Prolonged survival in a patient with BRCA2 associated metastatic pancreatic cancer after exposure to camptothecin: a case report and review of literature.

Germline mutations in the tumor suppressor genes BRCA1 and BRCA2 have been proven to predict a drastically increased lifetime risk of breast and ovarian cancers in the individuals who carry them. A number of studies have shown that the third most common cancer associated with these mutations is pancreatic cancer. There is evidence of in vivo therapeutic response to the cross-linking agents; such as mitomycin C (MMC) in BRCA2 mutated pancreatic cell lines. We present the 'first patient' who achieved a prolonged survival on irinotecan, a topoisomerase I poison, administered alone and then in combination with cetuximab. Our patient presented at the age of 71 years with a dual diagnosis of prostate carcinoma and pancreatic carcinoma on the background of a significant family history of cancer. On genetic testing, he was found to have the common Ashkenazi Jewish BRCA2 mutation, 6174delT. To date, he has received 22 cycles of docetaxel, capecitabine, and gemcitibine followed by single agent irinotecan every 3 weeks for 27 cycles, and then weekly cetuximab was added to the regimen at cycle 28. His disease then remained stable for an additional 13 months. He did not have mutated KRAS. MMC and oxaliplatin was then introduced upon progression. His current treatment is MMC plus irinotecan as oxaliplatin was removed because of a hypersensitivity reaction. This patient is stable with an Eastern Cooperative Oncology Group performance status of 0, four and a half years (56 months) after his initial diagnosis. DNA topoisomerases are nuclear enzymes responsible for the regulation of DNA topology. They are involved in basic DNA transactions during replication, transcription, and recombination. BRCA2-deficient human cells are deficient in the repair of double-strand breaks and DNA cross-links through homologous recombination. Active poisons of topoisomerase I include derivatives of camptothecin. Our case is the first clinical piece of evidence that demonstrates an increased sensitivity to camptothecin-11 and a reduced topoisomerase I relaxation activity in BRCA2 associated pancreatic cancer. This case shows that patients with metastatic pancreatic carcinoma and BRCA2 mutations may have disease that is biologically more chemosensitive and consequently prolong survival despite prognostically unfavorable disease.