How it is administered

Idelalisib is taken by mouth as a tablet. The recommended dose is 150 mg orally twice daily, with or without food. Tablets should be swallowed whole and not crushed or chewed. If a dose is missed by less than 6 hours, take it as soon as possible; if more than 6 hours have passed, skip the missed dose and resume at the usual time.

How it works

Idelalisib is a targeted therapy known as a kinase inhibitor. It works by blocking a specific enzyme called PI3Kδ (phosphatidylinositol 3-kinase delta), which is found in normal and malignant B-cells. By inhibiting this enzyme, idelalisib interferes with several cell signaling pathways that are important for the survival, growth, and movement of B-cells, including those involved in B-cell receptor signaling and the movement of B-cells to lymph nodes and bone marrow.

This action leads to the death (apoptosis) of cancerous B-cells and stops their proliferation. In clinical studies, idelalisib has been shown to reduce the viability of lymphoma cells and inhibit their ability to migrate and adhere to other tissues. This makes it effective in treating certain blood cancers, particularly when other treatments have not worked or are not suitable.

Who Should take it

Idelalisib is indicated for patients with relapsed chronic lymphocytic leukemia (CLL) who cannot tolerate standard chemoimmunotherapy due to other medical conditions. It is used in combination with rituximab for these patients. While there is no specific FDA indication for B-Cell Prolymphocytic Leukemia (B-PLL), idelalisib may sometimes be considered in rare or refractory cases of B-cell blood cancers, especially when other therapies are not suitable or have failed.

Idelalisib is not recommended as a first-line treatment for any blood cancer, including CLL or indolent non-Hodgkin lymphomas. It is reserved for patients who have relapsed or are unable to tolerate other standard therapies.

Who should not take it

Idelalisib should not be taken by patients who have had serious hypersensitivity reactions to idelalisib, such as anaphylaxis, or who have experienced toxic epidermal necrolysis with any drug. It is also not recommended for use in patients with severe liver problems or active, serious infections unless these are being properly managed.

Pregnant women should avoid idelalisib, as it may cause harm to an unborn baby. Women of childbearing potential should use effective contraception during treatment and for at least one month after the last dose. Men with female partners of reproductive potential should also use contraception during treatment and for three months after the last dose. Idelalisib is not recommended for pediatric patients, as safety and effectiveness have not been established.

Commonly used with

Idelalisib is most commonly used in combination with rituximab for the treatment of relapsed CLL. It is not recommended for use with bendamustine and rituximab or for first-line treatment of any blood cancer.

Patients may also be given supportive medications to prevent infections, such as prophylaxis for Pneumocystis jirovecii pneumonia (PJP), when taking idelalisib.

Commonly tested with

In clinical studies, idelalisib has been tested in combination with rituximab and, in some trials, with other agents such as ofatumumab and bendamustine. However, its approved and recommended use is only in combination with rituximab for relapsed CLL.

It is important to note that idelalisib is not recommended in combination with certain other chemotherapy regimens due to increased risk of serious and fatal adverse reactions.