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Antisense Drug For Acromegaly Shows Promise in Phase 2 Study

SEPTEMBER 02, 2014
james Radke

Antisense Therapeutics announced their phase 2 study in patients with acromegaly met its primary efficacy endpoint showing a statistically significant average reduction in the serum insulin-like growth factor-I (sIGF-I) levels of 26% from baseline following treatment with its drug ATL1103 that the company is developing in-licensed from Isis Pharmaceuticals.

Acromegaly – or giantism – is a rare endocrine disorder due to excess secretion of growth hormone (GH) by benign pituitary tumors.  Treatment may involve surgery/raditotherapy to remove benign tumors and drug treatments such as somatostatin analogs, GH receptor antagonists, and/or dopamine agonists.  ATL1103 is an antisense drug designed to block growth hormone receptor (GHr) expression.

Phase 2 Study

The ATL1103 Phase II trial was a randomized, open-label, parallel group study of the safety, tolerability, pharmacokinetics and efficacy of two subcutaneous dosing regimens of ATL1103 in 26 adult patients with acromegaly dosed with ATL1103 for 13 weeks (3 months) with two months of follow up. Two ATL1103 dosing regimens were tested:
  1. 200 mg 3 times in the first week then once weekly (200 mg/week)
  2. 200 mg 3 times in the first week then twice weekly (400 mg/week).

The primary endpoints were safety and pharmacokinetics but efficacy was also measured by the evaluation of ATL1103's effect on serum insulin like growth factor I (IGF-I) levels in patients.

In a press release, Antisense Therapeutics reported that all patients treated with 400mg per week of ATL1103 had a reduction in sIGF-I levels from baseline at week 14.  Greater reductions in sIGF-I were observed in patients who had lower body weights and thereby received a relatively higher dose per kg bodyweight.  In addition, the company noted that the Phase 2 trial met its primary efficacy endpoint showing a statistically significant average reduction in the serum insulin-like growth factor-I (sIGF-I) levels of 26% from baseline (P<0.0001) at week 14 (one week past the last dose) at the 400mg per week dose tested.  More details of the study can be found at antisense.com.au/investor-relations/asx-announcements

Dr Peter Trainer, Professor of Endocrinology, The Christie NHS Foundation Trust, UK,  and Chief Investigator for the study said, "There are limited therapeutic options for patients with acromegaly and there is an acknowledged need for new therapies. The results achieved in this Phase II trial suggest ATL1103 with appropriate dose adjustment should be capable of achieving disease control in a significant proportion of patients with acromegaly. ATL1103's profile as a potentially efficacious and well tolerated conveniently dosed therapy strongly supports its move into Phase III stage of development."

Mark Diamond, Managing Director and CEO of Antisense Therapeutics added,  "We are very pleased to have achieved this significant milestone in the late stage development of ATL1103. These results greatly enhance our partnering prospects for the drug and we expect a number of interested pharmaceutical companies to enter formal due diligence on ATL1103 in coming months."

Moving Forward

The Company plans to present the phase 2 study data at the 7th International Congress of the GRS and IGF-I Society in Singapore, in October.  The company also plans to conduct a small study at a higher dose than 400 mg per week for potential use in a Phase 3 clinical trial.

In their press release, Antisense Therapeutics stated “The positive results achieved in this Phase II trial position ATL1103 to move into Phase III stage of development. Consequently, ANP will accelerate out-licensing activities to secure a pharmaceutical development partner for the drug's further development.“

Antisense Therapeutics is an Australian based company who has 4 products in its development pipeline that it has in-licensed from Isis Pharmaceuticals Inc.

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