Category: Research Publications

Ibrutinib is a Highly Effective Therapy for Patients with Relapsed or Refractory CLL or SLL with 17p deletion: Results from the Phase II RESONATE -17 Trial

Picture3By Dr. Richard Furman, MD

Patients with chronic lymphocytic leukemia (CLL) with deletion of the short arm of chromosome 17 (del 17p) follow an aggressive clinical course and demonstrate a median survival of less than 2 years. Ibrutinib is a first-in-class inhibitor of Bruton’s tyrosine kinase (BTK), currently approved as treatment for CLL patients relapsed after one prior therapy or patients with del 17p at any line of therapy. Ibrutinib’s initial approval was based upon phase II data published in June 2013. The expanded approval is based upon results from the RESONATE trial comparing ibrutinib to ofatumumab.

At the 56th annual meeting of the American Society of Hematology (ASH), investigators presented the results of the phase II RESONATE -17 (PCYC-1117-CA) study investigating ibrutinib in relapsed CLL patients with deletion of 17p.

The study was designed to evaluate the efficacy and safety of single-agent ibrutinib as treatment of patients with relapsed or refractory CLL with del 17p or small lymphocytic leukemia (SLL). 144 patients (137 CLL patients, 7 SLL patients)  were enrolled and received ibrutinib 420 mg once daily until progression. The primary endpoint was overall response rate (ORR), with secondary endpoints including duration of response (DOR), progression-free survival (PFS), and safety of ibrutinib.

At a median follow up of 13 months, the median PFS and DOR had not been reached. At 12 months, 79.3% of patients were alive and progression-free, and 88.3% of responders were progression-free, with only 20 patients (13.9%) reporting progressive disease. At the time of data cut, the median treatment duration was 11.1 months, and 101 of 144 patients (70%) continued treatment with ibrutinib.

Efficacy results were consistent with earlier results, and the PFS compares favorably to that of treatment-naïve del 17p CLL patients receiving FCR or alemtuzumab. These results support ibrutinib as an effective therapy for patients with del 17p CLL/SLL.

Second Interim Analysis of Idelalisib and Rituximab for Patients with Relapsed CLL Confirms Previous Findings

Picture3By Dr. Richard Furman, MD

There is high unmet need for treatment of unfit patients with relapsed CLL, particularly in those characterized by adverse prognostic factors including del (17p) and/or TP53 mutations. Idelalisib is a first-in-class, targeted, highly selective, oral inhibitor of PI3 Kinase-delta enzyme recently approved for the treatment of relapsed CLL in combination with rituximab. During the 56th annual meeting of the American Society of Hematology (ASH) updated results were presented from a phase III study evaluating idelalisib in combination with rituximab in patients with relapsed CLL.

This study tested the efficacy of idelalisib in combination with rituximab compared to placebo with rituximab in patients with relapsed and refractory CLL who were considered unfit to receive cytotoxic therapy due to comorbidities, poor kidney function, or myelosuppression. 220 randomized patients (110 per group) received idelalisib + rituximab or a placebo + rituximab.  At progression, patients were given the option of enrolling in an extension study where they would receive idelalisib.  The primary endpoint was progression free survival.

At the first interim analysis, the results supported a marked improvement for patients who received idelalisib + rituximab compared with placebo + rituximab, with the median PFS not reached for patients taking idelalisib + rituximab compared with  5.5 months for patients taking the placebo. At 12 months, PFS rates for patients on idelalisib + rituximab was 66% compared to 13% for placebo + rituximab. The benefit favoring idelalisib + rituximab was seen in all risk‑groups. At the time of this analysis, 19 total deaths had occurred on the primary study: 6 on idelalisib + rituximab and 13 on placebo + rituximab.

For patients unfit to receive chemotherapy with relapsed CLL, idelalisib + rituximab demonstrated significant improvement over placebo + rituximab in terms of PFS, ORR, and OS with an acceptable safety profile. These results confirm the 1st interim analysis of the study.

Updated Efficacy Results of Ibrutinib Compared with Ofatumumab in Relapsed CLL (RESONATE Trial), with Analysis of Genetic and Prognostic Subgroups

Picture3By Dr. Richard Furman, MD

The role of various prognostic factors in CLL/SLL is not yet fully understood, including the implications of new genetic markers associated with high risk. Ibrutinib is a first-in-class Bruton’s tyrosine kinase inhibitor that is approved for the treatment of CLL patients who have received at least 1 prior therapy, and for patients with 17p deletion CLL. In results presented before the 56th annual meeting of the American Society of Hematology, updated efficacy results from the phase 3 RESONATE (PCYC-1112) study comparing ibrutinib to ofatumumab were reported.

In the phase III study 391 randomized patients received 420 mg daily of ibrutinib or ofatumumab daily, until disease progression or unacceptable toxicity for up to 24 weeks. During an interim analysis at the median follow up of 9.4 months, patients in the ofatumumab arm were provided access to the ibrutinib arm.

Comparatively, progression free survival (PFS) was significantly longer for ibrutinib compared to ofatumumab. Overall survival (OS) was significantly better for ibrutinib compared to ofatumumab, with 18-month OS rates of 85% and 78% respectively. Higher number of prior therapies (≥3) and 11q deletion were associated with significantly lower 12-month PFS rate for ofatumumab, but not for ibrutinib. The overall response rate (ORR) for ibrutinib versus ofatumumab was 90% to 25%. Compared to ofatumumab, ibrutinib improved 12-month PFS and ORR regardless of baseline genetics, complex cytogenetics, or number of prior therapies. No significant difference in 12-month PFS was observed in ibrutinib treated patients with or without del(17p) or for those who developed lymphocytosis compared to those without lymphocytosis. Median treatment duration was longer for ibrutinib versus ofatumumab and was 16 to 5 months respectively.

In this one on one comparison ibrutinib significantly outperformed ofatumumab in PFS, OS, and ORR in patients with CLL/SLL with at least one prior therapy. These results are consistent with previously published findings, and provide further evidence for the clinical utility  of ibrutinib in patients with CLL.