The issue of continuing Herceptin is complex but there is little firm evidence to support this practice. The current practice is supported solely by a retrospective chart review of 1000 women presented in 2002. However, NCCN currently on p. BINV-20 of its 2011 breast cqncer guideline says in a note that continuing trastuzumab after progression on first-line therapy is a option. Optimal duration is unknown.
Whether to continue trastuzumab after objective evidence of disease progression or not is an important unanswered clinical question for women with metastatic disease. This question is also relevant for those who relapse after adjuvant trastuzumab-containing therapy. Unfortunately, there is little evidence to guide decision-making. The modest toxicity and the possible, but unproven, benefit from the continued use of trastuzumab may account for the currently wide spread practice of continued administration of this drug after progression. However, there is no convincing evidence to support the use of extended trastuzumab therapy after progression. At least two randomized trials with no trastuzumab in the control arms were attempted but failed to accrue patients. In the absence of results from a randomized clinical trial, a central registry program that collects information longitudinally from a large number of patients with HER-2 positive breast cancer during the course of their disease was initiated (RegistHER, www.registher.com ) to learn about the long term side effects and benefits of prolonged trastuzumab therapy. The anticipated introduction of second generation HER2-targeted agents into the clinic also raises a new question; will switching to these agents be more effective than continuation of trastuzumab? Clinical trials are currently planned to address the question prospectively.
J. Mackey et al.Herceptin can be continued even after disease progression without worse side effects and with possible benefits, ASCO Program/Proceedings, May 2002, abstract #207
Pusztai, Lajos1; Esteva, Francisco, Continued Use of Trastuzumab (Herceptin) after Progression on Prior Trastuzumab Therapy in HER-2-Positive Metastatic Breast Cancer, Cancer Investigation, Volume 24, Number 2, March 2006, pp. 187-191(5)