Chemo-free combo should be option for rel/ref CLL, doc says
“[T]he treatment duration differed, although, of course, the capacity to deliver more than 6 cycles of bendamustine-rituximab would have been problematic,” he said. “There is some data that antibody treatment may prolong progression-free survival. However, when this study was designed, in 2013, that data was certainly not available. And I believe, currently, maintenance antibody is not an accepted standard of treatment.”
The median overall survival (OS) was not reached in either treatment arm. The 1-year OS rate was 95.9% in the VR arm and 91.1% in the BR arm. The 2-year OS rate was 91.9% and 86.6%, respectively (HR=0.48, P=0.0186).
“[W]ith median follow-up of just on 2 years, there is already a clinically meaningful difference [in OS between the treatment arms],” Dr Seymour said.
“This is not attributable to any difference in availability of novel therapies. Of the 54 patients who received subsequent therapy after progression on the bendamustine-rituximab arm, 40 of those received novel targeted agents.”
Response and MRD
According to investigators, the overall response rate was 93.3% (181/194) in the VR arm and 67.7% (312/195) in the BR arm (P<0.0001). According to the IRC, the overall response rate was 92.3% (179/194) and 72.3% (141/195), respectively (P<0.0001).
According to investigators, the rate of complete response (CR) or CR with incomplete marrow recovery (CRi) was 26.8% (n=52) in the VR arm and 8.2% (n=16) in the BR arm. According to the IRC, the CR/CRi rate was 8.2% (n=16) and 3.6% (n=7), respectively.
Dr Seymour acknowledged the differences in CR/CRi between investigator and IRC assessments. He said 28 of the 42 discrepancies in the VR arm “were attributable to residual CT scan nodal abnormalities in the 16- to 30-mm size.” However, he also noted that 88% of these patients were negative for minimal residual disease (MRD) in the peripheral blood at that time point.
MRD was assessed every 3 months. Patients were counted as MRD-positive if they were positive by either allele-specific oligonucleotide polymerase chain reaction or multicolor flow cytometry. Patients were also counted as MRD-positive if there was a failure to collect a sample.
The proportion of patients who were MRD-negative in the VR and BR arms, respectively, was:
- 45% and 6% at 4 months
- 62% and 13% at 9 months
- 60% and 10% at 12 months
- 57% and 9% at 15 months
- 60% and 5% at 18 months.
Dr Seymour pointed out that 65 patients in the VR arm surpassed the maximum treatment duration for venetoclax (2 years) and therefore stopped receiving the drug, but only 12 of these patients have follow-up beyond 3 months.
“So information about the durability of response after cessation remains immature at the moment,” he said.
Safety
All patients in the VR arm and 98% in the BR arm had at least 1 AE. The rate of serious AEs was 46% and 43%, respectively. The rate of grade 3/4 AEs was 82% and 70%, respectively.
Grade 3/4 AEs with at least a 2% difference in incidence between the treatment arms (in the VR and BR arms, respectively) were neutropenia (58% and 39%), anemia (11% and 14%), thrombocytopenia (6% and 10%), febrile neutropenia (4% and 10%), pneumonia (5% and 8%), infusion-related reactions (2% and 5%), TLS (3% and 1%), hypotension (0% and 3%), hyperglycemia (2% and 0%), and hypogammaglobulinemia (2% and 0%).
The rate of grade 5 AEs was 5% in the VR arm and 6% in the BR arm.
Grade 5 AEs in the VR arm were pneumonia (n=3), sepsis (n=1), cardiac failure (n=1), myocardial infarction (n=1), sudden cardiac death (n=1), colorectal cancer (n=1), status epilepticus (n=1), and acute respiratory failure (n=1).
