Novel Bispecific Antibody XmAb30819 Shows Promise in Advanced Clear Cell Renal Cell Carcinoma
核心洞察
XmAb30819, a novel 2+1 bispecific T-cell engager targeting ENPP3 (搜索) and CD3 (搜索), demonstrates initial antitumor activity in patients with advanced clear cell renal cell carcinoma (搜索) in an ongoing phase 1 trial.
The agent selectively targets ENPP3 (搜索), a protein highly expressed in 93% of clear cell RCC tumors but minimally present in normal tissues, offering a promising new mechanism of action.
Preliminary safety data shows manageable cytokine release syndrome with treatment durations exceeding one year in several patients, supporting continued dose escalation.
A novel bispecific T-cell engager targeting a protein highly expressed in kidney cancer cells is showing early promise in treating patients with advanced clear cell renal cell carcinoma (搜索) (RCC), according to data from an ongoing phase 1 clinical trial. XmAb30819, developed by Xencor, represents a new therapeutic approach for patients who have exhausted standard treatment options.
Targeting ENPP3 in Kidney Cancer
XmAb30819 is designed as a humanized ENPP3 (搜索) × CD3 (搜索) bispecific T-cell engager (BiTE) with a unique 2+1 configuration. The agent utilizes two binding sites for ENPP3 and one site that binds CD3, bringing T cells into close proximity with cancer cells to create a cytotoxic response.
"ENPP3 (搜索) is an extracellular protein that has been found to be uniquely expressed in kidney cancer cells, making it an attractive target for kidney cancer, in particular clear cell, but also papillary kidney cancer (搜索) and some other solid tumors such as colorectal cancer (搜索)," explained Randy F. Sweis, MD, assistant professor of medicine at the University of Chicago Medicine (搜索).
The target protein shows high expression rates in clear cell kidney cancer but low levels of expression in the gut and other normal tissues. According to Karie Runcie, MD, assistant professor of medicine at Columbia University Medical Center, this differential expression pattern addresses a key challenge in developing bispecific T-cell engagers for solid tumors.
"One of the challenges in finding novel targets for [the treatment of patients with] solid tumors, especially with bispecific T-cell engagers is finding a target that's specific to the cancer molecule that's not expressed widely in normal tissue [so that] you can elicit a strong, targeted response," Runcie noted.
Preclinical Evidence and Trial Design
Preclinical studies demonstrated that XmAb30819 was well tolerated and showed dose-dependent pharmacodynamics in nonhuman primates. The agent displayed selective killing of cells with high ENPP3 (搜索) expression in vitro and reduced median tumor volume over time in xenograft mice tumor models of clear cell RCC compared with phosphate-buffered saline and an anti-PD-1 (搜索) monoclonal antibody.
At day 18, increasing doses of XmAb30819 led to a significant reduction in tumor volume compared with control treatments (P < .05).
The ongoing first-in-human phase 1 trial (NCT05433142) is enrolling adult patients with advanced clear cell RCC who experienced disease progression following standard therapies. Eligible patients must have measurable disease per RECIST 1.1 criteria and an ECOG performance status of 0 or 1.
The study includes both dose escalation and expansion phases, evaluating subcutaneous and intravenous administration routes. During the dose escalation phase, patients receive a priming dose, step-up priming dose(s), and the minimum safe and biologically active dose.
Early Clinical Results
Preliminary data from the phase 1 study revealed that XmAb30819 displayed initial evidence of antitumor activity in patients with clear cell RCC, including responses per RECIST 1.1 criteria. Treatment duration for several patients in earlier dose cohorts exceeded one year.
The safety profile has been encouraging, with manageable instances of cytokine release syndrome. The maximum tolerated dose has not been reached, and the tolerability profile continues to support dose escalation.
"The point of having 2 binding sites for ENPP3 (搜索) is to try and home in on that target and have a strong specificity for that molecule," Runcie explained regarding the agent's unique design.
Addressing Unmet Medical Need
The development of XmAb30819 addresses a significant gap in treatment options for patients with advanced RCC. While combination immunotherapy approaches have substantially improved outcomes over the past decade, limited options exist for patients who progress after VEGF (搜索) tyrosine kinase inhibitor therapy and prior anti-PD-1 (搜索) therapy.
"In RCC, we've had a tremendous advancement in the life expectancy and PFS with combination immunotherapy approaches over the past 10 years," Sweis noted. "However, when patients progress after VEGF (搜索) TKI therapy and prior anti-PD-1 (搜索) therapy, with or without [anti]-CTLA4, there aren't great options. We cycle through different TKIs in the refractory space, but drugs with a novel mechanism of action are an unmet need and I believe that [XmAb30819] provides that."
Future Development Plans
Xencor plans to share full initial data from the phase 1 study at a medical conference during the fourth quarter of 2025. The company is evaluating different dosing routes and plans to expand into a larger cohort of RCC patients once an optimal dosing strategy is established.
Beyond clear cell RCC, the development program may extend to other tumor types. Papillary RCC also expresses ENPP3 (搜索), and other solid tumors including colorectal cancer (搜索) and non-small cell lung cancer represent potential future indications.
"We're looking at different dosing routes, but once we select a dosing route and dose that we believe will be beneficial, we will expand into a larger cohort of [patients with] RCC," Sweis said. "Ultimately, the goal is to bring this [drug] to other tumor types as well."
Competitive Landscape
XmAb30819 is not the only ENPP3 (搜索)-directed agent in development. JNJ-87890387, another ENPP3 × CD3 (搜索) BiTE developed by Johnson & Johnson, is also being evaluated in a phase 1 first-in-human study (NCT06178614) for patients with advanced solid tumors.
Preclinical data for JNJ-87890387 showed high ENPP3 (搜索) prevalence in clear cell RCC (93%) and papillary RCC (78%), as well as other solid tumors including lung adenocarcinoma (搜索) and colorectal carcinoma.
"It's exciting that there are multiple companies exploring this pathway and this [will] give our patients more options," Runcie concluded.