Abstract B31: Poly(ADP-ribose) Polymerase 1 as a novel target for alpha-particle therapy in high-risk neuroblastoma
Bibliographic record
Abstract
Abstract Introduction: Poly(ADP-ribose) Polymerase 1 (PARP-1) is the second most abundant nuclear protein next to histones and offers a unique target for the delivery of alpha emitting radionuclides directly to chromatin maximizing radiobiological effects. Alpha emitting radionuclides decay through the emission of a high linear energy transfer alpha particle that travels only 50-70 µM. This results in dense ionizations over the alpha particle track length, causing high levels of DNA double strand breaks. High-risk neuroblastoma is a deadly pediatric malignancy that overexpresses PARP-1 and approximately 80% of patients succumb to their disease. By utilizing the overexpression of PARP-1 we aim to selectively target high-risk neuroblastomas for the delivery of alpha particles to induce irreparable DNA damage and subsequent cell death. Methods: Astatine-211 was produced on a JSW BC3015 cyclotron at 28.5 MeV via the Bi-209(α,2n)At-211 nuclear reaction. Astatine-211 was isolated by dry distillation and radiochemically functionalized onto a small molecule PARP inhibitor to afford 211At-MM4. Using a panel of neuroblastoma cell lines, the pharmacology and cytotoxicity of 211At-MM4 was evaluated in vitro. Next, protein analysis was performed by Western to evaluate expression of classical and alternative non-homologous end joining proteins. In addition, PARP-1 expression and DNA damage were assessed in response to therapy. Furthermore, in vivo therapy studies with PET/CT imaging of PARP-1 were performed to assess therapeutic potential and predictive capabilities of companion diagnostics. Results: IMR-05, SK-N-SH, and NLF were the most sensitive cell lines evaluated and Be-2-c was the most resistant cell line. All cell lines evaluated were high-risk neuroblastomas and baseline Western protein analysis did not reveal specific pathway dependence for classical or alternative non-homologous end joining defined by protein expression. Response to therapy showed significant increases in DNA damage measured by gH2AX. Interestingly PARP-1 expression was upregulated post therapy in the resistant cell line Be-2-c. IMR-05 was the most sensitive cell line in vitro and was translated to in vivo models where therapeutic efficacy was shown. PET/CT imaging of PARP-1 post therapy showed low tumor uptake and was indicative of response. Conclusion: 211At-MM4 is a small molecule PARP inhibitor functionalized with an alpha emitting radionuclide astatine-211 that can effectively deliver alpha-particles to the nucleus of cancer cells. The neuroblastoma cell lines evaluated showed differential sensitivities and in vitro results translated into in vivo models. Furthermore we have characterized a novel therapy for high-risk neuroblastoma and aim for future clinical translation. Citation Format: Mehran Makvandi, Catherine Hou, Kuiying Xu, Redmond-Craig Anderson, Samuel Ander-Effron, Robert H. Mach, John M. Maris, Daniel A. Pryma. Poly(ADP-ribose) Polymerase 1 as a novel target for alpha-particle therapy in high-risk neuroblastoma [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr B31.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".