Zenocutuzumab Achieves 30% Response Rate in NRG1 Fusion-Positive Solid Tumors, Receives FDA Approval
核心洞察
The Phase 2 eNRGy trial demonstrated zenocutuzumab's clinical efficacy with a 30% objective response rate and 11.1-month median duration of response in patients with NRG1 (搜索) fusion-positive solid tumors.
Pancreatic cancer patients showed particularly promising results with a 42% response rate and 9.2-month median progression-free survival, offering hope for this historically difficult-to-treat malignancy.
Zenocutuzumab received accelerated FDA approval as the first targeted therapy for NRG1 (搜索)-positive non-small cell lung cancer and pancreatic adenocarcinoma.
The Phase 2 eNRGy trial has demonstrated compelling clinical efficacy for zenocutuzumab, a bispecific antibody targeting HER2 (搜索) and HER3 (搜索), in patients with Neuregulin 1 (NRG1 (搜索)) fusion-positive solid tumors. The international study, published in The New England Journal of Medicine, showed a 30% objective response rate with a median duration of response of 11.1 months, leading to the drug's accelerated FDA approval as the first targeted therapy for this rare molecular subset.
Targeting a Rare but Actionable Fusion
NRG1 (搜索) fusions occur in less than 1% of solid tumors overall but are notably enriched in specific malignancies, including invasive mucinous adenocarcinomas of non-small cell lung cancer (NSCLC) and KRAS (搜索) wild-type pancreatic ductal adenocarcinoma. Unlike other driver fusions that form chimeric receptors, NRG1 fusion proteins function as ligands, driving oncogenic signaling by binding to HER3 (搜索) through their epidermal growth factor-like domain.
Zenocutuzumab (MCLA-128), marketed as Bizengri, operates through a unique "dock and block" mechanism. One arm of the bispecific antibody binds to HER2 (搜索) while the other binds to HER3 (搜索), preventing the interaction between NRG1 (搜索) and HER3 and inhibiting HER2-HER3 heterodimerization. This mechanism blocks downstream signaling pathways including PI3K-AKT (搜索) and MAPK (搜索) pathways that promote cell survival and proliferation.
Phase 2 Trial Results Show Broad Activity
The eNRGy trial enrolled 204 patients with confirmed NRG1 (搜索) fusion-positive solid tumors identified via next-generation sequencing. Of these, 158 patients had measurable disease and were followed for at least 24 weeks. The study population represented 10 different tumor types, with NSCLC comprising 58% and KRAS (搜索) wild-type pancreatic cancer accounting for 22% of participants.
The median age was 62 years, with 60% of participants being female. The most common NRG1 (搜索) fusion partners were CD74 (35%), SLC3A2 (14%), and ATP1B1 (11%). Notably, 91% of trial participants had received prior systemic therapies, including chemotherapy, immunotherapy, hormonal agents, and targeted treatments.
The primary endpoint showed an objective response rate of 30% (95% CI, 23-37%) with a median duration of response of 11.1 months (95% CI, 7.4-12.9 months). The median progression-free survival was 6.8 months (95% CI, 5.5-9.1 months). Tumor regression was observed in 72% of participants across multiple tumor types and NRG1 (搜索) fusion partners.
Pancreatic Cancer Shows Particularly Promising Results
Subpopulation analysis revealed notable differences between tumor types. Patients with NSCLC achieved an ORR of 29% and a PFS of 6.8 months (95% CI, 5.3-7.5 months). However, patients with pancreatic cancer exhibited a remarkable ORR of 42% and a median PFS of 9.2 months (95% CI, 5.5-11.2 months). These findings are particularly encouraging for pancreatic cancer, a historically difficult-to-treat tumor with limited therapeutic options.
Favorable Safety Profile
Treatment-related adverse events were reported in 95% of participants, but fewer than 10% were grade 3 or higher. Notably, cardiac toxicities, a known risk associated with HER2 (搜索)-targeting therapies, were only observed in a small number of cases and had no clinical impact on patient outcomes. This favorable tolerability profile supported the drug's regulatory approval.
Expanding Treatment Landscape
The success of zenocutuzumab has prompted development of additional therapies targeting the NRG1 (搜索)-HER3 (搜索) axis. Several HER3-targeting agents are currently under investigation, including monoclonal antibodies such as seribantumab, GSK2849330, and HMBD-001, as well as antibody-drug conjugates like patritumab deruxtecan. Early data from the CRESTONE trial reported a 36% ORR with seribantumab in patients with NRG1 fusion-positive solid tumors.
Additionally, the Phase 2 TAPUR basket study showed that afatinib, a pan-ERBB inhibitor, exhibited clinical activity in three patients with NRG1 (搜索) fusion-positive tumors, including lung, colorectal, and pancreatic tumor types, though larger cohort studies are needed to confirm its efficacy.
Future Research Directions
While the clinical response to zenocutuzumab has been encouraging, several challenges remain. The mechanisms driving primary and secondary resistance are poorly understood, and elucidating these pathways could inform the development of rational combination therapies. Although NRG1 (搜索) fusions are found in multiple tumor types, zenocutuzumab has only received FDA approval for NSCLC and pancreatic adenocarcinoma, unlike tumor-agnostic agents such as larotrectinib and entrectinib for NTRK (搜索) fusion-positive tumors.
Zenocutuzumab has also shown activity in cholangiocarcinoma, breast cancer, and other tumor types, but the limited number of patients with these cancers in the trial makes it difficult to draw definitive conclusions. Expanded studies with larger cohorts are needed to further evaluate its efficacy across other tumor types.
Reliable detection of NRG1 (搜索) fusions remains a critical challenge for patient selection, particularly with non-invasive liquid biopsy approaches. Advancements in diagnostic technologies, such as nanopore sequencing, could enhance the accuracy of fusion detection, enabling better patient stratification and dynamic monitoring of fusion expression during treatment.