Copanlisib synergizes with conventional and targeted agents including venetoclax in B- and T-cell lymphoma models

Abstract

Copanlisib is a pan-class I phosphoinositide 3-kinase (PI3K) inhibitor with preferred activity toward PI3Kα and PI3Kδ. Despite the clear overall clinical benefit, the number of patients achieving complete remissions with the single agent is relatively low, a problem shared by the vast majority of targeted agents. Here, we searched for novel copanlisib-based combinations. Copanlisib was tested as a single agent, in combination with an additional 17 drugs in 26 cell lines derived from mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and T-cell lymphomas. In vivo experiments, transcriptome analyses, and immunoblotting experiments were also performed. Copanlisib as a single agent showed in vitro dose-dependent antitumor activity in the vast majority of the models. Combination screening identified several compounds that synergized with copanlisib. The strongest combination was with the B-cell lymphoma 2 (BCL2) inhibitor venetoclax. The benefit of the combination over single agents was also validated in an MZL xenograft model and in MCL primary cells, and was due to increased induction of apoptosis, an effect likely sustained by the reduction of the antiapoptotic proteins myeloid cell leukemia 1 (MCL1) and BCL-XL, observed in MCL and MZL cell lines, respectively. These data supported the rationale for the design of the Swiss Group for Clinical Cancer Research (SAKK) 66/18 phase 1 study currently exploring the combination of copanlisib and venetoclax in relapsed/refractory lymphomas.

Graphical abstract

Figure 1.

In vitro and in vivo antiproliferative effects of copanlisib-containing combinations in lymphoma models. (A) In vitro combination in B-cell lymphoma cell lines derived from MCL, MZL, and CLL. (B) In vitro combination in T-cell lymphomas cell lines derived from ALCL, PTCL, and CTCL. (C) Antitumor in vivo activity of copanlisib in combination with venetoclax or lenalidomide in the MZL SSK41 model. Mice were treated with vehicle (IV), copanlisib (14 mg kg IV, 2 days on/5 days off), venetoclax (200 mg/kg, postoperatively, once per day), lenalidomide (50 mg/kg, postoperatively, once per day), copanlisib plus venetoclax (same doses as the single agents), or copanlisib plus lenalidomide (same doses as the single agents). Lines show median values per time point with the corresponding upper interquartile range. The y-axis indicates the tumor volume in millimeters cubed; the x-axis, days of treatment (P values shown in supplemental Table 4).

Figure 2.

PI3K inhibitor copanlisib and the BCL2 inhibitor venetoclax are cytotoxic for MCL and MZL cells when combined and act via downregulating BCLXL or MCL1. (A) Four cell lines were exposed for 24 hours to copanlisib (30 nM, 300 nM), venetoclax (0.3 μM, 3 μM), or the combination of the 2 agents. (B) Three MCL and 2 MZL primary cells were exposed for 48 hours to copanlisib (100 or 200 nM), venetoclax (100 or 200 nM), or the combination of the 2 agents. The y-axis indicates the percentage of live cells, defined as Annexin V and 7AAD⁻, compared with dimethyl sulfoxide (DMSO)–treated cells. (C) Two cell lines exposed to copanlisib (30 nM, 300 nM), venetoclax (0.3 μM, 3 μM), or the combination of the 2 agents for 24 hours. cPARP, cleaved PARP; SMZL, splenic MZL.

Figure 3.

Combination of the PI3K inhibitor copanlisib with the CDK4/6 inhibitor palbociclib did not induce apoptosis in MCL and MZL cell lines, but did induce G0/G1 arrest with upregulation of PIK3IP1. (A) Four cell lines were exposed for 24 hours to copanlisib (30 nM, 300 nM), palbociclib (0.3 μM, 3 μM), or the combination of the 2 agents. (B) Cell-cycle analysis of 1 MCL (JEKO1) and 1 MZL (SSK41) cell line exposed for 24 hours to copanlisib (30 nM, 300 nM), palbociclib (0.3 μM, 3 μM), or the combination of the 2 agents. (C) RNA changes of PIK3IP1 in 1 MCL (JEKO1) and 1 MZL cell line exposed for 24 hours to copanlisib (30 nM, 300 nM), palbociclib (0.3 μM, 3 μM), or the combination of the 2 agents.