Mabwell (688062.SH), an innovation-driven biopharmaceutical company with a fully integrated industrial chain, announced that a recent clinical case report on its self-developed novel Nectin-4 ADC (bulumtatug fuvedotin, R&D code: 9MW2821) for the treatment of cervical cancer has been published in The New England Journal of Medicine (NEJM, Impact Factor: 78.5), a leading international medical journal.

The article, published by the team of Dr. Wang Shanbing, Director of the Oncology Center at the Second People's Hospital of Yibin, reveals for the first time globally a rare case of hepatic "pseudoprogression" phenomenon observed in a patient with advanced cervical cancer following treatment with the novel Nectin-4 ADC (9MW2821). Pseudoprogression generally refers to a phenomenon where existing lesions temporarily enlarge or new lesions appear early in immunotherapy, without clinical deterioration, followed by subsequent stabilization or shrinkage—typically not representing true tumor progression.

This article reports the case of a patient with metastatic cervical squamous-cell carcinoma whose disease was refractory to platinum–taxane chemotherapy with no prior immunotherapy. After just two cycles of treatment with 9MW2821, the patient's baseline metastatic lesions showed substantial regression, and serum squamous cell carcinoma (SCC) antigen levels dropped precipitously—from 37.0 ng/mL to 1.2 ng/mL (normal range ≤1.5). However, despite comprehensive improvement across multiple indicators, a CT scan unexpectedly revealed a "new hypoattenuating lesion " measuring 1.8 cm × 2.5 cm in the medial segment of the left lobe of the liver. A liver biopsy showed dense infiltration of lymphocytes, plasma cells, and neutrophils, with no evidence of granulomas, spindle cell proliferation, or viable tumor cells. The biopsy results ruled out disease progression, sarcoid-like reactions, or inflammatory pseudotumor. Given the patient's p16-positive status (implying high HPV antigenicity) and the absence of previous immunotherapy, Dr. Wang Shanbing's team hypothesized that the antibody-drug conjugate (ADC) targeted occult micrometastases, inducing immune-cell death and releasing damage-associated molecular patterns that triggered this robust inflammatory influx. The patient continued treatment, and subsequent imaging showed gradual resolution of the liver lesion, with no reappearance during two years of follow-up.

ADCs are hailed as "magic bullets" for precisely targeting tumors. Previously, pseudoprogression has been predominantly observed in immunotherapies such as PD‑1/PD‑L1 inhibitors, whereas its occurrence in ADC therapy for solid tumors is considered exceedingly rare. This finding by Dr. Wang Shanbing's team carries significant implications for the clinical management of advanced cervical cancer. The article strongly emphasizes that treatment that could prolong life should not be prematurely discontinued based solely on radiographic "false impressions," providing a valuable reference for the clinical application of ADCs and safeguarding optimal therapeutic benefits for oncology patients.

9MW2821 is the world's first Nectin-4 ADC candidate to enter Phase III clinical trials for cervical cancer. Currently, enrollment for the monotherapy Phase III trial has been completed. Interim analysis is expected to be conducted and pre-NDA to be submitted in H2 2026. The first-line combination study with toripalimab is in Phase II.