APTO-253 Induces KLF4 to Promote Potent in Vitro Pro-Apoptotic Activity in Hematologic Cancer Cell Lines and Antitumor Efficacy As a Single Agent and in Combination with Azacitidine in Animal Models of Acute Myelogenous Leukemia (AML)
Bibliographic record
Abstract
Abstract APTO-253, a small molecule that mediates anticancer activity through induction of the Krüppel-like factor 4 (KLF4) tumor suppressor, is being developed clinically for the treatment of acute myelogenous leukemia (AML) and high risk myelodysplastic syndromes (MDS). APTO-253 was well tolerated in a Phase I study in patients with solid tumors using a dosing schedule of days 1, 2, 15, 16 of a 28 day cycle (2T-12B-2T-12B), but recent scientific observations guided APTO-253 toward AML and high risk MDS. Indeed, suppression of KLF4 was reported as a key driver in the leukemogenesis of AML and subsets of other hematologic diseases. The vast majority (~90%) of patients with AML aberrantly express the transcription factor CDX2 in human bone marrow stem and progenitor cells (HSPC) (Scholl et al., J Clin Invest. 2007, 117(4):1037-48). The CDX2 protein binds to CDX2 consensus sequences within the KLF4 promoter, thereby suppressing KLF4 expression in HSPC (Faber et al., J Clin Invest. 2013, 123(1):299-314). Based on these observations, the anticancer activity of APTO-253 was examined in AML and other hematological cancers. APTO-253 showed potent antiproliferative activity in vitro against a panel of blood cancer cell lines, with ηM IC50values in AML (6.9 - 305 ηM), acute lymphoblastic leukemia and chronic myeloid leukemia (39 – 250 ηM), non-Hodgkin’s lymphoma (11 – 190 ηM) and multiple myeloma (72 – 180 ηM). To explore in vivo efficacy, dose scheduling studies were initially conducted in the H226 xenograft model in mice. In the H226 model, APTO-253 showed improved antitumor activity when administered for two consecutive days followed by a five day break from dosing (2T-5B) each week, i.e. on days 1,2, 8,9, 15,16, 22,23, compared to the 2T-12B-2T-12B schedule. The 2T-5B schedule was used to evaluate antitumor activity of APTO-253 in several AML xenograft models in mice. In Kasumi-1 AML and KG-1 AML xenograft models, APTO-253 showed significant antitumor activity (p = 0.028 and p=0.0004, respectively) as a single agent when administered using the 2T-5B schedule each week for four weeks compared to control animals. Mice treated with APTO-253 had no overt toxicity based on clinical observations and body weight measurements. Mice bearing HL-60 AML xenograft tumors were treated with APTO-253 for one day or two consecutive days per week for three weeks, either as a single agent or combined with azacitidine, or with azacitidine alone twice per week (on days 1,4, 8, 11, 15 and 18). APTO-253 as a single agent inhibited growth of HL-60 tumors to approximately the same extent as azacitidine. Furthermore, both once weekly and twice weekly dosing of APTO-253 in combination with azacitidine resulted in significantly enhanced antitumor activity relative to either single agent alone (p = 0.0002 and p = 0.0006 for 1X and 2X weekly APTO-253 treatment, respectively, compared to control). Likewise, using a THP-1 AML xenograft model, APTO-253 administered as a single agent using the 2T-5B per week schedule showed significant efficacy, similar to that of azacitidine, while the combination of APTO-253 and azacitidine demonstrated greatly improved antitumor effects relative to either drug alone. APTO-253 was effective and well tolerated as a single agent or in combination with azacitidine in multiple AML xenograft models, plus APTO-253 does not cause bone marrow suppression in animal models or humans. Taken together, our results indicate that APTO-253 may serve as a targeted agent for single agent use and may provide enhanced efficacy to standard of care chemotherapeutics for AML and other hematological malignancies. Disclosures Rice: Lorus Therapeutics Inc.: Employment. Vellanki:Lorus Therapeutics Inc.: Employment. Lee:Lorus Therapeutics Inc.: Employment. Lightfoot:Lorus Therapeutics Inc.: Employment. Peralta:Lorus Therapeutics Inc.: Employment. Jamerlan:Lorus Therapeutics Inc.: Employment. Jin:Lorus Therapeutics Inc.: Employment. Lum:Lorus Therapeutics Inc.: Employment. Cheng:Lorus Therapeutics Inc.: Employment.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".