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ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)
 3 Months Ended 12 Months Ended
Oct. 03, 2023
Mar. 31, 2024
Mar. 31, 2023
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Accounting Policies [Line Items]              
Cash, cash equivalents, and marketable securities       $ 39,500,000 $ 41,400,000    
Milestone payment received     $ 12,000,000.0 (3,178,066) 27,448,531    
Gross proceeds from sale of common stock       25,515,349 4,803,534    
Revenue recognized under "ERC"       191,463   $ 191,199  
Receivables under "ERC"       366,551   $ 738,778 $ 738,778
Depreciation       1,068,882 533,131    
Grant income       0 0    
Tax credit carryforward amount       50,700,000      
Research and development       36,448,039 21,816,949    
Comprehensive loss       22,156,973 28,914,288    
Long-lived assets impairment       0 0    
Interest and penalties related to unrecognized tax benefits       0 $ 0    
Registered Direct Offering [Member]              
Accounting Policies [Line Items]              
Gross proceeds from sale of common stock $ 23,000,000.0            
Domestic Country              
Accounting Policies [Line Items]              
Operating loss carryforwards       $ 106,900,000      
Operating loss carryforwards expiration year       2027      
Tax credit carryforward limitations on use       The post December 31, 2017 net operating losses generated of approximately $56.2 million will carryforward indefinitely, but may be subject to an 80% limitation upon utilization.      
Operating loss carry forwards indefinitely       $ 56,200,000      
State and Local Jurisdiction              
Accounting Policies [Line Items]              
Operating loss carryforwards       $ 147,300,000      
Operating loss carryforwards expiration year       2028      
General Business              
Accounting Policies [Line Items]              
Tax credit carryforward amount       $ 3,700,000      
Operating loss carryforwards expiration year       2035      
Research Tax Credit Carryforward              
Accounting Policies [Line Items]              
Tax credit carryforward amount       $ 6,200,000      
Tax credit carry forwards expiration Year       2027      
Research Tax Credit Carryforward | California              
Accounting Policies [Line Items]              
Tax credit carryforward amount       $ 2,200,000      
Warrant              
Accounting Policies [Line Items]              
Antidilutive securities       13,268,807 5,882,621    
Commercialization and Distribution Agreement with Nippon Shinyaku Co, Limited, Japan              
Accounting Policies [Line Items]              
Milestone payment received   $ 10,000,000.0          
Minimum              
Accounting Policies [Line Items]              
Estimated useful lives (in years)       5 years      
Maximum              
Accounting Policies [Line Items]              
Estimated useful lives (in years)       7 years