Re-challenge with temozolomide (TMZ) at recurrence in high-grade gliomas (HGG)

Abstract

2034 Background: TMZ is standard therapy for patients (pts) with HGG. Recent data suggest potentially enhanced efficacy of alternative schedules of TMZ administration based on optimizing depletion of MGMT. However, no prospective data have been published on the efficacy of TMZ regimens after failure of first-line TMZ (FL-TMZ). We therefore assessed the outcome of rechallenge with TMZ in pts with HGG. Methods: A retrospective review of pt with recurrent HGG who were rechallenged with TMZ between Jan 2000 and Oct 2006 was conducted. Standard criteria for rechallenge were as follows: if pts relapsed=8 wks after discontinuation of FL-TMZ, they were treated with the same or an alternative regimen of TMZ; however, if they progressed while still receiving TMZ, they were treated with an alternative regimen. Results: Of a total 81 pts identified, 54 intra-institutional pts were evaluable, 23 glioblastoma (GBM), 22 anaplastic glioma (AG). Median age was 44 yr with median KPS of 80. The response rate (RR) to FL-TMZ was 65% in GBM and 95% in AG using Macdonald criteria. At rechallenge, pts received one of four TMZ regimens: 150–200 mg/m2/d for 5/28 days (n=35), 150 mg/m2/d for 7/14 days (n=7), 75 mg/m2/d for 21/28 days (n=4), or continuous 50 mg/m2/d (n=7). All pts had progressed during FL-TMZ or after initial discontinuation of TMZ. Discontinuation during rechallenge TMZ was due to progressive disease in 36 pts and patient request in 6 pts. None of the pts discontinued due to toxicity. The response rates were 66% and 70% in GBM and AG, respectively. 8/12 non-responders to FL-TMZ responded to alternate regimens of TMZ. Median time to progression (TTP) was 20 weeks and 22 weeks, respectively. Six-month progression-free survival was 41% in GBM and 43% in AG. Conclusions: TMZ was well tolerated without major toxicities and had a good RR in pts who had previously failed TMZ. Durable responses were observed in patients who had not initially responded to front-line TMZ. These data suggest that rechallenge with TMZ in previous responders and non-responders warrants further investigation in a prospective study. No significant financial relationships to disclose.