Immunocore (IMCR) Presents Net KIMMTRAK Data

Immunocore Holdings plc (Nasdaq: IMCR) presented updated clinical data from its clinical trials of KIMMTRAK (tebentafusp-tebn) in metastatic cutaneous melanoma (mCM) and metastatic uveal melanoma (mUM) at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting.

In a Phase 1b trial of tebentafusp in combination with checkpoint inhibitors in mCM, the maximum target doses of tebentafusp (68 mcg) plus durvalumab (20 mg/kg) were well tolerated. In mCM patients who progressed on prior anti-PD(L)1, tebentafusp with durvalumab continues to demonstrate promising overall survival (OS) (1-yr ~75%) compared to recent benchmarks (1-yr ~55%). Cutaneous and uveal melanoma both overexpress gp100, with greater than 80% of cutaneous melanoma tumor cells expressing gp100 by immunohistochemistry (IHC). The pattern of tumor shrinkage and its association with OS observed in mUM are replicated in this mCM study including 37% of patients with any tumor shrinkage of whom 89% lived at least 1-year. 58% of patients with any tumor increase were alive at 1-year, compared to 64% in the Phase 3 study in mUM. These data provide a rationale for a randomized study of tebentafusp monotherapy and in combination with an anti-PD1 in mCM, which the Company plans to start by year end.

“KIMMTRAK (tebentafusp-tebn) was designed to target gp100-positive melanoma, regardless of site of origin, tumor mutational burden or prior therapy. We remain encouraged by the similarities in clinical benefit for this Phase 1 study in metastatic cutaneous melanoma relative to our Phase 3 experience in uveal melanoma and look forward to starting a randomized trial in melanoma by year end,” stated David Berman, Head of Research and Development at Immunocore. “Additionally, we presented further analysis of KIMMTRAK, the first T cell receptor therapeutic to demonstrate an OS benefit in a randomized study versus investigator’s choice, on treatment beyond radiographic progression and the effect of the systemic corticosteroids on efficacy.”

In an analysis of the Phase 3 trial of tebentafusp, an OS benefit observed for tebentafusp among mUM patients who have initial radiographic progression demonstrates that radiographic assessment underestimates the benefit. In a post-hoc analysis of OS following initial radiographic progression, continued treatment with tebentafusp was associated with numerically longer OS even after adjusting for the difference in key prognostic variables. Tebentafusp treatment beyond progression was tolerated without new safety signals and, in some patients, was associated with radiological stabilization of target lesions for ≥ 4 months following the initial progression.

In another post hoc analysis of the Phase 3 trial, the vast majority patients treated with tebentafusp (84%) either did not require corticosteroids (74%) or only received them on a single day (10%). The most frequent reason for corticosteroid use was an emergent adverse event (AE), including CRS and rash. Corticosteroid use following the pre-specified AE guidelines was not associated with any significant impact on efficacy of tebentafusp.

Presentations and posters will be available for registered attendees on the ASCO website from June 3-7, 2022.

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About Uveal MelanomaUveal melanoma is a rare and aggressive form of melanoma, which affects the eye. Although it is the most common primary intraocular malignancy in adults, the diagnosis is rare, and up to 50% of people with uveal melanoma will eventually develop metastatic disease. Unresectable or metastatic uveal melanoma typically has a poor prognosis and had no approved treatment until KIMMTRAK.

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