YO20 - A Case Series of Second-line Trastuzumab Deruxtecan for the Treatment of Metastatic HER2-Expressing Gastric-Type Mucinous Carcinoma of Cervix in Singapore

Case summary

Background: Gastric-type mucinous carcinoma of cervix uteri (GAS) is rare, aggressive and chemoresistant. HER2 IHC (immunohistochemistry) 3+/2+ expression in GAS is estimated at 19–46% and may be a putative therapeutic target. The phase II DESTINY-PanTumor02 showed promising activity of the HER2-directed antibody-drug conjugate (ADC), Trastuzumab deruxtecan (T-DXd), in pretreated HER2 3+/2+ solid tumours, including cervical cancers.

Methods: We describe 3 Chinese adult female patients (pts) with metastatic HER2 3+/2+ GAS at 2 centres in Singapore who were treated with 2^nd line T-DXd after progression on platinum-based regimen. 2 pts had de novo metastatic disease; 1 had metastatic relapse after radical radiotherapy and salvage surgery. Peritoneum was their main disease site, complicated by intestinal obstruction (IO) in 2 pts before T-DXd use. All received 1^st line (1L) Paclitaxel/Carboplatin/Bevacizumab; 1 pt with concurrent Pembrolizumab.

Results: All pts had baseline LVEF >50%. Mean age at Cycle 1 was 59.3y (range 53–63); PS ECOG 0–1. Starting dose T-DXd was 5.4 mg/kg q21d. Early treatment-emergent adverse events (TEAEs) included increased creatinine, diarrhoea*, venous thrombosis* and vomiting. Treatment is ongoing in all pts; responses and dose modifications will be reported later.

Conclusions: To our knowledge, this is the first reported case series of ADC treatment, specifically T-DXd, for metastatic GAS which is underrepresented in trials. We anticipate an increase in the real-world application of ADC against this difficult-to-treat entity.

Table: Patient Characteristics and Treatments

* Scoring per CAP/ASCP/ASCO 2017 guideline for gastro-oesophageal carcinoma

Clinical trial identification

Editorial acknowledgement