v3.26.1
Segments
 6 Months Ended
Jun. 30, 2026
Segment Reporting [Abstract]  
Segments Segments
As a single reportable segment entity, the Company’s segment performance measure is consolidated net loss. Asset information is not used by the Company’s President and Chief Executive Officer, its chief operating decision maker (“CODM”) to allocate resources. Certain significant segment expenses below loss from operations are presented in the Company’s consolidated statements of operations and are therefore not presented below. Additional disaggregated significant segment expenses on a functional basis, that are not separately presented on the Company’s condensed consolidated statements of operations, are presented below (in thousands):
Three months ended
June 30,		Six months ended
June 30,
2026202520262025
Personnel expenses excluding stock-based compensation$6,019 $5,685 $12,268 $11,468 
Stock-based compensation expenses3,554 2,005 6,378 3,973 
Direct external program expenses:
ALTO-1002,044 1,501 3,808 2,625 
ALTO-3001,754 653 3,261 1,575 
ALTO-1011,874 893 7,230 1,862 
ALTO-20354 599 60 1,336 
ALTO-2076,744 358 10,887 358 
Other research and development expenses (a)
3,182 4,050 4,380 5,179 
General and administrative expenses (b)
3,904 2,938 7,995 5,982 
Loss from operations$29,129 $18,682 $56,267 $34,358 
(a) Other research and development expenses primarily consists of license fees, facility charges, third party consultant costs, early research costs related to other product candidates, and other unallocated costs.
(b) General and administrative costs include professional fees, insurance, consultant fees and facility charges.