The aim of this clinical trial is to evaluate the safety, preliminary effectiveness, and pharmacokinetic profiles of SM-1 (Obitrexate Fumarate Enteric-coated Pellet Capsules) combined with temozolomide, and conduct systematic dose exploration for the treatment of refractory or recurrent high-grade gliomas in adult patients. The core focus is to screen the optimal clinical dose regimen of SM-1, fully monitor adverse reactions, and preliminarily observe the anti-tumor efficacy of the combination regimen. The main questions it aims to answer are:
* What is the safety profile and tolerability of different dose cohorts of SM-1 in combination with temozolomide in patients with refractory or recurrent high-grade gliomas?
* What are the pharmacokinetic characteristics of SM-1 across different dose levels, supporting accurate dose optimization for subsequent clinical medication?
* Can the optimized SM-1 combined regimen exert preliminary anti-tumor effectiveness in patients with refractory or recurrent high-grade gliomas, and confirm the recommended Phase II dose? Researchers will enroll eligible patients and assign them to different gradient dose groups of SM-1 for dose-escalation exploration, match with standardized temozolomide combination therapy, comprehensively collect full-cycle safety data, and preliminarily evaluate the clinical anti-tumor efficacy of different dose combinations to determine the optimal safe and effective therapeutic dose for subsequent large-scale clinical trials.