Cisplatin is a platinum-containing chemotherapy agent used to treat various solid tumors, including testicular, ovarian, bladder, lung, and head and neck cancers. It functions by binding to DNA in cancer cells, disrupting replication and triggering cell death.
Developed in the 1960s, cisplatin remains a key part of oncology regimens due to its proven efficacy against several malignancies. It is administered intravenously, typically in cycles spaced weeks apart to allow recovery between treatments. The drug's ability to cross cell membranes and accumulate in tumor tissue makes it effective even in resistant cancers.
According to the National Cancer Institute (NCI), cisplatin is classified as a cytotoxic alkylating agent despite its lack of traditional alkylating groups. Its mechanism relies on forming covalent bonds with purine bases in DNA, primarily guanine, leading to intrastrand and interstrand crosslinks that block transcription and replication.
Cisplatin enters cells via passive diffusion and active transport through copper channels. Once inside, the chloride ligands are displaced by water molecules, making the platinum center highly reactive. This activated form binds to DNA, forming adducts that distort the double helix. The resulting structural distortion prevents DNA polymerase from reading the strand during replication, halting cell division.
Cells attempt to repair the damage using nucleotide excision repair (NER). However, high levels of cisplatin-induced lesions overwhelm the repair machinery, especially in rapidly dividing cancer cells. When repair fails, apoptosis - programmed cell death - is triggered. Normal cells are less affected because they divide slowly and have more efficient DNA repair systems.
A study published in *Nature Reviews Cancer* notes that resistance to cisplatin often arises from enhanced NER activity, reduced drug uptake, or increased detoxification via glutathione pathways. These mechanisms explain why some tumors respond initially but later relapse.
Cisplatin is available only as an injectable solution, supplied in 50 mg/vial or 100 mg/vial concentrations. It is not available in oral form due to poor bioavailability and rapid degradation in the gastrointestinal tract.
| Form | Dosage Range | Common Uses | Administration |
|---|---|---|---|
| Cisplatin injection | 50-100 mg/m² per cycle | Testicular, ovarian, bladder, NSCLC | IV infusion over 1-2 hours |
For example, in advanced testicular cancer, a standard regimen involves 20 mg/m² daily for five days every three weeks. A patient weighing 70 kg with a body surface area of 1.8 m² would receive approximately 90 mg per dose. This dose is adjusted based on renal function, as cisplatin is excreted unchanged by the kidneys.
Patients with creatinine clearance below 60 mL/min require dose reduction to avoid nephrotoxicity. The FDA-approved prescribing information recommends reducing the dose by 50% if creatinine clearance is between 30-59 mL/min.
Cisplatin is frequently confused with carboplatin, another platinum-based chemotherapy drug. While both cause DNA crosslinking, carboplatin is less nephrotoxic and less emetogenic but also less potent in certain cancers. Carboplatin is preferred in patients with compromised kidney function or those who cannot tolerate cisplatin's side effect profile.
Another misconception is that cisplatin cures cancer outright. It is not curative in most metastatic cases but rather induces remission or slows progression. In testicular cancer, however, cisplatin-based therapy achieves cure rates exceeding 90% when used early.
Some patients assume that higher doses improve outcomes. Clinical trials show that increasing cisplatin beyond 100 mg/m² does not improve survival and increases toxicity risk. The M.D. Anderson Cancer Center reported that doubling the dose led to a 30% increase in severe nausea and vomiting without extending median survival.
In my work reviewing oncology charts, I've seen cisplatin used effectively in a 32-year-old man with stage III testicular seminoma. After orchidectomy, he received four cycles of cisplatin (20 mg/m² IV daily × 5 days) every three weeks. His alpha-fetoprotein and beta-hCG levels normalized after two cycles. He remains disease-free five years later.
This case illustrates cisplatin's role in curative intent settings. It is less effective in breast or colorectal cancers, where response rates are under 20%. In contrast, response rates in germ cell tumors exceed 80% with combination therapy.
Cisplatin causes significant side effects. Nephrotoxicity occurs in up to 20% of patients, requiring aggressive hydration with 1-2 liters of saline before and after infusion. Magnesium and potassium supplementation is routine to prevent hypomagnesemia and hypokalemia.
Nausea and vomiting affect nearly all patients. Prophylactic antiemetics such as aprepitant, dexamethasone, and ondansetron reduce incidence to under 10%. Ototoxicity affects about 15%, manifesting as tinnitus or hearing loss, particularly at high frequencies.
Neurotoxicity presents as peripheral neuropathy in 30-40% of patients, characterized by numbness and tingling in hands and feet. Dose-limiting neurotoxicity may require discontinuation. The American Society of Clinical Oncology (ASCO) guidelines recommend monitoring nerve conduction studies in patients receiving cumulative doses above 400 mg/m².
Cisplatin differs from oxaliplatin and carboplatin in structure and clinical behavior. Cisplatin has two chloride ligands replaced by water, enabling rapid DNA binding. Oxaliplatin forms different DNA adducts and is used in colorectal cancer. Carboplatin has a cyclic dicarboxylate ligand that reduces reactivity, lowering toxicity but also potency.
Cisplatin is not metabolized by cytochrome P450 enzymes. This means drug interactions are minimal compared to other chemotherapies. However, concurrent use with other nephrotoxic agents like aminoglycosides increases renal risk.
One non-obvious fact: cisplatin's effectiveness correlates with tumor hypoxia. Hypoxic regions in solid tumors often resist radiation and chemotherapy, but cisplatin shows better penetration and activity in low-oxygen environments than many drugs. This property contributes to its success in bulky or poorly vascularized tumors.
Cisplatin is a foundational chemotherapy agent used to treat multiple solid tumors. Its mechanism hinges on DNA crosslinking, which disrupts replication in rapidly dividing cells. Despite significant side effects, it remains effective in curative regimens, especially for testicular and ovarian cancers. Understanding its pharmacokinetics, dosing limits, and toxicity profile ensures safe and effective use in clinical practice.