BIM Regulation Is BTK Dependent and Can be Targeted By Entospletinib in Ibrutinib Refractory Mutants
Notice bibliographique
Résumé
Ibrutinib is especially effective in CLL patients with unmutated IgHV (UM-CLL), although presence of unmutated IgHV is usually associated with poor clinical outcome and shorter PFS. Sustained BCR signaling is one major reason for this. The BCL2 protein BIM plays a pivotal role in regulating apoptosis and high expression of BIM has been associated with presence of unmutated IgHV. This led us to investigate if there is a causality between BIM regulation and ibrutinib sensitivity. Methods: We used quantitative mass spectometry (MS) to analyze the (phospho) proteome of CLL patients with unmutated and mutated IgHV (n=3 respectively) upon BCR stimulation and ibrutinib treatment. BTKC481S overexpressing cells were used to validate our findings from MS. Results: Among all identified (phospho)peptides we found a striking phosphorylation pattern of BIM when comparing UM-CLL and M-CLL. Interestingly, we found that only phosphorylation of S77 was significantly altered, but not phosphorylation of S69 as previously reported. Phosphorylation of BIM S77 was upregulated upon BCR stimulation only in UM-CLL, but not in M-CLL. It is known, that BIM phosphorylation of both S69 and S77 leads to degradation of the protein by ubiquitination. In line with this and with the increase in BIM phosphorylation, total level of BIM decreased upon BCR stimulation. Furthermore we identified BIM as a target of ibrutinib. The BTK inhibitor was able to reduce phosporylation of BIM S77 both in UM-CLL and M-CLL. In accord with the observations of decreased BIM expression upon BCR stimulation, the decrease in phosphorylation of BIM induced by ibrutinib led to higher total levels of BIM. In order to investigate if phosphorylation of BIM is BTK dependent we generated an ibrutinib-resistant BTK mutant (C481S) that was overexpressed in Ramos cells. While ibrutinib treatment led to a decrease of phosphorylation of BIM S77 in wildtype cells, no change in phosphorylation could be observed in cells expressing the BTKC481S mutant, which suggests that BIM regulation by ibrutinib is indeed BTK dependent. Similar to ibrutinib, SYK inhibitor entospletinib leads to reduction of BIM phoshorylation in wildtype Ramos. But in contrast to ibrutinib, both BTK and BIM phosphorlyation were also reduced upon entospletinib treatment in Ramos cells expressing the BTKC481S mutant, which indicates that entospletinib can overcome ibrutinib resistance caused by BTKC481S mutation. Conclusion: For the first time we found that BIM S77 is a target of ibrutinib. Whereas BCR stimulation led to a differential response dependent on IgHV, ibrutinib was able to target BIM both in UM-CLL and M-CLL in a BTK dependent manner. Furthermore, ibrutinib can regulate total BIM levels by preventing protein degradation. Interestingly, the SYK inhibitor entospletinib can also target BIM, but is able to overcome ibrutinib resistance mediated by BTKC481S mutation. Disclosures Hallek: Roche, Gilead Sciences, Inc., Mundipharma, Janssen, Celgene, Pharmacyclics, AbbVie: Honoraria, Research Funding, Speakers Bureau. Frenzel:Gilead: Research Funding; Abbvie: Consultancy.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».