Photo courtesy of CDC
SAN DIEGO—Ibrutinib can produce favorable results in heavily pretreated patients with chronic lymphocytic leukemia (CLL) who have undergone allogeneic transplant, according to studies presented at the 2015 BMT Tandem Meetings.
One study showed that ibrutinib prompted an 88% overall response rate (ORR) in 16 patients with relapsed/refractory CLL.
Another analysis showed that ibrutinib can promote full donor chimerism and resolution of chronic graft-vs-host disease (GVHD).
David B. Miklos, MD, PhD, of the Stanford University Medical Center in California, presented the outcomes in 16 patients as abstract 75.
Christine E. Ryan, also of the Stanford University Medical Center, and her colleagues presented the other analysis, which included 5 patients, in a poster at the meeting (abstract 444*).
High response rate
The data Dr Miklos presented were collected from 4 clinical trials (phases 2 and 3) in relapsed/refractory CLL. The research was sponsored by Pharmacyclics, the company co-developing ibrutinib with Janssen Biotech, Inc.
All 16 patients analyzed had prior allogeneic
hematopoietic stem cell transplant (allo-HSCT). They had a median of 5 prior therapies, 12 (75%) had received 4 or more prior therapies, and 10 (63%) had del 17p.
Patients received ibrutinib as a single agent or in combination with ofatumumab. The study endpoints were investigator-assessed ORR, duration of response, progression-free survival (PFS), and overall survival (OS).
The ORR was 88%, with 2 complete responses, 9 partial responses, and 3 partial responses with lymphocytosis.
The median duration of response, PFS, and OS were not reached at a median follow-up of 23 months. The estimated PFS at 24 months was 77%, and the estimated OS at that time point was 75%.
The median time on ibrutinib was 18 months (range, 0.4 to 38.8 months), with 69% (n=11) of patients continuing on treatment.
Five (31%) patients discontinued ibrutinib—2 due to disease progression, 2 due to pneumonia, and 1 as a voluntary patient withdrawal. Both patients who developed pneumonia died.
Grade 3 or higher treatment-emergent severe adverse events occurred in 11 patients. Six patients had infections.
And there was 1 case each of febrile neutropenia, atrial flutter, colitis, perirenal hematoma, subdural hematoma, postprocedural hemorrhage, hypercalcemia, bone lesion, syncope, hematuria, urinary retention, and dyspnea (some patients had more than 1 event).
‘Promising’ donor immune modulation
Ryan and her colleagues presented data from 5 patients with relapsed/refractory CLL. They had relapsed 1 to 8.5 years after allo-HSCT.
Four patients had never achieved donor CD3 T-cell chimerism greater than 95%. And 1 patient had chronic GVHD when ibrutinib treatment began.
Patients received single-agent ibrutinib at 420 mg daily, starting 1 month to 2 years after relapse. Four patients remain on treatment, with courses ranging from 3 to 17 months.
The researchers reported that all patients showed sustained disease response and promising donor immune modulation. Four patients with abnormal lymph nodes prior to ibrutinib treatment experienced a “dramatic” reduction in lymph node size—a 68% reduction after 3 months.
Two patients achieved undetectable minimal residual disease (MRD) after 39 months and 8 months, respectively. One of these patients achieved full donor CD3 chimerism after 1 year of ibrutinib treatment and has maintained undetectable MRD for more than 10 months after stopping therapy.
And the patient with chronic GVHD achieved complete resolution of the condition after 6 months of ibrutinib treatment.
Three investigators involved in this research work for Sequenta, Inc., the company developing the ClonoSIGHT MRD test, which was used to detect MRD in this study.
*Information in the abstract differs from that presented at the meeting.