SALIVARY GLAND CANCER

In this video, Dr Willem Lybaert and Dr Pieterjan Vanclooster discuss and comment on the data of two studies in salivary gland cancer presented at ESMO 2024.  

The first study, the MYTHOS trial, was an investigator-initiated Phase 2 trial conducted in Japan focusing on HER2-positive recurrent or metastatic salivary gland cancer. In this trial, trastuzumab deruxtecan, a HER2-targeted therapy, was administered to patients with confirmed HER2-positive tumours (HER2 2+ to HER2 3+). All patients had already received previous treatments like chemotherapy or radiation. The results were promising, with an overall response rate of around 40% and an improvement in progression-free survival. The adverse events were mostly manageable, though the incidence of interstitial lung disease (ILD) was slightly higher, a phenomenon often seen in Japanese populations receiving this therapy. The MYTHOS trial is significant as it highlights a positive response in a rare tumour subtype, demonstrating the potential of HER2-targeted therapies in salivary gland tumours.

The second study, EORTC1206, explored androgen receptor-positive salivary gland tumours and involved three treatment arms. One arm used standard chemotherapy (cisplatin with adriamycin or carbo-taxol), the second involved androgen deprivation therapy (bicalutamide and triptorelin), and the third offered chemotherapy followed by androgen deprivation therapy. The primary histological subtype was salivary duct carcinoma, though there were also cases of adenocarcinoma. This trial, however, did not yield particularly positive results, as the androgen deprivation therapy arm showed numerically lower PFS compared to chemotherapy. Nonetheless, it was not inferior either. The adverse events associated with androgen deprivation therapy were as expected, but overall, chemotherapy appeared to offer a slight advantage in terms of PFS.

Key takeaways from these studies include the importance of accurate histological and molecular profiling before treatment. The studies emphasised the need to confirm the specific subtype of salivary gland cancer, such as HER2 status or androgen receptor positivity, to determine the most appropriate therapy. The MYTHOS trial suggests trastuzumab deruxtecan may be a viable second-line treatment option for HER2-positive salivary gland tumours following initial chemotherapy and trastuzumab-based regimens. On the other hand, the EORTC1206 trial suggests that in androgen receptor-positive cases, the choice between chemotherapy and androgen deprivation therapy may depend on factors like the patient’s disease burden and performance status. For aggressive cases, chemotherapy may be preferred, while androgen deprivation therapy could be considered in slower-progressing diseases.

These studies offer new insights and potential treatment avenues for rare salivary gland tumours, demonstrating the importance of molecular-targeted approaches in these difficult-to-treat cancers.