6P - RC48-ADC for metastatic salivary duct carcinoma with HER2 expression: A single-center retrospective study

Background

Agents targeting HER2 arepromising and the best studied therapies in patients with HER2-positive salivary duct carcinoma (SDC). RC48-ADC (Disitamab vedotin) is a novel humanized anti-HER2 antibody-drug conjugate (ADC). But the efficacy and safety of RC48-ADC is still unknown in metastatic SDC with HER2-positive.

Methods

Eligible patients from Zhejiang Cancer Hospital were 35∼76 years old, with confirmed, histologically HER2 expression (IHC1+, 2+, 3+), metastatic SDC. Patients had at least one line of systemic chemotherapy. Patients received RC48-ADC at 1.5 or 2 mg/kg, every two weeks. Clinical efficacy and safety were assessed.

Results

This study enrolled HER2-expressing metastatic SDC patients from June 2022 to Dec 2022. 10 mSDC patients (8 males, 2 females) were enrolled. 90% patients had received ≥2 lines systemic chemotherapy. 80% patients had visceral metastases. As of 05 Jan 2023 (data cutoff), 1 patient achieved CR, 4 patients achieved PR, 4 patients achieved SD, and only 1 patient achieved PD. The overall confirmed DCR was 90%. Most common treatment-related AEs were hypoaesthesia (70%), asthenia (60%), leukopenia (30%), decreased appetite (20%), alopecia (10%). The grade≥3 TRAEs only included hypoaesthesia (30.0%) and neutropenia (10%).

Conclusions

RC48-ADC showed a promising efficacy with a manageable safety profile in HER2-expressing mSDC patients who had failed at least one line of systemic chemotherapy.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.