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Preprint WatchModerateAugust 31st, 2026

Cellular inhibitor of apoptosis protein (cIAP) is a convergent hub that couples BCR-CD40 signal dynamics to B cell fate

Inoue, K.; Shinohara, H.

Cellular inhibitor of apoptosis protein acts as a convergent node coupling B-cell receptor and CD40 signal dynamics to B-cell fate, with costimulation-dependent and cross-pathway antagonistic transcriptional classes.

Moderate contradiction

1 prior failure

Two documented clinical failures match this mechanism, or a single Phase 3 failure is on record.

The preprint describes CD40 signalling as one input to a convergent cIAP node whose output depends on what the B-cell receptor is doing at the same time, and it reports cross-pathway antagonism rather than simple additivity. Claidex holds one CD40 termination coded efficacy_failure, gen1042-cd40-4-1bb-immunoradiotherapy-solid-tumors-phase1-2-efficacy-termination, which combined CD40 and 4-1BB agonism with radiotherapy in metastatic solid tumours. The relevance is indirect, since the preprint studies primary mouse B cells rather than tumour immunotherapy, and it makes no claim about agonist antibodies or about myeloid CD40. What it does supply is a mechanistic reason why CD40 agonism might produce context-dependent output: if signal integration at cIAP determines the transcriptional response, then the effect of a CD40 agonist depends on the concurrent receptor state of the responding cell rather than on CD40 occupancy alone. The flag is moderate on archetype, not on strength of contradiction.

Abstract excerpt

BCR and CD40 signals are integrated to shape B cell transcriptional output, but how the two pathways are coordinated at the level of individual signaling nodes is incompletely understood. Using primary mouse B cells stimulated with anti-IgM, anti-CD40, or both (Both), we defined six DEG classes reflecting costimulation-dependence and cross-pathway antagonism. We also connected a CD40-driven, BCR-suppressed B-cell-identity module (Pax5, Aicda, Bcl6, Cd79a/b, Cd19) to an increase in Blimp1 protein at 24 h. Building on our previous work, which showed that cIAP prolongs IKK/ERK activity after single-pathway stimulation (Shinohara et al., 2016), we added an IAP inhibitor 10 min after Both stimulation and generated transcriptomic data. This profiling showed that cIAP is required not only for late canonical NF-{kappa}B-driven genes, as predicted, but also, unexpectedly, for the entire BCR-dominant, CD40-independent negative-feedback module (Cd5, Il10, Nfkbid, Spry1/2) identified in the first dataset. A separate module was instead amplified by IAP inhibition, with kinetics compatible with non-canonical NF-{kappa}B de-repression, directly addressing a question we left open in that study regarding the BCR-side partners of cIAP. Together, these correlative findings converge on a single model: cIAP is not a CD40-restricted adaptor but a hub shared by BCR and CD40, whose feedback simultaneously sustains canonical, fate-instructive signaling and restrains the non-canonical pathway, thereby coupling receptor-proximal signal dynamics to the B cell's downstream transcriptional and fate decisions.

Matching Claidex post-mortems

1 of 1 indexed

This is an automated contradiction flag, not an editorial judgment on the preprint's quality. Flags identify where the preclinical literature and the clinical failure record diverge.