Michael Wang, MD

Data from a matching-adjusted indirect comparison (MAIC) demonstrated that there was not a statistically significant difference in progression-free survival (PFS) or overall survival (OS) for acalabrutinib (Calquence) vs ibrutinib (Imbruvica) in patients with relapsed/refractory mantle cell lymphoma (MCL). However, acalabrutinib was associated with an improved safety profile compared with ibrutinib.

The MAIC, which was published in the Journal of Medical Economics, included patients treated with acalabrutinib (n = 122) during the phase 2 ACE-LY-004 trial (NCT02213926) and a polled population of patients treated with ibrutinib (n = 370) from the phase 2 SPARK (NCT01599949), phase 2 PCYC-1104 (NCT01236391), and phase 3 RAY (NCT01646021) trials.

This MAIC included updated data for patients treated during these studies; the median follow-up was 38.1 months for patients treated with acalabrutinib and 41.4 months for those given ibrutinib.

Prior to matching, acalabrutinib was associated with a statistically significant improvement in both PFS (HR, 0.75; 95% CI, 0.58-0.96; P = .02) and OS (HR, 0.67; 95% CI, 0.49-0.90; P = .01). After matching, which utilized an effective sample size (ESS) population for the acalabrutinib arm (n = 73), there was not a statistically significant difference in PFS between acalabrutinib and ibrutinib (HR, 0.92; 95% CI, 0.74-1.15; P = .48). The median PFS was 17.8 months for acalabrutinib vs 12.8 months for ibrutinib.

Additionally, there was not a statistically significant difference in OS for acalabrutinib vs ibrutinib after matching (HR, 0.87; 95% CI, 0.64-1.17; P = .35). The median OS was 36.5 months for acalabrutinib vs 27.9 months for ibrutinib.

“[The lack of a statistically significant difference in PFS and OS between acalabrutinib and ibrutinib after matching] may be due, in part, to the smaller effective sample size for acalabrutinib,” study author Michael Wang, MD, of The University of Texas MD Anderson Cancer Center in Houston, and colleagues wrote in the publication. “However, the MAIC method allows for matching of key variables to account for differences between patient populations when outcomes are compared, thus reducing bias.”

Safety data demonstrated that after matching, acalabrutinib was associated with lower rates of grade 3 or higher neutropenia (difference, 2.0%; 95% CI, –11.4% to 7.4%; P = .67), thrombocytopenia (difference, 7.1%; 95% CI, –13.3% to –0.8%; P < .05), pneumonia (difference, 4.0%; 95% CI, –11.7% to 3.7%; P = .31), atrial fibrillation (difference, 6.2%; 95% CI, –6.7% to –3.7%; P < .001), and hypertension (difference, 2.5%; 95% CI, –7.4% to 2.4%; P = .32). However, ibrutinib was linked with lower rates of grade 3 or higher anemia (difference, 4.8%; 95% CI, –4.3% to 14.0%; P = .30).

MAIC Background and Methodology

To conduct the MAIC, investigators collected individual patient data from those treated with acalabrutinib during the ACE-LY-004 trial to match with patients given ibrutinib across the SPARK, PCYC-1104, and RAY clinical trials. Prognostic variables for matching were selected based on previously published literature, clinical judgement, or statistically significant association with PFS in univariate and multivariate regression analyses of data for acalabrutinib.

The prognostic variables for matching included ECOG performance status (0-1 vs >1), simplified MCL International Prognostic Index (sMIPI; low [0-3] vs intermediate [4-5] or high [6-11]) lactate dehydrogenase (LDH) levels, (higher than the upper limit of normal [ULN] of 234 units/L vs below the ULN), prior lines of therapy (>1 vs 1), tumor burden (≥5 cm vs <5 cm), and blastoid histology (yes vs no).

ACE-LY-004 included 124 patients treated with acalabrutinib; however, 2 patients were excluded from the MAIC due to missing blastoid histology (n = 1) and missing sMIPI and LDH data (n = 1). After matching for the 6 prognostic variables, the ESS population included 73 patients treated with acalabrutinib.

Prior to matching, a higher proportion of patients treated with acalabrutinib had good prognosis, represented by a low sMIPI (39.3% vs 24%). A lower proportion of patients had high LDH levels (26.2% vs 55%), received more than 1 prior line of therapy (51.6% vs 73%), and had bulky disease of at least 5 cm (37.7% vs 49%). After matching, these variables were well balanced between the 2 arms.

Notably, after matching, the acalabrutinib arm had a lower proportion of patients below 65 years of age than in the ibrutinib arm (33.3% vs 38%, as well as a higher proportion of patients who were White (94.5% vs 89%), had extranodal disease (75.7% vs 58%), and had bone marrow involvement (56.0% vs 46%).

Study authors noted that limitations of the MAIC included difference in trial design for the studies used to compile data, timing of recruitment periods for the trial, and follow-up durations that could lead to potential bias. Notably, the data gathered for the MAIC did not allow for a direct comparison of the duration of treatment exposure between the trial populations.

“This analysis was based on clinical trial data, and conclusions were drawn for the population from the 3 pooled ibrutinib trials, which may not be generalizable to a real-world relapsed/refractory MCL population,” study authors concluded.

Reference

Cai L, Roos J, Miranda PAP, Liljas B, Rule S, Wang M. Matching-adjusted indirect comparison of Acalabrutinib versus Ibrutinib in relapsed/refractory mantle cell lymphoma. J Med Econ. Published online October 26, 2024. doi:10.1080/13696998.2024.2422227