Recent studies have shown that with panitumumab median PFS times were similar for patients with negative, low, and high levels of EGFR expression
(123). The efficacy of panitumumab monotherapy in patients with KRAS wild-type metastatic colorectal carcinoma refractory to standard chemotherapeutic agents has been shown in the pivotal open label phase III study (124,125) in which panitumumab significantly prolonged progression-free survival versus best supportive care (median Inhibitors,research,lifescience,medical 12.3 vs. 7.3 months, P<0.0001). Disease control was also improved with 51% versus 12% benefiting from treatment (PR, SD). OS was not significantly different between both groups- possibly because of crossover from the best supportive Inhibitors,research,lifescience,medical care alone to panitumumab after progression, which could confound the results. An exploratory analysis excluding crossover supports
this hypothesis. The selleck chemicals llc combination of panitumumab and FOLFOX for first-line treatment has been investigated in a randomized study (PRIME) where 1,183 patients were randomized to FOLFOX4 with panitumumab every two weeks versus Inhibitors,research,lifescience,medical FOLFOX4 alone. Patients with wild-type KRAS in the panitumumab group had a median PFS of 9.6 months and a RR of 55% compared to a PFS of 8 months and a RR 48% respectively in patients with unmutated KRAS treated with FOLFOX4 alone (126). The phase II multicentre, PACCE (Panitumumab Advanced Colorectal Cancer Evaluation)
study evaluated the efficacy and Inhibitors,research,lifescience,medical safety of adding panitumumab to combination chemotherapy with bevacizumab for the first-line treatment of mCRC (116). A planned interim analysis revealed that PFS and OS were worse in the panitumumab plus bevacizumab and chemotherapy arm compared to the standard bevacizumab and chemotherapy arm. In the second-line setting, patients with wild-type KRAS were Inhibitors,research,lifescience,medical found to have significantly increased OS in the FOLFIRI/panitumumab group (127) with 14.5 versus 12.5 months in the wild-type KRAS group over FOLFIRI alone. No significant difference in PFS or OS was noted in patients with KRAS mutations. Two phase Dacomitinib II trials have examined the integration of panitumumab into CRT schedules (61,63) see Table 5. In the StarPan (STAR-02) Study (61), pCR rate was 12/60 (20%), in the SAKK 41/07 trial this rate was 4/40 (10%) (63), which seems higher than the pCR achieved in the phase II studies based on cetuximab–fluoropyrimidine combination with or without oxaliplatin. Interestingly in the SAKK trial 43% achieved near complete regression (Dworak 3TRG) most of these residual cells were not apoptotic (63). The Italian group are intending to perfrom a further STAR Study (Rap Study/STAR-03) to evaluate panitumumab in combination with RT alone in selleck 17-DMAG low-risk LARC.