Clinical-stage biotech firm Dianthus Therapeutics has shared preclinical data of its investigational agent DNTH103 being tested in in vitro models of generalised myasthenia gravis (gMG) and chronic demyelinating polyneuropathy (CIDP).  

Data from the blood of three patients with gMG showed that DNTH103 reached a 24.8% – 27.8% reduction from baseline in the fatigue index, which measures improvements in neurotransmission and muscle contraction. Myasthenia gravis is an autoimmune disorder that causes muscle weakness and fatigue due to disrupted communication between nerves and muscles. 

A second dataset looked at the blood of patients with CIDP, showing that the highest dose of DNTH103 used restored levels of neuronal conduction velocity. CIDP is a neurological disorder characterised by progressive weakness and impaired sensory function in the legs and arms due to inflammation of the peripheral nerves. 

The preclinical data, presented at the European Academy of Neurology (EAN) 2024 Congress in Helsinki, Finland, also showed that DNTH103 has the potential to be formulated as a patient-friendly, infrequent, subcutaneous (SC) self-administration. 

DNTH103 is a fully human IgG4 monoclonal antibody that inhibits the active form of C1s, a protein involved in a pathway that promotes inflammation. This pathway, known as the classical complement system, typically functions to clear microbes and damaged cells but is also suggested to play a role in some autoimmune diseases. 

This data supports Dianthus’s recently initiated Phase II study. The MaGic trial (NCT06282159) – which will enrol 60 gMG patients who are anti-acetylcholine receptor (AChR) antibody-positive – was initiated in February 2024. Patients will receive DNTH103 via SC injection every two weeks, with topline data expected in H2 2025. 

Last month, the company received the green light from the US Food and Drug Administration (FDA) to begin a Phase II trial of DNTH103 to treat multifocal motor neuropathy (MMN). Initial topline results are set for H2 2026, with Dianthus planning another Phase II CIDP study of the drug in H2 2024. 

In October 2023, UCB’s ZILBRYSQ (zilucoplan) was approved by the FDA for the treatment of adults with gMG who are AChR antibody positive. The drug is a targeted peptide inhibitor of complement component 5 (C5). However, C5 inhibitors have an increased risk for serious bacterial infection, says Dianthus’ CEO Marino Garcia. 

“We aim to demonstrate that DNTH103 may become a best-in-class classical complement pathway inhibitor with infrequent self-administration that provides effective and consistent control of symptoms for people living with neuromuscular conditions, without inhibiting the alternative and lectin pathways that are critical in the defence against infection,” added Garcia.