Distinct Signaling Profiles of Gemtuzumab Ozogamicin Responsiveness and Refractoriness in Acute Myeloid Leukemia.
Bibliographic record
Abstract
Abstract Abstract 2745 Poster Board II-721 Background: Gemtuzumab Ozogamicin (GO, Mylotarg), a humanized CD33 monoclonal antibody linked to calicheamicin was approved by the US FDA for use as a monotherapy in patients older than 60 years with relapsed acute myeloid leukemia (AML) unfit to tolerate standard salvage therapy. GO is internalized rapidly after infusion, and calicheamicin, a potent enediyene, is subsequently released and acts as a cytotoxic agent by causing double strand DNA breaks. Currently GO is in multiple clinical trials as a single agent or in combination with other therapies for both induction and consolidation treatment of various clinical subgroups of AML. However, the mechanisms of action and resistance of GO are incompletely understood and it is unclear which patient subgroups benefit from GO-based therapy. Single cell network profiling (SCNP) has shown promise as a methodology wherein multiple signaling networks are measured after treatment with an exogenous modulator such as a growth factor, cytokine or therapeutic agent and the identified signaling profiles can be used as clinical and therapeutic enablement tools. Objectives: SCNP using multiparameter flow cytometry was used to identify intracellular pathways that were associated with responsiveness or refractoriness to in vitro GO exposure in both cancer cell lines and primary AML samples. Methods: Signaling pathways emphasizing DNA damage response, cell cycle, apoptosis and drug transporter activity were measured by SCNP after in vitro exposure of cell lines and AML primary samples to clinically relevant concentrations of GO. Samples were processed for cytometry by paraformaldehyde /methanol fixation and permeabilzation followed by incubation with fluorochrome-conjugated antibody cocktails that recognize cell surface proteins to delineate cell subsets and intracellular signaling molecules. Results: In cell lines, responsiveness to in vitro GO exposure was defined as a) induction of DNA Damage as measured by increased p-ATM, p-Chk2 and p-H2AX, b) cell cycle arrest at G2/M as measured by increased cyclin B1 and DNA content & c) induction of apoptosis as measured by cleaved PARP and viability dyes. Of note, inhibition of drug transporter activity in 2 MDR-1+ cell lines did not restore GO responsiveness, suggesting the presence of additional relevant resistance mechanisms in these cell lines. In primary AML diagnostic samples, DNA damage and apoptosis pathway readouts were able to identify responsiveness or refractoriness to GO exposure. In the GO responsive profile, induction of both DNA damage responses and apoptosis were seen. Within the refractory samples, two distinct profiles were observed: a) robust and early induction of DNA damage response without apoptosis and 2) delayed and attenuated DNA damage response without apoptosis. Conclusions: Characterization of intracellular Cell Cycle, DNA Damage, and Apoptosis networks in single cells after GO exposure distinguishes GO responsive from refractory AML cells. Further, these pathway signatures provide information about mechanisms of refractoriness. (e.g. a block between a successful DNA damage response and initiation of apoptosis versus a block in the initial induction of DNA damage after GO exposure). The ability of the same profiles to predict clinical responses to the drug will be tested in future studies. Disclosures: Rosen: Nodality, Inc.: Employment, Equity Ownership. Cordeiro:Nodality Inc.: Employment, Equity Ownership. Soper:Nodality Inc.: Employment, Equity Ownership. Huang:Nodality Inc.: Employment, Equity Ownership. Cesano:Nodality Inc.: Employment, Equity Ownership. Fantl:Nodality Inc.: Employment, Equity Ownership.
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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".