Sumitomo Pharma America, Inc. (SMPA) announced that the first patient has undergone subretinal implantation in its phase 1/2a study evaluating DSP-3077 for the treatment of non-syndromic retinitis pigmentosa (RP).
Let’s start with the company.
Building on the 100-year history of Sumitomo Pharma Group and its extensive global impact, SMPA was formed in 2005 through the consolidation of Sumitomo Pharma's seven U.S. affiliate companies.
Its focus: addressing patient needs in oncology, urology, women's health, rare diseases, cell and gene therapies, and the central nervous system (CNS).
That’s a broad portfolio … how does DSP-3077 fit in?
The investigative regenerative cell therapy leverages allogeneic retinal sheets derived from induced pluripotent stem (iPS) cells with photoreceptor precursors.
- To note: iPS cells are derived from adult somatic cells and have been genetically reprogrammed to an embryonic stem (ES) cell-like state through the forced expression of genes and factors important for maintaining the defining properties of ES cells.
In this case: The technology underlying DSP-3077 is based on a self-organizing cell culture technique known as the SFEBq method—a robust differentiation method to generate 3D neural tissues and organoids from pluripotent stem cells.
How unique … is there any clinical data on it yet?
Nope—none that’s been published so far (hence this first patient dosing news).
Any regulatory news on the candidate?
The FDA granted Orphan Drug Designation (ODD) for DSP-3077 for the treatment of RP in March 2026.
Note: ODD is a special regulatory status granted by the FDA for certain investigational drug candidates that demonstrate promise for diagnosing, treating, or preventing so-called “orphan” diseases.
- These are classified as rare, serious, or life-threatening diseases or conditions (such as RP) that affect <200,000 patients in the United States.
Hold up—does this designation require clinical data?
No, not human clinical data.
Gotcha. So what advantages come with ODD?
While candidates deemed to be “orphan drugs” undergo the same scientific review process as any other drug seeking regulatory approval for commercial licensing in the United States, they are also qualified to receive:
- Tax credits for qualified clinical trials
- User fees exemption
- Potential 7 years of market exclusivity following approval
Now talk about the study.
The phase 1/2a, open-label, single-arm, uncontrolled dose-escalation study (NCT06891885) is evaluating two dose levels of allogeneic iPS cell-derived retinal sheets administered with a single subretinal, uniocular injection in adults with RP.
Study participants will be treated in three cohorts, with each cohort comparison defined by best-corrected visual acuity (BCVA) criteria and dose level of DSP-3077 as follows:
- Cohort 1: BCVA in the study eye between hand motion and 20 Early Treatment Diabetic Retinopathy Study (ETDRS) letter score (approximately ≤ 20/400), inclusive at screening and baseline
- Dose: ≥ 0.8 to < 2.4 mm2
- Cohort 2: BCVA in the study eye between hand motion and 20 ETDRS letter score (approximately ≤ 20/400), inclusive at screening and baseline
- Dose: ≥ 2.4 to < 6.4 mm2
- Cohort 3: BCVA in the study eye between 20 ETDRS letter score (approximately ≥ 20/400) and 35 ETDRS letter score (approximately ≤ 20/200), inclusive at screening; BCVA in the study eye between 10 ETDRS letter score (approximately ≥ 20/640 Snellen equivalent) and 35 ETDRS letter score (approximately ≤ 20/200) at baseline
- Dose: ≥ 2.4 to < 6.4 mm2
Note: Each cohort will include four participants for a total of 12 participants.
And how long will patients participate?
The total duration will be approximately 67 months from start of screening through the end of extension observation period in part B.
After an initial 2-week period of frequent visits after surgery, the visit frequency will be:
- Approximately monthly through Month 4
- Every 3 months through Month 24
- Every 6 months through Month 60
After completion of Month 60 Visit, SMPA will collect long-term data following treatment annually from 6 years to 15 years after DSP-3077 administration to further characterize its long-term safety.
What are the main outcome measures?
The primary objective of the study: evaluating the safety and tolerability of two dose levels of DSP-3077.
Secondary endpoints include assessing the safety, engraftment, and potential therapeutic response to DSP-3077 and evaluating its delivery device performance.
And any comments from the company?
Per President and CEO Tsutomu Nakagawa, PhD, noted the "important milestone” of the first study partipant’s dosing for DSP-307, referring to it as: “one that will aid in better understanding how it and future iPSC therapies could help improve the lives of RP patients and their families.”
Lastly: When can we expect an update?
We’ve got some time, as the estimated primary completion date for this study is Oct.31, 2028.
As always, stay tuned for developments.