Telomerase as cancer target
With help of canadianer (thank you) I think I found the right article, so just want to share.

This study not talking specifically about telomerase, but about the same approach of using promoters that are upregulated in tumors - exactly what I looked for. Published in 2014.

http://symbiosisonlinepublishing.com/genetic-science/genetic-science03.pdf


  However, the therapeutic approach in humans is limited by
  low efficiency of delivering the suicide genes and concerns regarding
  safety. Thus the number of clinical trials in human patients has been
  limited and treatment benefits observed modest. An intensive research
  effort is necessary to overcome these obstacles and turn suicide gene
  therapy into real benefit for our patients.