On September 19, 2014 Gilead Sciences reported that the European Commission has granted marketing authorization for Zydelig (idelalisib), 150 mg tablets, a first-in-class oral treatment for two incurable blood cancers – chronic lymphocytic leukemia (CLL) and follicular lymphoma (FL) (Press release Gilead Sciences, SEP 19, 2014, View Source [SID:1234500758]). For the treatment of CLL, Zydelig has been approved for use in combination with rituximab for patients who have received at least one prior therapy; or as first-line treatment in the presence of 17p deletion or TP53 mutation in patients unsuitable for chemo-immunotherapy. For the treatment of FL, Zydelig has been approved as a monotherapy in patients who are refractory to two prior lines of treatment. Zydelig inhibits PI3K delta, a protein that is overexpressed in many B-cell malignancies and plays a role in the viability, proliferation and migration of these cancer cells.

CLL and FL are slow-growing incurable blood cancers that can lead to life-threatening complications such as anemia, serious infection and bone marrow failure requiring treatment. The goal of therapy for patients with these cancers is to improve overall survival and quality of life.

“Although chemo-immunotherapy is initially used to treat both CLL and FL, relapse is common and many patients run out of treatment options to treat the disease as it progresses,” said Peter Hillmen, PhD, Professor of Experimental Haematology and Honorary Consultant Haematologist at Leeds Teaching Hospitals NHS Trust. “Further, CLL patients with the 17p deletion or TP53 mutation are not suitable for chemo-immunotherapy, requiring alternative first-line treatment options. Thus, Zydelig is a welcomed treatment option that offers a new approach in the management of these cancers.”

A chromosome 17 deletion – del (17p) or a mutation in the TP53 gene in CLL cells have been linked to poor prognosis and a more rapid disease progression. For these patients most conventional chemotherapy treatments are not effective and deliver poor responses of relatively short duration. Treatment options are limited for these patients.

“Zydelig represents an important therapeutic advance for patients living with CLL and FL,” said John C. Martin, PhD, Chairman and Chief Executive Officer, Gilead Sciences. “Gilead is pleased to be making a difference in the lives of people living with these blood cancers and we are committed to helping ensure timely access to the treatment for patients who may benefit from therapy.”

The approval of Zydelig in CLL is supported primarily by data from a randomized, placebo-controlled Phase 3 trial (Study 116) of Zydelig plus rituximab in 220 patients with relapsed CLL who were not able to tolerate standard chemotherapy. Study 116 was stopped early in October 2013 by an independent Data Monitoring Committee due to a highly statistically significant benefit in progression-free survival (PFS) in the Zydelig plus rituximab arm compared with the rituximab only treatment arm (hazard ratio = 0.18 (95 percent CI: 0.10, 0.32), p<0.0001). Median PFS was not reached in the Zydelig plus rituximab arm (95 percent CI: 10.7 months, NR) and was 5.5 months in the placebo plus rituximab arm (95 percent CI: 3.8, 7.1). The approval in FL, the most common type of indolent non-Hodgkin lymphoma (iNHL), is supported by data from a single-arm Phase 2 study (Study 101-09) of Zydelig monotherapy in 125 iNHL patients refractory to rituximab and alkylating-agent-containing chemotherapy. In the 72 patients with FL in this study, Zydelig achieved an overall response rate of 54 percent and the median duration of response was not reached (range: 0.0, 14.8+ months). Results of Study 116 and Study 101-09 were published in The New England Journal of Medicine in March 2014. Adverse drug reactions (including Grade ≥3) reported in clinical studies in patients with hematological malignancies receiving Zydelig included infections, neutropenia, pneumonitis, diarrhea/colitis, increased transaminase (indicator of liver function), rash and pyrexia. For additional safety information, see the Summary of Product Characteristics at www.ema.europa.eu.