Monotherapy brenetafusp (IMC-F106C) in late-line cutaneous melanoma demonstrated promising disease control (partial response and stable disease), progression free survival (PFS), and ctDNA molecular response

Clinical activity was enriched in PRAME positive patients with 58% disease control rate and 4.2 months median PFS

Peripheral blood T cell fitness was associated with increased brenetafusp clinical activity and was higher in earlier lines of therapy

Brenetafusp is well tolerated as monotherapy and in combination with anti-PD1

Currently screening patients in a Phase 3 clinical trial (PRISM-MEL-301) of brenetafusp with nivolumab in first-line advanced cutaneous melanoma

OXFORDSHIRE, UK & CONSHOHOCKEN, PA & ROCKVILLE, MD, USA I May 31, 2024 I Immunocore Holdings plc (Nasdaq: IMCR) (“Immunocore” or the “Company”), a commercial-stage biotechnology company pioneering and delivering transformative immunomodulating medicines to radically improve outcomes for patients with cancer, infectious diseases and autoimmune diseases, today released Phase 1 data with the first off-the-shelf ImmTAC® targeting PRAME, brenetafusp (IMC-F106C), in patients with late-line, post-checkpoint cutaneous melanoma. Brenetafusp was shown to be well tolerated, in monotherapy and in combination with anti-PD1, and demonstrated durable clinical benefit.

“Brenetafusp continues to demonstrate promising monotherapy clinical activity in late-line cutaneous melanoma patients who were previously treated with checkpoint therapies,” said Dr. Omid Hamid, Chief, Translational Research and Immunotherapy, Co-Director, Melanoma Therapeutics at Cedars-Sinai Cancer at the Angeles Clinic and Research Institute. “The disease control and PFS benefit for these brenetafusp-treated melanoma patients compares favorably to data with other immunotherapies.”

“The best measure of brenetafusp monotherapy activity is disease control, which is observed in 56% of checkpoint pre-treated melanoma patients,” said David Berman, Head of Research and Development. “We expect brenetafusp PFS to be even higher in first-line based on our analysis of blood T cell fitness. These data points, in conjunction with the significant molecular response and the expected additive benefit of combining with an active anti-PD1, provide confidence for PFS as an endpoint in our ongoing Phase 3 first-line trial.”

Phase 1 data in post-checkpoint cutaneous melanoma

As of 18 March 2024, 47 patients have received brenetafusp (IMC-F106C) monotherapy at clinically active target dose levels. All monotherapy treated patients had received prior immune checkpoint inhibitors (100% anti-PD1, 81% anti-CTLA4). PRAME expression was high amongst evaluable patients (median H score of 215). Only 11% of patients had PRAME negative tumors, as measured by immunohistochemistry.

Brenetafusp was well-tolerated, with treatment-related adverse events (TRAEs) that were manageable and consistent with the mechanism of action. The most frequent TRAE reported was Grade 1 or 2 cytokine release syndrome (CRS) and rash; these events occurred predominantly following the initial three doses. There were no Grade 3 or higher CRS TRAEs.

Of the 47 monotherapy patients, 36 had a RECIST evaluable tumor assessment. The disease control rate (DCR), consisting of partial response (PR) and stable disease (SD), was 56% including 4 PR (ORR 11%) and 16 SD (44%). Durable tumor reduction, confirmed by at least one subsequent scan, was observed in 28% of patients and is an attribute of the ImmTAC platform1. Clinical benefit was enriched in the 31 evaluable PRAME positive patients. The DCR in this group was 58% and included all 10 patients (32%) with confirmed tumor reduction.

Both median progression free survival (mPFS) and 6-month overall survival (OS) rates were greater in PRAME positive than in PRAME negative monotherapy patients: 4.2 vs 2.1 months and 95% vs 40%, respectively.

42% of ctDNA-evaluable, PRAME positive monotherapy patients had a molecular response (10/24) and there was a trend for longer PFS and OS in molecular responders. No ctDNA-evaluable PRAME negative patients had ctDNA reduction.

In addition to the monotherapy patients treated with brenetafusp, there were 9 cutaneous melanoma patients who received brenetafusp in combination with an anti-PD1 (pembrolizumab), all of whom had received prior checkpoint inhibitors (100% prior anti-PD1, 89% prior CTLA4). Overall, patients were more heavily pre-treated in the combination cohort compared to monotherapy (median prior lines: 4 vs 2; PD-1 refractory: 67% vs 30%). Brenetafusp in combination with pembrolizumab was well tolerated, with TRAEs that were manageable and consistent with the mechanism of action of both agents. There was one dose-limiting toxicity (transaminitis) reported in one patient with prior history of checkpoint inhibitor induced autoimmune hepatitis.

Of the 7 patients evaluable for efficacy in combination, 4 achieved disease control including 1 ongoing PR (confirmed after the data cut off for the presentation), and 3 of the 4 ctDNA evaluable patients having molecular response.

In 41 gene-expression evaluable monotherapy patients, a gene signature was identified from baseline peripheral blood that was a measure of systemic T cell fitness. Patients with gene signature expression levels greater than or equal to the median had higher clinical benefit including a median PFS of 6 months and DCR of 69%, compared to those with less than the median gene expression levels (2 months and 42%, respectively). Patients with only 1-2 prior lines of therapy had higher T cell fitness gene signature, on average, than those with 3 or more prior lines of therapy.

The advanced cutaneous melanoma data from the ongoing Phase 1/2 trial of brenetafusp will be presented today at 2:45 PM CT / 3:45 PM ET, in the Melanoma/Skin Cancers oral abstract session at the 2024 American Society of Oncology (ASCO) Annual Meeting. The presentation will be accessible in the ‘Events & Presentations’ section of the Investor Relations section of the Company’s website.

PRISM-MEL-301 – First PRAME Phase 3 clinical trial with brenetafusp in first-line advanced cutaneous melanoma

The Company is enrolling patients in a registrational Phase 3 clinical trial with brenetafusp in first-line advanced cutaneous melanoma (CM) with a primary endpoint of progression-free survival (PFS) (NCT06112314). The trial will randomize HLA-A*02:01-positive, first-line advanced CM patients to brenetafusp + nivolumab versus a control arm of either nivolumab or nivolumab + relatlimab, depending on the country where the patient is enrolled.

Under the terms of a clinical trial collaboration and supply agreement, Immunocore will sponsor and fund this registrational Phase 3 clinical trial, and Bristol Myers Squibb will provide nivolumab.

About ImmTAC® molecules for cancer

Immunocore’s proprietary T cell receptor (TCR) technology generates a novel class of bispecific biologics called ImmTAC (Immune mobilizing monoclonal TCRs Against Cancer) molecules that are designed to redirect the immune system to recognize and kill cancerous cells. ImmTAC molecules are soluble TCRs engineered to recognize intracellular cancer antigens with ultra-high affinity and selectively kill these cancer cells via an anti-CD3 immune-activating effector function. Based on the demonstrated mechanism of T cell infiltration into human tumors, the ImmTAC mechanism of action holds the potential to treat hematologic and solid tumors, regardless of mutational burden or immune infiltration, including immune “cold” low mutation rate tumors.

About PRISM-MEL-301 – Phase 3 trial with brenetafusp (IMC-F106C; PRAME-A02) in 1L advanced cutaneous melanoma

The Phase 3 registrational trial will randomize patients with previously untreated, HLA-A*02:01-positive, advanced melanoma to brenetafusp + nivolumab versus nivolumab or nivolumab + relatlimab, depending on the country where the patient is enrolled. The study will initially randomize to three arms: two brenetafusp dose regimens (40 mcg and 160 mcg) and control arm and will discontinue one of the brenetafusp dose regimens after an initial review of the first 60 patients randomized to the two experimental arms (90 patients randomized total). The primary endpoint of the trial is progression free survival (PFS) by blinded independent central review (BICR), with secondary endpoints of overall survival (OS) and overall response rate (ORR).

About the IMC-F106C-101 Phase 1/2 trial

IMC-F106C-101 is a first-in-human, Phase 1/2 dose escalation trial in patients with multiple solid tumor cancers including non-small cell lung cancer (NSCLC), small-cell lung cancer (SCLC), endometrial, ovarian, cutaneous melanoma, and breast cancers. The Phase 1 dose escalation trial was designed to determine the maximum tolerated dose (MTD), as well as to evaluate the safety, preliminary anti-tumor activity and pharmacokinetics of IMC-F106C (brenetafusp), a bispecific protein built on Immunocore’s ImmTAC technology, and the Company’s first molecule to target the PRAME antigen. The Company has initiated patient enrollment into four expansion arms in cutaneous melanoma, ovarian, NSCLC, and endometrial carcinomas. The IMC-F106C-101 trial is adaptive and includes the option for Phase 2 expansion, allowing for approximately 100 patients treated per tumor type in the Phase 1 and 2 expansion arms. Ph1 monotherapy continues in additional solid tumors as well as multiple combinations with standards-of-care, including checkpoint inhibitors, chemotherapy, targeted therapies, and tebentafusp.

About Cutaneous Melanoma

Cutaneous melanoma (CM) is the most common form of melanoma. It is the most aggressive skin carcinoma and is associated with the vast majority of skin cancer-related mortality. The majority of patients with CM are diagnosed before metastasis and survival remains poor for the large proportion of patients with metastatic disease. Despite recent progress in advanced melanoma therapy, there is still an unmet need for new therapies that improve first-line response rates and duration of response as well as for patients who are refractory to first-line treatments.


KIMMTRAK is a novel bispecific protein comprised of a soluble T cell receptor fused to an anti-CD3 immune-effector function. KIMMTRAK specifically targets gp100, a lineage antigen expressed in melanocytes and melanoma. This is the first molecule developed using Immunocore’s ImmTAC technology platform designed to redirect and activate T cells to recognize and kill tumor cells. KIMMTRAK has been approved for the treatment of HLA-A*02:01-positive adult patients with unresectable or metastatic uveal melanoma in the United States, European Union, Canada, Australia, and the United Kingdom.

About Immunocore

Immunocore is a commercial-stage biotechnology company pioneering the development of a novel class of TCR bispecific immunotherapies called ImmTAX – Immune mobilizing monoclonal TCRs Against X disease – designed to treat a broad range of diseases, including cancer, autoimmune, and infectious disease. Leveraging its proprietary, flexible, off-the-shelf ImmTAX platform, Immunocore is developing a deep pipeline in multiple therapeutic areas, including nine active clinical and pre-clinical programs​ in oncology, infectious diseases, and autoimmune diseases. The Company’s most advanced oncology TCR therapeutic, KIMMTRAK has been approved for the treatment of HLA-A*02:01-positive adult patients with unresectable or metastatic uveal melanoma in the United States, European Union, Canada, Australia, and the United Kingdom.

SOURCE: Immunocore