Search

PURPOSE To verify whether the intensification of the upfront chemotherapy backbone with a modified schedule of modified fluorouracil, leucovorin, oxaliplatin, and irinotecan (mFOLFOXIRI) increases the activity of fluorouracil, leucovorin, and oxaliplatin when both regimens are combined with panitumumab as initial treatment for RAS and BRAF wild-type (wt) metastatic colorectal cancer (mCRC). METHODS TRIPLETE was a prospective, open-label, phase III trial in which previously untreated patients with unresectable RAS and BRAF wt mCRC were randomly assigned 1:1 to modified FOLFOX/panitumumab (control group) or mFOLFOXIRI/panitumumab (experimental group) up to 12 cycles, followed by fluorouracil/-leucovorin/panitumumab until disease progression. The primary end point was objective response rate (ORR) according to RECIST 1.1. Hypothesizing an ORR of 60% in the control group, 432 cases provided 90% power to a two-sided chi-square test for heterogeneity with a two-sided alpha error of .05 to detect ≥ 15% differences between arms (ClinicalTrials.gov identifier: NCT03231722 ). RESULTS From September 2017 to September 2021, 435 patients were enrolled (control group/experimental group: 217/218) in 57 Italian sites. One hundred sixty (73%) patients treated with mFOLFOXIRI plus panitumumab and 165 (76%) patients treated with modified FOLFOX plus panitumumab achieved RECIST response (odds ratio 0.87, 95% CI, 0.56 to 1.34, P = .526). No differences in early tumor shrinkage rate (57%/58%, P = .878) and deepness of response (median: 48%/47%, P = .845) were reported, nor in R0 resection rate (25%/29%, P = .317). No significant difference between arms was reported in terms of progression-free survival (median progression-free survival: 12.7 in the experimental group v 12.3 months in the control group, hazard ratio: 0.88, 95% CI, 0.70 to 1.11, P = .277). CONCLUSION The intensification of the upfront chemotherapy backbone in combination with panitumumab does not provide additional benefit in terms of treatment activity at the price of increased gastrointestinal toxicity in patients with RAS and BRAF wt mCRC.

4077 Background: In the TRIBE2 study molecularly unselected and untreated mCRC patients were randomized to receive FOLFOXIRI/bevacizumab (bev) followed by the same agents after disease progression (PD) or FOLFOX/bev followed by FOLFIRI/bev after PD. We performed a comprehensive NGS analysis of samples from randomized patients in order to investigate the prognostic impact of tumor mutational load (TML), its additional value with respect to the assessment of microsatellite instability (MSI), and the overall prevalence of potentially actionable alterations. Methods: Tumor DNA was obtained from formalin-fixed, paraffin-embedded blocks from primary tumors of 296 (44%) out of 679 randomized patients and underwent NGS analysis using the Caris MI TumorSeek panel, assessing 592 genes. TML was defined low, intermediate or high if < 7, 7-16 or > 16 mutations/Mb were found. MSI status was determined both by NGS and by IHC. Results: TML and MSI were successfully determined by NGS in 224 (76%) cases. NGS and IHC results were concordant in 221 (99%) cases. TML was low, intermediate or high in 56 (25%), 157 (70%) and 11 (5%) cases, respectively. When compared with TML low and intermediate tumors, TML high were more frequently right-sided (p = 0.013), mucinous (p < 0.001) and MSI-high (p < 0.001). TML high tumors were MSI-high or MSS in 8 (73%) and 3 (27%) cases, respectively. Two out of 3 TML high and MSS tumours showed a pathogenic POLE mutation (p.S459F and p.P286R). The other TML high, MSS and POLE wt tumor was dMMR at IHC (loss of MSH6 expression) and showed a pathogenic MSH6 mutation (p.F1040fs). As compared with low and intermediate TML, high TML was associated with longer PFS (median PFS: 17.3 vs 10.6; HR: 0.54 [95%CI: 0.35-1.09], p = 0.098) and OS (median OS: not reached vs 23.7: HR: 0.45 [95%CI:0-28-1.13], p = 0.106). No interaction effect between TML and treatment arm was observed, and no difference between TML low and intermediate tumors was reported in terms of baseline characteristics and prognosis. Actionable alterations ( HER2 mutations [N = 2] and amplifications [N = 4], KRAS G12C [N = 10] and BRAF V600E mutation [N = 39]) were found in 55 (19%) out of 296 cases. No NTRK/ROS/ALK or MET amplification was found. Conclusions: TML high tumors are not limited to MSI-high ones but showed POLE or MSH6 somatic mutation and shower longer PFS and OS. No differences are reported between TML low and intermediate tumors. Molecular alterations predictive of benefit from targeted strategies currently available are detectable only in a small percentage of mCRCs.

e15593Background: The high mutational load of dMMR CRCs elicits a considerable endogenous immune anti-tumor response, counterbalanced by immune inhibitory signals. We aimed at describing the immune...

636 Background: The histopathological response to pre-operative chemotherapy is associated with clinical outcome in patients (pts) undergoing secondary resection of CRCLM. Three different histopathological growth patterns (HGPs) of CRCLM have been described: desmoplastic (i.e. with a capsule of stroma separating tumor and normal cells), pushing (i.e. with limited infiltration of normal hepatic plates by tumor cells) and replacement (i.e. with abundant infiltration of normal hepatic plates by tumor cells and vessel cooption). Methods: Histopathological parameters of response were evaluated in specimens from 159 pts who underwent secondary resection of CRCLM, after receiving triplet (FOLFOXIRI or COI) plus bev (N = 103) or anti-EGFR (N = 56) in 5 first-line clinical studies (TRIBE, MOMA, MACBETH, COI-B and COI-E). The aims of this analysis were to evaluate the prognostic role of histopathologic response and to investigate the prognostic role of HGPs and their potential different sensitivity to targeted agents. Results: When compared with partial (TRG 3) and no (TRG 4-5) pathologic response (N = 118), major response (TRG 1-2, N = 41) was associated with longer RFS (mRFS: 28.0 versus 11.0 mos, HR = 0.57, 95%CI = 0.39–0.86; p = 0.007) and OS (mOS: unreached versus 42.1 mos, HR = 0.54, 95%CI = 0.31-0.93; p = 0.027). No association of baseline clinical characteristics and RAS and BRAF status with major response was found. Major response was more frequent among pts treated with bev than with anti-EGFRs (OR = 2.83, 95%CI = 1.20–6.65; p = 0.015) and was associated with deepness of response as a continuous variable (HR = 1.02, 95% CI = 1.00–1.04; p = 0.011). In the desmoplastic HGP (N = 28) a higher percentage of major response was reported (57% vs 17% in pushing and 22% in replacement HGP, p < 0.001) and a numerical advantage from anti-EGFR vs bev was evident in terms of both major response and RFS. Conversely, in the pushing HGP (N = 66) a significant benefit from bev vs anti-EGFR in major response and RFS was observed. No difference was described in the replacement HGP (N = 65). Conclusions: The assessment of HGPs may be useful to predict benefit from available targeted agents.

11508 Background: Almost half of RAS and BRAFwt mCRC patients do not respond to anti-EGFRs. Different molecular alterations suggested as predictors of resistance have not been validated. Methods: We conducted a case-control study to prospectively demonstrate the negative predictive impact of HER-2 amplification or mutations (mut), MET amplification, NTRK/ROS1/ALK/RET rearrangements, and mut activating MAPKs or PI3K/Akt axis. Patients with RAS and BRAFwt mCRC clearly resistant (cases) or clearly sensitive (controls) to anti-EGFRs were selected. Hypothesizing a prevalence of candidate alterations of 0% and 15% among controls and cases, 47 cases and 47 controls were needed to be able to reject the null hypothesis of equally prevalent alterations, with a- and b- error 0.05 and 0.20. Since hypermutated tumors may hardly rely on a single pathway for their growth, we also evaluated the impact of microsatellite instability. Results: 47 cases and 47 controls were included. Primary endpoint was met: mentioned alterations were reported in 20 (42.6%) cases and 1 (2.1%) control (p

e20656 Background: In lung cancer the evaluation of MET, a tyrosine kinase receptor involved in tumor growth and invasiveness, for copy number amplification and point mutations is relevant for prognosis and therapy. In lung adenocarcinoma (ADC) MET amplification is observed in 1-2% and MET mutations in 3-4% of cases. Mutations mainly occur in exon 14 (ex14), which encodes for the juxtamembrane negative regulatory domain, including splice site alterations and missense mutations within the exon.Commonly, MET ex14 alterations, in particular splice site ones, are mutually exclusive with other driver mutations, but co-occurrence with MET and MDM2 amplification and KRAS mutations was described. We evaluated METex14 mutation frequency and coexistence with additional driver alterations in a prospective cohort of Italian ADC patients. Methods: 315 ADC patients were tested (January-December 2016) for MET ex14 alterations by Sanger Sequencing on formalin-fixed paraffin-embedded tissues and cytological smears (tumor cells > 40%). MET positive cases were screened also for other oncogenes, among which KRAS, BRAF and PIK3CA, using a MALDI-TOF platform, and for ROS1 translocations and MET amplification by FISH. Results: 16 patients (5%) were MET positive: 7 splice site mutations (43%) and 9 (57%) other alterations within ex14. Among splice site mutations 1 co-occurred with ROS1 translocation and 1 with MET amplification. Among other mutations we found 5 T1010I missense mutations: 3 co-occurring with G12D/G13C/Q61H KRAS, 1 with G469A BRAF and 1 with a MET intron 13 point mutation; 2 R988C mutations: 1 with G13C KRAS and 1 with G13C KRAS plus ROS1 translocation; 1 P1026S mutation and 1 frameshift deletion (p.A991del;R992fs*999), both with G12C KRAS. Conclusions: Splice site mutations cause MET activation by exon skipping and increase sensitivity to tyrosine-kinase inhibitors, whereas how other ex14 mutations affect MET function is not fully understood. In our cohort we found a high rate of METex14 mutations together with alterations in other oncogenes, mostly KRAS. The interaction of MET with cancer signaling pathways deserve further investigation in order to better define the role of ex14 mutations in the context of target therapy.

Background: The phase III TRIBE study met its primary endpoint by demonstrating that first-line FOLFOXIRI plus bev significantly prolongs PFS, as compared to FOLFIRI plus bev (Loupakis et al, N Eng J Med 2014). At a median follow-up of 32.2 months a preliminary OS analysis indicated a borderline OS improvement with FOLFOXIRI plus bev (HR = 0.79, p = 0.054) with a consistent effect across RAS (KRAS and NRAS codons 12, 13, 61) and BRAFV600E molecular subgroups. Methods: 508 pts were randomized to either FOLFIRI plus bev (Arm A, N = 256) or FOLFOXIRI plus bev (Arm B, N = 252). On available samples from RAS and BRAF wild-type (wt) pts (N = 129), also KRAS and NRAS codons 59, 117 and 146 were analysed by means of Sequenom MassArray, identifying a new ???all wt??? population (N = 93). Results: At a median follow-up of 48.1 months, in the ITT population, updated median OS for Arm B vs Arm A was 29.8 vs 25.8 months (HR = 0.80, 95%CI, 0.65-0.98, p = 0.030). Estimated 5-years OS rate were: Arm B, 24.9% vs Arm A, 12.4%. Molecular results were informative for 357 pts (70.3%). All wt patients had longer OS as compared to RAS mutant (HR = 0.70, p = 0.006) and to BRAF mutant (HR = 0.24, p < 0.001). The benefit from FOLFOXIRI plus bev was consistent across all molecular subgroups (Table 1). All wt pts treated with FOLFOXIRI plus bev reported a median OS of 41.7 months as compared to 33.5 months in the FOLFIRI plus bev group (HR = 0.75, 95%CI, 0.45-1.24). Conclusions: FOLFOXIRI plus bev significantly improves survival of metastatic colorectal cancer pts and the OS advantage increases over time. Benefit from FOLFOXIRI plus bev is independent of RAS and BRAF mutational status. All wt pts have a better outcome independently from the treatment arm. Notable results with FOLFOXIRI plus bev are achieved in all wt pts. Arm A FOLFIRI+bev Arm B FOLFOXIRI+bev HR [95%CI] Arm A FOLFIRI+bev Arm B FOLFOXIRI+bev HR [95%CI] Median PFS (mos) Median PFS (mos) Median OS (mos) Median OS (mos) All wt (N = 93) 12.2 13.7 0.82 [0.53-1.26] 33.5 41.7 0.75 [0.45-1.24] RAS mut (N = 236) 9.5 12.0 0.82 [0.63-1.07] 23.9 27.3 0.95 [0.71-1.27] BRAF mut (N = 28) 5.5 7.5 0.56 [0.20-1.14] 10.8 19.1 0.60 [0.27-1.33]

3519 Background: Phase III TRIBE trial demonstrated that first-line FOLFOXIRI plus bev improved PFS and RECIST response and, at adjusted analyses, OS as compared to FOLFIRI plus bev. The prognostic...

476 Background: Up today there are no molecular markers to identify mCRC pts candidate to curative liver surgery at high risk of relapse. There are conflicting results about the prognostic role of KRAS mutation in mCRC pts, while BRAF mutation is a well-known negative prognostic factor characterizing a subgroup of mCRCs with a distinct metastatic spread. We analyzed the impact of BRAF and KRAS mutations on relapse free-survival (RFS) and overall survival (OS) in pts undergoing liver resection with curative intent. Methods: Medical records of pts referred to 3 Italian institutions between 1995 and 2012 were reviewed. 3024 mCRC pts were identified. 401 pts (13.3%) underwent liver resection with curative intent and had adequate follow-up. Mutational status was assessable on 360 samples from primary tumors (n=63), metastases (mts) (n=59) or both (n=238). Primary objective was to evaluate the impact of BRAF mutation on RFS in mCRC pts candidate to liver resection. Secondary objectives were to evaluate the prognostic role of BRAF status on OS, and of KRAS status on RFS and OS in this population. Results: BRAF and KRAS were mutated in 11 (3%) and 116 (32%) out of 360 cases respectively. In 238 cases in which paired samples from primary and metastases were available, no discordance was found in BRAF status while 18 cases (7.6%) showed a discrepancy in KRAS status and were thus excluded from analysis. Pts with BRAF mutation had significantly shorter median RFS compared to pts with BRAF wt tumor (5.7 mos vs 11.7 mos, HR=4.25; 95%CI: 1.52-11.88, p=0.005). OS was significantly reduced in pts with BRAF mutated tumors vs wt (HR=5.39; 95%CI: 1.59-18.27, p=0.007). Mutated KRAS was not prognostic for RFS (HR=1.14; 95%CI: 0.87-1.49, p=0.34), while demonstrated a weak prognostic impact on OS (HR=1.52; 95%CI: 1.05-2.21, p=0.03). In this cohort high-risk Fong score were significantly associated with shorter RFS (p

e14042 Background: The KRAS aKtive program was started on March 2009, promoted by the Italian Association of Medical Oncology (AIOM) and the Italian Society of Surgical Pathology and Cytopathologyy (SIAPEC) to support the activity of oncologists and pathologists involved in the management of metastatic colorectal cancer patients who need the assessment of the mutational status of the KRAS gene. Methods: The program was specifically devised to facilitate the exchange of biologic material, clinicopathological data and diagnostic reports within a network of oncologist, pathologists and pathology/molecular biology reference laboratories throughout Italy, connected through the site www.kras-aKtive.it. KRAS mutation analysis was performed by Sanger sequencing (SS), real time PCR or other techniques, including pyrosequencing and hybridization strip assays. Data were collected in a common database. Results: The KRAS aKtive program has involved 478 oncologists, 144 pathologists, and 24 reference laboratories. A total of 7,432 KRAS mutations analyses were performed. The tests were informative in 7,265 cases (98%). The vast majority of tests (5,626 cases, 77.4%) were conducted by SS. In 529 (7.3%) cases a real-time PCR assay was used, other detection techniques were used in 1,110 (15.3%) cases. KRAS mutations at codons 12-13 were detected in 2,874 cases (39,6%). The frequency of mutations detected by real-time PCR or other techniques (45%, and 43%, respectively) was significantly higher (p=0.002, and p=0.008%, respectively) than that observed by SS (38%). The percentage of cases evaluated by non-SS-based methods has increased during the first three years of the program. Conclusions: The results of this large survey allow an accurate estimation of the actual prevalence of KRAS mutations and their types in caucasian colorectal cancer patients. Our data indicate that the frequency of mutations detected by non-SS-based methods is higher than that obtained by SS.

3521 Background: MicroRNAs (MiRNAs) are post-transcriptional regulators that bind to complementary sequences on target messenger RNA transcripts, usually resulting in gene silencing. Microarray technology is a powerful high-throughput tool capable of monitoring the expression of thousands of small noncoding RNAs at once. In the present study we aimed to investigate whether MiRNA signature was predictive for sensitivity to anti-EGFR monoclonal antibodies in mCRC. Methods: A total of 183 mCRC from two independent cohorts (cohort 1: 74 cases; validation cohort: 109 cases) treated with cetuximab/panitumumab either alone (n=19) or in combination with chemotherapy (n=164) were included onto the study. MiRNA arrays were analysed using Agilent’s miRNA platform. Results: MiRNA array analyses identified the cluster miR-99a/Let7c/miR-125b located on 21p11.1 as associated with different outcome to anti-EGFR therapies. In the first cohort, individuals with high signature (n=25, 33.8%) had a significantly longer progression free survival (PFS, 6.1 versus 2.3 months, p=0.01, HR=0.42) and overall survival (OS, 29.8 versus 7.0 months, p=0.04, HR=0.39) than patients with low signature (n=25, 33.8%). Similar results were observed in the validation cohort. Patients with high signature (n=60, 32.8%) had a significantly longer PFS and longer OS than individuals with low signature (PFS 8.2 versus 4.2 months, p=0.04, HR=0.52; OS 12.8 versus 6.8 months, p=0.09, HR=0.65). To further assess the potential confounding effect of KRAS and BRAF mutations, we analyzed the outcome of patients with high and low signature in the 75 cases with KRAS or BRAF mutation and in 90 cases KRAS and BRAF wild-type. In the wild-type population, high signature patients (n=29, 32.2%) had a significantly longer PFS (8.8 versus 4 months, p=0.002, HR:0.46) and longer OS (17.7 versus 10 months, p=0.015, HR=0.62) than low signature individuals, with no difference in the KRAS or BRAF mutated patients. Conclusions: MiR-99a/Let7c/miR-125b signature is useful for improving selection of KRAS/BRAF wild-type mCRC patients candidate for anti-EGFR strategies.

e14000 Background: The Italian Association of Medical Oncology (AIOM) and the Italian Society of Surgical Pathology and Cytopathologyy (SIAPEC) collaborated to promote a national program (KRAS aKtive) to support the activity of oncologists and pathologists involved in the management of metastatic colorectal cancer patients who need the assessment of the mutational status of the KRAS gene. Methods: The KRAS aKtive program was specifically devised to facilitate the exchange of biologic material, clinicopathological data and diagnostic reports within a network of oncologist, pathologists and pathology/molecular biology reference laboratories throughout Italy, connected through the site www.kras-aKtive.it. KRAS mutation analysis was performed by PCR-Sanger sequencing, real time PCR or other techniques. Data were collected in a common database. Results: Started on March 2009, the KRAS aKtive program has involved 407 oncologists, 125 pathologists, and 24 reference laboratories from 16 of the 21 Italian regions....