Patel, Priti

PURPOSE Among Bruton's tyrosine kinase inhibitors, acalabrutinib has greater selectivity than ibrutinib, which we hypothesized would improve continuous therapy tolerability. We conducted an open-label, randomized, noninferiority, phase III trial comparing acalabrutinib and ibrutinib in patients with chronic lymphocytic leukemia (CLL). METHODS Patients with previously treated CLL with centrally confirmed del(17)(p13.1) or del(11)(q22.3) were randomly assigned to oral acalabrutinib 100 mg twice daily or ibrutinib 420 mg once daily until progression or unacceptable toxicity. The primary end point was independent review committee–assessed noninferiority of progression-free survival (PFS). RESULTS Overall, 533 patients (acalabrutinib, n = 268; ibrutinib, n = 265) were randomly assigned. At the data cutoff, 124 (46.3%) acalabrutinib patients and 109 (41.1%) ibrutinib patients remained on treatment. After a median follow-up of 40.9 months, acalabrutinib was determined to be noninferior to ibrutinib with a median PFS of 38.4 months in both arms (95% CI acalabrutinib, 33.0 to 38.6 and ibrutinib, 33.0 to 41.6; hazard ratio: 1.00; 95% CI, 0.79 to 1.27). All-grade atrial fibrillation/atrial flutter incidence was significantly lower with acalabrutinib versus ibrutinib (9.4% v 16.0%; P = .02); among other selected secondary end points, grade 3 or higher infections (30.8% v 30.0%) and Richter transformations (3.8% v 4.9%) were comparable between groups and median overall survival was not reached in either arm (hazard ratio, 0.82; 95% CI, 0.59 to 1.15), with 63 (23.5%) deaths with acalabrutinib and 73 (27.5%) with ibrutinib. Treatment discontinuations because of adverse events occurred in 14.7% of acalabrutinib-treated patients and 21.3% of ibrutinib-treated patients. CONCLUSION In this first direct comparison of less versus more selective Bruton's tyrosine kinase inhibitors in CLL, acalabrutinib demonstrated noninferior PFS with fewer cardiovascular adverse events.

7500 Background: Increased selectivity of the Bruton tyrosine kinase inhibitor (BTKi) acalabrutinib (Aca) vs ibrutinib (Ib) may improve tolerability. We conducted an open-label, randomized, noninferiority, phase 3 trial to compare Aca vs Ib in patients (pts) with chronic lymphocytic leukemia (CLL). Methods: Previously treated CLL pts with del(17p) or del(11q) by central lab were randomized to receive oral Aca 100 mg BID or Ib 420 mg QD (stratified by del(17p) status, ECOG PS [2 vs ≤1], and number of prior therapies [1–3 vs ≥4]) until progression or unacceptable toxicity. Primary endpoint was progression-free survival (PFS) as assessed by IRC; secondary endpoints of all grade atrial fibrillation (AF), grade ≥3 infection, Richter transformation, and overall survival (OS) were assessed in hierarchical order. Results: 533 pts (Aca, n=268; Ib, n=265) were randomized (median age 66 y; median 2 prior therapies; del(17p) 45.2%; del(11q) 64.2%). At a median follow-up of 40.9 mo (range 0.0–59.1), Aca was noninferior to Ib with a median PFS of 38.4 mo in both arms (HR 1.00; 95% CI 0.79–1.27). Aca was statistically superior to Ib in all-grade AF incidence (9.4% vs 16.0%; P=0.023). Among the other secondary endpoints, incidences of grade ≥3 infection (Aca: 30.8%, Ib: 30.0%) and Richter transformation (Aca: 3.8%, Ib: 4.9%) were comparable between arms. Median OS was not reached in either arm (HR 0.82 [95% CI 0.59–1.15]), with 63 (23.5%) deaths in the Aca arm and 73 (27.5%) in the Ib arm. Among any-grade AEs in ≥20% of pts in either arm, Aca was associated with a lower incidence of hypertension (9.4%, 23.2%), arthralgia (15.8%, 22.8%), and diarrhea (34.6%, 46.0%) but a higher incidence of headache (34.6%, 20.2%) and cough (28.9%, 21.3%). AEs led to treatment discontinuation in 14.7% of Aca- vs 21.3% of Ib-treated pts. Among any-grade events of clinical interest, cardiac, hypertension, and bleeding events were less frequent with Aca (Table). Conclusions: In this first head-to-head trial of BTKis in CLL, Aca demonstrated non-inferior PFS with less cardiotoxicity and fewer discontinuations due to AEs vs Ib. Clinical trial information: NCT02477696. [Table: see text]

7519 Background: Acalabrutinib, a highly selective, potent, covalent Bruton tyrosine kinase (BTK) inhibitor, has a 24% overall response rate (ORR) as a single agent in R/R DLBCL. Pem targets PD-1, an immune checkpoint that limits anticancer responses. Pem showed responses in patients (pts) with Richter transformation who failed ibrutinib and can augment acalabrutinib activity in vitro. This study assessed acalabrutinib + Pem in R/R DLBCL. Methods: Pts with DLBCL, ≥1 prior chemoimmunotherapy and no prior allogeneic transplant received acalabrutinib 100 mg PO BID until progressive disease (PD) + Pem 200 mg/kg IV Q3W up to 2 y. Germinal center B-cell (GCB) vs non-GCB subtype was assessed by immunohistochemistry. Primary endpoint was safety. Results: Sixty-one pts (30 GCB; 31 non-GCB) were accrued, with a median age (range) of 67 y (30-85) and a median of 3 (1-8) prior therapies; 1 pt had prior autologous transplant. The most common Gr 3/4 adverse events (AEs) were neutropenia (15%) and anemia (11%). Gr 5 AEs were respiratory failure (n=3), sepsis, septic shock and abdominal abscess (n=1 each). All Gr atrial fibrillation was 5% (n=3), and major hemorrhage (≥ Gr 3) was 11% (4 gastrointestinal, 1 pulmonary, 1 epistaxis, 1 hematuria). Gr 3/4 immune-mediated events were elevated alanine aminotransferase (n=4), pneumonitis (n=2) and colitis (n=1). The ORR was 26% (Table) and was similar in GCB (27%) and non-GCB (26%) tumors. The median time on study was 5.2 mo (0.4-30.4+). Acalabrutinib/Pem discontinuations were due to PD (62%/56%) and AEs (15%/26%). As of June 2018, 10 pts remain on study; 6 on active therapy and 7 without PD. Conclusions: Acalabrutinib + Pem was well tolerated, with meaningful activity and some exceptional responders (>24 mo) in these R/R DLBCL pts. Randomized trials of the combination vs single agent are needed. Clinical trial information: NCT02362035. [Table: see text]