Apitope preps Graves’ disease drug for phase 2 after positive trial

Apitope's facility in Chepstow, U.K. (Apitope)

Apitope has taken a step closer to developing the first new treatment option for thyroid disorder Graves’ disease in decades after posting positive results in a first-in-human trial of its ATX-GD-59 antibody.

The U.K. and Belgium-based biotech said the phase 1 trial shows signs of efficacy in the majority of patients with Graves, an autoimmune disease affecting up to 10 million people across the U.S. and Europe that leads to an overgrowth of the thyroid gland.

Armed with the clinical data, Apitope said it intends to press on with a phase 2 trial in the first quarter of 2019, giving it a second mid-stage clinical candidate to sit alongside multiple sclerosis therapy ATX-MS-1467.

In Graves’ disease, the immune system mistakenly attacks the thyroid gland, causing it to become overactive and enlarged. Excess levels of thyroid hormones in turn can cause skin abnormalities, tremors, weight loss, osteoporosis and eye complications including blindness.  

ATX-GD-59 is designed to reduce levels of thyroid hormones by targeting the underlying immunological basis of the disease and in the study was able to reduce levels of thyroid stimulating hormone receptor (TSHR) antibodies “with close correlations between percentage decreases in antibody and thyroid hormone levels in line with the mechanism of action.”

There are already drugs available such as methimazole and propylthiouracil that try to block the production of thyroid hormones, but these have a high failure rate, according to endocrinology professor Simon Pearce, M.D., of Newcastle University in the U.K., the lead investigator in Apitope’s trial.

Second-line treatment is limited to invasive surgery and radioiodine therapy to destroy the thyroid, and means patients have to take lifelong thyroid hormone replacement therapy, while in some cases surgery can result in scarring and vocal cord damage.

“ATX-GD-59 demonstrates the potential to address the high medical need for a new, safe and effective treatment for the neglected field of those suffering from Graves' disease,” said professor Pearce.

Apitope’s decision to move ahead with the program comes against a backdrop of very little R&D effort in Graves’ disease, and what seems to be some recent failures.

GlaxoSmithKline spinout Thyritope Biosciences was launched in 2014 to work in this area, but now seems to be inactive. Novartis has also been developing CD40 antigen inhibitor CFZ533 in phase 2 for the disease, but only lists organ transplantation as a target indication for that drug in its latest pipeline update. A small, investigator-led trial of a TSHR-blocking antibody (K1-70) is underway in the U.K., with results due in 2020.

Last October, Apitope said it intended to raise new funds through an IPO on the Euronext exchange in order to provide funds for the development of its clinical pipeline, including the MS program and a third in uveitis—but hasn’t yet followed through on those plans.

“These findings are important for Graves' disease patients in providing a potential new treatment paradigm aimed at the cause of the disease not just the symptoms,” said Apitope’s CEO Keith Martin Ph.D.

“We're highly encouraged by these data as they provide further evidence that our Apitope platform identifies safe and effective treatments for autoimmune diseases,” he added.