Why Is Blood Cancer-Focused Shattuck Labs Stock Soaring Today?

Shattuck Labs Inc STTK announced initial topline dose-expansion data from its ongoing Phase 1A/B trial of SL-172154 in combination with Azacitidine (AZA) in frontline high-risk myelodysplastic syndromes (HR-MDS) and TP53 mutant (TP53m) acute myeloid leukemia (AML) patients.

The study observed an Objective Response Rate (ORR) of 79% in frontline HR-MDS patients, primarily with TP53 mutations, with an initial complete response (CR)/marrow complete response (mCR) rate of 64%.

Observed 27% initial CR/complete response with incomplete hematologic recovery (CRi) in frontline TP53m AML patients, and 5/11 evaluable patients achieved stable disease with decreasing blast counts and peripheral blood count improvement.

• HR-MDS: In 14 evaluable patients with previously untreated HR-MDS (13 of whom had TP53m or deletion), five patients achieved a CR. Four patients achieved a mCR (3 with hematologic improvement in at least one lineage), and two patients achieved stable disease (both with hematologic improvement in at least one lineage). 
• TP53m AML: In 11 evaluable patients with previously untreated TP53m AML, two patients achieved a CR. Another patient achieved a CRi and was taken to allogeneic hematopoietic cell transplantation (allo-HCT). 
• Seven additional subjects with stable disease had blast reductions, five of which had recovery of platelets or neutrophils and remain on study, and their response may improve. One subject died during the first cycle.

Safety: Preliminary data suggest that SL-172154 has an acceptable safety and tolerability profile in combination with azacitidine.

• Early signals of activity, in the form of rapid blast count reductions, were observed in 100% of frontline TP53m AML patients treated with SL-172154 in combination with AZA who received an on-treatment bone marrow biopsy.
• Most patients in the HR-MDS cohort showed blast count reductions with hematologic improvement early in the treatment course.

Price Action: STTK shares are up 91.3% at $4.03 on the last check Wednesday.