Idelalisib: The First-in-Class Phosphatidylinositol 3-Kinase Inhibitor for Relapsed CLL, SLL, and Indolent NHL

Idelalisib induces PUMA-dependent apoptosis in colon cancer cells

Idelalisib, a PI3K inhibitor, specifically targeting p110δ, has been approved for the treatment of chronic lymphocytic leukemia/small lymphocytic lymphoma and follicular lymphoma. However, the mechanisms of action of idelalisib in colon cancer cells are not well understood. We investigated how idelalisib suppresses colon cancer cells growth and potentiates effects of other chemotherapeutic drugs. In this study, we found that idelalisib treatment induces PUMA in colon cancer cells irrespective of p53 status through the p65 pathway following AKT inhibition and glycogen synthase kinase 3β (GSK3β) activation. PUMA is necessary for idelalisib-induced apoptosis in colon cancer cells. Idelalisib also synergized with 5-FU or regorafenib to induce marked apoptosis via PUMA in colon cancer cells. Furthermore, PUMA deficiency suppressed apoptosis and antitumor effect of idelalisib in xenograft model. These results demonstrate a critical role of PUMA in mediating the anticancer effects of idelalisib in colon cancer cells and suggest that PUMA induction can be used as an indicator of idelalisib sensitivity, and also have important implications for it clinical applications.

Combination Strategies Using EGFR-TKi in NSCLC Therapy: Learning from the Gap between Pre-Clinical Results and Clinical Outcomes

Although epidermal growth factor receptor (EGFR) inhibitors have been used to treat non-small cell lung cancer (NSCLC) for decades with great success in patients with EGFR mutations, acquired resistance inevitably occurs after long-term exposure. More recently, combination therapy has emerged as a promising strategy to overcome this issue. Several experiments have been carried out to evaluate the synergism of combination therapy both in vitro and in vivo. Additionally, many clinical studies have been carried out to investigate the feasibility of treatment with EGFR-tyrosine kinase inhibitors (TKi) combined with other NSCLC treatments, including radiotherapy, cytotoxic chemotherapies, targeted therapies, and emerging immunotherapies. However, a significant gap still exists when applying pre-clinical results to clinical scenarios, which hinders the development and use of these strategies. This article is a literature review analysing the rationalities and controversies in the transition from pre-clinical investigation to clinical practice associated with various combination strategies. It also highlights clues and challenges regarding future combination therapeutic options in NSCLC treatment.

Idelalisib for the treatment of indolent non-Hodgkin lymphoma: a review of its clinical potential

Idelalisib is a first-in-class, oral, selective phosphatidylinositol 3-kinase δ inhibitor that offers a chemotherapy-free option for patients with relapsed or refractory (R/R) indolent non-Hodgkin lymphoma (iNHL). Clinical trials in iNHL have evaluated idelalisib as monotherapy and as combination therapy with rituximab, bendamustine, and rituximab + bendamustine. When administered to heavily pretreated patients with R/R iNHL, idelalisib monotherapy or combination therapy showed durable antitumor activity accompanied by sustained or improved quality-of-life outcomes. Idelalisib has an acceptable safety profile; however, serious or fatal diarrhea/colitis, hepatoxicity, pneumonitis, and intestinal perforation have occurred in treated patients. Selective inhibition of phosphatidylinositol 3-kinase δ with idelalisib is a valuable addition to available treatment options for patients with iNHL, many of whom do not respond to or cannot tolerate chemoimmunotherapy. Two Phase III, randomized, placebo-controlled trials of idelalisib as combination therapy with rituximab or bendamustine + rituximab and a Phase I trial of idelalisib in combination with the Bruton’s tyrosine kinase inhibitor ONO/GS-4059 in R/R B-cell malignancies are currently ongoing. A Phase III monotherapy trial in previously treated follicular lymphoma or small lymphocytic lymphoma is planned. The development of other kinase inhibitors for the treatment of iNHL raises the potential for new treatment combinations. Additional research is needed to determine optimal therapy (monotherapy vs combination regimens), treatment sequencing, and long-term management.