The FDA has released its final recommendation on how to optimally design cancer drug trials that include patients with central nervous system (CNS) metastases.1
The guidance, entitled, "Evaluating Cancer Drugs in Patients with Central Nervous System Metastases; Guidance for Industry," details important considerations for trials involving systemic therapies for this patient population should the agent's label describe antitumor activity in the CNS. Further considerations referenced in the guidance include ideal patient populations, available therapies, and prior therapies, as well as noting that trial designs need to take prior therapies into consideration and better plan for assessing CNS metastases.
The preferred modality cited by the guidance is baseline and periodic MRI imaging with gadolinium contrast. Additionally, RECIST 1.1, Response Assessment in Neuro-Oncology - Brain Metastases, should be utilized for standard response criteria evaluation for patients with CNS metastases, according to the guidance.
The guidance also details appropriate end points for studies featuring patient populations with CNS metastases and discusses the optimal way in which leptomeningeal disease should be addressed. Notably, leptomeningeal disease is considered to be a disease of the entire CNS compartment by the FDA. It also assesses updates and suggestions that were given during the comment period while the document was being drafted.
Additional updates detailed in the final guidance elucidate the optimal number of stratification factors that should be included in CNS clinical trials to minimize bias, as well as detailing that duration of CNS and systemic response to treatment need to be tracked by clinical trial investigators. The final version of the document featured an additional 6-month time period, as well as the addition of progression-free survival for patients who have brain metastases when CNS is a common metastatic site.
1. Evaluating cancer drugs in patients with central nervous system metastases; guidance for industry. Federal Registrar. 2021;86(125):35305-35306.