Innovent Biologics' IBI363, a PD-1/IL-2α bispecific antibody fusion protein, has received Fast Track designation from the FDA for the treatment of unresectable locally advanced or metastatic melanoma in patients who have progressed following at least one line of systemic therapy, including a PD-(L)1 inhibitor. This designation seeks to expedite the development and review of IBI363, addressing a critical unmet need for patients with melanoma who have failed immunotherapy.
The Fast Track designation is designed to accelerate the development and review of drugs that treat serious conditions and fill unmet medical needs. Innovent Biologics, as the sponsor, will benefit from more frequent communication with the FDA and potential eligibility for priority review and accelerated approval, contingent upon meeting specific criteria.
Hui Zhou, MD, Senior Vice President of Innovent Biologics, stated, “Despite the success of immune checkpoint inhibitors in the treatment of melanoma, there is currently no drug approved for immunotherapy-failed melanoma around the world… Therefore, there is an urgent clinical need for patients who have previously failed immunotherapy.”
Clinical Efficacy of IBI363
Data supporting the Fast Track designation were presented at the European Society of Medical Oncology Virtual Plenary in June 2024. The phase 1/2 study (NCT04085185) evaluated IBI363 in solid tumors, with a cohort of 37 melanoma patients previously treated with immunotherapy receiving 1 mg/kg of IBI363. Results showed an objective response rate (ORR) of 29.7%, with 1 complete response (CR) and 10 partial responses (PRs). The disease control rate (DCR) was 73.0%.
In a subgroup of 8 treatment-naive mucosal melanoma patients, IBI363 demonstrated even more promising results, with an ORR of 75.0% (1 CR and 5 PRs) and a DCR of 100%.
Zhou noted the significance of these findings, stating, “IBI363 has demonstrated strong antitumor effects, which could potentially be the next breakthrough in this area. Moreover, a promising efficacy signal was shown in [immuno-oncology (IO)]-naive mucosal melanoma, a relatively 'cold' tumor, which brings us great confidence in the next step to expand the IO-naive population and also indicates the broad application potential of IBI363.”
Mechanism of Action
IBI363 is a first-in-class PD-1/IL-2α-bias bispecific antibody fusion protein independently developed by Innovent Biologics. It functions by blocking the PD-1/PD-L1 pathway and activating the IL-2 pathway. The IL-2 arm of IBI363 is modified to retain its affinity for IL-2Ra while weakening its binding ability to IL-2Rβ and IL-2Rγ, thereby reducing toxicity. The PD-1 binding arm simultaneously blocks PD-1 and selectively delivers IL-2. This differential strategy allows for more precise and effective targeting and activation of tumor-specific T cells, which express both PD-1 and IL-2a.
Melanoma Treatment Landscape
Melanoma, a malignant tumor arising from melanocytes, is the fifth most common cancer in the United States. While it accounts for only 3% of all skin cancers, it has the highest mortality rate and is prone to metastasis. In China, the incidence and mortality rates of melanoma are also increasing. Current treatment options for advanced melanoma include BRAF/MEK inhibitors for BRAF V600 mutation-positive cases, chemotherapy combined with anti-angiogenic drugs, and immunotherapy. However, options are limited for patients who progress on these therapies, highlighting the need for novel agents like IBI363.
