BAL0891 in Patients With Advanced Solid Tumors or Relapsed or Refractory Acute Myeloid Leukemia

This study is a multiple cohort, multicenter, open-label Phase 1 study with dose-escalation substudies investigating intravenous (IV) BAL0891 as monotherapy, and in combination with tislelizumab or paclitaxel, to determine the safety and tolerability of increasing doses of BAL0891 in patients with advanced solid tumors or relapsed or refractory acute myeloid leukemia. An adaptive model-based design will be used to guide the dose escalation. Subject assignment to Substudy 1, 2, 3 and 4 will be finalized following approval from the investigator and sponsor. The dose-expansion stage will be conducted with the RP2D to further evaluate the preliminary anti-tumor activity, safety, and tolerability in metastatic TNBC and GC.

Substudy 1 (monotherapy dose-escalation cohorts) This study will be initiated with enrollment into Substudy 1 and will estimate the safety, tolerability, PK, and PD of increasing doses of BAL0891 in patients with advanced solid tumors. The starting dose will be 5 mg based on the GLP (Good Laboratory Practice) toxicology studies. Dose escalation will comprise a dose range from a dose of 5 mg up to a maximum absolute dose of 480 mg, with eight nominal dose levels (DLs) of 5 / 10 / 20 / 40 / 80 / 160 / 320 / 480 mg. Intra-patient dose escalations are only allowed for patients enrolled in single-patient DL Cohorts 1.1, 1.2, and 1.3. From DL Cohort 1.4 onwards, the projected maximum dose-escalation factor will be two-fold; if the DL cohort investigates an increased dose, dosing of the patients within the cohort must be separated by at least 7 days. For cohorts in which doses are not increased (including backfill enrollment), patients may be enrolled concurrently. BAL0891 will be administered intravenously (IV) on Day (D) 1 and D8 every 3 weeks (Q3W); for the schedule of assessments of Regimen A. Alternative 21-day or 28-day dosing regimens may be investigated; for the schedule of assessments of Regimens B-D. Substudies 2 and 3 (dose-escalation cohorts for combination regimens) Enrollment into Substudies 2 and 3 may commence as early as first signs of expected target toxicity and/or efficacy with Regimen A (or an alternative monotherapy regimen) have been observed, or alternatively, once the MTD of BAL0891 monotherapy has been assessed. Patients enrolled into Substudies 2 and 3 will be treated with increasing doses of BAL0891 in combination with tislelizumab or paclitaxel, respectively, and dose escalation of both BAL0891 and tislelizumab/paclitaxel if required will use the same cumulative BLRM-EWOC model as Substudy 1. The starting dose of BAL0891 in combination with tislelizumab or paclitaxel will be a safe DL determined in Substudy 1 but not higher than approximately half the MTD. Backfill enrollment of up to a total of 30 additional patients for both substudies (who may be enrolled concurrently) may be used to better estimate the RP2D for each combination if required. Substudy 4 (dose escalation cohort for monotherapy in r/r AML) Substudy 4 will evaluate BAL0891 monotherapy in patients with relapsed/refractory AML (r/r AML) using the same BLRM-EWOC model and study design described for Substudy 1. BAL0891 will be administered intravenously on Day 1 and Day 8 every three weeks (Regimen A; see Table 13 for schedule of assessments). Dose exploration will proceed until the highest planned dose level (DL) is determined to be safe and tolerable, or the MTD/RP2D is identified. Each DL cohort will enroll three patients, with DLT observation required before advancing to the next DL. From DL2 onward, the projected maximum dose-escalation factor will be two-fold, with concurrent enrollment allowed for cohorts without dose increases. Backfill enrollment may be conducted to refine the RP2D and further characterize safety, efficacy and PD. Part 2 : Dose expansion The commencement of the dose expansion stage will follow the determination of the RP2D achieved during the dose-escalation phase. This stage will consist of four cohorts, each comprising 24 patients who have previously undergone at least one systemic regimen for advanced or metastatic disease. Specifically, two cohorts will be allocated for TNBC, investigating BAL0891 both as a monotherapy and in combination with Paclitaxel. Additionally, two cohorts will be designated for GC, investigating the outcomes of BAL0891 as a monotherapy and in combination with Paclitaxel.