L-asparaginase anti-tumor activity in pancreatic cancer is dependent on its glutaminase activity and resistance is mediated by glutamine synthetase.

l-Asparaginase is a cornerstone of acute lymphoblastic leukemia (ALL) therapy since lymphoblasts lack asparagine synthetase (ASNS) and rely on extracellular asparagine availability for survival. Resistance mechanisms are associated with increased ASNS expression in ALL. However, the association between ASNS and l-Asparaginase efficacy in solid tumors remains unclear, thus limiting clinical development. Interestingly, l-Asparaginase also has a glutaminase co-activity that is crucial in pancreatic cancer where KRAS mutations activate glutamine metabolism. By developing l-Asparaginase-resistant pancreatic cancer cells and using OMICS approaches, we identified glutamine synthetase (GS) as a marker of resistance to l-Asparaginase. GS is the only enzyme able to synthesize glutamine, and its expression also correlates with l-Asparaginase efficacy in 27 human cell lines from 11 cancer indications. Finally, we further demonstrated that GS inhibition prevents cancer cell adaptation to l-Asparaginase-induced glutamine starvation. These findings could pave the way to the development of promising drug combinations to overcome l-Asparaginase resistance.

Multiparametric characterization of red blood cell physiology after hypotonic dialysis based drug encapsulation process.

Red blood cells (RBCs) can act as carriers for therapeutic agents and can substantially improve the safety, pharmacokinetics, and pharmacodynamics of many drugs. Maintaining RBCs integrity and lifespan is important for the efficacy of RBCs as drug carrier. We investigated the impact of drug encapsulation by hypotonic dialysis on RBCs physiology and integrity. Several parameters were compared between processed RBCs loaded with l-asparaginase ("eryaspase"), processed RBCs without drug and non-processed RBCs. Processed RBCs were less hydrated and displayed a reduction of intracellular content. We observed a change in the metabolomic but not in the proteomic profile of processed RBCs. Encapsulation process caused moderate morphological changes and was accompanied by an increase of RBCs-derived Extracellular Vesicles release. Despite a decrease in deformability, processed RBCs were not mechanically retained in a spleen-mimicking device and had increased surface-to-volume ratio and osmotic resistance. Processed RBCs half-life was not significantly affected in a mouse model and our previous phase 1 clinical study showed that encapsulation of asparaginase in RBCs prolonged its in vivo half-life compared to free forms. Our study demonstrated that encapsulation by hypotonic dialysis may affect certain characteristics of RBCs but does not significantly affect the in vivo longevity of RBCs or their drug carrier function.

Hypocalcaemia after total thyroidectomy: incidence, control and treatment.

INTRODUCTION: Hypocalcaemia, although usually transitory, is the most frequent complication after total thyroidectomy. OBJECTIVE: To identify factors associated with a higher risk of hypoparathyroidism and related to aetiology and surgical procedure. MATERIALS AND METHODS: A total of 254 total thyroidectomies were analysed for the incidence of transitory or permanent hypocalcaemia based on the relationship with etiological and surgical factors. RESULTS: Transient hypocalcaemia was present in 29.1% of the cases and permanent hypocalcemia was present in 4.7%. Postoperative hypocalcaemia was lower in patients with completion thyroidectomy than in patients that underwent total thyroidectomy in a single operation, 12% vs. 31%. Patients with Graves-Basedow disease developed postoperative hypocalcaemia in 50% of the cases. Mean recovery time of parathyroid function was 5.2 months, with 72.2% of the patients recovering before 6 months. CONCLUSIONS: Postoperative hypocalcaemia is a frequent complication of total thyroidectomy, but it is seldom permanent. Patients with Graves-Basedow disease have a higher incidence of postoperative hypocalcaemia and need closer follow-up. Postoperative calcium level analysis at 24 and 48 h after surgery is not useful for rapid identification of patients at high risk of hypocalcaemia.