High-dose etoposide and marrow transplantation

Area of Science:

• Pharmacology and Toxicology
• Oncology
• Clinical Trials

Background:

• Etoposide (VP-16) is a chemotherapeutic agent that underwent initial Phase I testing in the 1970s.
• Conventional etoposide therapy demonstrated mild myelosuppression as the primary dose-limiting toxicity.
• The steep dose-response relationship of etoposide suggests potential benefits from dose escalation.

Purpose of the Study:

• To evaluate the feasibility and toxicity of high-dose etoposide regimens.
• To explore the antitumor activity of escalated etoposide doses in various cancers.
• To determine the maximum tolerated dose (MTD) of etoposide in different treatment settings.

Main Methods:

• Phase I clinical trials were conducted to assess dose-escalation strategies for etoposide.
• High-dose etoposide was administered as a single agent or in combination with other agents (cyclophosphamide, irradiation, carmustine, carboplatin).
• Intensive hematologic supportive care, including autologous marrow transplantation, was employed in some trials.

Main Results:

• As a single agent, high-dose etoposide (2.4-3.0 g/m²) showed mucositis and hepatic dysfunction as dose-limiting toxicities.
• Combination regimens with etoposide resulted in dose-limiting mucosal toxicity, with increased hepatic and pulmonary issues.
• Etoposide demonstrated significant efficacy in lymphomas (80% response rate) and germ cell tumors (50-75% response rate), with notable long-term survival.
• Etoposide-containing regimens showed less favorable outcomes in breast cancer and small cell lung cancer (SCLC).

Conclusions:

• High-dose etoposide is a viable treatment option for lymphomas and germ cell tumors, offering significant response rates.
• Mucositis and hepatic dysfunction are key dose-limiting toxicities that require careful management.
• The efficacy of high-dose etoposide in solid tumors like breast cancer and SCLC requires further optimization.