Dr Brohl on the Safety and Efficacy of IFx-Hu2.0 in MCC and CSCC

Andrew S. Brohl, MD, medical oncologist, Moffitt Cancer Center, member, The Cancer Genome Atlas sarcoma project, discusses the safety and immunologic responses with intratumoral administration of Idx-Hu2.0 in patients with advanced Merkel cell carcinoma (MCC) and cutaneous squamous cell carcinoma (CSCC).

The novel cancer vaccine IFx-Hu2.0 was designed to encode for the immunogenic bacterial protein Emm55, and it features a transfection agent for direct intratumoral injection. Moreover, the vaccine could have immune priming effects for patients who previously received immune checkpoint inhibitors.

In a phase 1b study (NCT04160065), IFx-Hu2.0 was administered intratumorally at a fixed dose of 0.1 mg/lesion per time point in up to 3 lesions. Patients received either a single dose (cohort 1), 2 doses 1 week apart (cohort 2), or 3 doses weekly (cohort 3). The study's primary end point was safety with repeated dosing. An unplanned exploratory analysis of responses to rechallenge with an immune checkpoint inhibitor was also conducted in patients with MCC or cSCC treated with IFx-Hu2.0.

Initial results for the study included 5 patients with MCC and 4 with CSCC. All patients had previously progressed on an immune checkpoint inhibitor.

Initial results showed that the regimen was safe and well tolerated, and at all dose schedules, the vaccine produced minimal toxicity, Brohl reports. No grade 2 or higher treatment-related adverse effects (TRAEs) were reported. Grade 1 TRAEs were experienced by 33% of patients, including 2 patients who experienced an injection site reaction and/or tumor-related bleeding at the injection site, he expands.

The agent showed modest efficacy, although no systemic responses were observed with the agent, Brohl continues. Two patients experienced stable disease and experienced a clinical response at the injection site, but this did not meet the criteria for a partial response, he says. However, 71% of patients (n = 7) experienced an objective response with a single-agent PD-L1 inhibitor immediately after completion of IFx-Hu2.0. Responses were ongoing in 4 patients, with the longest duration of response being 23 months. This indicates that the agent may enhance the success of immune checkpoint inhibitor rechallenge in patients with MCC or CSCC, Brohl concludes.

Disclosures: Dr Brohl reports serving as a consultant or in an advisory role for Bayer and Deciphera; he provided expert testimony to GlaxoSmithKline.