Results of a Prospective Non-Interventional Post-Authorization Safety Study of Idelalisib in Germany.

BACKGROUND: In pivotal studies, idelalisib demonstrated remarkable efficacy and manageable tolerability in patients with chronic lymphocytic leukemia (CLL) and follicular lymphoma (FL). This prospective, multicenter, non-interventional post-authorization study assessed the characteristics, clinical management, and outcome of CLL and FL patients receiving idelalisib in routine clinical practice in Germany. PATIENTS: Observational study in CLL and FL patients treated with idelalisib between September 2015 and December 2020. RESULTS: A total of 147 patients with CLL and FL were included with a median age of 75 and 71 years, respectively. More than 80% of patients presented with comorbidity and many CLL patients with documented high-risk genetic features, including del(17p)/TP53 mutation or unmutated IGHV. The median progression-free survival (PFS) and overall survival (OS) were not reached in the CLL cohort irrespective of del(17p)/TP53 or unmutated IGHV. The estimated 6-month PFS and OS rates in CLL were 82% and 92%. The estimated 6-month PFS and OS rates for FL were 32.2% and 77.2%. Overall response rates in the CLL and FL cohorts were 70.4% and 36.4%, with the presence of high-risk genetics having no negative impact. No unexpected adverse events were observed. Most frequently reported adverse drug reactions (ADRs) were diarrhea, nausea, pneumonia, rash, and fatigue. CONCLUSION: This real-world study shows that idelalisib is an effective therapy for CLL and FL, regardless of age and high-risk genetic features, consistent with results from previous clinical trials. Collected safety data and the pattern of ADRs reflect those from previous studies.

Heterochromatin dysregulation in human diseases.

Heterochromatin is a repressive chromatin state that is characterized by densely packed DNA and low transcriptional activity. Heterochromatin-induced gene silencing is important for mediating developmental transitions, and in addition, it has more global functions in ensuring chromosome segregation and genomic integrity. Here we discuss how altered heterochromatic states can impair normal gene expression patterns, leading to the development of different diseases. Over the last years, therapeutic strategies that aim toward resetting the epigenetic state of dysregulated genes have been tested. However, due to the complexity of epigenetic gene regulation, the "first-generation drugs" that function globally by inhibiting epigenetic machineries might also introduce severe side effects. Thus detailed understanding of how repressive chromatin states are established and maintained at specific loci will be fundamental for the development of more selective epigenetic treatment strategies in the future.

A yeast two-hybrid system reconstituting substrate recognition of the von Hippel-Lindau tumor suppressor protein.

The von Hippel-Lindau tumor suppressor protein (pVHL) is inactivated in the hereditary cancer syndrome von Hippel-Lindau disease and in the majority of sporadic renal carcinomas. pVHL is the substrate-binding subunit of the CBC(VHL) ubiquitin ligase complex that negatively regulates cell growth by promoting the degradation of hypoxia-inducible transcription factor subunits (HIF1/2alpha). Proteomics-based identification of novel pVHL substrates is hampered by their short half-life and low abundancy in mammalian cells. The usefulness of yeast two-hybrid (Y2H) approaches, on the other hand, has been limited by the failure of pVHL to adopt its native structure and by the absence of prolylhydroxylase activity critical for pVHL substrate recognition. Therefore, we modified the Y2H system to faithfully reconstitute the physical interaction between pVHL and its substrates. Our approach relies on the coexpression of pVHL with the cofactors Elongin B and Elongin C and with HIF1/2alpha prolylhydroxylases. In a proof-of-principle Y2H screen, we identified the known substrates HIF1/2alpha and new candidate substrates including diacylglycerol kinase iota, demonstrating that our strategy allows detection of stable interactions between pVHL and otherwise elusive cellular targets. Additional future applications may include structure/function analyses of pVHL-HIF1/2alpha binding and screens for therapeutically relevant compounds that either stabilize or disrupt this interaction.