title: Retreatment after secondary resistance or mixed response: a pilot study.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors: The University of Texas, MD Anderson Cancer Center, Houston, Tex.
authors: Aung
authors: A
authors: Naing
authors: Rishi
authors: R
authors: Agarwal
authors: Gerald
authors: G
authors: Falchook
authors: David S
authors: DS
authors: Hong
authors: Filip
authors: F
authors: Janku
authors: Jennifer
authors: J
authors: Wheler
authors: Siqing
authors: S
authors: Fu
authors: Razelle
authors: R
authors: Kurzrock
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy*; D010865:Pilot Projects; D019233:Retreatment