Background: Despite the well-known negative prognostic value of the V600E BRAF mutation in patients with metastatic colorectal cancer (mCRC), its outcome is quite heterogeneous, and the basis for this prognostic heterogeneity should be better defined. Methods: Two large retrospective series of V600E BRAF-mutated mCRC from 22 institutions served as an exploratory and validation set to develop a prognostic score. The model was internally and externally validated. Results: A total of 395 V600E BRAF-mutated mCRCs were included in the exploratory set. Performance status, CA19.9, lactate dehydrogenase, neutrophil/lymphocyte ratio, grading and liver, lung and nodal involvement emerged as independent prognostic factors for overall survival (OS). Two different scoring systems were built: a 'complete' score (0e16) including all significant covariates and a 'simplified' score (0e9), based only on clinicopathological covariates, and excluding laboratory values. Adopting the complete score, proportions of patients with a low (0e4), intermediate (5e8) and high (9e16) score were 44.7%, 42.6% and 12.6%, respectively. The median OS was 29.6, 15.5 (hazard ratio [HR] for intermediate vs low risk: 2.16, 95% confidence interval [CI]: 1.44e3.22, p < .001) and 6.6 months (HR for high vs low risk: 4.72, 95% CI: 2.72e8.20, p < .001). Similar results were observed also after adjusting for the type of first-line treatment and adopting the simplified score. The simplified prognostic score derived from the exploratory set was then applied to the validation set for external confirmation. Conclusions: These scoring systems are based on easy-to-collect data and defined specific subgroups with relevant differences in their life expectancy. These tools could be useful in clinical practice, would allow better stratification of patients in clinical trials and may be adopted for proper adjustments in exploratory translational analyses.

4002 Background: Data on first-line treatment efficacy in elderly patients are limited. Many analyses adopt a questionable cut-off of 65 years and specific evidence with anti-EGFRs is low. FOLFOX-panitumumab (pan) is an option for RAS wild-type (wt) untreated mCRC patients. Guidelines recommend considering fluoropyrimidine monotherapy as an option for elderly patients, but no randomized studies have ever explored the role of the combination with an anti-EGFR. Methods: This is a prospective, open-label, multicenter phase II randomized trial. Unresectable and previously untreated RAS- BRAF wt mCRC patients aged ≥70 were randomized to receive FOLFOX-pan (arm A), or 5FU/LV-pan (arm B) for up to 12 cycles followed by pan maintenance until PD. The primary EP was PFS in both arms. Stratification criteria were age (≤75 vs > 75 years), ECOG PS (0–1 vs 2) and geriatric assessment with G8 Score (≤14 vs > 14). In each treatment arm, the null hypothesis for median PFS was set at ≤6 months. Assuming an expected median PFS time ≥9.5 months with both experimental regimens, a sample size of 90 patients in each arm granted to the study a power of 90%, with a type I error rate equal to 5% (1-sided Brookmeyer-Crowley test) for rejecting the null hypothesis. No formal comparison between the two arms was planned. Results: From Jul 2016 to Apr 2019 a total of 394 patients were screened, 211 were deemed eligible for inclusion and 185 were randomized (92 arm A and 93 arm B). Main pts’ characteristics were (arm A/B): males 66%/61%; median age 77/77y; PS≥1 49%/55%; right colon 23%/21%; G8 > 14 31%/30%. At a median follow up of 20.5 mos, 135 (arm A/B: 64/71) PD events were collected. Median PFS was 9.6 (95% CI 8.8-10.9) in arm A with FOLFOX-pan and 9.1 (95% CI 7.7-9.9) in arm B with 5FU/LV-pan. Response rates were (arm A/B): 65%/57%. Grade 3-4 toxicities were (arm A/B): neutropenia 9.8%/1.1%; diarrhea 16.3%/1.1%; stomatitis 9.8%/4.4%; neurotoxicity 3.3%/0%; fatigue 6.5%/4.4%; skin rash 25%/24.2%, hypomagnesemia 3.3%/7.7%. Conclusions: Large prospective randomized studies in molecularly selected elderly mCRC are feasible with multicenter collaborative efforts. Primary EP was met in both treatment arms. 5FU/LV plus panitumumab for up to 12 cycles followed by panitumumab maintenance until PD might be a reasonable option in elderly mCRC patients with RAS/BRAF wt tumors deserving further investigations in phase III trials. Clinical trial information: NCT02904031 .

BackgroundFew data are available regarding the treatment of metastatic colorectal cancer elderly patients with anti-EGFR agents in combination with chemotherapy. FOLFOX plus panitumumab is a standard first-line option for RAS wild-type metastatic colorectal cancer. Slight adjustments in chemo-dosage are commonly applied in clinical practice to elderly patients, but those modified schedules have never been prospectively tested. Clinical definition of elderly (≥70 years old) patients that may deserve a more or less intensive combination therapy is still debated. Several geriatric screening tools have been developed to predict survival and risk of toxicity from treatment. Among those, the G8 screening tool has been tested in cancer patients showing the strongest prognostic value for overall survival, while the CRASH score can stratify patients according to an estimated risk of treatment-related toxicities.MethodsThe PANDA study is a prospective, open-label, multicenter, randomized phase II trial of first-line therapy with panitumumab in combination with dose-adjusted FOLFOX or with 5-fluorouracil monotherapy, in previously untreated elderly patients (≥70 years) with RAS and BRAF wild-type unresectable metastatic colorectal cancer. RAS and BRAF analyses are centralized. Geriatric assessment by means of G8 and CRASH score is planned at baseline and G8 will be re-evaluated at disease progression. The primary endpoint is duration of progression-free survival in both arms. Secondary endpoints include prospective evaluation of the prognostic role of G8 score and the correlation of CRASH risk categories with toxicity.DiscussionThe PANDA study aims at exploring safety and efficacy of panitumumab in combination with FOLFOX or with 5FU/LV in elderly patients affected by RAS and BRAF wild-type metastatic colorectal cancer, to identify the most promising treatment strategy in this setting. Additionally, this is the first trial in which the prognostic role of the G8 score will be prospectively evaluated. Results of this study will drive further experimental developments for one or both combinations.Trial RegistrationPANDA is registered at Clinicaltrials.gov: NCT02904031, July 11, 2016. PANDA is registered at EudraCT-No.: 2015–003888-10, September 3, 2015.

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