Anti-coagulant Treatment of Cancer-Associated Thrombosis in Frail Patients: Impact of Frailties on the Management of Drug–Drug Interactions

Low molecular weight heparins (LMWH) and anti-Xa direct oral anti-coagulants (DOACs) are recommended for the long-term treatment of cancer-associated thrombosis (CAT) based on well-documented randomised controlled trials. Anti-Xa DOACs are viewed as a first choice for the treatment of patients with CAT. A large number of drug–drug interactions have been reported between DOACs and chemotherapy drugs, modifying circulating levels of DOAC leading to fears of increased bleeding risks or thrombotic recurrence. Progresses in anti-neoplastic therapies have improved the prognosis and the survival, thus increasing the prevalence of frail patients with cancer. However, since frailties tend to be excluded from large trials due to multiple co-morbidities, current guidelines are not fully applicable to this population. The management of these frail patients with CAT is particularly complex and requires a risk assessment on a case-by-case basis with specific focus on cancer, patient-related risk factors and drug–drug interactions. In this brief review we have identified age, co-morbidities and co-medications as key factors of frailty that require careful attention and we have developed a therapeutic decision algorithm to help clinicians optimising the use of anti-coagulants in patients with cancer with CAT, especially in case of anti-Xa DOACs concomitant medications. With the evaluation of the bleeding risk according to the type of cancer, and anticipating drug–drug interactions intensity, taking into account patient frailties allows the optimisation of the anti-coagulant choice. A systematic collaboration between oncologists, vascular pathology specialists and pharmacists is warranted to ensure an optimal patient management. Clinical studies are needed to determine the real impact of these interactions.