LUGANO, SWITZERLAND – Copanlisib, an investigational intravenous inhibitor of phosphatidylinositol 3-kinase (PI3K), was associated with “promising” efficacy and a better safety profile than has been seen with oral PI3K inhibitors in patients with relapsed or refractory indolent lymphomas.
In a phase 2 trial of the drug as monotherapy in patients with indolent lymphomas, copanlisib was associated with an overall response rate of 58.6% among 104 patients with follicular lymphoma (FL), including 14.4% complete responses (CR) and 44.2% partial responses (PR), reported Martin Dreyling, MD, of the Universität München-Grosshadern in Munich, Germany.
“The favorable risk-benefit profile of this compound suggests further [need for] testing in follicular lymphoma. My personal interpretation is that the different safety profile is due to the intermittent dosing and the IV application, avoiding adverse cause-effect both in the gut and the liver,” he said at the 14th International Conference on Malignant Lymphoma.
Dr. Dreyling noted that the oral PI3K inhibitor idelalisib (Zydelig) is approved for the treatment of patients with relapsed chronic lymphocytic leukemia in combination with rituximab and in patients with relapsed FL or small lymphocytic lymphomas (SLL) who have received at least two prior lines of systemic therapy. This agent, however, carries a black box warning about fatal and serious toxicities, including hepatic events, severe diarrhea, colitis, pneumonitis, infections, and intestinal perforation.
Copanlisib inhibits all isoforms of P13K but is predominantly active against the alpha and delta isoforms of the kinase. The alpha form, expressed in many cell types, is involved in insulin signaling and angiogenesis and in resistance mechanisms to lymphoma. The delta form, expressed in leukocytes, is involved in B-cell signaling, development, and survival, making PIK3 an attractive target, Dr. Dreyling explained.
The study included patients with indolent B-cell lymphomas, including FL grades 1-3a, marginal zone lymphoma, SLL, or lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia (LPL/WM) for whom at least two prior lines of therapy had failed.
The patients received copanlisib 60 mg IV on days 1, 8, and 15 of each 28-day cycle until disease progression or unacceptable toxicity.
Of 142 assigned to and started on treatment, 46 patients (32.3%) remained on treatment at the time of data cutoff. Of the 96 patients (67.7%) who discontinued, 35 did so because of adverse events, 36 discontinued for radiologic or clinical evidence of progression, 16 withdrew, 5 were discontinued on the treating physician’s decision, and 4 stopped for other, unspecified reasons.
Among all 142 patients, the median duration of therapy was 22 weeks and the median number of cycles was 5.5. In all, 26.1% of patients required a dosage reduction to 45 mg, and 5.6% required reduction to 30 mg.
As noted, the objective tumor response rate (ORR) among patients was 58.6% for 104 patients with FL. For the 23 patients with marginal zone lymphoma, the ORR was 69.6%, consisting of two complete and 14 partial responses. Among eight patients with SLL, there were six partial responses and no complete responses. For the six patients with LPL/WM, there was one partial response.
The overall median duration of response was 22.6 months. Among patients with refractory disease and in all patients with FL the median duration of response was 12.2 months.
The median progression-free survival after 24 months of follow-up was 11.2 months for all patients. The median overall survival has not been reached.
The most frequent adverse events of grade 3 or 4 were hyperglycemia in 40.1% (33.1% grade 3 and 7.0% grade 4) and hypertension in 22.5% (all grade 3).
Grade 3 diarrhea, a significant problem with idelalisib, occurred in 4.2% of patients, and there were no grade 4 events.
Grade 3 pneumonitis was seen in two patients, and one had grade 4 colitis. There were three drug related deaths, including one patient each from lung infection, respiratory failure, or thromboembolic event..
The study was supported by Bayer. Dr. Dreyling disclosed receiving honoraria from the company and serving on a scientific/advisory board for the company.