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Among neuroendocrine neoplasms (NENs), a non-negligible proportion (9-22%) is represented by sufferers of NENs of unknown primary origin (UPO), a poor prognostic group with largely unmet clinical needs. In the absence of standard therapeutic algorithms, current guidelines suggest that the treatment of UPO-NENs should be based on tumor clinical-pathological characteristics, disease burden, and patient conditions. Chemotherapy represents the backbone for the treatment of high-grade poorly differentiated UPO-NENs, usually providing deep but short-lasting responses. Conversely, the spectrum of available systemic therapy options for well-differentiated UPO-NENs may range from somatostatin analogs in indolent low-grade tumors, to peptide receptor radioligand therapy, tyrosine kinase inhibitors (TKIs), or chemotherapy for more aggressive tumors or in case of high disease burden. In recent years, molecular profiling has provided deep insights into the molecular landscape of UPO-NENs, with both diagnostic and therapeutic implications. Although preliminary, interesting activity data have been provided about upfront chemoimmunotherapy, the use of immune checkpoint inhibitors (ICIs), and the combination of ICIs plus TKIs in this setting. Here, we review the literature from the last 30 years to examine the available evidence about the treatment of UPO-NENs, with a particular focus on future perspectives, including the expanding scenario of targeted agents in this setting.

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)., (© 2024. The Author(s).)

Colorectal cancer is the third-most-diagnosed cancer in males and in females, representing 8% of estimated new cases, and the third cause of cancer-related death in both sexes, accounting for 9% of cancer deaths in men and 8% in women. About 20% of patients diagnosed with CRC present metastatic disease. Although lung metachronous or synchronous metastatic spread without other involved sites has been reported in only a small proportion of patients, considering that this tumor is frequently diagnosed, the clinical approach to CRC pulmonary metastases represents a major issue for thoracic surgeons and CRC oncologists. Among patients diagnosed with pulmonary metastases from CRC, about 9-12% are eligible for local treatments with radical intent, including surgical resection, SBRT (stereotactic body radiation therapy) and ablation therapy. Due to the lack of randomized controlled trials among different local strategies, there is no definitive evidence about the optimal approach, although surgical resection is considered the most effective therapeutic option in this clinical scenario. Oncological achievement of primary radical resection, the biology of primary tumor and metastatic sites, disease free interval and or progression free survival are independent prognostic factors which make it possible to define a cohort of patients which might significantly benefit from pulmonary metastasectomy.

Background: Pemigatinib is approved for patients with pretreated, locally advanced or metastatic CCA harboring FGFR2 rearrangements or fusions. We aim to assess the effectiveness and safety of pemigatinib in real-world setting., Material and Methods: A joint analysis of two multicentre observational retrospective cohort studies independently conducted in France and Italy was performed. All consecutive FGFR2-positive patients affected by CCA and treated with pemigatinib as second- or further line of systemic treatment in clinical practice, within or outside the European Expanded Access Program, were included., Results: Between July 2020 and September 2022, 72 patients were treated with pemigatinib in 14 Italian and 25 French Centres. Patients had a median age of 57 years, 76% were female, 81% had ECOG-PS 0-1, 99% had intrahepatic CCA, 74% had ≥ 2 metastatic sites, 67% had metastatic disease at diagnosis, while 38.8% received ≥ 2 previous lines of systemic treatment. At data cut-off analysis (April 2023), ORR and DCR were 45.8% and 84.7%, respectively. Median DoR was 7 months (IQR: 5.8-9.3). Over a median follow-up time of 19.5 months, median PFS and 1-year PFS rate were 8.7 months and 32.8%. Median OS and 1-year OS rate were 17.1 months and 60.6%. Fatigue (69.4%), ocular toxicity (68%), nail toxicities (61.1%), dermatologic toxicity (41.6%) hyperphosphataemia (55.6%), stomatitis (48.6%), and diarrhea (36.1%) were the most frequent, mainly G1-G2 AEs. Overall incidence of G3 AEs was 22.2%, while no patient experienced G4 AE. Dose reduction and temporary discontinuation were needed in 33.3% and 40.3% of cases, with 1 permanent discontinuation due to AEs., Conclusions: These results confirm the effectiveness and safety of pemigatinib in a real-world setting., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: High body mass index (BMI) plays a key role in the development of colon cancer (CC). Our post-hoc analysis from the TOSCA trial analyzed the association between BMI and survival outcomes in terms of relapse-free survival (RFS) and overall survival (OS) in stage II/III CC patients., Patients and Methods: Patients enrolled in the TOSCA trial between 2007-2013 with BMI data entered the study. The prognostic impact of BMI on survival outcomes was investigated through uni- and multivariable Cox regression analyses., Results: Overall, 1455 patients with stage II/III CC patients were included. The median follow-up was of 61.5 months; 16.1% of patients relapsed, 11.2% died and 19.5% patients relapsed or died. No impact of BMI on RFS was detected at univariate or multivariable analyses. By univariate analysis for OS, a significantly impact of a BMI > 30 kg/m 2 was reported (HR [>30 vs <25] 1.57, 95% CI 1.00-2.47, p = 0.049; HR [>30 vs <30] 1.55, 95% CI 1.01-2.37, p = 0.045). Multivariable analyses did not confirm this data. In the subgroup of stage III patients, a negative survival impact of BMI was found in univariate and multivariable models both for RFS and for OS., Conclusions: In our study, obesity with BMI > 30 kg/m 2 was an independent prognostic factor for RFS and OS in CC patients treated with adjuvant chemotherapy, regardless of its duration (3 or 6 months). However, the prognostic impact of adiposity and body composition measurement should be considered to better classify patients with high visceral fat and refine their risk assessment., (Copyright © 2023. Published by Elsevier Inc.)

Background: The optimal treatment strategy after first-line induction therapy in advanced HER2-positive oeso-gastric adenocarcinoma (OGA) remains challenging., Methods: Patients treated with trastuzumab (T) plus platinum salts and fluoropyrimidine (F) as first-line chemotherapy between 2010 and 2020 for HER2-positive advanced OGA at 17 academic care centers in France, Italy, and Austria were included. The primary objective was the comparison of F + T vs T alone as maintenance regimen in terms of progression-free survival (PFS) and overall survival (OS) after a platinum-based chemotherapy induction + T. As secondary objective, PFS and OS between patients treated with reintroduction of initial chemotherapy or standard second-line chemotherapy at progression were assessed., Results: Among the 157 patients included, 86 (55%) received F + T and 71 (45%) T alone as a maintenance regimen after a median of 4 months of induction chemotherapy. Median PFS from start of maintenance therapy was 5.1 months in both groups (95% CI 4.2-7.7 for F + T and 95% CI 3.7-7.5 for T alone; p = 0.60) and median OS was 15.2 (95% CI 10.9-19.1) and 17.0 months (95% CI 15.5-21.6) for F + T and T alone, respectively (p = 0.40). Of 112/157 patients (71%) receiving systemic therapy after progression under maintenance, 26/112 (23%) were treated with a reintroduction of initial chemotherapy + T and 86/112 (77%) with a standard second-line regimen. Here, median OS was significantly longer with the reintroduction (13.8 (95% CI 12.1-19.9) vs 9.0 months (95% CI 7.1-11.9); p = 0.007) as confirmed by multivariate analysis (HR 0.49; 95% CI 0.28-0.85; p = 0.01)., Conclusion: No additional benefit of adding F to T monotherapy as a maintenance treatment could be observed. Reintroduction of initial therapy at first progression may be a feasible approach to preserve later treatment lines., (© 2023. The Author(s) under exclusive licence to The International Gastric Cancer Association and The Japanese Gastric Cancer Association.)

Genomics has greatly improved how patients with cancer are being treated; however, clinical-grade genomic biomarkers for chemotherapies are currently lacking. Using whole-genome analysis of 37 patients with metastatic colorectal cancer (mCRC) treated with the chemotherapy trifluridine/tipiracil (FTD/TPI), we identified KRAS codon G12 (KRAS G12 ) mutations as a potential biomarker of resistance. Next, we collected real-world data of 960 patients with mCRC receiving FTD/TPI and validated that KRAS G12 mutations were significantly associated with poor survival, also in analyses restricted to the RAS/RAF mutant subgroup. We next analyzed the data of the global, double-blind, placebo-controlled, phase 3 RECOURSE trial (n = 800 patients) and found that KRAS G12 mutations (n = 279) were predictive biomarkers for reduced overall survival (OS) benefit of FTD/TPI versus placebo (unadjusted interaction P = 0.0031, adjusted interaction P = 0.015). For patients with KRAS G12 mutations in the RECOURSE trial, OS was not prolonged with FTD/TPI versus placebo (n = 279; hazard ratio (HR) = 0.97; 95% confidence interval (CI) = 0.73-1.20; P = 0.85). In contrast, patients with KRAS G13 mutant tumors showed significantly improved OS with FTD/TPI versus placebo (n = 60; HR = 0.29; 95% CI = 0.15-0.55; P < 0.001). In isogenic cell lines and patient-derived organoids, KRAS G12 mutations were associated with increased resistance to FTD-based genotoxicity. In conclusion, these data show that KRAS G12 mutations are biomarkers for reduced OS benefit of FTD/TPI treatment, with potential implications for approximately 28% of patients with mCRC under consideration for treatment with FTD/TPI. Furthermore, our data suggest that genomics-based precision medicine may be possible for a subset of chemotherapies., (© 2023. The Author(s).)

Cholangiocarcinoma (CCA) is a heterogeneous group of neoplasms of the bile ducts and represents the second most common hepatic cancer after hepatocellular carcinoma; it is sub-classified as intrahepatic cholangiocarcinoma (iCCA) and extrahepatic cholangiocarcinoma (eCCA), the latter comprising both perihilar cholangiocarcinoma (pCCA or Klatskin tumor), and distal cholangiocarcinoma (dCCA). The global incidence of CCA has increased worldwide in recent decades. Chronic inflammation of biliary epithelium and bile stasis represent the main risk factors shared by all CCA sub-types. When feasible, liver resection is the treatment of choice for CCA, followed by systemic chemotherapy with capecitabine. Liver transplants represent a treatment option in patients with very early iCCA, in referral centers only. CCA diagnosis is often performed at an advanced stage when CCA is unresectable. In this setting, systemic chemotherapy with gemcitabine and cisplatin represents the first treatment option, but the prognosis remains poor. In order to ameliorate patients' survival, new drugs have been studied in the last few years. Target therapies are directed against different molecules, which are altered in CCA cells. These therapies have been studied as second-line therapy, alone or in combination with chemotherapy. In the same setting, the immune checkpoints inhibitors targeting programmed death 1 (PD-1), programmed death-ligand 1 (PD-L1), cytotoxic T-lymphocyte antigen-4 (CTLA-4), have been proposed, as well as cancer vaccines and adoptive cell therapy (ACT). These experimental treatments showed promising results and have been proposed as second- or third-line treatment, alone or in combination with chemotherapy or target therapies., Competing Interests: Conflicts of interest Pietro Invernizzi and Sara Massironi are members of the European Reference Network on Hepatological Diseases (ERN RARE LIVER), and they thank AMAF Monza ONLUS and AIRCS for the unrestricted research funding. The remaining authors have no conflicts of interest to declare., (Copyright © 2022 Fundación Clínica Médica Sur, A.C. Published by Elsevier España, S.L.U. All rights reserved.)

Introduction: The combination of anti-EGFRs and doublet chemotherapy is considered the optimal upfront option for patients with RAS/BRAF wild-type left-sided metastatic colorectal cancer (mCRC). The prophylactic or reactive treatment with tetracyclines for EGFR inhibitor-induced skin toxicity is currently clinical practice, though non-conclusive results are available., Methods: We performed a post hoc analysis of the Valentino study that randomized RAS wild-type mCRC patients to two panitumumab-based maintenance regimens after the first-line induction, aimed at assessing the safety and efficacy of the administration of a pre-emptive doxycycline prophylaxis for anti-EGFR-related skin toxicity. We assessed the rate of treatment-related and panitumumab-related adverse events (AEs), treatment intensity, progression-free survival (PFS), and overall survival (OS)., Results: A total of 226 patients, out of the 229 enrolled in the Valentino study, were eligible for the analysis. Overall, 143 (63%) and 83 (37%) patients received or not the antibiotic prophylaxis for skin toxicity. Any grade and G3/4 panitumumab-related AEs were reported in 89% versus 92% (p = 0.650) and 27% versus 27% (p = 1.000) patients who received or not the pre-emptive prophylaxis, respectively. Any grade and G3/4 skin rash occurred in 81% versus 90% (p = 0.085) and 27% versus 25% (p = 0.876) patients receiving or not the prophylaxis, respectively. No significant differences in terms of treatment duration, treatment delays or dose reductions, PFS, and OS were observed in the two sub-populations., Conclusion: The adequate management of anti-EGFR-related skin toxicity is fundamental to optimize the outcome of mCRC patients, balancing the survival benefit with patients' quality of life, especially in the first-line setting.

Introduction: The Trust in Oncologist Scale (TiOS) is an 18-item questionnaire aimed to assess the cancer patients' trust in their oncologist and has been validated in Dutch and English language. This study aims to validate the Italian version of the TiOS (IT-TiOS) and the TiOS-Short Form (IT-TiOS-SF)., Methods: The IT-TiOS was administered to 194 patients recruited in an Italian oncology department from April to December 2018. Data collected included socio-demographic data, health and clinical information, satisfaction with the most recent oncology visit and trust in the regional healthcare system. Internal consistency, test-retest reliability, convergent and the structural validity of both the full and short form were tested., Results: Factor analyses indicated that neither four-factor nor one-factor models of the full scale were acceptable. However, confirmatory factor analysis supported the one-dimensionality of the IT-TiOS-SF, and internal consistency assessed with Cronbach's alpha was 0.88. Mean scores on the IT-TiOS-SF correlated with satisfaction with the oncologist (rs = 0.64) and willingness to recommend the oncologist to others (rs = 0.67), confirming good construct validity., Conclusion: The IT-TiOS-SF demonstrates good psychometric properties and can be used to assess trust for both clinical and research purposes., (© 2020 John Wiley & Sons Ltd.)

Background: Quality of life (QoL) patient-reported outcomes (PROs) data from pivotal first-line trials in metastatic colorectal cancer (mCRC) are poor. The Valentino study showed that de-escalation to single-agent panitumumab after 4-month induction with panitumumab-FOLFOX is inferior to panitumumab-5-FU/LV in patients with RAS wild-type mCRC, although slightly reducing toxicity. We report QoL, a secondary end-point., Methods: PROs were assessed by European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire - Core 30 (QLQ-C30), EORTC QLQ-CR29, EuroQol EQ-5D questionnaires, at baseline and every 8 weeks until disease progression. First two evaluations correspond to induction treatment (identical in both arms), while subsequent to maintenance. To describe QoL changes over time, mean changes from baseline at each time point were calculated in overall population. To compare maintenance between two arms, mean changes and proportion of improved/stable/worse patients versus baseline were compared for each item., Results: In arm A/B, 91.5%/92.0% of enrolled patients completed questionnaires at baseline. No significant differences in the two arms were reported in compliance, baseline scores and mean changes versus baseline for the three questionnaires during maintenance (24/32/40 weeks). Overall, mean changes versus baseline showed an early deterioration during induction with partial recovering during maintenance for global QoL, functional scales and several symptoms/items of QLQ-C30 (fatigue, nausea/vomiting, appetite loss, diarrhoea) and QLQ-CR29 (body image, dry mouth, hair loss, taste, faecal incontinence, sore skin), and EQ-5D Visual Analogue Scale (VAS) score., Conclusion: In patients with RAS wild-type mCRC, induction with oxaliplatin-containing chemotherapy plus anti-EGFRs induces a transient significant QoL deterioration. After induction phase, treatment deintensification determines an overall recovery of health-related QoL, besides the expected prevention of oxaliplatin-related neurotoxicity., Competing Interests: Conflict of interest statement F.P. reports receiving honoraria for speaker activities and participation in advisory boards from Sanofi SA, Amgen, Inc, Bayer AG, Merck-Serono, Roche, and Servier Laboratories. A.S.-B. reports participation in advisory boards for Amgen, Bayer and Sanofi. L.R. reports being related to this manuscript as a member of the advisory board and for panitumumab supply from Amgen; unrelated to this manuscript as consulting or advisory role from Lilly, Bayer, Baxter, Sirtex Medical, Italfarmaco, Sanofi, ArQule, Incyte, Ipsen, Exelixis, Celgene, Eisai, Hengrui, MSD; has also received lecture fees from AstraZeneca, AbbVie, Gilead, Roche; has received travel expenses from ArQule, Ipsen. A.Z. reports receiving honoraria for speaker activities and participation in advisory boards from Sanofi SA, Amgen, Inc, Bayer AG, Merck-Serono, and Roche. M.D.B. reports receiving honoraria for speaker activities and participation in advisory boards from Amgen, Inc, Roche, Eli Lilly and Company, Servier Laboratories. Incyte Corp, and Celgene Corporation. F.d.B. reports receiving honoraria for speaker activities and participation in advisory boards from Amgen, Inc, Roche, and Novartis International AG. No other disclosures were reported., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Cholangiocarcinoma (CCA) represents a disease entity that comprises a heterogeneous group of biliary malignant neoplasms, with variable clinical presentation and severity. It may be classified according to its anatomical location and distinguished in intrahepatic (iCCA), perihilar (pCCA), or distal (dCCA), each subtype implying distinct epidemiology, biology, prognosis, and strategy for clinical management. Its incidence has increased globally over the past few decades, and its mortality rate remains high due to both its biological aggressiveness and resistance to medical therapy. Surgery is the only potentially curative treatment and is the standard approach for resectable CCA; however, more than half of the patients have locally advanced or metastatic disease at presentation. For patients with unresectable CCA, the available systemic therapies are of limited effectiveness. However, the advances of the comprehension of the complex molecular landscape of CCA and its tumor microenvironment could provide new keys to better understand the pathogenesis, the mechanisms of resistance and ultimately to identify promising new therapeutic targets. Recently, clinical trials targeting isocitrate dehydrogenase (IDH)-1 mutations and fibroblast growth factor receptor (FGFR)-2 fusions, as well as immunotherapy showed promising results. All these new and emerging therapeutic options are herein discussed., Competing Interests: The authors declare no conflict of interest.

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., (©2019 American Association for Cancer Research.)

Importance: Few studies are available on the role of maintenance strategies after induction treatment regimens based on anti-epidermal growth factor receptors, and the optimal regimen for an anti-epidermal growth factor receptors-based maintenance treatment in patients with RAS wild-type metastatic colorectal cancer is still to be defined., Objective: To determine whether maintenance therapy with single-agent panitumumab was noninferior to panitumumab plus fluorouracil and leucovorin after a 4-month induction treatment regimen., Design, Setting, and Participants: This open-label, randomized phase 2 noninferiority trial was conducted from July 7, 2015, through October 27, 2017, at multiple Italian centers. Patients with RAS wild-type, unresectable metastatic colorectal adenocarcinoma who had not received previous treatment for metastatic disease were eligible. Induction therapy consisted of panitumumab plus FOLFOX-4 (panitumumab, 6 mg/kg, oxaliplatin, 85 mg/m2 at day 1, leucovorin calcium, 200 mg/m2, and fluorouracil, 400-mg/m2 bolus, followed by 600-mg/m2 continuous 24-hour infusion at days 1 and 2, every 2 weeks). Cutoff date for analyses was July 30, 2018., Interventions: Patients were randomized (1:1) to first-line panitumumab plus FOLFOX-4 for 8 cycles followed by maintenance therapy with panitumumab plus fluorouracil-leucovorin (arm A) or panitumumab (arm B) until progressive disease, unacceptable toxic effects, or consent withdrawal. The minimization method was used to stratify randomization by previous adjuvant treatment and number of metastatic sites., Main Outcomes and Measures: The prespecified primary end point was 10-month progression-free survival (PFS) analyzed on an intention-to-treat basis with a noninferiority margin of 1.515 for the upper limit of the 1-sided 90% CI of the hazard ratio (HR) of arm B vs A., Results: Overall, 229 patients (153 male [66.8%]; median age, 64 years [interquartile range (IQR), 56-70 years]) were randomly assigned to arm A (n = 117) or arm B (n = 112). At a median follow-up of 18.0 months (IQR, 13.1-23.3 months]), a total of 169 disease progression or death events occurred. Arm B was inferior (upper limit of 1-sided 90% CI of the HR, 1.857). Ten-month PFS was 59.9% (95% CI, 51.5%-69.8%) in arm A vs 49.0% (95% CI, 40.5%-59.4%) in arm B (HR, 1.51; 95% CI, 1.11-2.07; P = .01). During maintenance, arm A had a higher incidence of grade 3 or greater treatment-related adverse events (36 [42.4%] vs 16 [20.3%]) and panitumumab-related adverse events (27 [31.8%] vs 13 [16.4%]), compared with arm B., Conclusions and Relevance: In patients with RAS wild-type metastatic colorectal cancer, maintenance therapy with single-agent panitumumab was inferior in terms of PFS compared with panitumumab plus fluorouracil-leucovorin, which slightly increased the treatment toxic effects., Trial Registration: ClinicalTrials.gov identifier: NCT02476045.