Juszczyński, Przemysław

Abstract Aggressive B-cell non-Hodgkin lymphomas represent a clinically heterogeneous group of malignancies characterized by rapid progression and varied molecular features. Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive B-cell non-Hodgkin lymphoma and encompasses a biologically diverse group of diseases, now classified into 18 molecular subtypes (Alaggio et al. Leukemia, 2022). While first-line R-CHOP therapy cures approximately 60% of patients (Coiffier et al. N Engl J Med. 2002), those with relapsed or refractory (R/R) disease face poor outcomes. Although CAR T-cell therapies (e.g. axicabtagene ciloleucel, tisagenlecleucel, lisocabtagene maraleucel) have improved outcomes, access remains limited due to logistical and disease-related constraints (Locke et al. N Engl J Med. 2022). More recently, bispecific CD20xCD3 antibodies such as epcoritamab and glofitamab have shown clinical activity in the R/R setting after ≥2 prior lines, with complete response (CR) rates of ~40% (Dickinson et al. N Engl J Med. 2022; Thieblemont et al. J Clin Oncol. 2023). However, treatment sequencing and mechanisms of resistance to CD20-targeted therapies remain areas of active investigation. One emerging resistance mechanism to CD20 bispecific antibodies is the downregulation or loss of CD20 expression, which has been associated with treatment failure and disease progression (Bannard et al. Clin. Cancer Research, 2022). This highlights the need for novel strategies to overcome CD20 resistance. Dapolsertib (MEN1703) is a first-in-class dual PIM/FLT3 kinase inhibitor that targets key oncogenic and survival pathways in hematologic malignancies. PIM kinases (PIM1, PIM2, PIM3) regulate translation, metabolism, apoptosis, and immune modulation. Overexpression and mutations in PIM genes are associated with poor prognosis in DLBCL, particularly in the ABC subtype, and are known to cooperate with MYC and BCL6 (Szydłowski et al. Cancer Res. 2021). Simultaneous inhibition of all three PIMs downregulates MYC and induces marked cytotoxicity in preclinical models. In AML, dapolsertib has demonstrated preliminary clinical single-agent activity, with ~10% CR/CRi reported in the DIAMOND study (NCT03008187; Martinelli et al. Blood Neoplasia, in press). Dapolsertib has also shown strong antitumor activity in lymphoma models, both in vitro and in vivo (Bellon et al. Mol Cancer. 2023). Notably, dapolsertib demonstrated synergy with anti-CD20 antibody, rituximab, providing a rationale for combination strategies (Szydłowski et al. Cancer Res. 2021). The rationale for combining dapolsertib with a CD20 bispecific antibody lies in its potential to modulate survival pathways, sensitize malignant B-cells to immunotherapy, and circumvent resistance mechanisms such as CD20 loss by inducing CD20 expression. JASPIS-01 (NCT06534437) is an ongoing, international multicenter, Phase 2 study evaluating dapolsertib as monotherapy or in combination with glofitamab in patients with R/R aggressive B-cell lymphoma after ≥2 prior lines of therapy. The trial consists of three parts: a safety run-in (Part 1), optional enrichment (Part 2), and a potential randomized comparison vs. glofitamab (Part 3). Part 1 will include 2 groups of patients. Group 1 comprises bispecific-naïve patients randomized to a prospective dose-optimization evaluation of the combination with dapolsertib. Patients receive either 125 mg on a 2 weeks on / 1 week off schedule or 150 mg on a 1 week on / 2 weeks off schedule for up to 12 cycles to investigate optimal therapeutic window. Group 2 comprises patients who exhausted therapeutic standard options and who will receive dapolsertib monotherapy at 125 mg on a 2 weeks on / 1 week off schedule until intolerable toxicity or disease progression. The initial safety run-in (Parts 1 of both groups) informs dose selection for Part 2. Dose continuation in Part 2 will be guided by Data and Safety Monitoring Board safety assessments after ≥2 completed treatment cycles. The primary objectives are to assess safety, tolerability, and preliminary anti-lymphoma activity. Key endpoints include incidence of adverse events, overall/complete response rates, and duration of response. As of July 11, 2025, Part 1 is enrolling in France, Poland, Spain and the UK with additional sites activation ongoing.

Abstract B-cell receptor (BCR) signaling pathway components represent promising treatment targets in multiple B-cell tumors including diffuse large B-cell lymphoma (DLBCL). BCR signaling activates proximal pathway components such as the spleen tyrosine kinase (SYK) and downstream effectors including PI3K/AKT and NF-κB. In recent studies, we characterized distinct SYK/PI3K/AKT-dependent viability pathways in BCR DLBCL cell lines and primary tumors with high- or low-baseline NF-κB activity and defined additional SYK/PI3K/AKT-dependent processes essential for BCR DLBCLs with low- or high-baseline NF-κB (Chen et al Cancer Cell 2013; 23:826-838). For example, SYK/PI3K/AKT-dependent cholesterol biosynthesis was identified as a feed-forward mechanism of preserving the integrity of BCRs in lipid rafts in all BCR-dependent DLBCLs. In the current study, we sought to identify biomarkers of intact BCR signaling in DLBCLs with low or high baseline NF-κB. We found highly significant transcriptional upregulation of CXCR4 in all BCR-dependent DLBCLs treated with a chemical SYK inhibitor (R406). These results were of particular interest because BCR signaling inhibits stromal cell-derived factor (SDF)-1α chemotaxis and promotes intermobilization of the SDF-1α receptor, CXCR4. To expand on our findings, we analyzed CXCR4 transcript abundance in a large panel of cell lines including BCR-dependent/ low NF-κB (GC type) and BCR-dependent/ high NF-κB (ABC type) and BCR-independent/ OxPhos DLBCLs. CXCR4 transcript abundance was significantly and selectively upregulated in all BCR-dependent DLBCL lines assessed by qRT-PCR following chemical SYK inhibition. Consistent with the qRT-PCR results, SYK blockade also selectively upregulated cell surface CXCR4 expression in all BCR-dependent DLBCLs. Similar results were obtained following SYK knockdown with multiple independent shRNAs; CXCR4 transcript abundance was significantly and selectively upregulated in all BCR-dependent/ low NF-κB (GCB) DLBCLs and BCR-dependent/ high NF-κB (ABC) DLBCLs but was not altered in BCR-independent/ OxPhos tumors. Following SYK blockade, we also observed significant CXCR4 induction (by qRT-PCR) in multiple primary BCR-dependent DLBCLs (NF-κB low and NF-κB high) and unchanged CXCR4 levels in primary BCR-independent tumors. These data confirm that the observations regarding SYK blockade and CXCR4 induction in BCR-dependent DLBCL cell lines translated to primary tumors. Our recent studies indicate that all BCR-dependent DLBCLs exhibit SYK/PI3K/AKT signaling and modulation of FOXO1 regardless of baseline NF-κB levels. Given the recent identification of CXCR4 as a FOXO1 target, we asked whether modulation of CXCR4 in DLBCLs was via a PI3K/AKT pathway. In BCR-dependent DLBCLs with low or high baseline NF-κB, chemical PI3K inhibition (LY294002) phenocopied chemical SYK blockade (R406) with highly significant transcriptional upregulation of CXCR4. Moreover, in BCR-dependent DLBCL cell lines, enforced expression of a constitutively active form of AKT (myrAKT) abrogated CXCR4 upregulation resulting from SYK blockade. These data indicate that in BCR-dependent DLBCLs, CXCR4 is modulated by a SYK/PI3K/AKT-dependent pathway. To assess the functional significance of CXCR4 upregulation in BCR-dependent DLBCLs, we performed a transwell chemotaxis assay and evaluated migration toward a SDF-1α gradient. Following chemical SYK inhibition, all BCR-dependent DLBCLs exhibited significantly increased migration toward the CXCR4 ligand, SDF-1α, whereas the BCR-independent/ OxPhos DLBCLs were unaffected. The enhanced SDF-1α dependent migration was abrogated when the chemotaxis assay was performed in the presence of the specific CXCR4 inhibitor, AMD3100, confirming the specificity of the observed effect. Therefore, in BCR-dependent DLBCLs with low or high baseline NF-kB, SYK/PI3K inhibition is associated with significant and functionally relevant upregulation of CXCR4. For these reasons, CXCR4 may serve as a robust biomarker to assess the integrity of the BCR pathway and evaluate the efficacy of BCR inhibition in DLBCL. Disclosures: Off Label Use: R406 is not get approved, but is being evaluated in DLBCL and CLL.

The role of B-cell receptor (BCR)–mediated survival signals in diffuse large B-cell lymphoma (DLBCL) remains undefined. Ligand-induced BCR signaling induces receptor oligomerization, Igα/β immunoreceptor tyrosine-based activation motif (ITAM) phosphorylation, and activation of the spleen tyrosine kinase (SYK), which initiates downstream events and amplifies the initial BCR signal. BCRs also transmit low-level tonic survival signals in the absence of receptor engagement. Herein, we assess the role of SYK-dependent tonic BCR survival signals in DLBCL cell lines and primary tumors and evaluate the efficacy of an ATP-competitive inhibitor of SYK, R406, in vitro. R406 induced apoptosis of the majority of examined DLBCL cell lines. In R406-sensitive DLBCL cell lines, R406 specifically inhibited both tonic- and ligand-induced BCR signaling (autophosphorylation of SYK525/526 and SYK-dependent phosphorylation of the B-cell linker protein [BLNK]). The majority of examined primary DLBCLs also exhibited tonic- and ligand-induced BCR signaling; in these primary tumors, BCR signaling was also inhibited by R406. Of note, BCR-dependent and R406-sensitive DLBCL cell lines were independently identified as “BCR-type” tumors by transcriptional profiling. Therefore, SYK-dependent tonic BCR signaling is an important and potentially targetable survival pathway in some, but not all, DLBCLs. In addition, R406-sensitive DLBCLs can be identified by their transcriptional profiles.