Data Show High Response Rate to Ibrutinib Combination for Patients With Hard-to-Treat MCL

Evidence-Based Oncology, The American Society of Hematology Annual Meeting, 2014, Volume 21, Issue SP1

Results presented December 8, 2014, at the 56th Annual Meeting of the American Society of Hematology (ASH) show that 88% of patients with relapsed or refractory mantle cell lymphoma (MCL) responded to a combination of ibrutinib and rixtuxmab.

The phase 2 trail, led by Michael Wang, MD, of the University of Texas MD Anderson Cancer Center in Houston, found responses in 40 of 46 patients, with a complete response (CR) in 40%.1 The trial also revealed an apparent marker for who will benefit most from the combination. Results found that in 34 evaluable patients with levels of less than 50% of the Ki-67 protein, the overall response rate (ORR) was 100%. Conversely, 10 patients who discontinued treatment when their MCL progressed had Ki-67 levels above 60%.1

Ibrutinib, being developed as Imbruvica by Pharmacyclics and Janssen Biotech,Inc, may offer an option in combination for patients whose MCL is especially difficult to treat, Wang said.2 Previously, Wang and colleagues reported a 68% ORR in patients with relapsed/ refractory MCL when ibrutinib was used as a monotherapy.3

“The positive outcomes seen with Imbruvica in combination with rituximab reinforce our decision to pursue its full potential as a single agent and in combination with other therapies, and underscores the potential Imbruvica may offer to patients living with hematologic malignancies,” said Danelle James, MD, MS, vice president, clinical development, Pharmacyclics.3

LONG-TERM DATA SHOW SAFETY, DURABILITY

or refractory MCL who were treated with

ibrutinib for more than 2 years remained

progression-free with no new or unexpected

adverse events (AEs), according

to results presented December 8, 2014, at

ASH.4 This second phase 2 trial looked at

ibrutinib’s safety and efficacy as a monotherapy

in MCL patients who had previously

been treated with rituximab combination

therapy and at least 2 cycles of

bortezomib. Of the 111 patients in the

original study, 47% were still alive at the

at the time of data cutoff.4

More than 30% of patients with relapsed

IBRUTINIB AFTER OTHER THERAPY

from a phase 2, multi-center, single-

arm trial (MCL2001) that investigated

once-daily ibrutinib in 120 patients with

relapsed/refractory MCL who previously

had received a rituximab-containing

treatment regimen and had progressed

after at least 2 cycles of bortezomib.5

Wang also presented a poster with results

An independent review committee

found that the ORR, which was the primary

endpoint, was 63% after a median

follow-up of 14.9 months, and 21% of the

patients achieved a complete response.

Secondary endpoints included duration

of response (DOR), progression-free survival

(PFS), overall survival (OS), and safety.

Median DOR based on the committee’s

assessment was 14.9 months, and

the median time to first response was

2.1 months. The median PFS was 10.5

months, with 47% of patients remaining

progression-free at 1 year. The median

PFS has not yet been reached. The OS

rate at 18 months was 61%.5

EBO

The most frequently reported AEs of any grade were fatigue (43%) and diarrhea (43%). Diarrhea, when observed generally occurred early after initial treatment, but resolved quickly and was not treatment limiting. The majority of AEs were grade 1 and 2. The most common AEs ≥ grade 3 were neutropenia (21%), thrombocytopenia (13%), and pneumonia (13%). Atrial fibrillation was reported in 13 patients (11%); 6 patients (5%) experienced Grade 3 or 4 atrial fibrillation which resolved in 1 to 4 days. Five of these 6 patients had a history of atrial fibrillation.5

References

1. Wang M, Hagemeister F, Westin JR, et al. Ibrutinib and rituximab are an efficacious and safe combination in relapsed mantle cell lymphoma: prelimary results from a phase 2 clinical trial. Blood. 2014;124(21):abstract 627.

2. Imbruvica (ibrutinib) in combination with rituximab data shows positive benefit-risk profile in hematologic malignancy [press release]. San Francisco, CA: Pharmacyclics; December 8, 2014.

3. Wang M, Rule S, Martin P, et al. Targeting BTK with ibrutinib in relapsed or refractory mantle-cell lymphoma. N Engl J Med. 2013;369:507-516.

4. Imbruvica (ibrutinib) data demonstrates safety and durability of responses at 2-year follow-up in mantle cell lymphoma [press release]. San Francisco, CA: Pharmcyclics; December 8, 2014.

5. Wang M, Goy A, Martin P, et al. Efficacy and safety of single-agent ibrutinib in patients with mantle cell lymphoma who progressed after bortezomib therapy. Blood. 2014;124(21):abstract 4471.