carboplatin + cyclophosphamide + etoposide + thiotepa

This is a high-dose chemotherapy combination regimen consisting of four cytotoxic agents—carboplatin, cyclophosphamide, etoposide, and thiotepa. Each drug has a distinct mechanism of action targeting cancer cells through different pathways to maximize cytotoxicity and minimize cross-resistance. Carboplatin is a platinum-based compound that forms DNA crosslinks, inhibiting DNA synthesis and function. Cyclophosphamide is an alkylating agent that interferes with DNA replication by forming covalent bonds with DNA bases. Etoposide inhibits topoisomerase II, leading to double-strand breaks in DNA during the cell cycle. Thiotepa is another alkylating agent that adds alkyl groups to DNA bases, resulting in cell death. This combination has been used primarily as part of high-dose chemotherapy regimens for advanced or relapsed solid tumors (such as neuroblastoma and germ cell tumors), often followed by autologous stem cell transplantation to rescue bone marrow function after myeloablative therapy[1][2]. The rationale for combining these agents includes their non-overlapping toxicities and synergistic anti-tumor effects[3][5]. Toxicities are mainly hematologic (myelosuppression), but mucositis and neurotoxicity can also occur at higher doses[3][5].