Metal-Chelating Polymers (MCPs) with Zwitterionic Pendant Groups Complexed to Trastuzumab Exhibit Decreased Liver Accumulation Compared to Polyanionic MCP Immunoconjugates
Bibliographic record
Abstract
Metal-chelating polymers (MCPs) can amplify the radioactivity delivered to cancer cells by monoclonal antibodies or their Fab fragments. We focus on trastuzumab (tmAb), which is used to target cancer cells that overexpress human epidermal growth factor receptor 2 (HER2). We report the synthesis and characterization of a biotin (Bi) end-capped MCP, Bi-PAm(DET-DTPA)36, a polyacrylamide with diethylenetriaminepentaacetic acid (DTPA) groups attached as monoamides to the polymer backbone by diethylenetriamine (DET) pendant groups. We compared its behavior in vivo and in vitro to a similar MCP with ethylenediamine (EDA) pendant groups (Bi-PAm(EDA-DTPA)40). These polymers were complexed to a streptavidin-modified Fab fragment of tmAb, then labeled with (111)In to specifically deliver multiple copies of (111)In to HER2+ cancer cells. Upon decay, (111)In emits γ-rays that can be used in single-photon emission computed tomography radioimaging, as well as Auger electrons that cause lethal double strand breakage of DNA. Our previous studies in Balb/c mice showed that radioimmunoconjugates (RICs) containing the Bi-PAm(EDA-DTPA)40 polymer had extremely short blood circulation time and high liver uptake and were, thus, unsuitable for in vivo studies. The polymer Bi-PAm(EDA-DTPA)40 carries negative charges on each pendant group at neutral pH and a net charge of (-1) on each pendant group when saturated with stable In(3+). To test our hypothesis that charge associated with the polymer repeat unit is a key factor affecting its biodistribution profile, we examined the biodistribution of RICs containing Bi-PAm(DET-DTPA)36. While this polymer is also negatively charged at neutral pH, it becomes a zwitterionic MCP upon saturation of the DTPA groups with stable In(3+) ions. In both nontumor bearing Balb/c mice and athymic mice implanted with HER2+ SKOV-3 human ovarian cancer tumors, we show that the zwitterionic MCP has improved biodistribution, higher blood levels of radioactivity, lower levels of normal tissue uptake, and higher tumor uptake. Surface plasmon resonance experiments employing the extracellular domain of HER2 show that the MCP immunoconjugates retain high affinity antigen recognition, with dissociation constants in the low nM range. In vitro studies with SKOV-3 cells for both MCP immunoconjugates show a combination of specific binding that can be completed in the presence of excess tmAb IgG and nonspecific binding (NSB) that persists in the presence of tmAb IgG. We conclude that zwitterionic MCPs represent a much better choice than polymers with charges along the backbone for in vivo delivery of RICs to HER2+ cancer cells.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".