Salvage Treatment With Topotecan in Patients With Irinotecan-Refractory Small Cell Lung Cancer

Trial Information

Salvage Treatment With Topotecan in Patients With Irinotecan-Refractory Small Cell Lung Cancer

Current commonly used second-line approaches for SCLC include re-induction with first-line
therapy for chemosensitive disease, or single-agent topotecan. Although the efficacy of
topotecan as second-line chemotherapy for SCLC has been consistently demonstrated in a
number of clinical studies, the choice of irinotecan as first-line therapy prevented use of
the evidence-based option such as topotecan. Topotecan and irinotecan are cytotoxic agents
that inhibit same intracellular pathway, namely topoisomerase I, which is an enzyme involved
in DNA replication and RNA transcription.

Although their mechanism of action is similar, the preclinical and clinical data of these
two drugs have some notable differences. Topotecan and irinotecan have different spectra of
antitumor activity in various models of human cancer. Clinical data support that these
agents may have different spectra of activity. The differences in antitumor activities may
also reflect different mechanisms of resistance. Furthermore, topotecan and irinotecan have
different limiting toxicities (myelosuppression and diarrhea, respectively).