Step down to 6 months of prophylactic-dose low molecular weight heparin after initial full-dose anticoagulation for the treatment of cancer-associated thrombosis (STEP-CAT): A pilot study

Background: Patients with cancer-associated thrombosis (CAT) are treated with full-dose anticoagulation for at least 3 months, but optimal dosing thereafter is unknown.

Aim: We explored the feasibility of extended prophylactic-dose low molecular weight heparin (LMWH) treatment following a minimum of 3 months of full-dose LMWH.

Methods: We conducted a multicenter prospective pilot study of patients with CAT who completed at least 3 months of therapeutic-dose LMWH. Patients received 6 months of prophylactic-dose subcutaneous enoxaparin (40 mg once daily). The primary outcome was recurrence of deep vein thrombosis (DVT) or pulmonary embolism (PE), and secondary outcomes included major, clinically relevant non-major (CRNM), and minor bleeding.

Results: From August 2016 to May 2019, 52 patients with a mean age of 64.1 years were included. The study was stopped early because of poor recruitment. Breast (23.1%) and colorectal (19.2%) were the most common cancers, and 61.0% had stage IV malignancy. Index CAT consisted of DVT alone in 57.7% of patients and pulmonary embolism (PE) with or without DVT in 42.3%. Patients received a mean of 7.6 months of weight-adjusted LMWH before enrollment. During a mean follow-up of 5.6 months, one patient was diagnosed with recurrent incidental PE (0.0035 events/subject-month). There were no major bleeding events, one CRNM, and one minor bleeding event. Eight (15.4%) patients died; six from cancer and two from respiratory disease unrelated to PE.

Conclusions: These results, in part, provide support for trials of extended reduced-dose anticoagulation for the secondary prevention of CAT. (ClinicalTrials.gov: NCT02752607).