Update On The Safety and Efficacy Of The Pan Class I PI3K Inhibitor SAR245408 (XL147) In Chronic Lymphocytic Leukemia and Non-Hodgkin’s Lymphoma Patients

Constitutive activation of phosphatidylinositol 3-kinase (PI3K)/ mammalian target of rapamycin (mTOR) pathway by various mechanisms has been implicated in the pathogenesis of chronic lymphocytic leukemia (CLL) and non-Hodgkin’s lymphoma (NHL). There is mounting evidence suggesting that along with PI3Kγ, PI3Kα may be involved in CLL/NHL. SAR245408 is a potent and selective inhibitor of all α, γ and δ class I PI3K isoforms. It has been shown to inhibit PI3K signaling and impact tumor growth in preclinical tumor models. The impact of SAR245408 on safety, tolerability, pharmacokinetics, pharmacodynamics and anti-tumor effect was evaluated in patients with relapsed/refractory CLL and NHL from the Sanofi sponsored phase 1 single-agent study (NCT00486135) [Brown et al. ASH Annual Meeting Abstracts 2011. 118 (21): 2683].

SAR245408 was administered orally, once daily, with continuous dosing in monthly cycles. A total of 25 patients were enrolled at the maximum tolerated dose identified in solid tumor patients as part of the expansion cohort in relapsed/refractory lymphoproliferative malignancies. Plasma cytokines and chemokines were evaluated using the Myriad RBM Human Discovery MAP250+ panel (> 250 analytes) and ELISA assays.

Among the 25 patients (pts), 40% (n=10) had refractory CLL and 60% (n=15) had various relapsed/refractory lymphomas (R/RL), including follicular lymphoma (FL) (n=5), diffuse large B-cell lymphoma (DLBCL) (n=4), Waldenstrom's macroglobulinemia (WM) (n=3), Hodgkin lymphoma (n=2) and B-cell prolymphocytic leukemia (n=1). The median age was 65 years (range 28–83), and 56% were female. Eighty percent of pts had stage III-IV disease and 48% had bulky disease. Five pts were categorized as having refractory disease and the median number of prior regimens was 1 (range 1-7) for CLL pts and 3 (range 0-9) for R/RL pts. For all 25 patients, the median starting absolute lymphocyte count was 1.15 x 10³/μL (range 0.3–37.2), the median starting hemoglobin was 11.4 g/dL (range 9.1–15) and the median platelet count was 162 x 10³/μL (range 60–431). The median number of cycles administered in CLL pts was 10 (range 5-24) and 5 (range 1-26) in R/RL pts. Six CLL pts experienced an increase in absolute lymphocyte counts within 2-4 weeks of treatment, as has been seen with other PI3K inhibitors. According to modified International Workshop on Chronic Lymphocytic Leukemia (IWCLL) response criteria, 4 CLL pts had partial response (PR), 1 had nodal PR with increased lymphocytosis, and 5 had stable disease (SD); the progression free survival (PFS) in the responding pts was 22, 21.2, 15.6 and 15.4 months while in the SD pts was 12.5, 9.2, 7.4, 5.6, 4.6 and 3.6 months. According to the modified International Working Group response criteria, 3 PRs were reported in R/RL pts [1 WM, 1 DLBCL (transformed) and one FL with PFS of 23.7, 18.4 and PFS 4.8 months respectively]. One hundred percent of CLL and 80% of R/RL pts reported grade 3 or higher AEs, with the most common (≥ 10% of patients) including neutropenia, diarrhea, anemia and hypotension. SAR245408 induced a reduction in levels of chemokines involved in lymphocyte trafficking in CLL subjects (n=8), including CXCL13, CCL3, CCL22 and CCL19 (64, 58, 52 and 54% reduction, respectively, p<0.05) similar to what was reported with PI3K δ specific inhibitors. In addition, a reduction of tumor necrosis factor receptor 2 (TNFR2) and interleukin-2 receptor alpha (IL-2Rα) levels was observed (63% reduction each, p<0.01).

The recommended phase 2 dose of SAR245408 in solid tumor patients was confirmed as safe and tolerable in patients with CLL and R/RL. Single agent SAR245408 demonstrates clinical activity in patients with relapsed or refractory CLL and promising pharmacodynamic effects on chemokine levels involved in lymphocyte trafficking.

Brown:Emergent: Consultancy; Onyx: Consultancy; Sanofi Aventis: Consultancy; Vertex: Consultancy; Novartis: Consultancy; Genzyme: Research Funding; Avila: Consultancy; Celgene: Consultancy, Research Funding; Genentech: Consultancy; Pharmacyclics: Consultancy. Off Label Use: The abstract shows scientific information on SAR245408 which is an investigational product developed by Sanofi. This investigational product is not approved by any health authority for any indication. Egile:Sanofi: Employment. Ruiz-Soto:Sanofi: Employment. Awan:Lymphoma Research Foundation: Research Funding; Spectrum Pharmaceuticals Inc.: Speakers Bureau.