Nowadays, treatment strategies for patients affected by metastatic pancreatic ductal adenocarcinoma (PDAC) are still very scant. Gemcitabine and fluoropyrimidine based chemotherapy regimens are standard I line chemotherapy. Recently, landmark genome-wide studies revealed the existence of a distinct subpopulation of PDAC with highly unstable genomic properties, due to mutations in DNA Damage Repair genes (DDR), in particular BRCA1/2 mutations. Germline mutations cause a deficiency in deoxyribonucleic acid (DNA) damage repair due to inhibition of DNA double-strand breaks repair by the mechanism of homologous recombination. Cancer cells rely on DNA repair to survive the damage induced by genotoxic stress and DNA repair enables cancer cells to accumulate genomic alterations that contribute to their aggressive phenotype. BRCA1/2 abrogation and homologous repair deficiency (HRD) confer sensitivity to DNA damage-inducing drugs, in particular those inflicting cytotoxic DNA crosslinks that interfere with DNA replication. The sensitivity of BRCA1/2-mutated tumors to platinum compounds has been validated in multiple pre-clinical and clinical studies. Nevertheless, similar lesions are induced by DNA-alkylating agents, which include mono-functional (e.g. mitomycin C) or bifunctional alkylators (e.g. chlorambucil). Small molecule inhibitors of poly(ADP-ribose) polymerase (PARP) have been recently developed and they showed an interesting activity and efficacy in breast, ovarian and pancreatic cancer tumors. Although platinum drugs and PARP inhibitors show initially good responses in the clinic, most patients acquire resistance to these drugs. Chlorambucil shows high selective toxicity against human cells and xenograft tumors with compromised BRCA1/2 function. Patients affected by metastatic ductal adenocarcinoma, pretreated with at least one previous platinum-based chemotherapy, will be treated with oral chlorambucil for 42 consecutive days After restaging, responder patients and those with stable disease will receive for 14 consecutive days every 28 days until disease progression (RECIST 1.1 criteria) or unbearable toxicity, patient refusal or medical decision.
The main objective of this trial is to explore the activity of chlorambucil, an alkylating agent commonly used in chronic lymphocytic leukemia treatment, in metastatic patients, gBRCA, including VUS, or DDR mutated, previously treated with a platinum-containing chemotherapy.