Mass, R.

3516 Background: A previous report noted that patients (pts) in the phase III study of IFL ± BV who received BV had significantly longer PFS and OS regardless of whether or not they responded according to RECIST criteria (Mass et al, ASCO 2005). It is unclear if this phenomenon is specific to the addition of a biologic to chemotherapy (CT) or a more general benefit from improved therapy since it has been suggested that stable as well as responding disease is beneficial for pts. We repeated the analysis of Mass et al on pts enrolled in N9741, a study which established the superiority of FOLFOX over IFL and contained no biologic compound. Methods: For this retrospective analysis, pts were defined as ‘responders‘ or ‘nonresponders‘ according to whether criteria for complete or partial response (by RECIST -AVF2107g or WHO criteria -N9741) were either achieved (responders) or not achieved (nonresponders). PFS and OS were estimated from Kaplan-Meier curves; hazard ratios (HR) for progression and death in each subgroup were estimated by Cox regression. Results: In both trials, response was associated with superior outcome. However, statistically significant improvements in PFS and OS were observed in both responders and non-responders treated with either IFL + BV or FOLFOX versus IFL, and the magnitude of improvement was similar regardless of response ( Table ). Conclusions: Analysis of two large recent mCRC phase III trials clearly demonstrate that pts who do not achieve a response according to traditional criteria still have significant benefit from the superior regimen, with a similar magnitude of benefit for responders and non-responders, regardless if the regimen called for CT alone or included the antiangiogenic biologic BV. These data support the conclusion that PFS and the percentage of pts experiencing tumor control may more accurately reflect pt benefit than does response rate in phase III trials in mCRC. [Table: see text] [Table: see text]

Purpose In the phase III study AVF2107g, bevacizumab (BV) demonstrated a survival benefit when added to irinotecan, fluorouracil, and leucovorin (IFL) in first-line metastatic colorectal cancer (mCRC). In a parallel phase III study, Intergroup N9741, oxaliplatin plus fluorouracil and leucovorin (FOLFOX) also demonstrated a survival benefit compared with IFL. As these two superior therapies have differing mechanisms of action, we explored whether the improved survival associated with the superior therapy was dependent on tumor response. Patients and Methods For these retrospective, exploratory analyses, patients were defined as responders or nonresponders by whether complete or partial response was achieved with first-line therapy. Results Compared with IFL alone, BV plus IFL and FOLFOX each demonstrated statistically significant improvements in progression-free survival (PFS) and overall survival (OS) regardless of objective tumor response. BV-treated nonresponders had a hazard ratio (HR) of 0.63 (P = .0001) for PFS and 0.76 (P = .0188) for OS compared with IFL-treated nonresponders. FOLFOX-treated nonresponders had an HR of 0.75 (P = .0029) for PFS and 0.74 (P = .0030) for OS compared with IFL-treated nonresponders. Conclusion In both AVF2107g and N9741, objective response did not predict the magnitude of PFS or OS benefit from the superior therapy; nonresponders, despite a poorer prognosis than responders, achieved extended PFS and OS from BV plus IFL or FOLFOX compared with IFL. On the basis of these data, tumor response in metastatic colorectal cancer is not a necessary factor for a therapy to provide benefit to an individual patient.