Evaluation of bleeding risk in patients who received pirtobrutinib in the presence or absence of antithrombotic therapy.

Clinical bleeding events are reported here from 773 patients with B-cell malignancies receiving pirtobrutinib monotherapy from the phase 1/2 BRUIN study (ClinicalTrials.gov identifier: NCT03740529), either in the presence or absence of antithrombotic therapy (antithrombotic exposed [AT-E], n = 216; antithrombotic nonexposed [AT-NE], n = 557). Among the AT-E cohort, 51.9% received platelet aggregation inhibitors, 36.6% received direct factor Xa inhibitors, 18.5% received heparins, 5.6% received salicylic acid for indications other than platelet aggregation inhibition, and 2.3% received thrombolytics. Warfarin was not permitted. Any-grade bleeding/bruising events occurred in 97 patients (44.9%; 95% confidence interval [CI], 38.3-51.5) in the AT-E cohort and 181 patients (32.5%; 95% CI, 28.6-36.4) in the AT-NE cohort. Most bleeding/bruising events in both cohorts began within the first 6 months of treatment (AT-E: 65.4%; AT-NE: 72.5%). Contusion was the most common bleeding/bruising event in both cohorts (AT-E: 22.7%; AT-NE: 18.1%). Grade ≥3 bleeding/bruising events were reported in six patients (2.8%) in the AT-E cohort and 11 patients (2.0%) in the AT-NE cohort. Bleeding/bruising events requiring or prolonging hospitalization were reported in 2.3% and 1.6% of patients in the AT-E and AT-NE cohorts, respectively. No bleeding/bruising events led to pirtobrutinib dose reduction or permanent discontinuation in the AT-E cohort, and one patient (0.2%) in the AT-NE cohort experienced an event requiring dose reduction. These data support the safety of pirtobrutinib in patients requiring antithrombotic therapies.

Blocking Orai1 constitutive activity inhibits B-cell cancer migration and synergistically acts with drugs to reduce B-CLL cell survival.

Orai1 channel capacity to control store-operated Ca2+ entry (SOCE) and B-cell functions is poorly understood and more specifically in B-cell cancers, including human lymphoma and leukemia. As compared to normal B-cells, Orai1 is overexpressed in B-chronic lymphocytic leukemia (B-CLL) and contributes in resting B-CLL to mediate an elevated basal Ca2+ level through a constitutive Ca2+ entry, and in BCR-activated B-cell to regulate the Ca2+ signaling response. Such observations were confirmed in human B-cell lymphoma and leukemia lines, including RAMOS, JOK-1, MEC-1 and JVM-3 cells. Next, the use of pharmacological Orai1 inhibitors (GSK-7975 A and Synta66) blocks constitutive Ca2+ entry and in turn affects B-cell cancer (primary and cell lines) survival and migration, controls cell cycle, and induces apoptosis through a mitochondrial and caspase-3 independent pathway. Finally, the added value of Orai1 inhibitors in combination with B-CLL drugs (ibrutinib, idelalisib, rituximab, and venetoclax) on B-CLL survival was tested, showing an additive/synergistic effect including in the B-cell cancer lines. To conclude, this study highlights the pathophysiological role of the Ca2+ channel Orai1 in B-cell cancers, and pave the way for the use of ORAI1 modulators as a plausible therapeutic strategy.

RIPK1 is aberrantly expressed in multiple B-cell cancers and implicated in the underlying pathogenesis.

According to the latest epidemiology of the US, B-cell cancers account for > 3% of all new cancer cases and > 80% of non-Hodgkin lymphomas. However, the disease-modifying small molecular drug suitable for most B-cell cancers is still lacking. RIPK1 (receptor-interacting serine/threonine-protein kinase 1) has been observed to be dysregulated and implicated in the pathogenesis of multiple solid cancers, of which, however, the roles in blood cancers are quite unclear. In our study, to identify multi-function targets for B-cell cancer treatment, we reanalyzed a public transcriptomic dataset from the database of Gene Expression Omnibus, which includes CD19+ B-cell populations from 6 normal donors and patients of 5 CLL, 10 FL, and 8 DLBCL. After overlapping three groups (CLL vs. normal, FL vs. normal, and DLBCL vs. normal) of differentially expressed genes (DEGs), we obtained 69 common DEGs, of which 3 were validated by real-time quantitative PCR, including RIPK3, IGSF3, TGFBI. Interestingly, we found that the loss function of RIPK1 significantly increases the proliferation and viability of GM12878 cells (a normal human B lymphocyte cell line). Consistently, overexpression of RIPK1 in TMD8 and U2932 cells effectively inhibited cell proliferation and growth. More importantly, modifying RIPK1 kinase activity by a small molecule (such as necrostain-1, HOIPIN-1, etc.) alters the cell growth status of B-cell lymphoma, showing that RIPK1 exhibits anti-tumor activity in the context of B-cell lymphoma. Taken together, we consider that RIPK1 may be a potential target in the clinical application of B-cell lymphoma (including CLL, DLBCL, and FL) treatment.