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Purpose Panitumumab plus FOLFOX (P-FOLFOX) is standard first-line treatment for RAS wild-type (WT) metastatic colorectal cancer. The value of panitumumab rechallenge is currently unknown. We assessed addition of panitumumab to FOLFIRI (P-FOLFIRI) beyond progression to P-FOLFOX in patients with no RAS mutations in liquid biopsy (LB). Methods In this randomized phase II trial, patients were assigned (3:2 ratio) to second-line P-FOLFIRI (arm A) or FOLFIRI alone (arm B). LB for circulating tumor DNA analysis was collected at study entry and at disease progression. Primary endpoint was 6-month progression-free survival. Two-stage Simon design required 85 patients to be included (EudraCT 2017-004519-38). Results Between February 2019 and November 2020, 49 patients were screened (16 RAS mutations in LB detected) and 31 included (18 assigned to arm A and 13 to arm B). The study was prematurely closed due to inadequate recruitment. Serious adverse events were more frequent in arm A (44% vs. 23%). Overall response rate was 33% (arm A) vs. 7.7% (arm B). Six-month progression-free survival rate was 66.7% (arm A) and 38.5% (arm B). Median progression-free survival was 11.0 months (arm A) and 4.0 months (arm B) (hazard ratio, 0.58). At disease progression, RAS or BRAF mutations in LB were found in 4/11 patients (36%) in arm A and 2/10 (20%) in arm B. Conclusions The BEYOND study suggests a meaningful benefit of P-FOLFIRI beyond progression to P-FOLFOX in metastatic colorectal cancer patients with WT RAS status selected by LB. This strategy deserves further investigation.

[Background] Gastrointestinal stromal tumor (GIST) initiation and evolution is commonly framed by KIT/PDGFRA oncogenic activation, and in later stages by the polyclonal expansion of resistant subpopulations harboring KIT secondary mutations after the onset of imatinib resistance. Thus, circulating tumor (ct)DNA determination is expected to be an informative non-invasive dynamic biomarker in GIST patients., [Methods] We performed amplicon-based next-generation sequencing (NGS) across 60 clinically relevant genes in 37 plasma samples from 18 GIST patients collected prospectively. ctDNA alterations were compared with NGS of matched tumor tissue samples (obtained either simultaneously or at the time of diagnosis) and cross-validated with droplet digital PCR (ddPCR)., [Results] We were able to identify cfDNA mutations in five out of 18 patients had detectable in at least one timepoint. Overall, NGS sensitivity for detection of cell-free (cf)DNA mutations in plasma was 28.6%, showing high concordance with ddPCR confirmation. We found that GIST had relatively low ctDNA shedding, and mutations were at low allele frequencies. ctDNA was detected only in GIST patients with advanced disease after imatinib failure, predicting tumor dynamics in serial monitoring. KIT secondary mutations were the only mechanism of resistance found across 10 imatinib-resistant GIST patients progressing to sunitinib or regorafenib., [Conclusions] ctDNA evaluation with amplicon-based NGS detects KIT primary and secondary mutations in metastatic GIST patients, particularly after imatinib progression. GIST exhibits low ctDNA shedding, but ctDNA monitoring, when positive, reflects tumor dynamics., This research is supported by a Fero Fellowship Award (C.S.), Asociación Española Contra el Cáncer (J.P. Barcelona) (C.S.), and ISCIII PI16/01371 (C.S.). C.S. and A.V. acknowledge to the Cellex Foundation for providing facilities and equipment.

Background: About 40% of RAS/BRAF wild-type metastatic colorectal cancer (mCRC) patients undergoing anti-EGFR-based therapy have poor outcomes. Treatment failure is not only associated with poorer prognosis but higher healthcare costs. Our aim was to identify novel somatic genetic variants in the primary tumor and assess their effect on anti-EGFR response. Patients and Methods: Tumor (somatic) and blood (germline) DNA samples were obtained from two well-defined cohorts of mCRC patients, those sensitive and those resistant to EGFR blockade. Genetic variant screening of 43 EGFR-related genes was performed using targeted next-generation sequencing (NGS). Relevant clinical data were collected through chart review to assess genetic results. Results: Among 61 patients, 38 were sensitive and 23 were resistant to treatment. We identified eight somatic variants that predicted non-response. Three were located in insulin-related genes (I668N and E1218K in IGF1R, T1156M in IRS2) and three in genes belonging to the LRIG family (T152T in LRIG1, S697L in LRIG2 and V812M in LRIG3). The remaining two variants were found in NRAS (G115Efs*46) and PDGFRA (T301T). We did not identify any somatic variants related to good response. Conclusions: This study provides evidence that novel somatic genetic variants along the EGFR-triggered pathway could modulate the response to anti-EGFR drugs in mCRC patients. It also highlights the influence of insulin-related genes and LRIG genes on anti-EGFR efficacy. Our findings could help characterize patients who are resistant to anti-EGFR blockade despite harboring RAS/BRAF wild-type tumors.

The role of vascular endothelial growth factor (VEGF) gene polymorphisms in the prognosis of colon cancer prognosis remains unclear. We evaluated the influence of 28 single-nucleotide polymorphisms in 12 genes in the VEGF pathway on the prognosis of 347 patients with stage II-III colon cancer. We found that rs9513070 (VEGFR1) and rs1137282 (KRAS) were associated with overall survival in stage II colon cancer patients (p = 0.025 and p = 0.001, respectively). When primary tumor location was considered, rs9513070 was also associated with relapse-free and overall survival (p = 0.033 and p = 0.031, respectively) in left colon cancer patients. Additionally, rs35251833 in the ITGAV gene correlated with relapse-free survival (p = 0.032). This study provides evidence that germline polymorphisms in VEGFR1, KRAS and ITGAV genes are associated with prognosis in stages II-III colon cancer patients. As stage and tumor location are correlated with prognosis, future genetic studies should stratify colon cancer patients according to these parameters.

Aim: Few inherited familial syndromes include transitional cell cancer; however the field carcinogenesis is a common problem for patients diagnosed of transitional cell carcinoma. Besides smoking, other risk factors are associated with developing second neoplasms such as alcohol intake and aging. While there are some published studies about secondary smoking-related tumours in this population, data about the incidence of other not-smoking related tumours is limited. The objective of this study was to analyse the cumulative incidence of second neoplasms in this population and determine the type of second neoplasms: urinary tract vs not-related urinary tract. Methods: Retrospective analysis of 629 patients diagnosed with invasive transitional cell carcinoma of the urinary tract treated in a single medical center from 1999 to 2012. Patients with a follow-up shorter than 6 months were excluded. Synchronic prostate carcinoma were not included, tumours included in our analyses were those diagnosed during the follow-up. Cumulative incidence of secondary tumours was calculated by kaplan-meier. Results: Median age of patients was 67 years (30-87). Median follow-up time was 60 months. There were 45 patients who developed a second neoplasm (8%); 32 corresponded to non-urothelial tumours (71%) and 13 urothelial tumours (29%). The actuarial cumulative incidence of a second neoplasm was 27% at 10 years. Incidence of not-urinary tumours was 19% at 10 years. There were 14 cases of lung cancer (31,1 %) (2 oat cell and 12 NSCLC) 3 colon cancers (6,7%), 2 cancers of the rectum (4,4%), 2 renal cancers (4,4%), 2 Hepatocellular carcinomas (4,2%), 2 haematological tumours (4,4%), and 1 case of each of the following tumours: GIST, prostate, parotid, biliary track, glottis, thyroid, vagina and brain. The interval between the diagnosis of urothelial cancer and the second neoplasm was on average 46,88 months. Smoking was common in all patients with second neoplasms (93,3%). Conclusions: Diagnosis of second neoplasms is a major concern for this population, which is heavily exposed to risk factors, such as smoking. Specific follow-up is required as well as programs for smoking cessation. Disclosure: All authors have declared no conflicts of interest.