Rat-Specific Decreases in Platelet Count Caused by a Humanized Monoclonal Antibody Against Sclerostin
Bibliographic record
Abstract
LY2541546 is a humanized monoclonal antibody (IgG(4)) that has been optimized for neutralizing activity against sclerostin. In 5-week and 6-month nonclinical safety studies in rats, LY2541546 caused dose-dependent reversible decreases in platelet counts accompanied by accelerated platelet production, increased megakaryocytes, and altered megakaryocyte morphology. These treatment-related effects resulted in altered primary hemostasis as manifested by prolonged bleeding after phlebotomy or incidental toenail break. In some cases, the defects in hemostasis were sufficient to result in death of the affected rats. There was no evidence in rats of general bone marrow suppression or processes (e.g., disseminated intravascular coagulopathy) that may result in thrombocytopenia. Cynomolgus monkeys given LY2541546 for 5 weeks or 9 months had no changes in platelet count or megakaryocytes. In vitro cross-reactivity studies in rats, cynomolgus monkeys, and humans revealed LY2541546-bound rat but not cynomolgus monkey or human platelets and megakaryocytes. These data taken together demonstrated that the platelet and megakaryocyte effects in rats had a species-specific pathogenesis which likely involved LY2541546 binding of a rat-specific antigen on the surface of platelets and megakaryocytes resulting in the increased clearance of platelets and megakaryocyte hyperplasia. The species-specific nature of these reversible toxicological findings combined with the ease of clinical monitoring using standard hematology enabled the safe initiation of clinical studies in human volunteers.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".