Krystal’s KB113 Shows 83% BCC Regression in Gorlin Syndrome

Krystal Biotech reported preliminary clinical findings on October 15, 2026, from a three-patient pilot study of investigational KB113 in adults with Gorlin syndrome, a genetic disorder associated with a high lifetime burden of basal cell carcinomas (BCCs).

At the final assessment, 69 of 83 evaluated lesions (83.1%) had decreased in size following treatment. Regression was also observed in lesions that were not directly injected, raising the possibility of a systemic immune response. However, the findings remain preliminary because the study involved only three patients and lacked a control group.

The data were scheduled for presentation at the 14th Pediatric Dermatology Research Alliance (PeDRA) Annual Conference, held October 15–17, 2026, in Alexandria, Virginia.

Addressing the BCC burden in Gorlin syndrome

Gorlin syndrome predisposes patients to developing multiple BCCs, sometimes beginning early in life. Repeated tumour formation can require numerous surgical procedures, contributing to cumulative scarring, tissue loss and treatment burden.

KB113 is an investigational intratumoral immunotherapy designed to promote local expression of interleukin-2 (IL-2) and interleukin-12 (IL-12), cytokines involved in immune activation. The approach aims to stimulate antitumour immunity within the tumour microenvironment, with the potential to affect lesions beyond the injection site.

Krystal describes KB113 as a low-dose version of its intratumoral immunotherapy KB707. The company previously reported early efficacy signals with KB707 in the OPAL-1 Phase 1/2 study (NCT05970497), which evaluated patients with injection-accessible solid tumours.

Three-patient pilot evaluated six-dose treatment

The Gorlin syndrome pilot was a multicentre, single-arm, open-label study designed to assess KB113’s safety and preliminary efficacy. Three adults received six doses over 14 weeks, using a concentration of (10^8) plaque-forming units (PFU)/mL and a maximum volume of 2 mL per dosing session.

The first two doses were administered two weeks apart, followed by dosing every three weeks. Eligible landmark lesions were facial BCCs measuring at least 5 mm or non-facial BCCs measuring at least 9 mm. Investigators selected which eligible lesions to inject.

Lesion regression was assessed visually using a prespecified five-point clearance scale during treatment and 30 days after the final dose.

Regression extended beyond injected lesions

At the final assessment, 69 of 83 landmark lesions (83.1%) showed some regression in size. The findings included both injected and non-injected lesions:

• Injected lesions: 29 of 36 (80.6%) showed regression.
• Non-injected lesions: 40 of 47 (85.1%) showed regression.
• Regression exceeding 50%: 42 of 83 lesions (50.6%).
• Regression of at least 90%: Eight of 83 lesions (9.6%), comprising four injected and four non-injected lesions.

One injected lesion from each patient that had achieved at least 90% regression was biopsied. All three biopsies showed complete histological response, with no residual tumour identified.

Safety findings and remaining uncertainties

KB113 was reported to be well tolerated in all three patients. The accompanying conference data reported 22 adverse events, all assessed as treatment-related, mild or moderate, transient and resolved during the study. No serious adverse events were reported.

The safety findings are encouraging but cannot establish the treatment’s safety profile given the very small number of participants.

Clinical Interpretation

The most notable preliminary finding is the regression observed in non-injected lesions, which suggests a possible antitumour effect beyond directly treated sites. Histological clearance in three selected injected lesions provides additional evidence of a treatment response, although it does not establish complete clearance across the broader lesion population.

The findings require cautious interpretation. The study involved only three patients, used investigator-assessed visual measurements and lacked a control group. Moreover, the 83.1% regression rate includes any reduction in lesion size, while 50.6% of lesions regressed by more than 50% and only 9.6% by at least 90%. Because only selected lesions with substantial regression underwent biopsy, the histological findings cannot be generalized to all treated lesions. Follow-up extended only 30 days beyond the final dose, leaving durability and recurrence unresolved. Whether KB113 can reduce repeated surgical procedures also remains unproven.

The results support further clinical investigation but do not establish efficacy or superiority over existing management approaches.

FDA discussions will guide further development

Krystal Biotech has initiated discussions with the US Food and Drug Administration (FDA) regarding the next stage of KB113 development in Gorlin syndrome. The company plans to update its development strategy following alignment with the agency.

Larger studies with more patients, standardized lesion assessment and longer follow-up will be needed to determine whether KB113 can deliver durable clinical benefit in Gorlin syndrome. Until further evidence is available, KB113 remains investigational, and its safety and efficacy have not been established.

Reference

Krystal Biotech Announces Positive Clinical Data for New Dermatology Program KB113 Demonstrating Broad Basal Cell Carcinoma Regression in Patients with Gorlin Syndrome, Krystal Biotech, 15 October 2026