Adagene presents data on ADG126 at SITC Annual Meeting

Adagene (ADAG) announced data at the SITC 39th Annual Meeting, taking place in Houston, Nov. 6 – 10, 2024. The two poster presentations provide new insights on the increased therapeutic index for ADG126 and reinforce its clinical safety and efficacy profiles in combination with pembrolizumab including in advanced Metastatic Microsatellite-stable Colorectal Cancer. In the first poster, Deciphering Improved Clinical Therapeutic Index of Muzastotug, a Masked Anti-CTLA-4 SAFEbody over its Unmasked Form as Monotherapy or in Combination with anti-PD-1 Therapy , data demonstrate how the improved TI of ADG126 allows for higher and repeat dosing to unleash its efficacy to the maximum potential, while maintaining an improved safety profile. Analyses of the masked ADG126 SAFEbody and its unmasked version, ADG116, show the improved TI relative to commercially available anti-CTLA-4 therapies via enhanced epitope-dependent ADCC and T cell priming. By targeting the constitutively over-expressed CTLA-4 on T regulatory cells in the tumor microenvironment for potent CTLA-4 mediated intratumoral Treg depletion, ADG126 achieves tumor-specific targeting with minimal on-target off-tumor toxicities. Key highlights include: The unique epitope of ADG126 and its activated form drives species cross-reactivity enabling the same antibody to be used across mice, monkey and human studies, with a unified set of physiologically relevant parameters for population pharmacokinetic modeling. Analyses show a significantly higher and sustained steady state tumor-specific engagement of CTLA-4 with the masked ADG126, suggesting increased exposure in the TME and a stronger ADCC effect. New analyses show the seamless translation of preclinical PK analyses to clinical PK data, including: head-to-head comparison of ADG126 to ipilimumab in MC38 mice, a single dose of ADG126 showed a three-fold increased active drug exposure in homogenized tumor tissue samples at 10 mg/kg versus a single dose of ipilimumab at 1 mg/kg while maintaining similar plasma active drug exposures. A second analysis in the MC38 mice model showed two consecutive doses of ADG126 at 20 mg/kg increased the tumor cleaved and total PK versus a single dose, demonstrating continuous intratumoral cleavage of intact ADG126 and accumulation within the TME. This reflects the effectiveness of ADG126 repeat dosing to increase drug exposure within the TME, supporting its mechanism with CTLA-4 mediated intratumoral Treg depletion. The second poster, Phase 1b/2, Multicenter Dose Escalation and Expansion Study of Muzastotug in Combination with Pembrolizumab in Advanced/Metastatic MSS CRCs, presents additional follow up data from an ongoing trial showing the best-in-class therapeutic potential of ADG126 in combination with anti-PD-1 therapy in patients with the most common form of colorectal cancer, MSS CRC. The trial, conducted in patients with advanced MSS CRC without liver metastases, showed that ADG126 administered at 10 mg/kg Q6W or Q3W in combination with pembrolizumab demonstrated an encouraging efficacy signal, durable disease control and an early survival benefit in MSS CRC patients, with dose-dependent efficacy and objective responses per RECIST criteria observed for the Q3W schedule. New findings in the poster at SITC 2024 include: In MSS CRC patients, a lower rate of key TRAEs with ADG126 at the 10 mg/kg dosing level in combination with pembrolizumab relative to lower doses of 1-2 mg/kg of an Fc engineered anti-CTLA-4 antibody in clinical development when used in combination with anti-PD-1. Clinical PK, particularly the monitoring of active species of ADG126 in peripheral blood, supports long-term safety of the combination therapy. The rate of Grade 3 and higher TRAEs for ADG126 in combination with pembrolizumab was also shown to be much lower than historically reported with currently approved standard of care combinations. In the combination cohort, there was no Grade 3 or higher colitis, which is common with other anti-CTLA-4 therapies. A case study of one responder who received two prior lines of therapy before receiving ADG126 in combination with pembrolizumab showed an 80% decrease in target lesions. This confirmed partial response correlated with a 100% decrease in carcinoembryonic antigen levels versus baseline. Individualized PK data also demonstrated the correlation of tumor shrinkage and plasma exposure. After five cycles, the patient experienced TRAEs, after which dosing was modified and treatment resumed, showing durable clinical benefit for over 12 months. This response is one of four PRs reported from the ongoing 10 mg/kg Q3W combination cohort of MSS CRC patients without liver metastases. Repeat doses of ADG126 10 mg/kg in combination with pembrolizumab shows encouraging dose-dependent clinical efficacy and well-tolerated safety in accordance with plasma cleaved ADG126 concentrations. These data support that ADG126 may be a potential best-in-class anti-CTLA-4 and may be considered as a backbone therapy. Follow up continues for MSS CRC patients treated with ADG126 10 mg/kg doses in combination with pembrolizumab. In addition, Adagene is evaluating a single dose of ADG126 at 20 mg/kg followed by a 10 mg/kg Q3W maintenance dose in combination with pembrolizumab in a cohort of 12 enrolled patients with data expected in 2025.