Impact of age and gender on the efficacy and safety of upfront therapy with panitumumab plus FOLFOX followed by panitumumab-based maintenance: a pre-specified subgroup analysis of the Valentino study

BACKGROUND: The safety and efficacy outcome of elderly metastatic colorectal cancer (mCRC) patients fit enough to receive combination chemotherapy plus biological agents is an issue of growing interest. Also, gender-specific differential toxicity and efficacy of anti-epidermal growth factor receptor (EGFR)-based upfront treatments need to be explored. PATIENTS AND METHODS: Valentino was a multicenter, randomized, phase II trial, investigating two panitumumab-based maintenance strategies following first-line panitumumab plus FOLFOX in RAS wild-type mCRC patients. We carried out a subgroup analysis, aimed at assessing the differences in efficacy, safety and quality of life (QoL) according to age (<70 versus ≥70 years) and gender (male versus female). Efficacy endpoints were progression-free survival (PFS), overall survival (OS) and overall response rate (ORR); safety endpoints were rates of any grade and grade 3/4 adverse events (AEs). RESULTS: No significant differences in terms of PFS, OS and ORR were observed between patients aged <70 or ≥70 years and the effect of the maintenance treatment arm on survival outcomes was similar in the two subgroups. The safety profile of both induction and maintenance treatment and the impact on QoL were similar in elderly and younger patients. No significant differences in PFS, OS, ORR or clinical benefit rate were observed according to gender. A significantly higher rate of overall grade 3/4 AEs (P = 0.008) and of grade 3/4 thrombocytopenia (P = 0.017), any grade and grade 3/4 neutropenia (P < 0.0001) and any grade conjunctivitis (P = 0.033) was reported in female as compared to male patients. Conversely, we reported a significantly higher incidence of any grade skin rash (P = 0.0007) and hypomagnesemia (P = 0.029) in male patients. CONCLUSIONS: The upfront choice of an anti-EGFR-based doublet chemotherapy followed by a maintenance strategy represents a valuable option in RAS wild-type mCRC irrespective of gender and age, though a careful evaluation of patients to maximize the risk/benefit ratio is warranted.