Krystal Biotech, Inc. (NASDAQ:KRYS) reported preliminary clinical findings from a pilot study of KB113, an investigational intratumoral immunotherapy being developed for patients with Gorlin syndrome, showing regression in more than 80% of assessed basal cell carcinoma (BCC) lesions.
The study involved three adult patients with Gorlin syndrome, a genetic condition associated with an increased risk of developing multiple basal cell carcinomas.
According to the company, 69 of 83 assessed lesions showed some degree of clinical regression at the final evaluation, conducted 30 days after the last treatment dose.
More substantial reductions were recorded in a subset of lesions, while biopsies of three selected treated lesions confirmed complete histological responses.
Krystal Biotech said it has initiated discussions with the US Food and Drug Administration (FDA) regarding further clinical development of KB113 for Gorlin syndrome.
KB113 Shows Regression in 69 of 83 Assessed Lesions
The Gorlin Syndrome Pilot Study evaluated the clinical activity of KB113 across 83 designated landmark lesions in three adult patients.
At the final assessment, 69 lesions, or approximately 83%, demonstrated some degree of clinical regression.
Of the total lesions assessed, 42, representing approximately 51%, showed regression greater than 50%.
A further eight lesions, approximately 10% of the total, achieved regression of at least 90%.
The company reported that evidence of lesion regression was observed as early as two weeks after treatment began.
These findings suggested that KB113 demonstrated clinical activity within the small study population, although the degree of response varied between lesions.
The results remain preliminary, and the limited number of patients means that larger studies will be required to establish the treatment’s effectiveness and safety more reliably.
Biopsies Confirm Complete Responses in Three Selected Lesions
Krystal Biotech also reported histological findings from selected lesions that demonstrated substantial clinical regression.
One injected lesion from each of the three patients was selected for biopsy after achieving at least 90% clinical regression.
All three biopsied lesions showed a histologically confirmed complete response, with no residual tumour tissue detected in the samples.
The findings provided additional evidence of treatment activity in the selected lesions beyond the clinical assessments of their appearance and size.
However, the complete responses were confirmed only in the three biopsied lesions and should not be interpreted as complete clearance of all lesions or disease in the participating patients.
The company did not report longer-term follow-up data establishing whether the responses were sustained after the final assessment.
Further clinical investigation will be necessary to determine the durability of responses and whether similar results can be reproduced in a larger patient population.
Non-Injected Lesions Also Show Signs of Regression
An additional finding from the pilot study was the observation of regression in lesions that had not been directly injected with KB113.
Among 47 non-injected landmark lesions assessed, 40 demonstrated some degree of regression.
Krystal Biotech described the finding as consistent with a potential abscopal effect, in which treatment directed at one tumour is associated with a response in other, untreated tumours.
Such effects can occur when a local treatment stimulates a broader immune response, although the mechanism responsible for the observed regression has not yet been established in this study.
The company reported clinical regression in both injected and non-injected lesions, suggesting that KB113 may have activity beyond the immediate treatment sites.
However, the small, uncontrolled pilot study does not establish that KB113 caused the regression of non-injected lesions through a systemic immune mechanism.
Additional research will be needed to investigate the biological processes involved and determine whether these findings are reproducible.
Three Patients Receive Six Doses Over 14 Weeks
The Gorlin Syndrome Pilot Study enrolled three adult patients, each of whom received six doses of KB113 over a 14-week treatment period.
KB113 is derived from the low-dose regimen of KB707, another investigational therapy being evaluated in Krystal Biotech’s OPAL-1 Phase 1/2 clinical trial.
The pilot study was designed to provide initial information about the treatment’s activity and tolerability in patients with Gorlin syndrome.
According to the company, all reported adverse events were mild to moderate in severity and transient.
No additional detailed safety findings were provided in the announcement.
While the reported tolerability profile was encouraging within the limited study population, the findings cannot establish the safety of KB113 across a broader group of patients.
Larger studies with longer follow-up will be required to assess potential adverse effects, treatment durability and the appropriate dosing regimen.
Gorlin Syndrome Associated With Recurrent Basal Cell Carcinomas
Gorlin syndrome is a hereditary condition that increases the risk of developing basal cell carcinomas, a common form of skin cancer.
Affected individuals may develop multiple BCC lesions over their lifetime, with some cases appearing during childhood or even infancy.
The condition can create a substantial treatment burden because patients may require repeated interventions to manage newly developing or recurrent lesions.
According to information cited by Krystal Biotech, the number of people living with Gorlin syndrome in the United States may exceed 10,000.
The company is investigating KB113 as a potential treatment approach for patients affected by the condition.
An intratumoral immunotherapy capable of treating multiple lesions could offer a different therapeutic approach if its safety and effectiveness are established in larger clinical trials.
However, KB113 remains investigational, and the current pilot study does not provide sufficient evidence to determine its potential role in routine clinical care.
Krystal Biotech Begins FDA Discussions on Further Development
Following the pilot study findings, Krystal Biotech confirmed that it has initiated discussions with the FDA regarding the advanced clinical development of KB113 for Gorlin syndrome.
The company said it intends to provide further information about its development plans after reaching alignment with the regulator.
The announcement did not specify the design, size or expected timing of a subsequent clinical trial.
Regulatory discussions may help determine the clinical evidence required to support further development, including appropriate study endpoints, patient populations and safety assessments.
KB113 has not been approved by the FDA or any other regulatory authority.
Its potential clinical use will depend on the outcome of additional studies and the applicable regulatory review process.
Clinical Findings Presented at Dermatology Research Conference
The pilot study results are being presented by study investigator Dr Shireen Guide at the 14th Pediatric Dermatology Research Alliance Annual Conference.
The event takes place from 15 to 17 October 2026 in Alexandria, Virginia.
The presentation provides an opportunity for the clinical findings to be discussed within the dermatology research community.
For Krystal Biotech, the next stage of development will focus on determining whether the responses observed in the three-patient pilot study can be confirmed in a larger and more representative population.
The preliminary data showed lesion regression in both treated and untreated sites, including three biopsy-confirmed complete responses in selected injected lesions.
Nevertheless, the limited sample size, absence of a control group and short follow-up period mean that the results should be interpreted cautiously.
Further clinical trials will be necessary to establish whether KB113 can provide a safe, effective and durable treatment option for patients with Gorlin syndrome.