The total funding is set to amount to $9.1m and the initial research grant of $1m was announced in January this year.
The additional funding from RSRT will enable ProQR to accelerate its RNA editing approaches, which are tailored to the genetic mutations causing Rett Syndrome.
The focus will be on optimising therapeutic candidates targeting the transcription factor Methyl CpG binding protein 2 (MECP2) and advancing them towards clinical development.
ProQR Therapeutics chief scientific officer Gerard Platenburg said: “We are deeply committed to bring innovative solutions to patients with high unmet needs, such as those living with Rett Syndrome, and are grateful for the expanded partnership with the Rett Syndrome Research Trust.
“The increased support from RSRT underscores the potential of our Axiomer RNA editing technology platform to address complex genetic CNS conditions.
“The expanded collaboration enables us to accelerate the development of AX-2402 for Rett syndrome and to advance this programme into clinical trials.”
AX-2402, developed for individuals with the R270X mutation in the MECP2 gene, is based on ProQR’s Axiomer RNA editing platform.
The platform enables the targeting of several mutations beyond R270X, potentially impacting a large segment of the Rett Syndrome population.
The success of AX-2402 could lay the groundwork for developing a new class of RNA editing therapeutics to target the remaining mutations.
A neurodevelopmental disorder, Rett Syndrome affects nearly 350,000 individuals globally, primarily girls.
Rett Syndrome Research Trust founder and CEO Monica Coenraads said: “Individuals with Rett Syndrome live with the profound effects of this condition every day, and they deserve transformative therapies.
“This partnership with ProQR is exciting and ambitious. We are encouraged by the progress we’ve seen so far and believe that together we are taking critical steps toward achieving our mission of eradicating Rett Syndrome.”