Deregulation and epigenetic modification of BCL2-family genes cause resistance to venetoclax in hematologic malignancies.

The BCL2 inhibitor venetoclax has been approved to treat different hematological malignancies. Because there is no common genetic alteration causing resistance to venetoclax in chronic lymphocytic leukemia (CLL) and B-cell lymphoma, we asked if epigenetic events might be involved in venetoclax resistance. Therefore, we employed whole-exome sequencing, methylated DNA immunoprecipitation sequencing, and genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 screening to investigate venetoclax resistance in aggressive lymphoma and high-risk CLL patients. We identified a regulatory CpG island within the PUMA promoter that is methylated upon venetoclax treatment, mediating PUMA downregulation on transcript and protein level. PUMA expression and sensitivity toward venetoclax can be restored by inhibition of methyltransferases. We can demonstrate that loss of PUMA results in metabolic reprogramming with higher oxidative phosphorylation and adenosine triphosphate production, resembling the metabolic phenotype that is seen upon venetoclax resistance. Although PUMA loss is specific for acquired venetoclax resistance but not for acquired MCL1 resistance and is not seen in CLL patients after chemotherapy-resistance, BAX is essential for sensitivity toward both venetoclax and MCL1 inhibition. As we found loss of BAX in Richter's syndrome patients after venetoclax failure, we defined BAX-mediated apoptosis to be critical for drug resistance but not for disease progression of CLL into aggressive diffuse large B-cell lymphoma in vivo. A compound screen revealed TRAIL-mediated apoptosis as a target to overcome BAX deficiency. Furthermore, antibody or CAR T cells eliminated venetoclax resistant lymphoma cells, paving a clinically applicable way to overcome venetoclax resistance.

Targeting transcription-coupled nucleotide excision repair overcomes resistance in chronic lymphocytic leukemia.

Treatment resistance becomes a challenge at some point in the course of most patients with chronic lymphocytic leukemia (CLL). This applies to fludarabine-based regimens, and is also an increasing concern in the era of more targeted therapies. As cells with low-replicative activity rely on repair that triggers checkpoint-independent noncanonical pathways, we reasoned that targeting the nucleotide excision repair (NER) reaction addresses a vulnerability of CLL and might even synergize with fludarabine, which blocks the NER gap-filling step. We interrogated here especially the replication-independent transcription-coupled-NER ((TC)-NER) in prospective trial patients, primary CLL cultures, cell lines and mice. We screen selected (TC)-NER-targeting compounds as experimental (illudins) or clinically approved (trabectedin) drugs. They inflict transcription-stalling DNA lesions requiring TC-NER either for their removal (illudins) or for generation of lethal strand breaks (trabectedin). Genetically defined systems of NER deficiency confirmed their specificity. They selectively and efficiently induced cell death in CLL, irrespective of high-risk cytogenetics, IGHV status or clinical treatment history, including resistance. The substances induced ATM/p53-independent apoptosis and showed marked synergisms with fludarabine. Trabectedin additionally perturbed stromal-cell protection and showed encouraging antileukemic profiles even in aggressive and transforming murine CLL. This proof-of-principle study established (TC)-NER as a mechanism to be further exploited to resensitize CLL cells.

[Experiences with the intramedullary open Rush-pin fixation of femur shaft fractures in children]. / Erfahrungen mit der intramedullären offenen Rush-pin-Schienung kindlicher Femurschaftfrakturen.

This is a report of 47 followed-up children in whom open intramedullary splinting of the medullary space was effected because of fracture of the shaft of the femur, using the rush-pinning technique developed by the authors. In 33 children, a slight increase of longitudinal growth was seen, which amounted to 2-20 mm. The average longitudinal extension was 9.4 mm. In 10 children, there was a shortening amounting to 1-15 mm, the average being 4.6 mm. The change in length was independent of age, localisation of the fracture, and length of time during which the pin remained in position. The effect that a slight change in valgus positioning was seen in 7 children, whereas slight turning of the hip into varus occurred in 9 children only, points to a merely slight irritation of the trochanter metaphysis.

The effectiveness of shoe modifications for intoeing.

Shoe wedges have no immediate clinically significant effect on the angle of gait in children. The circular Torqheel was found to be more effetive, but still corrected only a quarter of the apparent rotatory deformity during gait.