F. Rivera

Bevacizumab in Combination With Oxaliplatin-Based Chemotherapy As First-Line Therapy in Metastatic Colorectal Cancer: A Randomized Phase III Study

PURPOSEnTo evaluate the efficacy and safety of bevacizumab when added to first-line oxaliplatin-based chemotherapy (either capecitabine plus oxaliplatin [XELOX] or fluorouracil/folinic acid plus oxaliplatin [FOLFOX-4]) in patients with metastatic colorectal cancer (MCRC).nnnPATIENTS AND METHODSnPatients with MCRC were randomly assigned, in a 2 x 2 factorial design, to XELOX versus FOLFOX-4, and then to bevacizumab versus placebo. The primary end point was progression-free survival (PFS).nnnRESULTSnA total of 1,401 patients were randomly assigned in this 2 x 2 analysis. Median progression-free survival (PFS) was 9.4 months in the bevacizumab group and 8.0 months in the placebo group (hazard ratio [HR], 0.83; 97.5% CI, 0.72 to 0.95; P = .0023). Median overall survival was 21.3 months in the bevacizumab group and 19.9 months in the placebo group (HR, 0.89; 97.5% CI, 0.76 to 1.03; P = .077). Response rates were similar in both arms. Analysis of treatment withdrawals showed that, despite protocol allowance of treatment continuation until disease progression, only 29% and 47% of bevacizumab and placebo recipients, respectively, were treated until progression. The toxicity profile of bevacizumab was consistent with that documented in previous trials.nnnCONCLUSIONnThe addition of bevacizumab to oxaliplatin-based chemotherapy significantly improved PFS in this first-line trial in patients with MCRC. Overall survival differences did not reach statistical significance, and response rate was not improved by the addition of bevacizumab. Treatment continuation until disease progression may be necessary in order to optimize the contribution of bevacizumab to therapy.

Platinum-Based Chemotherapy plus Cetuximab in Head and Neck Cancer

BACKGROUNDnCetuximab is effective in platinum-resistant recurrent or metastatic squamous-cell carcinoma of the head and neck. We investigated the efficacy of cetuximab plus platinum-based chemotherapy as first-line treatment in patients with recurrent or metastatic squamous-cell carcinoma of the head and neck.nnnMETHODSnWe randomly assigned 220 of 442 eligible patients with untreated recurrent or metastatic squamous-cell carcinoma of the head and neck to receive cisplatin (at a dose of 100 mg per square meter of body-surface area on day 1) or carboplatin (at an area under the curve of 5 mg per milliliter per minute, as a 1-hour intravenous infusion on day 1) plus fluorouracil (at a dose of 1000 mg per square meter per day for 4 days) every 3 weeks for a maximum of 6 cycles and 222 patients to receive the same chemotherapy plus cetuximab (at a dose of 400 mg per square meter initially, as a 2-hour intravenous infusion, then 250 mg per square meter, as a 1-hour intravenous infusion per week) for a maximum of 6 cycles. Patients with stable disease who received chemotherapy plus cetuximab continued to receive cetuximab until disease progression or unacceptable toxic effects, whichever occurred first.nnnRESULTSnAdding cetuximab to platinum-based chemotherapy with fluorouracil (platinum-fluorouracil) significantly prolonged the median overall survival from 7.4 months in the chemotherapy-alone group to 10.1 months in the group that received chemotherapy plus cetuximab (hazard ratio for death, 0.80; 95% confidence interval, 0.64 to 0.99; P=0.04). The addition of cetuximab prolonged the median progression-free survival time from 3.3 to 5.6 months (hazard ratio for progression, 0.54; P<0.001) and increased the response rate from 20% to 36% (P<0.001). The most common grade 3 or 4 adverse events in the chemotherapy-alone and cetuximab groups were anemia (19% and 13%, respectively), neutropenia (23% and 22%), and thrombocytopenia (11% in both groups). Sepsis occurred in 9 patients in the cetuximab group and in 1 patient in the chemotherapy-alone group (P=0.02). Of 219 patients receiving cetuximab, 9% had grade 3 skin reactions and 3% had grade 3 or 4 infusion-related reactions. There were no cetuximab-related deaths.nnnCONCLUSIONSnAs compared with platinum-based chemotherapy plus fluorouracil alone, cetuximab plus platinum-fluorouracil chemotherapy improved overall survival when given as first-line treatment in patients with recurrent or metastatic squamous-cell carcinoma of the head and neck. (ClinicalTrials.gov number, NCT00122460.)

Randomized, Phase III Trial of Panitumumab With Infusional Fluorouracil, Leucovorin, and Oxaliplatin (FOLFOX4) Versus FOLFOX4 Alone As First-Line Treatment in Patients With Previously Untreated Metastatic Colorectal Cancer: The PRIME Study

PURPOSEnPanitumumab, a fully human anti-epidermal growth factor receptor (EGFR) monoclonal antibody that improves progression-free survival (PFS), is approved as monotherapy for patients with chemotherapy-refractory metastatic colorectal cancer (mCRC). The Panitumumab Randomized Trial in Combination With Chemotherapy for Metastatic Colorectal Cancer to Determine Efficacy (PRIME) was designed to evaluate the efficacy and safety of panitumumab plus infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX4) versus FOLFOX4 alone as initial treatment for mCRC.nnnPATIENTS AND METHODSnIn this multicenter, phase III trial, patients with no prior chemotherapy for mCRC, Eastern Cooperative Oncology Group performance status of 0 to 2, and available tissue for biomarker testing were randomly assigned 1:1 to receive panitumumab-FOLFOX4 versus FOLFOX4. The primary end point was PFS; overall survival (OS) was a secondary end point. Results were prospectively analyzed on an intent-to-treat basis by tumor KRAS status.nnnRESULTSnKRAS results were available for 93% of the 1,183 patients randomly assigned. In the wild-type (WT) KRAS stratum, panitumumab-FOLFOX4 significantly improved PFS compared with FOLFOX4 (median PFS, 9.6 v 8.0 months, respectively; hazard ratio [HR], 0.80; 95% CI, 0.66 to 0.97; P = .02). A nonsignificant increase in OS was also observed for panitumumab-FOLFOX4 versus FOLFOX4 (median OS, 23.9 v 19.7 months, respectively; HR, 0.83; 95% CI, 0.67 to 1.02; P = .072). In the mutant KRAS stratum, PFS was significantly reduced in the panitumumab-FOLFOX4 arm versus the FOLFOX4 arm (HR, 1.29; 95% CI, 1.04 to 1.62; P = .02), and median OS was 15.5 months versus 19.3 months, respectively (HR, 1.24; 95% CI, 0.98 to 1.57; P = .068). Adverse event rates were generally comparable across arms with the exception of toxicities known to be associated with anti-EGFR therapy.nnnCONCLUSIONnThis study demonstrated that panitumumab-FOLFOX4 was well tolerated and significantly improved PFS in patients with WT KRAS tumors and underscores the importance of KRAS testing for patients with mCRC.

Panitumumab-FOLFOX4 treatment and RAS mutations in colorectal cancer

BACKGROUNDnPatients with metastatic colorectal cancer that harbors KRAS mutations in exon 2 do not benefit from anti-epidermal growth factor receptor (EGFR) therapy. Other activating RAS mutations may also be negative predictive biomarkers for anti-EGFR therapy.nnnMETHODSnIn this prospective-retrospective analysis, we assessed the efficacy and safety of panitumumab plus oxaliplatin, fluorouracil, and leucovorin (FOLFOX4) as compared with FOLFOX4 alone, according to RAS (KRAS or NRAS) or BRAF mutation status. A total of 639 patients who had metastatic colorectal cancer without KRAS mutations in exon 2 had results for at least one of the following: KRAS exon 3 or 4; NRAS exon 2, 3, or 4; or BRAF exon 15. The overall rate of ascertainment of RAS status was 90%.nnnRESULTSnAmong 512 patients without RAS mutations, progression-free survival was 10.1 months with panitumumab-FOLFOX4 versus 7.9 months with FOLFOX4 alone (hazard ratio for progression or death with combination therapy, 0.72; 95% confidence interval [CI], 0.58 to 0.90; P=0.004). Overall survival was 26.0 months in the panitumumab-FOLFOX4 group versus 20.2 months in the FOLFOX4-alone group (hazard ratio for death, 0.78; 95% CI, 0.62 to 0.99; P=0.04). A total of 108 patients (17%) with nonmutated KRAS exon 2 had other RAS mutations. These mutations were associated with inferior progression-free survival and overall survival with panitumumab-FOLFOX4 treatment, which was consistent with the findings in patients with KRAS mutations in exon 2. BRAF mutations were a negative prognostic factor. No new safety signals were identified.nnnCONCLUSIONSnAdditional RAS mutations predicted a lack of response in patients who received panitumumab-FOLFOX4. In patients who had metastatic colorectal cancer without RAS mutations, improvements in overall survival were observed with panitumumab-FOLFOX4 therapy. (Funded by Amgen and others; PRIME ClinicalTrials.gov number, NCT00364013.).

OPTIMOX1: A Randomized Study of FOLFOX4 or FOLFOX7 With Oxaliplatin in a Stop-and-Go Fashion in Advanced Colorectal Cancer—A GERCOR Study

PURPOSEnIn metastatic colorectal cancer, a combination of leucovorin (LV) and fluorouracil (FU) with oxaliplatin (FOLFOX) 4 is a standard first-line regimen. The cumulative neurotoxicity of oxaliplatin often requires therapy to be stopped in patients who are still responding. This study evaluates a new strategy of intermittent oxaliplatin treatment that is based on FOLFOX7, a simplified leucovorin and fluorouracil regimen with high-dose oxaliplatin.nnnPATIENTS AND METHODSnPreviously untreated patients were randomly assigned to either FOLFOX4 administered every 2 weeks until progression (arm A) or FOLFOX7 for six cycles, maintenance without oxaliplatin for 12 cycles, and reintroduction of FOLFOX7 (arm B).nnnRESULTSnSix hundred twenty patients were enrolled, including an exploratory cohort of 95 elderly or poor prognosis patients. Median progression-free survival and survival times were 9.0 and 19.3 months, respectively, in patients allocated to arm A compared with 8.7 and 21.2 months, respectively, in patients allocated to arm B (P = not significant). Response rates were 58.5% with arm A and 59.2% with arm B. National Cancer Institute Common Toxicity Criteria grade 3 or 4 toxicity was observed in 54.4% of the patients in arm A v 48.7% of patients in arm B. From cycle 7, fewer patients experienced grade 3 or 4 toxicity in arm B. Grade 3 sensory neuropathy was observed in 17.9% of the patients in arm A v 13.3% of patients in arm B (P = .12). In arm B, oxaliplatin was reintroduced in only 40.1% of the patients but achieved responses or stabilizations in 69.4% of these patients.nnnCONCLUSIONnOxaliplatin can be safely stopped after six cycles in a FOLFOX regimen. Further study is needed to fully evaluate oxaliplatin reintroduction.

Randomized Phase III Study of Capecitabine Plus Oxaliplatin Compared With Fluorouracil/Folinic Acid Plus Oxaliplatin As First-Line Therapy for Metastatic Colorectal Cancer

PURPOSEnTo evaluate whether capecitabine plus oxaliplatin (XELOX) is noninferior to fluorouracil. folinic acid, and oxaliplatin (FOLFOX-4) as first-line therapy in metastatic colorectal cancer (MCRC).nnnPATIENTS AND METHODSnThe initial design of this trial was a randomized, two-arm, noninferiority, phase III comparison of XELOX versus FOLFOX-4. After patient accrual had begun, the trial design was amended in 2003 after bevacizumab phase III data became available. The resulting 2 x 2 factorial design randomly assigned patients to XELOX versus FOLFOX-4, and then to also receive either bevacizumab or placebo. We report here the results of the analysis of the XELOX versus FOLFOX-4 arms. The analysis of bevacizumab versus placebo with oxaliplatin-based chemotherapy is reported separately. The prespecified primary end point for the noninferiority analysis was progression-free survival.nnnRESULTSnThe intent-to-treat population comprised 634 patients from the original two-arm portion of the study, plus an additional 1,400 patients after the start of the amended 2 x 2 design, for a total of 2,034 patients. The median PFS was 8.0 months in the pooled XELOX-containing arms versus 8.5 months in the FOLFOX-4-containing arms (hazard ratio [HR], 1.04; 97.5% CI, 0.93 to 1.16). The median overall survival was 19.8 months with XELOX versus 19.6 months with FOLFOX-4 (HR, 0.99; 97.5% CI, 0.88 to 1.12). FOLFOX-4 was associated with more grade 3/4 neutropenia/granulocytopenia and febrile neutropenia than XELOX, and XELOX with more grade 3 diarrhea and grade 3 hand-foot syndrome than FOLFOX-4.nnnCONCLUSIONnXELOX is noninferior to FOLFOX-4 as a first-line treatment for MCRC, and may be considered as a routine treatment option for appropriate patients.

Safety and efficacy of first-line bevacizumab with FOLFOX, XELOX, FOLFIRI and fluoropyrimidines in metastatic colorectal cancer: the BEAT study

BACKGROUNDnBevacizumab significantly improves survival when added to chemotherapy for metastatic colorectal cancer (mCRC). The Bevacizumab Expanded Access Trial (BEAT) evaluated the safety and efficacy of bevacizumab plus first-line chemotherapy in a general cohort of patients with mCRC.nnnPATIENTS AND METHODSnPatients with unresectable mCRC received chemotherapy (physicians choice) plus bevacizumab [5 mg/kg every 2 weeks (5-fluorouracil regimens) or 7.5 mg/kg every 3 weeks (capecitabine regimens)]. The primary end point was safety, including prospective data collection in patients receiving unanticipated surgery during the study. Secondary objectives were progression-free survival (PFS) and overall survival (OS).nnnRESULTSnThe final analysis comprised 1914 assessable patients (male 58%; median age 59 years). Chemotherapy included 5-fluorouracil/leucovorin (5-FU/LV) + oxaliplatin (29%), irinotecan plus 5-FU/LV (26%), capecitabine plus oxaliplatin (18%) and monotherapy (16%). Serious/grade 3-5 adverse events of interest for bevacizumab included bleeding (3%), gastrointestinal perforation (2%), arterial thromboembolism (1%), hypertension (5.3%), proteinuria (1%) and wound-healing complications (1%). Sixty-day mortality was 3%. Median PFS was 10.8 months [95% confidence interval (CI) 10.4-11.3 months] and median OS reached 22.7 months (95% CI 21.7-23.8 months).nnnCONCLUSIONSnThe BEAT study shows that the efficacy and safety profile of bevacizumab in routine clinical practice is consistent with results observed in prospective randomised clinical trials and another large observational study in the United States (BRiTE study).

Bevacizumab plus oxaliplatin-based chemotherapy as adjuvant treatment for colon cancer (AVANT): a phase 3 randomised controlled trial

BACKGROUNDnBevacizumab improves the efficacy of oxaliplatin-based chemotherapy in metastatic colorectal cancer. Our aim was to assess the use of bevacizumab in combination with oxaliplatin-based chemotherapy in the adjuvant treatment of patients with resected stage III or high-risk stage II colon carcinoma.nnnMETHODSnPatients from 330 centres in 34 countries were enrolled into this phase 3, open-label randomised trial. Patients with curatively resected stage III or high-risk stage II colon carcinoma were randomly assigned (1:1:1) to receive FOLFOX4 (oxaliplatin 85 mg/m(2), leucovorin 200 mg/m(2), and fluorouracil 400 mg/m(2) bolus plus 600 mg/m(2) 22-h continuous infusion on day 1; leucovorin 200 mg/m(2) plus fluorouracil 400 mg/m(2) bolus plus 600 mg/m(2) 22-h continuous infusion on day 2) every 2 weeks for 12 cycles; bevacizumab 5 mg/kg plus FOLFOX4 (every 2 weeks for 12 cycles) followed by bevacizumab monotherapy 7·5 mg/kg every 3 weeks (eight cycles over 24 weeks); or bevacizumab 7·5 mg/kg plus XELOX (oxaliplatin 130 mg/m(2) on day 1 every 2 weeks plus oral capecitabine 1000 mg/m(2) twice daily on days 1-15) every 3 weeks for eight cycles followed by bevacizumab monotherapy 7·5 mg/kg every 3 weeks (eight cycles over 24 weeks). Block randomisation was done with a central interactive computerised system, stratified by geographic region and disease stage. Surgery with curative intent occurred 4-8 weeks before randomisation. The primary endpoint was disease-free survival, analysed for all randomised patients with stage III disease. This study is registered with ClinicalTrials.gov, number NCT00112918.nnnFINDINGSnOf the total intention-to-treat population (n=3451), 2867 patients had stage III disease, of whom 955 were randomly assigned to receive FOLFOX4, 960 to receive bevacizumab-FOLFOX4, and 952 to receive bevacizumab-XELOX. After a median follow-up of 48 months (range 0-66 months), 237 patients (25%) in the FOLFOX4 group, 280 (29%) in the bevacizumab-FOLFOX4 group, and 253 (27%) in the bevacizumab-XELOX group had relapsed, developed a new colon cancer, or died. The disease-free survival hazard ratio for bevacizumab-FOLFOX4 versus FOLFOX4 was 1·17 (95% CI 0·98-1·39; p=0·07), and for bevacizumab-XELOX versus FOLFOX4 was 1·07 (0·90-1·28; p=0·44). After a minimum follow-up of 60 months, the overall survival hazard ratio for bevacizumab-FOLFOX4 versus FOLFOX4 was 1·27 (1·03-1·57; p=0·02), and for bevacizumab-XELOX versus FOLFOX4 was 1·15 (0·93-1·42; p=0·21). The 573 patients with high-risk stage II cancer were included in the safety analysis. The most common grade 3-5 adverse events were neutropenia (FOLFOX4: 477 [42%] of 1126 patients, bevacizumab-FOLFOX4: 416 [36%] of 1145 patients, and bevacizumab-XELOX: 74 [7%] of 1135 patients), diarrhoea (110 [10%], 135 [12%], and 181 [16%], respectively), and hypertension (12 [1%], 122 [11%], and 116 [10%], respectively). Serious adverse events were more common in the bevacizumab groups (bevacizumab-FOLFOX4: 297 [26%]; bevacizumab-XELOX: 284 [25%]) than in the FOLFOX4 group (226 [20%]). Treatment-related deaths were reported in one patient receiving FOLFOX4, two receiving bevacizumab-FOLFOX4, and five receiving bevacizumab-XELOX.nnnINTERPRETATIONnBevacizumab does not prolong disease-free survival when added to adjuvant chemotherapy in resected stage III colon cancer. Overall survival data suggest a potential detrimental effect with bevacizumab plus oxaliplatin-based adjuvant therapy in these patients. On the basis of these and other data, we do not recommend the use of bevacizumab in the adjuvant treatment of patients with curatively resected stage III colon cancer.nnnFUNDINGnGenentech, Roche, and Chugai.

Phase III Study of Capecitabine Plus Oxaliplatin Compared With Continuous-Infusion Fluorouracil Plus Oxaliplatin As First-Line Therapy in Metastatic Colorectal Cancer: Final Report of the Spanish Cooperative Group for the Treatment of Digestive Tumors Trial

PURPOSEnThe aim of this phase III trial was to compare the efficacy and safety of capecitabine plus oxaliplatin (XELOX) versus Spanish-based continuous-infusion high-dose fluorouracil (FU) plus oxaliplatin (FUOX) regimens as first-line therapy for metastatic colorectal cancer (MCRC).nnnPATIENTS AND METHODSnA total of 348 patients were randomly assigned to receive XELOX (oral capecitabine 1,000 mg/m2 bid for 14 days plus oxaliplatin 130 mg/m2 on day 1 every 3 weeks) or FUOX (continuous-infusion FU 2,250 mg/m2 during 48 hours on days 1, 8, 15, 22, 29, and 36 plus oxaliplatin 85 mg/m2 on days 1, 15, and 29 every 6 weeks).nnnRESULTSnThere were no significant differences in efficacy between XELOX and FUOX arms, which showed, respectively, median time to tumor progression (TTP; 8.9 v 9.5 months; P = .153); median overall survival (18.1 v 20.8 months; P = .145); and confirmed response rate (RR; 37% v 46%; P = .539). The safety profile of the two regimens was similar, although there were lower rates of grade 3/4 diarrhea (14% v 24%) and grade 1/2 stomatitis (28% v 43%), and higher rates of grade 1/2 hyperbilirubinemia (37% v 21%) and grade 1/2 hand-foot syndrome (14% v 5%) with XELOX versus FUOX, respectively.nnnCONCLUSIONnThis randomized study shows a similar TTP of XELOX compared with FUOX in the first-line treatment of MCRC, although there was a trend for slightly lower RR and survival. XELOX can be considered as an alternative to FUOX.

Final results from PRIME: randomized phase III study of panitumumab with FOLFOX4 for first-line treatment of metastatic colorectal cancer

BACKGROUNDnThe Panitumumab Randomized trial In combination with chemotherapy for Metastatic colorectal cancer to determine Efficacy (PRIME) demonstrated that panitumumab-FOLFOX4 significantly improved progression-free survival (PFS) versus FOLFOX4 as first-line treatment of wild-type (WT) KRAS metastatic colorectal cancer (mCRC), the primary end point of the study.nnnPATIENTS AND METHODSnPatients were randomized 1:1 to panitumumab 6.0 mg/kg every 2 weeks + FOLFOX4 (arm 1) or FOLFOX4 (arm 2). This prespecified final descriptive analysis of efficacy and safety was planned for 30 months after the last patient was enrolled.nnnRESULTSnA total of 1183 patients were randomized. Median PFS for WT KRAS mCRC was 10.0 months [95% confidence interval (CI) 9.3-11.4 months] for arm 1 and 8.6 months (95% CI 7.5-9.5 months) for arm 2; hazard ratio (HR) = 0.80; 95% CI 0.67-0.95; P = 0.01. Median overall survival (OS) for WT KRAS mCRC was 23.9 months (95% CI 20.3-27.7 months) for arm 1 and 19.7 months (95% CI 17.6-22.7 months) for arm 2; HR = 0.88; 95% CI 0.73-1.06; P = 0.17 (68% OS events). An exploratory analysis of updated survival (>80% OS events) was carried out which demonstrated improvement in OS; HR = 0.83; 95% CI 0.70-0.98; P = 0.03 for WT KRAS mCRC. The adverse event profile was consistent with the primary analysis.nnnCONCLUSIONSnIn WT KRAS mCRC, PFS was improved, objective response was higher, and there was a trend toward improved OS with panitumumab-FOLFOX4, with significant improvement in OS observed in an updated analysis of survival in patients with WT KRAS mCRC treated with panitumumab + FOLFOX4 versus FOLFOX4 alone (P = 0.03). These data support a positive benefit-risk profile for panitumumab-FOLFOX4 for patients with previously untreated WT KRAS mCRC. KRAS testing is critical to select appropriate patients for treatment with panitumumab.BACKGROUNDnThe Panitumumab Randomized trial In combination with chemotherapy for Metastatic colorectal cancer to determine Efficacy (PRIME) demonstrated that panitumumab-FOLFOX4 significantly improved progression-free survival (PFS) versus FOLFOX4 as first-line treatment of wild-type (WT) KRAS metastatic colorectal cancer (mCRC), the primary end point of the study.nnnPATIENTS AND METHODSnPatients were randomized 1:1 to panitumumab 6.0 mg/kg every 2 weeks + FOLFOX4 (arm 1) or FOLFOX4 (arm 2). This prespecified final descriptive analysis of efficacy and safety was planned for 30 months after the last patient was enrolled.nnnRESULTSnA total of 1183 patients were randomized. Median PFS for WT KRAS mCRC was 10.0 months [95% confidence interval (CI) 9.3-11.4 months] for arm 1 and 8.6 months (95% CI 7.5-9.5 months) for arm 2; hazard ratio (HR) = 0.80; 95% CI 0.67-0.95; P = 0.01. Median overall survival (OS) for WT KRAS mCRC was 23.9 months (95% CI 20.3-27.7 months) for arm 1 and 19.7 months (95% CI 17.6-22.7 months) for arm 2; HR = 0.88; 95% CI 0.73-1.06; P = 0.17 (68% OS events). An exploratory analysis of updated survival (>80% OS events) was carried out which demonstrated improvement in OS; HR = 0.83; 95% CI 0.70-0.98; P = 0.03 for WT KRAS mCRC. The adverse event profile was consistent with the primary analysis.nnnCONCLUSIONSnIn WT KRAS mCRC, PFS was improved, objective response was higher, and there was a trend toward improved OS with panitumumab-FOLFOX4, with significant improvement in OS observed in an updated analysis of survival in patients with WT KRAS mCRC treated with panitumumab + FOLFOX4 versus FOLFOX4 alone (P = 0.03). These data support a positive benefit-risk profile for panitumumab-FOLFOX4 for patients with previously untreated WT KRAS mCRC. KRAS testing is critical to select appropriate patients for treatment with panitumumab.