busulfan + paclitaxel + afatinib + ceritinib + crizotinib

This is a combination regimen consisting of five distinct small molecule antineoplastic agents: - **Busulfan** is an alkylating agent that crosslinks DNA, leading to cell death, and is primarily used in conditioning regimens for hematopoietic stem cell transplantation. - **Paclitaxel** is a microtubule-stabilizing agent that promotes tubulin polymerization and inhibits depolymerization, disrupting mitosis and inducing apoptosis[7]. - **Afatinib** is an irreversible inhibitor of the ErbB family of tyrosine kinases (including EGFR/HER1, HER2, and HER4), approved for non-small cell lung cancer (NSCLC) with EGFR mutations[6]. - **Ceritinib** is a second-generation ALK inhibitor targeting ALK-rearranged NSCLC; it also inhibits ROS1. - **Crizotinib** is a first-generation multi-targeted tyrosine kinase inhibitor active against ALK, ROS1, and MET rearrangements in NSCLC[8][9][10]. These drugs have different mechanisms of action targeting various pathways involved in cancer proliferation. While combinations involving some pairs or subsets (e.g., afatinib plus ceritinib) have been studied experimentally to overcome resistance mechanisms in NSCLC[6], there are no established clinical protocols or approvals for the simultaneous use of all five agents together. Such a combination would be highly experimental due to overlapping toxicities.