Japanese phase Ib study of the oral PI3K-δ and -γ inhibitor duvelisib in patients with relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma

This phase Ib, open-label, single-arm, multicenter study assessed the efficacy and safety of duvelisib, an oral dual inhibitor of phosphatidylinositol 3-kinase-δ and -γ, in Japanese patients with relapsed or refractory (r/r) chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). Duvelisib was administered orally at 25 mg twice a day (BID) until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) and all responses were assessed by an independent review committee. Nine CLL patients and 1 SLL patient were enrolled. ORR was 80% (95% confidence interval 44.4, 97.5) for all 10 patients. All 6 patients previously treated with a Bruton's tyrosine kinase (BTK) or BCL2 inhibitor achieved a partial response. The most common adverse events were neutropenia (50%), diarrhea (40%), anemia, hypokalemia, constipation and rash (30% each). The most common grade ≥ 3 adverse events were neutropenia (50%), anemia (30%) and thrombocytopenia (20%). Duvelisib 25 mg BID showed favorable efficacy and a manageable safety profile in selected Japanese patients with r/r CLL/SLL, including patients previously treated with BTK or BCL2 inhibitors (Clinical trial registration: jRCTs2080224791).

Duvelisib: A comprehensive profile

Duvelisib (DUV) is chemically named as (S)-3-(1-((9H-Purin-6-yl)amino)ethyl)-8-chloro-2-phenylisoquinolin-1(2H)-one. It is a novel drug with a small molecular weight and characterized by dual phosphoinositide-3-kinase (PI3K)- and PI3K-inhibitory activity. The Food and Drug Administration (FDA) recently approved DUV for the management of small lymphocytic lymphoma (SLL) and relapsed or refractory chronic lymphocytic leukemia (CLL) in adult patients. DUV is marketed under the brand name of Copiktra® (Verastem, Inc., Needham, MA, USA). This chapter provides a critical extensive review of the literature, the description of DUV in terms of its names, formulae, elemental composition, appearance, and use in the treatment of CLL, SLL, and follicular lymphoma. The chapter also describes the methods for preparation of DUV, its physical-chemical properties, analytical methods for its determination, pharmacological properties, and dosing information.

Combination strategies to overcome drug resistance in FLT+ acute myeloid leukaemia

BACKGROUND

Acute myeloid leukaemia (AML) remains difficult to treat despite the development of novel formulations and targeted therapies. Activating mutations in the FLT3 gene are common among patients and make the tumour susceptible to FLT3 inhibitors, but resistance to such inhibitors develops quickly.

METHODS

We examined combination therapies aimed at FLT3+-AML, and studied the development of resistance using a newly developed protocol. Combinations of FLT3, CDK4/6 and PI3K inhibitors were tested for synergism.

RESULTS

We show that AML cells express CDK4 and that the CDK4/6 inhibitors palbociclib and abemaciclib inhibit cellular growth. PI3K inhibitors were also effective in inhibiting the growth of AML cell lines that express FLT3-ITD. Whereas resistance to quizartinib develops quickly, the combinations overcome such resistance.

CONCLUSIONS

This study suggests that a multi-targeted intervention involving a CDK4/6 inhibitor with a FLT3 inhibitor or a pan-PI3K inhibitor might be a valuable therapeutic strategy for AML to overcome drug resistance. Moreover, many patients cannot tolerate high doses of the drugs that were studied (quizartinib, palbociclib and PI3K inhibitors) for longer periods, and it is therefore of high significance that the drugs act synergistically and lower doses can be used.

Duvelisib attenuates bleomycin-induced pulmonary fibrosis via inhibiting the PI3K/Akt/mTOR signalling pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive interstitial lung disease that seriously threatens the health of patients. The pathogenesis of IPF is still unclear, and there is a lack of effective therapeutic drugs. Myofibroblasts are the main effector cells of IPF, leading to excessive deposition of extracellular matrix (ECM) and promoting the progression of fibrosis. Inhibiting the excessive activation and relieving autophagy blockage of myofibroblasts is the key to treat IPF. PI3K/Akt/mTOR pathway plays a key regulatory role in promoting fibroblast activation and autophagy inhibition in lung fibrosis. Duvelisib is a PI3K inhibitor that can simultaneously inhibit the activities of PI3K-δ and PI3K-γ, and is mainly used for the treatment of relapsed/refractory chronic lymphocytic leukaemia (CLL) and small lymphocytic lymphoma tumour (SLL). In this study, we aimed to examine the effects of Duvelisib on pulmonary fibrosis. We used a mouse model of bleomycin-induced pulmonary fibrosis to evaluate the effects of Duvelisib on pulmonary fibrosis in vivo and further explored the potential pharmacological mechanisms of Duvelisib in lung fibroblasts in vitro. The in vivo experiments showed that Duvelisib significantly alleviated bleomycin-induced collagen deposition and improved pulmonary function. In vitro and in vivo pharmacological experiments showed that Duvelisib dose-dependently suppressed lung fibroblast activation and improved autophagy inhibition by inhibiting the phosphorylation of PI3K, Akt and mTOR. Our results indicate that Duvelisib can alleviate the severity of pulmonary fibrosis and provide potential drugs for the treatment of pulmonary fibrosis.

Synthesis, spectroscopic and computational studies on hydrogen bonded charge transfer complex of duvelisib with chloranilic acid: Application to development of novel 96-microwell spectrophotometric assay

Duvelisib (DUV) is a is a small-molecule with inhibitory action for phosphoinositide 3-kinase (PI3K). It has been recently approved for the effective treatment of chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). Novel charge transfer complex (CTC) between DUV, as electron donor, with chloranilic acid (CLA), as π electron acceptor has been synthesized and characterized using different spectroscopic and thermogravimetric techniques. UV-visible spectroscopy ascertained the formation of the CTC in different solvents of varying polarity indexes and dielectric constants via formation of new broad absorption band with maximum absorption peak (λ_max) in the range of 488-532 nm. The molar absorptivity of the CTC was dependent on the polarity index and dielectric constant of the solvent; the correlation coefficients were 0.9955 and 0.9749, respectively. The stoichiometric ratio of DUV:CLA was 1:1. Electronic spectral analysis was conducted for characterization of the complex in terms of its electronic constants. Computational calculation for atomic charges of energy minimized DUV was conducted and the site of interaction on DUV molecule was assigned. The solid-state CTC of DUV:CLA (1:1) was synthesized, and its structure was characterized by UV-visible, mass, FT-IR, and ¹H NMR spectroscopic techniques. Both FT-IR and ¹H NMR confirmed that both CT and hydrogen bonding contributed to the molecular composition of the complex. The reaction was adopted as a basis for developing a novel 96-microwell spectrophotometric assay (MW-SPA) for DUV. The assay limits of detection and quantitation were 0.57 and 1.72 µg/well, respectively. The assay was validated and all validation parameters were acceptable. The method was implemented successfully with great precision and accuracy to the analysis of the DUV in its bulk and capsules.

UHPLC-Q-TOF-MS/MS based metabolite profiling of duvelisib and establishment of its metabolism mechanisms

Duvelisib is a dual inhibitor of phosphoinositide 3 kinase that received global approval by USFDA in 2018 to treat follicular lymphoma after at least two prior systemic therapies. An extensive literature search revealed that till date, metabolites of duvelisib are not characterized and information on the same is not available in any literature. Moreover, its metabolism pathway is yet to be established. This study aimed to investigate and characterize the metabolites of duvelisib generated in microsomes and S9 fractions. In this study, five duvelisib metabolites have been identified using UHPLC-Q-TOF-MS/MS technique of analysis. The structural characterisation of the metabolites was performed by comparing the fragmentation pattern of duvelisib and its metabolites through an accurate mass measurement technique. Three metabolites were found to be generated through phase I hydroxylation and dechlorination reaction. The other two metabolites were generated through a phase II glucuronidation reaction. The metabolism mechanism established through this study can be useful to improve the safety profile of the drug of its similar category in the future after establishment their toxicity profile of the identified metabolites.

Duvelisib as bridge to allotransplantation in refractory peripheral T-cell lymphoma with T-follicular helper phenotype: case report

OBJECTIVE

Peripheral T-cell lymphomas (PTCLs) are a group of heterogeneous T-cell malignancies representing 5%-10% of aggressive lymphomas. The prognosis is poor for patients with relapsed/refractory (R/R) disease, with a median overall survival of less than 6 months and no standardized treatments. We discuss the role of the phosphatidylinositol 3-kinase (PI3K) γδ inhibitor duvelisib as bridge to allotransplantation in a patient with R/R PTCL.

METHODS

Case report.

RESULTS

A 55-year-old woman diagnosed with relapsed nodal PTCL with T-follicular helper phenotype received PI3K γδ inhibitor duvelisib in the context of the phase II PRIMO clinical trial. After two cycles at a dose of 75 mg twice daily, the patient achieved complete response (CR), which was subsequently consolidated with human leukocyte antigen fully matched unrelated donor allotransplantation. No major toxicities were recorded during the duvelisib treatment period or during hospitalization for allotransplantation. At the latest follow-up, the patient was alive and still in CR 10 months posttransplant.

CONCLUSIONS

Duvelisib should be further explored as a bridge to allotransplantation in patients with R/R PTCL, given the success and low toxicity in our patient.

The Evolving Use of Phosphatidylinositol 3-Kinase Inhibitors for the Treatment of Chronic Lymphocytic Leukemia

B cells express 4 phosphatidylinositol 3-kinase (PI3K) isoforms and have a dependence on p110δ for survival. The design of isoform-selective inhibitors is possible, and pharmacologic inhibition of p110δ is toxic to neoplastic chronic lymphocytic leukemia (CLL) cells for both cell-intrinsic and cell-extrinsic reasons. Idelalisib is a first-in-class p110δ inhibitor that exhibits efficacy for the treatment of relapsed CLL irrespective of adverse prognostic features. Duvelisib is a p110γ/δ inhibitor with a similar efficacy and safety profile to idelalisib. Recent data indicate that umbralisib, a p110δ/CK-1ε dual inhibitor, is safe and effective when administered to patients with CLL.

Current Treatment of Refractory/Relapsed Chronic Lymphocytic Leukemia: A Focus on Novel Drugs

Recently, the use of novel targeted drugs has changed the treatment paradigms in chronic lymphocytic leukemia (CLL). Among the several drugs used for the management of relapsed/refractory (R/R) CLL, Bruton tyrosine kinase inhibitors (ibrutinib and acalabrutinib), phosphatidylinositol 3-kinase inhibitors (idelalisib and duvelisib), B-cell lymphoma 2 inhibitor (venetoclax), and novel CD20 monoclonal antibodies have demonstrated the greatest improvements in survival among R/R CLL patients. However, patients with relapsed but asymptomatic CLL do not need immediate alternative treatment and should be observed until evident sign of progression. Among available approved treatments, venetoclax + rituximab for 24 months or ibrutinib as continuous therapy is recommended. Another, less recommended, option is idelalisib in combination with rituximab. The correct treatment selection depends on the type of prior therapy, response to previous treatment and side effects, presence of comorbidities, and the risk of drug toxicity. Allogeneic hematopoietic stem cell transplantation and investigational therapies such as chimeric antigen receptor-T-cell therapy are promising treatment options for high-risk patients, including those progressing after 1 or more targeted therapies. The present review discusses current treatment strategies for patients with R/R CLL.

Phase I study of duvelisib in Japanese patients with relapsed or refractory lymphoma

Duvelisib is a novel dual inhibitor of phosphoinositide-3-kinase (PI3K)-δ and -γ. This single-arm, multicenter phase I study investigated its safety, pharmacokinetics, and preliminary efficacy in Japanese patients with relapsed or refractory lymphoma. Duvelisib was administered orally twice daily at 25 mg in 28-day cycles. Seven patients, comprising 4 with follicular lymphoma (FL), 2 with diffuse large B-cell lymphoma, and 1 with mantle cell lymphoma (MCL) were enrolled. No dose-limiting toxicity occurred in any patient. The most commonly experienced treatment-related adverse events of any grade were neutropenia and thrombocytopenia, occurring in 3 patients each (42.9%); followed by lymphopenia, diarrhea, enterocolitis, stomatitis, hepatic function abnormal, ALT increased, and AST increased, occurring in 2 patients each (28.6%). The most common grade ≥ 3 treatment-related adverse events were neutropenia, which occurred in 3 patients (42.9%), and thrombocytopenia, lymphopenia, and hepatic function abnormal, which occurred in 2 patients each (28.6%). One patient with FL achieved a complete response; the remaining 3 with FL and the 1 with MCL achieved a partial response. The overall response rate was 71.4% (5/7 patients). Duvelisib was well tolerated in Japanese patients with relapsed or refractory lymphoma. Safety and preliminary efficacy data support further development of duvelisib in Japanese patients.

Development of a novel and quick UPLC-MS/MS method for the pharmacokinetic analysis of duvelisib in beagle dogs

Duvelisib, a new oral phosphoinositide-3-kinase (PI3K)-δ and PI3K-γ inhibitor, was recently approved in the USA as the therapeutic drug for patients with the diseases of relapsed or refractory chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL). In the present study of our research, a quick and simple bioanalytical method based on ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) technique was fully explored and established for the quantification of plasma duvelisib concentrations from beagle dog in which gilteritinib was used as the internal standard (IS). After a simple and quick protein precipitation treated with acetonitrile, the chromatographic separation of the analyte was carried out on an Acquity BEH C18 column (2.1 mm × 50 mm, 1.7 μm) conducted in a gradient elution procedure where acetonitrile (solvent A) and 0.1 % formic acid in water (solvent B) consisted as the mobile phase. The measurements of the analyte and IS were explored using a XEVO TQS triple quadrupole tandem mass spectrometer, which was comprised with electrospray ionization (ESI) source in positive ion mode. Selected reaction monitoring (SRM) mode was employed to detect the parent-to-daughter ion transitions as follows: m/z 416.88 → 281.88 for duvelisib, and m/z 553.09 → 436.01 for IS, respectively. The assay was successfully established in the calibration range from 0.5 to 3000 ng/mL for duvelisib, where the lower limit of quantification (LLOQ) was set at 0.5 ng/mL. The precisions of intra-day and inter-day for duvelisib were all below 12.6 %, and the accuracies were from -2.5% to 14.1%. Both matrix effect and mean recovery of the analyte and IS were all acceptable, and the analyte was stable during the assay and storage in dog plasma samples. The novel established bioanalytical method based on UPLC-MS/MS technique was effectively employed to the investigation of the pharmacokinetic profile of duvelisib in beagle dogs following a 1.34 mg/kg single dose of oral administration.

Duvelisib for the treatment of chronic lymphocytic leukemia

INTRODUCTION

Duvelisib, a first in class, oral, dual PI3 k-delta/gamma inhibitor recently received FDA approval for previously treated CLL (chronic lymphocytic leukemia)/SLL (small lymphocytic lymphoma) and follicular lymphoma. Data coming from the phase III 'DUO' trial, in fact, showed a superior progression-free survival (PFS) in CLL patients treated with duvelisib compared to ofatumumab.

AREAS COVERED

This review provides analysis of the mechanism of action of duvelisib and includes the rationale for the use of double inhibition. The authors also give their clinical experience with duvelisib. Overall, despite the high efficacy of the drug, some concern remains on duvelisib-related adverse events leading to treatment interruption in a significant proportion of patients.

EXPERT OPINION

Considering the unmet need of salvage therapies in patients failing BTK and/or Bcl2 inhibitors, treatment with duvelisib represents a new valid option in the CLL therapeutic armamentarium. Therefore, the correct management of adverse events with early treatment suspension, dose reductions and prompt supportive treatment could help to manage treatment, thus improving patient outcome. Finally, the association of duvelisib with other targeted therapies, such as ibrutinib or venetoclax, could allow clinicians to capitalize on the synergistic activity of these agents.

Novel Therapies in Chronic Lymphocytic Leukemia: A Rapidly Changing Landscape

OPINION STATEMENT

Treatment landscape of chronic lymphocytic leukemia (CLL) has changed since 2014 after the introduction of inhibitors of B-cell receptor signaling pathway (ibrutinib, acalabrutinib, idelalisib and duvelisib) and the inhibitor of the anti-apoptotic protein BCL-2 (venetoclax). In 2019, novel agents were upgraded from being a "great treatment option" to the "preferred choice" for all lines of treatment after number of randomized clinical trials proved their superiority compared to conventional chemoimmunotherapy (CIT) regimens. A growing number of next-generation molecules are in clinical trials with a promise of improved efficacy and less toxicity. This includes agents with expected better safety profile (zanubrutinib, umbralisib, etc.) or more importantly with a potential to overcome the resistance mechanism to early generation agents (ARQ-531, LOXO-305, or vecabrutinib). Early intervention has once again become an active topic of research and, if proven to provide an overall survival benefit, will eliminate the "watch and wait" strategy for asymptomatic CLL patients. Until then, treatment should only be offered to patients who meet the standard treatment indication in standard practice. With our upgraded therapeutic toolbox, there are and will be many unanswered questions. CLL field will need to define the optimal treatment sequence and most effective combinations with a goal of having a time-limited and chemotherapy-free regimen that provides longest remissions and potentially cure. Cellular immunotherapy with chimeric antigen receptor T-cell (CAR-T) may become available for high-risk CLL along with allogeneic stem cell transplant (allo-SCT). Financial toxicity of novel agents especially when used in combination will need to be an important aspect of research in coming years to avoid unnecessary overtreatment of patients. As current prognostic models (CLL-IPI, etc.) were developed and validated in the CIT era, there is ongoing effort to develop new models using clinical and molecular characteristics to accurately define high-risk CLL in the era of novel agents. We all need to keep in mind that access to the novel agents is currently limited to certain developed countries and every effort should be made to make sure patients around the world also benefit from these outstanding drugs.

Interleukin-6 mediates resistance to PI3K-pathway-targeted therapy in lymphoma

Background

The phosphoinositol 3-kinase (PI3K) pathway is associated with poor prognosis of hematologic malignancies, providing a strong rationale for the use of PI3K inhibitors in the treatment of malignant lymphoma. However, development of resistance limits the use of PI3K inhibitors in lymphoma patients.

Methods

We established copanlisib (pan-PI3K inhibitor)-resistant B-cell lymphoma and duvelisib (PI3Kδ and -γ inhibitor)-resistant T-cell lymphoma cell lines. The cytokine array and the phospho-kinase array were used to identify up-regulated proteins in the resistant cells. Cytokine expression and phospho-kinase levels were examined by ELISA and Western blot analysis, respectively. Cell proliferation capabilities were measured by using CCK-8 kit and colony formation assay. The effects of inhibitors on apoptosis were detected using an Annexin V-FITC Apoptosis Detection Kit and a flow cytometry system. The underlying mechanisms were studied by transfecting recombinant plasmids or siRNA into lymphoma cell lines. Cells were transiently transfected using the Amaxa electroporation system. We evaluated the effects of PI3K inhibitor alone and in combination with JAK inhibitor (BSK805) on lymphoma proliferation and signaling pathway activation.

Results

Cytokine arrays revealed upregulation of interleukin (IL)-6 in both copanlisib- and duvelisib-resistant cell lines. Phosphorylated STAT5, AKT, p70S6K and MAPK were increased in copanlisib-resistant B-cell lymphoma cells, whereas phosphorylated STAT3 and NF-κB were increased in duvelisib-resistant T cell lymphoma cells. Conversely, depletion of IL-6 sensitized both resistant cell lines, and led to downregulation of phosphorylated STAT3 and STAT5 in copanlisib- and duvelisib-resistant cells, respectively. Moreover, combined treatment with a JAK inhibitor (BSK805) and a PI3K inhibitor circumvented the acquired resistance to PI3K inhibitors in lymphoma, and concurrent inhibition of the activated pathways produced combined effects.

Conclusions

IL-6–induced STAT3 or STAT5 activation is a critical mechanism underlying PI3K inhibitor resistance in lymphoma, supporting the utility of IL-6 as an effective biomarker to predict therapeutic response to PI3K inhibitors.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-6057-7) contains supplementary material, which is available to authorized users.

Antitumor effects of duvelisib on Epstein-Barr virus-associated lymphoma cells

Epstein–Barr virus (EBV) is a ubiquitous oncogenic virus that is associated with B cell lymphomas, including Burkitt lymphoma and Hodgkin lymphoma. Previous studies have shown that the phosphatidylinositol 3‐kinase (PI3K)/Akt pathway is activated in EBV‐associated lymphomas and can be a novel therapeutic target. An oral dual inhibitor of PI3Kγ and PI3Kδ, duvelisib, is in clinical trials for the treatment of lymphoid malignancies. In this study, we evaluated how duvelisib affects the activity of the PI3K/Akt signaling pathway and if it has antitumor effects in EBV‐associated lymphoma cell lines. We found that the PI3K/Akt signaling pathway was activated in most of the B and T cell lymphoma cell lines tested. Additionally, duvelisib treatment inhibited cellular growth in the tested cell lines. Overall, B cell lines were more susceptible to duvelisib than T and NK cell lines in vitro regardless of EBV infection. However, the additional influence of duvelisib on the tumor microenvironment was not assessed. Duvelisib treatment induced both apoptosis and cell cycle arrest in EBV‐positive and ‐negative B cell lines, but not in T cell lines. Furthermore, duvelisib treatment reduced the expression of EBV lytic genes (BZLF1 and gp350/220) in EBV‐positive B cell lines, suggesting that duvelisib suppresses the lytic cycle of EBV induced by B cell receptor signaling. However, duvelisib did not induce a remarkable change in the expression of EBV latent genes. These results may indicate that there is therapeutic potential for duvelisib administration in the treatment of EBV‐associated B cell lymphomas and other B cell malignancies.

Pharmacological targeting of PI3K isoforms as a therapeutic strategy in chronic lymphocytic leukaemia

PI3Kδ inhibitors such as idelalisib are providing improved therapeutic options for the treatment of chronic lymphocytic leukaemia (CLL). However under certain conditions, inhibition of a single PI3K isoform can be compensated by the other PI3K isoforms, therefore PI3K inhibitors which target multiple PI3K isoforms may provide greater efficacy. The development of compounds targeting multiple PI3K isoforms (α, β, δ, and γ) in CLL cells, in vitro, resulted in sustained inhibition of BCR signalling but with enhanced cytotoxicity and the potential for improve clinical responses. This review summarises the progress of PI3K inhibitor development and describes the rationale and potential for targeting multiple PI3K isoforms.

•

Inhibition of PI3K may still be effective in CLL patients resistant to ibrutinib.

•

Functional redundancy between PI3K isoforms may be a mechanism of drug resistance.

•

Targeting multiple PI3K isoforms can increase cytotoxicity against CLL cells.