Caelum Biosciences and Alexion Pharmaceuticals, Inc. announced new Phase 2 safety and tolerability data for CAEL-101, a potentially first-in-class amyloid fibril targeted therapy, in combination with standard-of-care (SoC) therapy in patients with AL amyloidosis. The data, presented in two e-posters at the European Hematology Association (EHA) Congress 2021, strengthen the safety and tolerability profile of CAEL-101, further support the dose selection for the ongoing Phase 3 study, and suggest possible cardiac and renal response. An e-poster featuring the first data from a new arm of the study demonstrated that CAEL-101 administered in combination with cyclophosphamide-bortezomib-dexamethasone (CyBorD) plus daratumumab was generally safe and well-tolerated in the first four weeks of treatment. Data presented in a second e-poster showed longer-term evidence that CAEL-101 in combination with CyBorD was generally well-tolerated for a median treatment duration of 49 weeks, and exploratory clinical biomarker data suggesting possible cardiac disease improvements and renal response among patients with cardiac or renal impairment at baseline, respectively. As was previously announced, the Phase 2 study of CAEL-101 in combination with CyBorD met its primary objectives, supporting the safety and tolerability of CAEL-101 and the selection of the 1000 mg/m2 dose for the ongoing Phase 3 study. Results presented from an additional study arm that included 11 patients receiving CAEL-101 (1000 mg/m2 dose) in combination with CyBorD plus daratumumab suggested that treatment with this combination was generally well-tolerated in the first four weeks of treatment. Specifically, adding daratumumab to the CAEL-101 and CyBorD regimen did not result in any new safety signals, nor did it alter the pharmacokinetic (PK) exposure to CAEL-101. The most common adverse events (AEs) reported in the first four weeks in the additional arm were nausea, constipation, and insomnia. Additional longer-term data presented from the Phase 2 study demonstrated that CAEL-101 in combination with CyBorD in patients with AL amyloidosis (N=13) was generally well tolerated up to a median treatment duration of 49 weeks (range 12-57 weeks), with most patients having received more than 20 infusions of CAEL-101. The most common AEs reported were diarrhea, nausea, fatigue, rash, and anemia. In addition, exploratory clinical biomarker evaluations showed early signals suggesting possible cardiac and renal response. Specifically, median percent changes for biomarkers of cardiac disease (cTnT and NT-proBNP) were lower at each subsequent time point measured, suggesting improvement in cardiac function among eight patients with active cardiac disease at baseline. Additionally, seven patients with active renal impairment at baseline demonstrated renal response, as defined by a decrease of at least 30% in proteinuria (an excess of protein in the urine) following treatment.