NEW YORK (TheStreet) -- Here is a summary of American Society of Clinical Oncology (ASCO) annual meeting research abstracts released tonight focused on the chronic lymphocytic leukemia (CLL) drugs from Pharmacyclics (PCYC), Gilead Sciences (GILD) and Abbvie (ABBV).
Results from the phase III "RESONATE" study of Imbruvica were not disclosed tonight. The research abstract No. LBA7008 is being withheld for presentation at the ASCO meeting.
Last January, Pharmacyclics and Johnson & Johnson (JNJ) announced the early stopping of the Imbruvica RESONATE study because the primary and secondary endpoints -- progression-free survival and overall survival -- were achieved. The study compared Imbruvica to GlaxoSmithKline's (GSK) Arzerra in CLL patients no longer responding to at least one prior therapy.
Imbruvica is already approved for use in patients with mantle cell lymphoma and CLL following progression on at least one prior treatment.
Abstract no. 7014 summarizes three-year, follow-up data from a separate study of Imbruvica in 132 CLL/SLL patients, both treatment naive and relapsed/refractory. The updated overall response rate was 78% for all-treated patients (84% for treatment naive, 76% for relapsed/refractory.) In the subgroup of harder-to-treat del(17p) patients, the response rate to Imbruvica treatment was 56%. Median duration of response was 25 months.
Abstract no. 7009 evaluates the combination of Imbruvica and GSK's Arzerra in 71 patients with relapsed/refractory CLL/SLL. Three different dosing schedules of Imbruvica and Arzerra were studied, with an overall response rate of 83%. At 12 months, progression-free survival was 89%, 85% and 90% in the three different dosing schedules; 76% of patients continued receiving Imbruvica in an extension study. Two patients moved to a bone marrow transplant.
The FDA is currently reviewing two approval applications for idelalisib for the following indications: 1) relapsed/refractory CLL, with a decision is expected on Aug. 6; and 2) refractory indolent non-Hodgkins lymphoma, with an approval decision expected on Sept. 11.
Abstract No. 7011 covers updated results from high-risk subgroups of CLL patients enrolled in the previously presented (and positive) phase III study of idelalisib in combination with Roche's Rituxan.
In patients with del(17p) and TP53 mutations, idelalisib+Rituxan achieved a 76.5% overall response rate and a progression-free survival hazard ratio of 0.13 (87% reduction in the risk of progression.) This compares to an 80.4% overall response rate and a PFS hazard ratio of 0.17 for patients negative for del(17p) and TP53.
Overall results from a second interim analysis of the idelalisib+Rituxan phase III study in CLL are summarized in abstract no. 7012. Treatment with idelalisib+Rituxan reduced the risk of tumor progression by 82% compared to Rituxan+placebo. The risk of death was reduced by 72% favoring the idelalisib.
Gilead also has a selective Syk inhibitor, GS-9973, in clinical development for CLL. Abstract no. 7007 summarizes a phase II study enrolling 44 patients with relapsed/refractory CLL and treated with twice-daily, 800 mg dose of GS-9793. Results: 40 of 41 evaluable patients (91%) experienced reduced tumor bulk; 64% achieved tumor reduction of 50% or more, according to the investigator review. Twenty-seven patients are still on treatment for a median of 22 weeks.
Two patients died while on the study, one from progressive disease, one from sepsis. The most common adverse events reported (all grades) were diarrhea (48%), fatigue, nausea and headache.
Abstract no. 7059 reports on a study combining GS-9793 with idelalisib in CLL and NHL patients. After 66 patients were enrolled, the study was stopped due to reports of severe, steroid-responsive pneumonitis in 9 patients. Reversible grade 3/4 liver enzyme elevations occurred in 15% of patients. Five patients died during the study -- two from disease progression, one from pneumonitis, one from pneumonia and one from sepsis.
Abstract no. 7013 reports on a phase I study of ABT-199 combined with Rituxan in relapsed/refractory CLL patients. Thirty-seven patients were treated in five dose cohorts. Eighteen patients were evaluable for efficacy, with 7 patients (39%) achieving a complete response and 7 patients (39%) achieving a partial response. Minimal residual disease (MRD) found in 6 of 7 patients, while 5 patients were MRD negative. Of 19 patients still being treated with combination therapy, 4 have confirmed partial response and 9 have unconfirmed partial response.
One patient died due to hyperkalemia in the setting of tumor lysis syndrome. The common grade 3-4 adverse events reported were neutropenia (43%), thrombocytopenia (16%) and anemia (11%.)