Retreatment after secondary resistance or mixed response: a pilot study
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Aung Naing1, Rishi Agarwal, Gerald Falchook
1The University of Texas, MD Anderson Cancer Center, Houston, Tex.
Objective:
Oncologists usually avoid retreatment with drugs to which patients have shown secondary resistance or a mixed response. Here, we report our findings in a pilot study in patients rechallenged with agents previously producing prolonged stable disease (SD), partial or complete remission (PR/CR) or a mixed response, followed by progression.
Results:
Eleven individuals with advanced cancers (median number of prior systemic therapies in the metastatic setting = 4, range 2-7) were included (8 men; median age 57 years; median Eastern Cooperative Oncology Group performance status of 1). The median duration between initial treatment and retreatment was 92 weeks. Eight of 11 patients (73%) on a retreatment regimen showed SD ≥24 weeks/PR/CR. Of these 8 individuals, 2 were retreated with the same agent(s), 1 with a different agent possessing the same mechanism of action (e.g., in case of an epidermal growth factor receptor inhibitor, using gefitinib first, then erlotinib), and 5 with the same agent(s) in combination with other agents.
Conclusion:
Our pilot data suggest that patients who develop acquired resistance after durable SD/CR/PR or who have an initial mixed response may attain SD ≥6 months/PR/CR with a retreatment approach.
