Intralesional BO-112 achieved visual and pathological response in 61% of patients with resectable primary basal cell carcinoma (BCC) at week 24, meeting the primary endpoint of the phase 2b Spotlight-204 study. Highlight Therapeutics presented the topline results at the European Academy of Dermatology and Venereology (EADV) congress in Vienna.

The multicenter, single-arm trial enrolled 46 patients with resectable primary low- and high-risk BCC. Among the high-risk subgroup, 58% achieved visual and pathological response, compared with 70% of low-risk patients.

In the high-risk head and neck group — the population with the greatest unmet need — 56% reached complete pathological response. Among patients with facial lesions, 62% achieved complete pathological response.

The safety profile supports advancement. Investigators reported no serious adverse events and no grade 3 or higher treatment-related adverse events. Grade 1 adverse events occurred in 91% of patients and resolved within three days in 88% of them.

First clinical validation in BCC

"Today marks an important milestone for Highlight Therapeutics as these results represent the first clinical validation of BO-112 in BCC and give us strong conviction to advance into late-stage development," Mercedes Diz, CEO of Highlight Therapeutics, said in the release. "We are excited to bring this potential non-surgical option a step closer to patients, particularly those with high-risk BCC in the head and neck, where the need is greatest."

BCC is the most common type of skin cancer. It arises in the basal cells of the outer skin layers, most frequently on the face, head, neck and arms, after UV-induced mutation and proliferation of those cells.

Mechanism: turning cold tumors hot

BO-112 is a double-stranded RNA nanoparticle designed to convert immunologically cold tumors into hot tumors that the immune system can recognize. According to the company, it activates innate antiviral sensing pathways and induces immunogenic tumor cell death, leading to tumor-specific adaptive immunity.

The Spanish biotech, founded in 2010 as Bioncotech Therapeutics, entered a phase 2 clinical trial collaboration with MSD, a subsidiary of Merck, in 2019 to evaluate BO-112 in combination with Keytruda in patients with advanced-stage solid tumors and liver metastases. The company currently runs multiple phase 1 and 2 trials in advanced and resistant melanoma, sarcoma and hepatocellular carcinoma.

Competitive context

If BO-112 reaches late-stage development, it would enter a BCC immunotherapy field currently occupied by systemic and targeted options. The FDA approved Sanofi and Regeneron's PD-1 antibody Libtayo for advanced BCC in 2021. Novartis' Odomzo (sonidegib) and Genentech's oral Erivedge (vismodegib) are also established in the field. A locally delivered, non-surgical agent for localized primary disease would address a distinct niche — patients with high-risk head and neck lesions for whom surgery carries functional and cosmetic consequences.

The week 24 data, with no serious adverse events reported, position Highlight to move BO-112 into late-stage development for localized primary BCC, where an intralesional, immunotherapy-based alternative to surgery could reshape treatment of high-risk facial and head and neck tumors.