Venetoclax Plus Dexamethasone As First-Line Treatment for t(11; 14) Light-Chain Amyloidosis: Preliminary Result of a Phase II Prospective, Multicenter, Single-Arm Study

Background: Venetoclax has shown promise in providing rapid and high-quality hematologic responses in relapsed/refractory t(11;14) light-chain (AL) amyloidosis cases and offers the convenience of home treatment. To evaluate the efficacy and safety of venetoclax combined with dexamethasone (Ven-D) as an initial treatment for t(11;14) AL amyloidosis patients, we conducted a phase II prospective, multicenter, single-arm study (NCT05996406). Here, we report the preliminary findings.

Method: The study aimed to enroll 36 patients aged 18 or older with newly diagnosed t(11;14) AL amyloidosis. Participants received 12 cycles (28 days per cycle) of Ven-D, consisting of oral venetoclax at 400 mg qd and oral dexamethasone at 20-40 mg qw for the first six cycles, reduced to 10-20 mg for the remaining cycles. Hematologic and organ responses were evaluated at one month, three months and every three months thereafter while on study treatment. Patients who died before the response assessment were categorized under the no-response group. Treatment discontinuation criteria included drug intolerance, unsatisfactory efficacy at the physician’s discretion, or disease progression. The primary endpoint was achieving a complete hematologic response (CR) and very good partial response (VGPR) at three months of treatment initiation.

Results: Between September 8, 2023, and June 25, 2024, 36 patients were enrolled, with a median age of 62 years (range 27-75) and predominantly male (80.6%). The distribution of Mayo 2004 stages was as follows: stage I (16.7%), stage II (50.0%), stage IIIA (19.4%), and stage IIIB (13.9%). Heart, kidney, and liver involvement was observed in 80.6%, 50.0%, and 8.3% of patients. By July 25, 2024, all patients had received a median of 5 treatment cycles (range 1-12). Among evaluable patients (n=29), the CR+VGPR rate at three months was 58.6%, with a CR rate of 27.6%. Considering the best hematologic response at any time, the estimate of the CR+VGPR rate was 62.9%, and the CR rate was 37.1%. At six months, cardiac and renal responses were observed in 35.0% and 90.9% of patients, respectively. There were three deaths due to cardiac events and six patients discontinued treatment due to lack of efficacy. Grade 3-4 hematological adverse events included lymphopenia (5.6%) and neutropenia (2.8%), while non-hematological adverse events included edema (2.8%), infection (2.8%) and liver dysfunction (5.6%).

Conclusion: The combination of Ven-D as an initial treatment for t(11;14) AL amyloidosis demonstrates rapid induction of high hematologic responses with a favorable tolerability profile.