Incyte Advances KRAS G12D Inhibitor to Phase 3 Despite Fatal Pneumonitis and European Clinical Hold
Key Insights
Incyte's KRAS G12D (search) inhibitor INCB161734 remains on clinical hold in four European countries following a fatal grade 5 pneumonitis (search) case at the 1.2g daily dose.
Despite ongoing safety concerns, Incyte has launched the pivotal Dawn-03 phase 3 trial evaluating INCB161734 plus chemotherapy in first-line KRAS G12D (search)-mutant pancreatic cancer (search).
The company's second KRAS G12D (search) inhibitor INCB186748 prematurely ended recruitment after enrolling only 30 of 308 planned patients in its first-in-human study.
Incyte Corporation has moved its KRAS G12D (search) inhibitor INCB161734 into pivotal development with the launch of the Dawn-03 phase 3 trial, despite the drug remaining on clinical hold in four European countries following a fatal pneumonitis (search) case. The regulatory action represents a significant setback for what had initially appeared to be a promising oncology asset.
Fatal Pneumonitis Triggers European Clinical Hold
The clinical hold was implemented by Spain, Belgium, Italy, and France after a patient receiving 1.2g daily of INCB161734 died from grade 5 pneumonitis (search). Following this fatality, Incyte conducted a comprehensive review of approximately 300 other enrolled patients, which revealed three additional cases of confirmed or suspected pneumonitis, all associated with the same 1.2g dose that the company had previously identified as the optimal go-forward dose.
Notably, three of the four pneumonitis (search) cases occurred in cohorts receiving INCB161734 in combination with chemotherapy, while one case involved monotherapy treatment. The European Union registry indicates that while the clinical hold is described as "temporary," patients already enrolled in the study can continue receiving the investigational drug.
Contrast with Earlier Promising Data
The safety concerns represent a stark departure from the positive initial data presented at the European Society for Medical Oncology (ESMO) conference. At that time, INCB161734 demonstrated a 34% response rate at the 1.2g dose, which Dr. Ignacio Garrido-Laguna of the University of Utah described as "remarkable."
Among the 67 patients who received the 1.2g dose in the initial analysis, treatment-related adverse events of grade 3 or higher were limited to isolated cases of nausea, diarrhea, decreased appetite, and two instances of increased lipase. No "additional AEs of significance" were noted in the earlier safety profile.
Dawn-03 Phase 3 Trial Launches
Despite the ongoing European clinical hold, Incyte has initiated the Dawn-03 pivotal trial, which is already recruiting patients according to clinicaltrials.gov. The study represents an unusual leap directly from phase 1 to phase 3 development, bypassing the traditional phase 2 stage.
Dawn-03 is designed to evaluate INCB161734 in combination with chemotherapy versus chemotherapy alone as first-line treatment for patients with KRAS G12D (search)-mutant pancreatic cancer (search). The trial's primary endpoints include overall survival, progression-free survival, and overall response rate.
The registry entry does not specify the dose that will be used in the pivotal study, though it is presumed to be the same 1.2g daily dose associated with the safety concerns. This raises questions about risk mitigation strategies, particularly given that three of the four pneumonitis (search) cases occurred in chemotherapy combination cohorts—the same treatment regimen being investigated in Dawn-03.
Second KRAS G12D Asset Also Encounters Problems
Incyte's challenges in KRAS G12D (search) inhibition extend beyond INCB161734. The company's second asset in this space, INCB186748, appears to have prematurely concluded its first-in-human trial. While Incyte has not disclosed the mechanism of action for INCB186748, its targeting of KRAS G12D-mutated solid tumors suggests it is another G12D inhibitor, potentially a follow-up version of INCB161734.
The INCB186748 study, which began a year ago with a target enrollment of 308 patients, changed status from "recruiting" to "active, not recruiting" after enrolling only 30 subjects—representing just 10% of the planned recruitment target. The timeline of this recruitment halt occurred months before INCB161734 went on clinical hold, suggesting separate underlying issues rather than a precautionary measure related to the pneumonitis (search) cases.
Unanswered Questions
Critical questions remain regarding the safety profile of INCB161734, particularly concerning which tumor types or patient subgroups might be at highest risk for pneumonitis (search). The phase 1 study enrolled patients with diverse solid tumors including pancreatic ductal adenocarcinoma (search), colorectal cancer (search), non-small cell lung cancer (search), and ovarian cancer (search), but it remains unclear whether any of the patients who experienced serious toxicity had pancreatic cancer (search) specifically.
Incyte has not issued public statements regarding the clinical hold or the nature of the adverse events, leaving the medical community without clarity on what additional precautions, if any, will be implemented in the phase 3 setting to mitigate pneumonitis (search) risk.