Last reviewed 2026-05-13 · How we verify

Camptosar (onivyde)

Camptosar works by inhibiting topoisomerase I, an enzyme that helps DNA replicate, causing DNA damage and cancer cell death.

Camptosar (irinotecan), a topoisomerase inhibitor, is a small molecule developed by Pfizer Inc. It targets and inhibits topoisomerase I, an enzyme involved in DNA replication, leading to DNA damage and apoptosis in cancer cells. Camptosar is approved for the treatment of adenocarcinoma of the pancreas, metastasis from a malignant tumor of the colon, and secondary malignant neoplasm of the pancreas. The drug has a half-life of 9.0 hours and bioavailability of 8%. Camptosar is still under patent ownership by Pfizer Inc.

At a glance

Mechanism of action

Irinotecan is derivative of camptothecin. Camptothecins interact specifically with the enzyme topoisomerase I, which relieves torsional strain in DNA by inducing reversible single-strand breaks. Irinotecan and its active metabolite SN-38 bind to the topoisomerase I-DNA complex and prevent religation of these single-strand breaks. Current research suggests that the cytotoxicity of irinotecan is due to double-strand DNA damage produced during DNA synthesis when replication enzymes interact with the ternary complex formed by topoisomerase I, DNA, and either irinotecan or SN-38. Mammalian cells cannot efficiently repair these double-strand breaks.

Approved indications

• Adenocarcinoma of pancreas
• Metastasis from malignant tumor of colon
• Secondary malignant neoplasm of pancreas

Boxed warnings

• WARNING: DIARRHEA and MYELOSUPPRESSION • Early and late forms of diarrhea can occur. Early diarrhea may be accompanied by cholinergic symptoms which may be prevented or ameliorated by atropine. Late diarrhea can be life threatening and should be treated promptly with loperamide. Monitor patients with diarrhea and give fluid and electrolytes as needed. Institute antibiotic therapy if patients develop ileus, fever, or severe neutropenia. Interrupt CAMPTOSAR and reduce subsequent doses if severe diarrhea occurs [see Dosage and Administration (2.2) and Warnings and Precautions (5.1) ] . • Severe myelosuppression may occur [see Warnings and Precautions (5.2) ] . WARNING: DIARRHEA and MYELOSUPPRESSION See full prescribing information for complete boxed warning . • Early and late forms of diarrhea can occur. Early diarrhea may be accompanied by cholinergic symptoms which may be prevented or ameliorated by atropine. Late diarrhea can be life threatening and should be treated promptly with loperamide. Monitor patients with diarrhea and give fluid and electrolytes as needed. Institute antibiotic therapy if patients develop ileus, fever, or severe neutropenia. Interrupt CAMPTOSAR and reduce subsequent doses if severe diarrhea occurs. ( 2.2 , 5.1 ) • Severe myelosuppression may occur. ( 5.2 )

Common side effects

• Diarrhea
• Vomiting
• Nausea
• Fatigue/asthenia
• Stomatitis
• Pyrexia
• Decreased appetite
• Neutropenia
• Lymphopenia
• Thrombocytopenia
• Sepsis
• Gastroenteritis

Drug interactions

• phenytoin
• ritonavir

Key clinical trials

• Studying Chemotherapy With or Without Panitumumab for Unresectable, Locally Advanced, or Metastatic Pancreatic Cancer Without KRAS Mutations (PHASE3)
• A Study to Evaluate the Effectiveness and Safety of Setidegrasib, Given With Either mFOLFIRINOX or NALIRIFOX Chemotherapies, in People With Pancreatic Cancer (PHASE3)
• Comparing Two Treatment Combinations, Gemcitabine and Nab-Paclitaxel With 5-Fluorouracil, Leucovorin, and Liposomal Irinotecan for Older Patients With Pancreatic Cancer That Has Spread (PHASE2)
• Apatinib Combined With Liposomal Irinotecan for Refractory or Metastatic Osteosarcoma (PHASE1,PHASE2)
• Monthly Alternating NALIRIFOX and GnP in the First-Line Setting for Metastatic Pancreatic Ductal Adenocarcinoma (PHASE2)
• SCRT-NALIRIXELOX+Sintilimab as TNT for High-Risk LARC (NA)
• A Study to Assess the Effectiveness and Safety of Irinotecan Liposome Injection, 5-fluorouracil/Leucovorin Plus Oxaliplatin in Patients Not Previously Treated for Metastatic Pancreatic Cancer, Compared to Nab-paclitaxel+Gemcitabine Treatment (PHASE3)
• Liposomal Irinotecan, Vincristine, Temozolomide, and Anlotinib for R/R Pediatric Solid Tumors (PHASE2)

Patents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Camptosar CI brief — competitive landscape report
• Camptosar updates RSS · CI watch RSS
• Pfizer portfolio CI