mCRC patients resulted in comparable overall response rates (ORR) and progression free survival (PFS) when compared to FOLFIRI plus bev. Overall survival (OS) was significantly longer in the FOLFIRI plus cet arm. Methods: In a preplanned analysis, the effect of mutations within the EGFR dependent pathway were investigated. Next to mutations within KRAS (exon 2, 3, 4), NRAS (exon 2, 3, 4) and BRAF (V600E), mutations within PIK3CA (exon 9 and 20) and Akt were investigated and their impact on ORR, PFS and OS within the FIRE-3 population was evaluated. The analysis of all mutations was carried out employing pyrosequencing. Results: The ITT population consisted of 592 KRAS WT (exon 2) patients. The current analysis includes 488 cases (82.4%) with tumor tissue available. In 407 pts sequencing of all RAS mutations was possible. The ORR within the WT RAS patient group was higher in the FOLFIRI plus cet arm (65.5% vs 59.6%; Fisher´s p: 0.157). HRs (cet; bev) for pts with WT RASwere 0.93 (95% CI, 0.74-1.17; p = 0.54) for PFS and 0.70 (95% CI, 0.53-0.92; p = 0.01) for OS. PIK3CA mutation did not influence PFS nor OS when compared to the RAS wt population. Conclusions: ORR and OS were increased in patients with cet plus FOLFIRI as compared to bev plus FOLFIRI in patients without RAS mutations. Exclusion of patients with RAS mutations identifies a population which is more likely to benefit from cetuximab. Clinical trial information: NCT00433927.

Early tumor shrinkage (ETS) and depth of response (DpR) in wild-type (WT) RAS tumors from the phase III trial of panitumumab (pmab) plus best supportive care (BSC) versus BSC in chemorefractory metastatic colorectal cancer (mCRC).

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. 3561-3561 ◽  
Author(s):  
Tae Won Kim ◽  
Anneli Elme ◽  
Joon Ho Park ◽  
Anghel Adrian Udrea ◽  
Nebojsa S. Manojlovic ◽  
...  
Keyword(s):  
Final Analysis ◽  
Best Supportive Care ◽  
Tumor Burden ◽  
Phase Iii ◽  
Tumor Shrinkage ◽  
Exon 2 ◽  
Depth Of Response ◽  
Early Tumor ◽  
A Prospective Study ◽  
Kras Exon

3561 Background: Activating RAS mutation is a negative predictor of anti-EGFR therapy. In the final analysis of 20100007, the first phase 3 study to prospectively evaluate efficacy and safety of WT RAS ( KRAS and NRAS exons 2, 3, 4 ) mCRC, pmab + BSC continued to show improved survival (OS and PFS) and ORR. Recent data suggest that tumor burden reduction and ETS may contribute to improved OS. Previous studies have shown that pmab plus chemotherapy results in ETS, which correlates with OS benefit (Douillard et al, EJC, 2015; Rivera et al, JCO, 2015; Mansmann et al, JCO 2013). Here we report analyses of ETS and DpR and the effect on OS in patients (pts) with WT RAS mCRC treated with pmab monotherapy in the ‘0007 trial. Methods: Anti-EGFR naïve pts with WT KRAS exon 2 mCRC were randomized 1:1 to pmab + BSC or BSC. Pt tumors were further evaluated for RAS status, and DpR (percent tumor shrinkage at nadir or progression) and ETS (≥/< 0% or ≥/< 20% by week 8) were analyzed in WT RAS pts. OS and PFS were compared for each ETS group. Results: Of 377 pts with WT KRAS exon 2 mCRC, 270 were WT RAS (142 pmab + BSC, 128 BSC alone). In the pmab + BSC arm, 69.5% and 38.2% of pts had ≥0% and ≥20% ETS, respectively, and median (Q1, Q3) DpR was 16.9% (0%, 37.5%). OS was improved in pts with higher ETS (≥0% or ≥20%) compared with lower ETS (<0% or <20%; Table). Conclusions: In this post-hoc analysis, pmab monotherapy provided any ETS benefit (≥0%) in 69.5% of WT RAS mCRC pts, and ETS was associated with improved PFS and OS. Pmab should be considered both in combination and as monotherapy for its significant impact on OS and also for its ability for substantial ETS in pts with WT RAS mCRC. Validation is necessary to investigate the value and cutoff of ETS in a prospective study. Clinical trial information: NCT01412957. [Table: see text]

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