In Slides 20 and 21 of today’s presentation, Rohan Hockings, with multiple caveats, has compared early data for VP-001 in RP11 with that of two gene therapies in development for X-linked Retinitis Pigmentosa.
Efficacy
At this stage, PYC’s data is drawn from the single dose studies – the rate of improvement with repeated doses is currently being tested.
Despite the limitations of comparing data across different trials, PYC’s early data compares favourably and is showing clear promise.
Safety
Slide 21 also compares PYC’s early safety data with the safety outcomes reported in the early trials of the two gene therapies – Meira GTx/J & J’s MGT-009 and Beacon Therapeutics’ AGTC-501.
To date, no adverse events have been seen with PYC’s VP-001 treatment, which is administered via intravitreal injection.
In the trials of both gene therapies, which are delivered by riskier sub-retinal injection, adverse events have been reported.
In its Phase1/2 trial, MeiraGTx reported a total of 3 serious adverse events - 2 were observed in the dose-escalation phase of the study (n=10; one retinal tear and one panuveitis in the low dose cohort). In the dose expansion phase of the study (n=32), one serious adverse event was reported - increased intraocular pressure which resolved with treatment.
For Beacon Therapeutics there was one case of severe glaucoma which was found to be related to protocol required corticosteroids. It was treated with medication and resolved. There was also one case of visual impairment, found to be related to the injection procedure. Other treatment-related adverse events included vitritis, eye pain, metamorphopsia, photopsia, and reduced visual acuity (all n = 1). All adverse events were considered to be mostly non-serious, mild or moderate in severity.
The Gene Therapy (DNA) Landscape
It has been reported that investment in cell and gene therapies has nosedived this year.
Two gene therapies for sickle cell disease, developed by Vertex Pharmaceuticals and bluebird bio, were approved in the US late last year. Each costs US$2-3m. To date, only a few dozen patients have begun the process to receive treatment.
Similarly, CSL’s haemophilia B gene therapy Hemgenix, and BioMarin’s haemophilia A gene therapy Roctavian have been slow to sell.
Hemgenix, which was FDA approved in late 2022, is priced at US$3.5m. R &D costs for the drug are reported to have been ~US$1bn and it has been estimated that the vector manufacturing cost alone of one dose could be in the range of US$1-2 m.
Roctavian costs US$2.9m. From Biomarin’s accounts, I have calculated that the drug has cost ~US$1.2bn to date to develop and market. The gene therapy was approved in the EU in August 2022 and in the US in June 2023 and was predicted to be a blockbuster US$2bn drug. Only 3 sales were made in 2023 and BioMarin is rapidly adjusting its plans for both Roctavian and further gene therapy development.
Gene therapies have struggled with a combination of challenges including massive development costs, especially with vector manufacturing costs, safety concerns, payers baulking at the price tags, patient suitability (e.g. having antibodies to the virus used as the vector), patient hesitancy driven by safety concerns and lingering questions over long-term side effects and treatment durability.
In comparison, the landscape for RNA therapeutics is looking brighter. As quoted on Slide 11 of today’s presentation, from Stifel’s Biopharma Market Update report, released on the 12th of this month
“RNA is now leading the market with stellar clinical results and outstanding long-term potential”.
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