By Sharan Sharma

Plitidepsin (Aplidine) is isolated from Aplidium albicans, a tunicate that lives in the Mediterranean sea. It was identified as harbouring better therapeutic indexes with markedly higher antitumour activity than its' previous predecessors. According to a study published in April in the American Journal of Clinical Oncology, Plitidepsin induces a clinical benefit in pretreated Medullary thyroid cancer (MTC).

MTC is a rare type of cancer which represents only 3-12% of all thyroid malignancies. Patients with unresectable disease are eventually offered chemotherapy with palliative care and support. Unfortunately, the activity of available anticancer drugs remains limited and new drugs that can control the disease progression and/or provide clinical benefit are still being desperately sought for MTC.

In this study researchers retrospectively reported the outcome of 10 patients with advanced MTC among 215 patients who have entered the Phase I trial with Plitidepsin. Patients were given 5 cycles of the drug. One patient experienced a confirmed partial response, 8 patients had stable disease and 1 patient had progressive disease. Two patients treated at the maximum tolerated dose were shown to have experienced muscular dose-limiting toxicity. The other toxicities were low grade myalgia, diarrhoea, nausea and vomiting. However, all the toxicities were manageable.

The study authors write "We report in this study signs of antitumor activity with plitidepsin in 10 patients with advanced MTC treated in the context of phase I clinical trials. Our study has limitations, in particular regarding the assessment of clinical benefit, for 2 reasons. First, only 5 patients among 10 had a measurable disease. Second, the clinical assessment of symptom relief was not based on formal measurements and may therefore have been fraught with error".