Abstract Background. Among approved anti-TNF biologics, infliximab carries the highest lymphoma reporting odds ratio in theFDA Adverse Event Reporting System (ROR 6.61), four-fold higher than certolizumab pegol (ROR 1.65). This gradient isnot explained by differential TNF-α blockade potency, which is pharmacologically comparable across all four agents.Infliximab is the only anti-TNF produced in Sp2/0 murine myeloma cells — whose genome harbors constitutivelyactivated c-Myc, murine endogenous retroviruses, and LINE-1 elements — and the only one administered by intravenousinfusion, delivering the intact formulation directly to the hepatosplenic reticuloendothelial system. The mechanismunderlying this differential risk has not been identified.The Vectorizing Excipient Hypothesis. We propose that polysorbate 80 (PS80), present in infliximab formulations at~3× its critical micelle concentration in the reconstituted vial, functions as an unintended vectorizing agent for residualplasmid-derived DNA fragments co-present in the finished drug. The mechanism operates through four sequentiallydocumented steps: (i) electrostatic association of residual DNA with cationic patches on the infliximab variable domains,forming a protein-DNA complex within the vial; (ii) PS80-mediated adsorption of plasma ApoE onto the complex surface,enabling LDL-R-mediated uptake by hepatic Kupffer cells and splenic macrophages; (iii) partial endosomal escapeactivating the cGAS-STING innate immune sensing pathway; and (iv) sequence-specific nuclear import of SV40enhancer/promoter-containing fragments via the importin-α/β mechanism — a DNA nuclear targeting sequence active inall mammalian cell types, including post-mitotic macrophages, and unique among viral regulatory elements in thisproperty. Under conservative assumptions, a standard 350 mg infliximab infusion contains ~2 × 106 such fragments, with aPS80:DNA fragment molar ratio (~5 × 108) that far exceeds stoichiometric requirements for complex formation.Epidemiological coherence. The observed lymphoma ROR gradient — infliximab (6.61) > golimumab (3.03) >adalimumab (2.36) > certolizumab (1.65) — is isomorphic with the combined profile of host cell oncogenic DNA content(Sp2/0 myeloma > CHO > E. coli) and route-of-administration hepatosplenic amplification (intravenous > subcutaneous).Intravenous infliximab delivers residual DNA intact to the precise cellular populations of origin of the hepatosplenic T-celllymphoma most specifically associated with this agent, while subcutaneously administered anti-TNF biologics undergolymphatic filtration and temporal attenuation before systemic distribution.Falsifiable predictions and regulatory implications. The hypothesis generates six experimentally testable predictions,four of which are addressable immediately with commercially available materials and standard methodology, includingNGS detection of SV40-containing sequences in the protein-associated residual DNA fraction of commercial infliximabvials. Current residual DNA regulatory limits are quantity-only and route-independent — a framework that cannot detectthe sequence-functional and formulation-interaction properties central to this hypothesis. A tiered characterizationframework and linkage of lot-specific quality data to pharmacovigilance outcomes are proposed as actionable regulatoryresponses.
Añaños et al. (Sun,) studied this question.