RESUMEN
BACKGROUND: Biliary tract cancers (BTCs) are rare and lethal cancers, with a 5-year survival inferior to 20%(1-3). The only potential curative treatment is surgical resection. However, despite complex surgical procedures that have a remarkable risk of postoperative morbidity and mortality, the 5-year survival rate after radical surgery (R0) is 20-40% and recurrence rates are up to ~ 75%(4-6). Up to ~ 40% of patients relapse within 12 months after resection, and half of these patient will recur systemically(4-6). There is no standard of care for neoadjuvant chemotherapy (NAC) in resectable BTC, but retrospective reports suggest its potential benefit (7, 8). METHODS: PURITY is a no-profit, multicentre, randomized phase II/III trial aimed at evaluating the efficacy of the combination of gemcitabine, cisplatin and nabpaclitaxel (GAP) as neoadjuvant treatment in patients with resectable BTC at high risk for recurrence. Primary objective of this study is to evaluate the efficacy of neoadjuvant GAP followed by surgery as compared to upfront surgery, in terms of 12-month progression-free survival for the phase II part and of progression free survival (PFS) for the phase III study. Key Secondary objectives are event free survival (EFS), relapse-free survival, (RFS), overall survival (OS), R0/R1/R2 resection rate, quality of life (QoL), overall response rate (ORR), resectability. Safety analyses will include toxicity rate and perioperative morbidity and mortality rate. Exploratory studies including Next-Generation Sequencing (NGS) in archival tumor tissues and longitudinal ctDNA analysis are planned to identify potential biomarkers of primary resistance and prognosis. DISCUSSION: Considering the poor prognosis of resected BTC experiencing early tumor recurrence and the negative prognostic impact of R1/R2 resections, PURITY study is based on the rationale that NAC may improve R0 resection rates and ultimately patients' outcomes. Furthermore, NAC should allow early eradication of microscopic distant metastases, undetectable by imaging but already present at the time of diagnosis and avoid mortality and morbidity associated with resection for patients with rapid progression or worsening general condition during neoadjuvant therapy. The randomized PURITY study will evaluate whether patients affected by BTC at high risk from recurrence benefit from a neoadjuvant therapy with GAP regimen as compared to immediate surgery. TRIAL REGISTRATION: PURITY is registered at ClinicalTrials.gov (NCT06037980) and EuCT(2023-503295-25-00).
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Neoplasias del Sistema Biliar , Gemcitabina , Humanos , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Neoplasias del Sistema Biliar/tratamiento farmacológico , Neoplasias del Sistema Biliar/cirugía , Cisplatino , Desoxicitidina , Terapia Neoadyuvante/métodos , Recurrencia Local de Neoplasia/tratamiento farmacológico , Calidad de Vida , Estudios RetrospectivosRESUMEN
The consequences of the Italian privacy legislation, that represents a very restrictive implementation of the general European regulation on data protection, have mainly been felt at the level of observational research. In this field is not always possible to obtain the consent of subjects, and as for retrospective studies, it is not currently clear which is the correct regulatory procedure to follow. This uncertainty in the law's implementation has given way to multiple interpretations, making it difficult to obtain a homogeneous path in Italy. However, it is possible that the observation point has been totally wrong so far and that it would be more correct to choose a different legal bases than consent, both to preserve scientific progress and collective ethics, without losing the protection of the subject. This approach, which has already been followed by other European countries, could bring us closer to the rest of Europe and allow us to competitively participate in community projects that we are often cut off from.
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Consentimiento Informado , Privacidad , Humanos , Estudios Retrospectivos , Europa (Continente) , ItaliaRESUMEN
Observational trials are crucial to assess the generalizability in the real world of evidence deriving from registration studies. Despite the unquestionable importance of this type of studies, Italian researchers have had to face many obstacles over the years, mainly due to ambiguous definitions and to a complex but at the same time incomplete legislation. The regulatory adjustments to the European Regulation 536/2014 have further complicated the operating and operational framework, making observational research a real "Cinderella" of the Italian system.
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Estudios Observacionales como Asunto , Italia , Estudios Observacionales como Asunto/legislación & jurisprudenciaRESUMEN
BACKGROUND: Anti-EGFR antibodies plus doublet chemotherapy is the standard of care in RAS/BRAF wild-type metastatic colorectal cancer (mCRC). No phase-3 level of evidence is available to guide treatment de-escalation after anti-EGFR-based first-line. Several randomised clinical trials investigated de-intensification strategies with 5-fluorouracil/leucovorin (5-FU/LV) and/or anti-EGFR. METHODS: We performed an individual patient data pooled analysis of Valentino, Panama, MACRO-2, COIN-B trials including RAS wild-type mCRC patients who received first-line therapy with FOLFOX plus panitumumab or cetuximab followed by pre-specified maintenance strategy. Only patients who started maintenance according to the assigned arm were included. Patients were categorised by type of maintenance (i.e. 5-FU/LV, anti-EGFR or 5-FU/LV + anti-EGFR). Progression-free survival (PFS) and overall survival (OS) were calculated from the start of maintenance; toxicity was evaluated for the maintenance treatment period. RESULTS: A total of 518 patients were included in the pooled analysis. Overall, 123, 185 and 210 patients received maintenance with 5-FU/LV, anti-EGFR, 5-FU/LV + anti-EGFR, respectively. Median PFS was 5.6, 6.0 and 9.0 (P = 0.009) and OS was 25.7, 24.0 and 28.0 months (P = 0.134) in 5-FU/LV, anti-EGFR and 5-FU/LV + anti-EGFR arms, respectively. Monotherapy maintenance (either 5-FU/LV or anti-EGFR) was inferior to combination in terms of PFS (hazard ratios [HR] 1.26, P = 0.016) and non-significantly trending also in OS (HR 1.20, P = 0.111). An increase of overall any grade and grade ≥ 3 AEs and selected AEs was reported in combination compared to either 5-FU/LV or anti-EGFR arms. CONCLUSIONS: This pooled analysis including four randomised phase II supports the use of 5-FU/LV plus anti-EGFR as the preferred maintenance regimen. Data provide rational for a more individualised maintenance treatment approach based on tumour and patients features.
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Neoplasias del Colon , Neoplasias Colorrectales , Neoplasias del Recto , Humanos , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Cetuximab , Neoplasias del Colon/tratamiento farmacológico , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/genética , Fluorouracilo , Quimioterapia de Inducción , Leucovorina , Neoplasias del Recto/tratamiento farmacológicoRESUMEN
BACKGROUND: In clinical trials, the assessment of safety is traditionally focused on the overall rate of high-grade and serious adverse events (AEs). A new approach to AEs evaluation, taking into account chronic low-grade AEs, single patient's perspective, and time-related information, such as ToxT analysis, should be considered especially for less intense but potentially long-lasting treatments, such as maintenance strategies in metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: We applied ToxT (Toxicity over Time) evaluation to a large cohort of mCRC patients enroled in randomised TRIBE, TRIBE2, and VALENTINO studies, in order to longitudinally describe AEs throughout the whole treatment duration and to compare AEs evolution over cycles between induction and maintenance strategies, providing numerical and graphical results overall and per single patient. After 4-6 months of combination therapy, 5-fluorouracil/leucovorin (5-FU/LV) + bevacizumab or panitumumab was recommended in all studies except for the 50% of patients in the VALENTINO trial who received panitumumab alone. RESULTS: Out of 1400 patients included, 42% received FOLFOXIRI (5-FU/LV, oxaliplatin, and irinotecan)/bevacizumab, 18% FOLFIRI/bevacizumab, 24% FOLFOX/bevacizumab, 16% FOLFOX/panitumumab. Mean grade of general and haematological AEs was higher in the first cycles, then progressively decreasing after the end of induction (p < 0.001), and always remaining at the highest levels with FOLFOXIRI/bevacizumab (p < 0.001). Neurotoxicity became more frequent over the cycles with late high-grade episodes (p < 0.001), while the incidence but not the grade of hand-and-foot syndrome gradually increased (p = 0.91). Anti-VEGF-related AEs were more severe in the first cycles, then setting over at low levels (p = 0.03), while anti-EGFR-related AEs still affected patients during maintenance. CONCLUSIONS: Most of chemotherapy-related AEs (except for HFS and neuropathy) reach the highest level in the first cycles, then decrease, probably due to their active clinical management. Transition to maintenance allows relief from most AEs, especially with bevacizumab-based regimens, while anti-EGFR-related AEs may persist.
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Neoplasias del Colon , Neoplasias Colorrectales , Neoplasias del Recto , Humanos , Bevacizumab , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/patología , Panitumumab/uso terapéutico , Camptotecina , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Recto/tratamiento farmacológico , Fluorouracilo , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , LeucovorinaRESUMEN
PURPOSE: This is a multicenter, single-arm phase II trial evaluating the efficacy and safety of an immune-sensitizing strategy with temozolomide priming followed by a combination of low-dose ipilimumab and nivolumab in patients with microsatellite-stable (MSS) and O6-methylguanine-DNA methyltransferase (MGMT)-silenced metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: Patients with pretreated mCRC were centrally prescreened for MSS status and MGMT silencing (ie, lack of MGMT expression by immunohistochemistry plus MGMT methylation by pyrosequencing). Eligible patients received two priming cycles of oral temozolomide 150 mg/sqm once daily, days 1-5, once every 4 weeks (first treatment part) followed, in absence of progression, by its combination with ipilimumab 1 mg/kg once every 8 weeks and nivolumab 480 mg once every 4 weeks (second treatment part). The primary end point was the 8-month progression-free survival (PFS) rate calculated from enrollment in patients who started the second treatment part, with ≥ 4 out of 27 subjects progression-free by the 8-month time point as decision rule. RESULTS: Among 716 prescreened patients, 204 (29%) were molecularly eligible and 135 started the first treatment part. Among these, 102 (76%) were discontinued because of death or disease progression on temozolomide priming, whereas 33 patients (24%) who achieved disease control started the second treatment part and represented the final study population. After a median follow-up of 23.1 months (interquartile range, 14.9-24.6 months), 8-month PFS rate was 36%. Median PFS and overall survival were 7.0 and 18.4 months, respectively, and overall response rate was 45%. Grade 3-4 immune-related adverse events were skin rash (6%), colitis (3%), and hypophysitis (3%). No unexpected adverse events or treatment-related deaths were reported. CONCLUSION: The MAYA study provided proof-of-concept that a sequence of temozolomide priming followed by a combination of low-dose ipilimumab and nivolumab may induce durable clinical benefit in MSS and MGMT-silenced mCRC.
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Neoplasias del Colon , Neoplasias Colorrectales , Neoplasias del Recto , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Neoplasias del Colon/tratamiento farmacológico , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Humanos , Ipilimumab , Repeticiones de Microsatélite , Nivolumab/uso terapéutico , O(6)-Metilguanina-ADN Metiltransferasa/genética , O(6)-Metilguanina-ADN Metiltransferasa/uso terapéutico , Neoplasias del Recto/tratamiento farmacológico , Temozolomida/uso terapéuticoRESUMEN
PURPOSE: The routine use of liquid biopsy is not recommended for the choice of initial treatment for patients with metastatic colorectal cancer (mCRC). EXPERIMENTAL DESIGN: We included patients with left-sided, RAS/BRAF wild-type, HER2-negative, and microsatellite stable mCRC, treated with upfront panitumumab/FOLFOX-4 in the Valentino study. We performed amplicon-based genomic profiling of 14 genes in baseline plasma samples and compared these data with tumor tissue ultra-deep sequencing results. Specific gene mutations in circulating tumor DNA (ctDNA) and their clonality were associated with progression-free survival (PFS), overall survival (OS), and radiological dynamics. RESULTS: Ten and 15 of 120 patients had a mutation of RAS and PIK3CA in ctDNA, with a positive concordance with tissue deep sequencing of only 31.3% and 47.1%, respectively. Presence of RAS or PIK3CA mutations in baseline ctDNA was associated with worse median PFS [8 vs. 12.8 months; HR, 2.49; 95% confidence interval (CI), 1.28-4.81; P = 0.007 and 8.5 vs. 12.9 months; HR, 2.86; 95% CI, 1.63-5.04; P < 0.001] and median OS (17.1 vs. 36.5 months; HR, 2.26; 95% CI, 1.03-4.96; P = 0.042 and 21.1 vs. 38.9 months; HR, 2.18; 95% CI, 1.16-4.07; P = 0.015). RAS mutations in ctDNA were associated with worse RECIST response, early tumor shrinkage, and depth of response, while PIK3CA mutations were not. Patients with higher levels of RAS/PIK3CA variant allele fraction (VAF) in ctDNA had the worst outcomes (VAF ≥ 5% vs. all wild-type: median PFS, 7.7 vs. 13.1 months; HR, 4.02; 95% CI, 2.03-7.95; P < 0.001 and median OS, 18.8 vs. 38.9 months; HR, 4.07; 95% CI, 2.04-8.12; P < 0.001). CONCLUSIONS: Baseline ctDNA profiling may add value to tumor tissue testing to refine the molecular hyperselection of patients with mCRC for upfront anti-EGFR-based strategies.
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Biomarcadores de Tumor , ADN Tumoral Circulante , Neoplasias Colorrectales/diagnóstico , Neoplasias Colorrectales/genética , Biopsia Líquida , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Colorrectales/mortalidad , Neoplasias Colorrectales/terapia , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Estimación de Kaplan-Meier , Biopsia Líquida/métodos , Biopsia Líquida/normas , Masculino , Mutación , Panitumumab/administración & dosificación , Pronóstico , Proteínas Proto-Oncogénicas B-raf/genética , Transcriptoma , Carga Tumoral , Proteínas ras/genéticaRESUMEN
BACKGROUND: In patients with metastatic colorectal cancer (mCRC) receiving highly active first-line combination treatments, early tumor shrinkage (ETS) and depth of response (DoR) are associated with survival, but their influence on outcomes during maintenance therapy is unknown. The Valentino study showed inferior PFS in 229 RAS wild-type mCRC patients randomized to panitumumab plus FOLFOX followed by maintenance with panitumumab vs. panitumumab + 5-FU/LV. PATIENTS AND METHODS: After blinded independent central review of ETS (≥20% reduction of the sum of target lesions) and DoR in patients enrolled in Valentino, the prognostic and predictive role of such parameters was investigated, along with their combination with PRESSING panel (uncommon genomic alterations associated with anti-EGFRs resistance beyond RAS and BRAF). RESULTS: One hundred and ninety-six patients were included (ETS in 132 [67.3%], median DoR: 44.1%). Both ETS and DoR ≥34% were associated with longer mPFS (p = 0.010 and p < 0.001) and mOS (p = 0.006 and p < 0.001). The PFS benefit of 5-FU/LV added to panitumumab maintenance, reported in the study, was independent from ETS and DoR status (interaction tests NS for both PFS and OS). However, outcomes were extremely poor in patients who received single-agent panitumumab and had no-ETS (mPFS and mOS: 7.7 and 18.7 months) or DoR < 34% (mPFS and mOS: 6.5 and 18 months). Combining PRESSING panel ('molecular hyperselection') and response dynamics allowed to stratify both PFS (p < 0.001 and p < 0.001 for ETS and DoR, respectively) and OS (p < 0.001 and p = 0.017 for ETS and DoR, respectively). CONCLUSIONS: ETS and DoR allow on-treatment anticipation of outcomes following an anti-EGFR-based strategy planning de-escalation, and poor radiological response may guide enrolment in crossover strategy trials. As in vivo markers of drug sensitivity, ETS and DoR may be integrated with several patient- and tumor-related factors to wisely drive decision-making on upfront treatment duration and intensity.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias Colorrectales/mortalidad , Quimioterapia de Mantención/mortalidad , Proteínas ras/genética , Anciano , Bevacizumab/administración & dosificación , Neoplasias Colorrectales/tratamiento farmacológico , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Femenino , Fluorouracilo/administración & dosificación , Estudios de Seguimiento , Humanos , Masculino , Metástasis de la Neoplasia , Oxaliplatino/administración & dosificación , Panitumumab/administración & dosificación , Pronóstico , Tasa de SupervivenciaRESUMEN
In resectable gastric or gastroesophageal junction cancer (GC/GEJC), the powerful positive prognostic effect and the potential predictive value for a lack of benefit from the combination of adjuvant/peri-operative chemotherapy for the MSI-high status was demonstrated. Given the high sensitivity of MSI-high tumors for immunotherapy, exploratory trials showed that combination immunotherapy induces a high rate of complete pathological response (pCR), potentially achieving cancer cure without surgery. INFINITY is an ongoing phase II, multicentre, single-arm, multi-cohort trial investigating the activity and safety of tremelimumab and durvalumab as neoadjuvant (Cohort 1) or potentially definitive (Cohort 2) treatment for MSI-high/dMMR/EBV-negative, resectable GC/GEJC. About 310 patients will be pre-screened, to enroll a total of 31 patients, 18 and 13 in Cohort 1 and 2, at 25 Italian Centres. The primary endpoint of Cohort 1 is rate of pCR (ypT0N0) and negative ctDNA after neoadjuvant immunotherapy, of Cohort 2 is 2-year complete response rate, defined as absence of macroscopic or microscopic residual disease (locally/regionally/distantly) at radiological examinations, tissue and liquid biopsy, during non-operative management without salvage gastrectomy. The ongoing INFINITY proof-of-concept study may provide evidence on immunotherapy and the potential omission of surgery in localized/locally advanced GC/GEJC patients selected for dMMR/MSI-high status eligible for radical resection.
RESUMEN
The current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak poses a major challenge in the treatment decision-making of patients with cancer, who may be at higher risk of developing a severe and deadly SARS-CoV-2 infection compared with the general population. The health care emergency is forcing the reshaping of the daily assessment between risks and benefits expected from the administration of immune-suppressive and potentially toxic treatments. To guide our clinical decisions at the National Cancer Institute of Milan (Lombardy region, the epicenter of the outbreak in Italy), we formulated Coronavirus-adapted institutional recommendations for the systemic treatment of patients with gastrointestinal cancers. Here, we describe how our daily clinical practice has changed due to the pandemic outbreak, with the aim of providing useful suggestions for physicians that are facing the same challenges worldwide.
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Infecciones por Coronavirus/epidemiología , Atención a la Salud/organización & administración , Neoplasias Gastrointestinales/terapia , Neumonía Viral/epidemiología , COVID-19 , Toma de Decisiones Clínicas , Toma de Decisiones , Brotes de Enfermedades , Humanos , Italia/epidemiología , Pandemias , Medición de Riesgo , Índice de Severidad de la EnfermedadRESUMEN
PURPOSE: To determine whether second-line therapy with capecitabine and temozolomide was superior to irinotecan, leucovorin, and fluorouracil (FOLFIRI) in patients with RAS-mutated, methyl-guanine methyltransferase (MGMT)-methylated metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: In this randomized, phase II trial, we enrolled patients with RAS-mutated, MGMT-methylated mCRC after failure of oxaliplatin-based regimen. Patients with centrally confirmed MGMT methylation were stratified by first-line progression-free survival (PFS) and prior bevacizumab and randomized to either capecitabine plus temozolomide (arm A, CAPTEM) or FOLFIRI (arm B). The primary endpoint was PFS analyzed on intention-to-treat basis, with 90% power and one-sided significance level of 0.05 to detect an increase of median time from 2 months in arm B to 4 months in arm A. RESULTS: Between November 2014 and May 2019, 86 patients were randomly assigned to arm A (n = 43) or arm B (n = 43). After a median follow-up of 30.5 months (interquartile range, 12.2-36.3), 79 disease progression or death events occurred. Superiority of arm A was not demonstrated (one-sided P = 0.223). Progression-free survival and overall survival were 3.5 (2.0-5.0) and 9.5 (8.2-25.8) in arm A versus 3.5 (2.3-6.1) and 10.6 (8.5-20.8) in arm B [HR = 1.19 (0.82-1.72) and HR = 0.97 (0.58-1.61)], respectively. Grade ≥3 treatment-related adverse events had higher incidence in arm B versus A (47.6% vs 16.3%), and quality of life was significantly worse in arm B. Patients with positive MGMT expression by IHC did not benefit from CAPTEM. CONCLUSIONS: Temozolomide-based therapy warrants further investigation in molecularly hyperselected subgroups.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Biomarcadores de Tumor/genética , Neoplasias Colorrectales/tratamiento farmacológico , Metilación de ADN , Metilasas de Modificación del ADN/genética , Enzimas Reparadoras del ADN/genética , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Supresoras de Tumor/genética , Anciano , Bevacizumab/administración & dosificación , Biomarcadores de Tumor/metabolismo , Camptotecina/administración & dosificación , Capecitabina/administración & dosificación , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Femenino , Fluorouracilo/administración & dosificación , Humanos , Irinotecán/administración & dosificación , Leucovorina/administración & dosificación , Masculino , Persona de Mediana Edad , Oxaliplatino/administración & dosificación , Calidad de Vida , Tasa de Supervivencia , Temozolomida/administración & dosificación , Resultado del TratamientoRESUMEN
PURPOSE: We assessed the prognostic/predictive role of primary tumor sidedness and uncommon alterations of anti-epidermal growth factor receptor (EGFR) primary resistance (primary resistance in RAS and BRAF wild-type metastatic colorectal cancer patients treated with anti-EGFR monoclonal antibodies [PRESSING] panel) in patients with RAS/BRAF wild-type (wt) metastatic colorectal cancer (mCRC) who were randomly assigned to panitumumab plus fluorouracil, leucovorin, and oxaliplatin (FOLFOX-4) induction followed by maintenance with panitumumab with or without fluorouracil (FU) plus leucovorin (LV); Valentino trial (ClinicalTrials.gov identifier: NCT02476045). PATIENTS AND METHODS: This prespecified retrospective analysis included 199 evaluable patients with RAS/BRAF wt. The PRESSING panel included the following: immunohistochemistry (IHC) and in situ hybridization for HER2/MET amplification, IHC with or without RNA sequencing for ALK/ROS1/NTRKs/RET fusions, next-generation sequencing for HER2/PIK3CAex.20/PTEN/AKT1 and RAS mutations with low mutant allele fraction, and multiplex polymerase chain reaction for microsatellite instability. PRESSING status (any positive biomarker v all negative) and sidedness were correlated with overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) in the study population and by treatment arm. RESULTS: Overall, left- and right-sided tumors were 85.4% and 14.6%, respectively, and PRESSING-negative and -positive tumors were 75.4% and 24.6%, respectively. At a median follow-up of 26 months, inferior outcomes were consistently observed in right- versus left-sided tumors for ORR (55.2% v 74.1%; P = .037), PFS (8.4 v 11.5 months; P = .026), and OS (2-year rate: 50.2% v 65.1%; P = .062). Similar results were observed in the PRESSING-positive versus PRESSING-negative subgroup for ORR (59.2% v 75.3%; P = .030), PFS (7.7 v 12.1 months; P < .001), and OS (2-year rate: 48.1% v 68.1%; P = .021). The PFS benefit of FU plus LV added to panitumumab maintenance, reported in the study, was independent from sidedness and PRESSING status (interaction for PFS P = .293 and .127, respectively). However, outcomes were extremely poor in patients who received single-agent panitumumab and had right-sided tumors (median PFS, 7.7 months; 2-year OS, 38.5%) or PRESSING-positive tumors (median PFS, 7.4 months; 2-year OS, 47.0%). CONCLUSION: The combined assessment of sidedness and molecular alterations of anti-EGFR primary resistance identified a consistent proportion of patients with RAS/BRAF-wt mCRC who had inferior benefit from initial anti-EGFR-based regimens, particularly after maintenance with single-agent anti-EGFRs.