Leniolisib (JOENJA®) is an oral selective phosphoinositide 3-kinase-delta (PI3Kdelta) inhibitor being developed by Pharming Group NV in-licensed from Novartis for the treatment of immunodeficiency disorders. Leniolisib inhibits PI3K-delta by blocking the active binding site of PI3K-delta. In cell-free isolated enzyme assays, leniolisib was selective for PI3K-delta over PI3K-alpha (28-fold), PI3K-beta (43-fold), and PI3K-gamma (257-fold), as well as the broader kinome. In cell-based assays, leniolisib reduced pAKT pathway activity and inhibited proliferation and activation of B and T cell subsets. Gain-of-function variants in the gene encoding the p110-delta catalytic subunit or loss of function variants in the gene encoding the p85-alpha regulatory subunit each cause hyperactivity of PI3K-delta. Leniolisib inhibits the signalling pathways that lead to increased production of PIP3, hyperactivity of the downstream mTOR/AKT pathway, and to the dysregulation of B and T cells. In March 2023, leniolisib received its first approval for the treatment of activated PI3Kdelta syndrome (APDS) in adult and paediatric patients 12 years of age and older. Leniolisib is also under regulatory review in European Union for the treatment of APDS. Development of leniolisib for the treatment of Sjögren's syndrome has been discontinued.

Duvelisib (IPI-145), is an orally available, small-molecule, selective dual inhibitor of phosphatidylinositol 3 kinase (PI3K) δ and γ isoforms originated by Intellikine (owned by Takeda) and developed by Infinity Pharmaceuticals. Orally administered duvelisib was rapidly absorbed, with a dose-proportional increase in exposure. The compound produced a half-life of approximately 7-12 hours, following 14 days of dosing. Duvelisib exerts profound effects on adaptive and innate immunity by inhibiting B and T cell proliferation, blocking neutrophil migration, and inhibiting basophil activation. Duvelisib blockade of PI3K-δ and PI3K-γ potentially lead to significant therapeutic effects in multiple inflammatory, autoimmune, and hematologic diseases. The molecule is in phase III development as a combination therapy for patients with haematological malignancies such as chronic lymphocytic leukemia and follicular lymphoma.

Idelalisib is a first-in-class selective inhibitor of adenosine-5'-triphosphate (ATP) binding to PI3Kdelta kinase, resulting in inhibition of the P13K signalling pathway in malignant B cells. The compound is approved for the treatment of several types of blood cancer. Idelalisib is intended to be used in combination with rituximab as second or subsequent line therapy for the treatment of chronic lymphocytic leukaemia. The drug may cause fatal and/or severe diarrhea or colitis, hepatotoxicity, pneumonitis and intestinal perforation.

GSK-2269557 (nemiralisib), a PI3Kδ inhibitor, is in development as an anti-inflammatory drug for the treatment of inflammatory airways disease. Studies in moderate or severe stable COPD patients have shown an acceptable safety and tolerability profile when GSK-2269557 was administered via inhalation. Cough was the most commonly reported adverse event.

AMG-319 is an oral, small molecule inhibitor of PI3Kdelta which is now being tested in phase II for the treatment of head and neck squamous cell carcinoma and in phase I for lymphoid malignancy.

VS-5584 is a potent and selective oral small molecule inhibitor of all 4 PI3K isoforms and mTORC1 and mTORC2. VS-5584 inhibits mTOR, PI3Kα/β/δ/γ with IC50 of 3.4 nM and 2.6-21 nM, respectively. Verastem has patent protection of VS-5584 through 2029, and has received orphan drug designation for VS-5584 in mesothelioma in the US and EU. Verastem is currently conducting a Phase 1 trial of VS-5584 in patients with advanced solid tumors and lymphomas.

GS-9820 (formerly CAL-120) is an oral, small molecule delta selective Phosphatidylinositol 3-kinases (PI3 kinase) inhibitor, a first in class compound, with greater than 200-fold selectivity in cell-based assays for the delta isoform as compared to other class isoforms. GS-9820 is designed to induce cancer cell death and inhibit signaling pathways associated with cancer cell dependence on the tumor microenvironment. GS-9820 is on the phase I of clinical trial, where has to be determined the appropriate dosing regimen of drug in subjects with lymphoid malignancies.

Omipalisib, also known as GSK2126458, is a small-molecule pyridylsulfonamide inhibitor of phosphatidylinositol 3-kinase (PI3K) with potential antineoplastic activity. Omipalisib (GSK2126458, GSK458) is a highly selective and potent inhibitor of p110α/β/δ/γ, mTORC1/2 with Ki of 0.019 nM/0.13 nM/0.024 nM/0.06 nM and 0.18 nM/0.3 nM in cell-free assays, respectively. It is also a low picomolar inhibitor of the common activating mutants of p110a (E542K, E545K, and H1047R) found in human cancer. Omipalisib (GSK2126458) binds to and inhibits PI3K in the PI3K/mTOR signaling pathway, which may trigger the translocation of cytosolic Bax to the mitochondrial outer membrane, increasing mitochondrial membrane permeability and inducing apoptotic cell death. Bax is a member of the proapoptotic Bcl2 family of proteins. PI3K, often overexpressed in cancer cells, plays a crucial role in tumor cell regulation and survival. GlaxoSmithKline (GSK) is developing omipalisib, a phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) inhibitor as well as mTOR complex 1 and 2 inhibitor, for the potential oral treatment of cancer and idiopathic pulmonary fibrosis.

Seletalisib (UCB-5857) is a potent, ATP-competitive, and selective phosphoinositide 3-kinase (PI3K) delta inhibitor. Findings from cellular assays of adaptive immunity demonstrated that seletalisib blocks human T-cell production of several cytokines from activated T-cells. Additionally, seletalisib inhibited B-cell proliferation and cytokine release. In human whole blood assays, seletalisib inhibited CD69 expression upon B-cell activation and anti-IgE-mediated basophil degranulation. Seletalisib safety, tolerability and pharmacokinetic/pharmacodynamic profiles support its continued clinical development in immune-inflammatory diseases. UCB Pharma is developing Seletalisib for the treatment of immune and inflammatory diseases including Activated PI3K delta Syndrome (APDS), Sjogren's syndrome and psoriasis.