Target-specific dermatological adverse event reporting with T-Cell–engaging bispecific antibodies: a pharmacovigilance analysis of FAERS and Canada Vigilance, 2016–2026

Background
T-cell–engaging bispecific antibodies are increasingly utilised in haematological malignancies and are beginning to be adopted in solid-tumour treatment protocols. Cytokine release syndrome and neurotoxicity are well recognised, but target-specific dermatological adverse event reporting patterns remain poorly defined.

Methods
We analysed 12,333,305 deduplicated FAERS reports from 2016Q1 to 2026Q1, including 23,386 reports exposed to ten T-cell–engaging bispecific antibodies grouped by target: CD19, CD20, BCMA, GPRC5D and DLL3. A disease-matched haematologic-oncology comparator cohort contained 1,062,195 reports. Canada Vigilance provided a secondary directional comparison using 755,911 reports from 2016Q1 to 2025Q4 including 662 unique exposed reports. Outcomes were any cutaneous adverse event, broad severe cutaneous adverse reaction, and narrow Stevens-Johnson syndrome/toxic epidermal necrolysis. Multivariable models adjusted for age, sex, cancer indication, polypharmacy and classical culprit drugs. Cox models assessed target-specific timing.

Results
Among exposed FAERS reports, 1394 (5.96%) included any cutaneous adverse event, 61 (0.26%) broad severe cutaneous adverse reaction and 9 (0.04%) narrow Stevens-Johnson syndrome/toxic epidermal necrolysis. After disease matching, no clear class-level excess of severe cutaneous reaction reporting was observed. Talquetamab had the highest cutaneous reporting proportion (471/1822; 25.8%) and an elevated timing estimate (hazard ratio 1.34; 95% CI, 1.06–1.69), with enrichment for skin, hair, sweat-gland and rash phenotypes. Tarlatamab showed an exploratory early-onset pattern (hazard ratio 3.36; 95% CI, 1.68–6.72; median onset, 4 days), based on only eight reports with usable latency data. Canada Vigilance showed a similar direction of reporting for GPRC5D/any cutaneous adverse events.

Conclusions
T-cell–engaging bispecific antibodies did not show clear class-level excess in severe cutaneous adverse-event reporting after disease matching. Talquetamab showed higher reporting of skin changes, hyperhidrosis, hair abnormalities and rash, whereas tarlatamab showed a possible early-onset cutaneous reporting pattern based on a small number of reports with usable timing data. These findings support target- and timing-aware dermatological monitoring and require prospective confirmation.