Results from the first in human study of the HIF-2α inhibitor, PT2977 in patients with advanced renal cell carcinoma (RCC) were presented at the European Society for Medical Oncology (ESMO) conference in Barcelona over the weekend.

Hypoxia inducible factor 2α (HIF-2α) is known to stimulate the growth of tumours via the von Hippel-Lindau (VLH) group of genes. PT2977 (also known as MK-6482) blocks the action of HIF-2α.

In this dose expansion study, a total of 55 patients with advanced RCC and who were not responding to treatment were given the HIF-2α inhibitor, PT2977. The majority of patients (62%) had already received 3 or more prior drug treatments for their RCC, representing a very heavily pretreated population with limited therapeutic options.

Efficacy in this heavily pretreated population was encouraging, with an objective response rate of 24% (all partial responses). 56% of patients achieved stable disease, and 69% had tumour shrinkage. Only 16% of patients experienced progression of RCC. The toxicity profile compares very favourably to that of cabozantanib or everolimus plus lenvatinib.

In summary, although the trial awaits further follow-up data, responses to PT2977 were generally ongoing after 50 weeks on treatment, and several patients with tumour shrinkage continued to have disease control up to 70 weeks on therapy.

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