Ionis Pharmaceuticals recently concluded a Phase 1/2 clinical trial to evaluate IONIS-DMPK-2.5Rx in myotonic dystrophy patients. IONIS-DMPK-2.5Rx was designed to target the toxic DMPK RNA in muscle that is responsible for myotonia or muscle dysfunction in DM1 patients. The clinical trial used dose escalation to assess safety and explore biomarkers for target engagement in muscle biopsies.

Ionis reports that small but encouraging trends in biomarker and splicing changes were observed during the trial, and that this study provided a much better understanding of how future clinical trials and improved clinical endpoints may be used. However, drug levels measured in biopsy tissue from trial participants indicated that the amount of target engagement would not achieve the desired therapeutic benefit to treat this disease.

Without the desired drug levels in muscle, Ionis has decided not to advance IONIS-DMPK-2.5Rx. It will instead pursue the discovery of a more potent drug to target DMPK using new muscle-targeting LICA chemistry made at Ionis.

The company sincerely thanks everyone in the DM community that participated in the study – patients, caregivers and physicians, noting, “we are committed to the DM patient community and we hope to advance a new, more potent drug into development that will benefit people living with DM1.”

Ionis invites DM community members to submit questions regarding the above announcement via this email address. MDF will collect questions through January 12th and then work with Ionis to get answers out to the community as soon as possible.