Though Pyxis Oncology Inc.’s preliminary phase I data with antibody-drug conjugate (ADC) PYX-201 in solid tumors were characterized as positive, findings sent the Boston-based firm’s stock (NASDAQ:PYXS) into a tailspin. Shares dropped from $3.82 to $2.01 between Nov. 20 and the morning of Nov. 21, even as experts along with Wall Street agreed that the compound shows particular promise in head and neck squamous cell carcinoma – a space where developers aplenty remain busy.