Hi,
I am sorry about the delay in replying. Here is my answer again:
Wine may not reduce the effectiveness of topotecan. However, it may lead to other difficulties, like nausea, anorexia etc. Overall, I would say - avoid alcohol if you can. If you must drink, drink in moderation
Please read this write-up on this topic by Cancer Research UK.
http://www.cancerhelp.org.uk/help/default.asp?page=5552
All the best, and God Bless!