Growth curves of tumors and body weight of mice undergoing radioimmunotherapy with ⁹⁰Y-lableled antibodies.

<p>Tumor growth curve (<b>A</b>) and body weight (<b>B</b>) for mice treated with [⁹⁰Y]12A8. Tumor growth curve (<b>C</b>) and body weight (<b>D</b>) for mice treated with [⁹⁰Y]67A2 (closed circles, untreated (PBS); open circles, unlabeled IgG alone; closed triangles, 0.74 MBq; open diamonds, 1.85 MBq; black squares, 3.7 MBq).</p

Biodistribution of [¹¹¹In]67A2 in nude mice bearing SY xenograft.

<p>Data are expressed as decay-corrected % ID/g±SD normalized to a 20-g body weight mouse.</p

<i>In vitro</i> assay of [¹¹¹In]12A8, [¹¹¹In]67A2 and [¹²⁵I]67A2.

<p>(<b>A</b>) Cell binding assay for [¹¹¹In]12A8 (closed circles) and [¹¹¹In]67A2 (open circles). (<b>B</b>) Competitive inhibition assay for [¹¹¹In]12A8 (closed circles) and [¹¹¹In]67A2 (open circles). Internalization assay for [¹¹¹In]67A2 (<b>C</b>) and [¹²⁵I]67A2 (<b>D</b>). Changes in % of total radioactivity for each fraction are plotted against incubation time at 37°C (closed circles, internalized fraction; open circles, membrane-bound fraction; closed triangles, protein-bound fraction in the culture medium; cross marks, non-protein-bound fraction in the culture medium).</p

Histological analysis of tumors.

<p>(<b>A</b>) H&E and TUNEL stained tumor sections one week after injection of [⁹⁰Y]12A8 and [⁹⁰Y]67A2. (<b>B</b>) Quantification of apoptotic cells in tumors treated with [⁹⁰Y]12A8 (black bars) and [⁹⁰Y]67A2 (white bars). *<i>P</i><0.01 (Student's <i>t</i>-test).</p

<i>In vitro</i> characterization of ¹¹¹In-TSP-A01 and ¹¹¹In-TSP-A02.

<p>Cell binding assay of ¹¹¹In-TSP-A01 (A) and ¹¹¹In-TSP-A02 (B) to AsPC-1 (black circles), BxPC-3 (white triangles), and MIAPaCa-2 cells (white circles). Correlation analysis of cell binding at 6.25 × 10⁵ cells with TfR protein expression for ¹¹¹In-TSP-A01 (<b>C</b>) and ¹¹¹In-TSP-A02 (<b>D</b>). The a.u. means arbitrary unit. Competitive inhibition assay for TSP-A01 (<b>E</b>) and TSP-A02 (<b>F</b>) using the corresponding intact (black circles, solid line) and DOTA-conjugated (white circles, dashed line) antibodies.</p

TfR protein expression analysis.

<p>The expression in pancreatic cell lines (AsPC-1, BxPC-3, and MIAPaCa-2) was determined by immunofluorescence staining with the anti-TfR antibody (red). DAPI stained nuclei (blue).</p

Evaluation of Efficacy of Radioimmunotherapy with ^{90 - Fig 4}Y-Labeled Fully Human Anti-Transferrin Receptor Monoclonal Antibody in Pancreatic Cancer Mouse Models

<p>Growth curves of BxPC-3 <b>(A)</b> and MIAPaCa-2 <b>(B)</b> tumors in mice treated with 0 MBq (black circles), 0.74 MBq (white squares), 1.85 MBq (black triangles), and 3.7 MBq (white diamonds) of ⁹⁰Y-TSP-A01. *<i>P</i> < 0.05, **<i>P</i> < 0.01 (vs. 0 MBq). Growth curves of BxPC-3 (<b>C</b>) and MIAPaCa-2 (<b>D</b>) tumors of mice treated with 0 Gy (black circles), 15 Gy (white squares), 30 Gy (black triangles), and 60 Gy (white diamonds) of X-rays. **<i>P</i> < 0.01 (vs. 0 Gy).</p

Histological analysis of tumors with ⁹⁰Y-TSP-A01 treatment.

<p>H&E-stained BxPC-3 (left panels) and MIAPaCa-2 (right panels) tumor sections of untreated and at days 1, 3, and 7 after injection of 3.7-MBq ⁹⁰Y-TSP-A01.</p

Evaluation of Efficacy of Radioimmunotherapy with ⁹⁰Y-Labeled Fully Human Anti-Transferrin Receptor Monoclonal Antibody in Pancreatic Cancer Mouse Models

<div><p>Objective</p><p>Pancreatic cancer is an aggressive tumor and the prognosis remains poor. Therefore, development of more effective therapy is needed. We previously reported that ⁸⁹Zr-labeled TSP-A01, an antibody against transferrin receptor (TfR), is highly accumulated in a pancreatic cancer xenograft, but not in major normal organs. In the present study, we evaluated the efficacy of radioimmunotherapy (RIT) with ⁹⁰Y-TSP-A01 in pancreatic cancer mouse models.</p><p>Methods</p><p>TfR expression in pancreatic cancer cell lines (AsPC-1, BxPC-3, MIAPaCa-2) was evaluated by immunofluorescence staining. ¹¹¹In-labeled anti-TfR antibodies (TSP-A01, TSP-A02) were evaluated <i>in vitro</i> by cell binding assay with the three cell lines and by competitive inhibition assay with MIAPaCa-2. <i>In vivo</i> biodistribution was evaluated in mice bearing BxPC-3 and MIAPaCa-2 xenografts. Tumor volumes of BxPC-3 and MIAPaCa-2 were sequentially measured after ⁹⁰Y-TSP-A01 injection and histological analysis of tumors was conducted.</p><p>Results</p><p>MIAPaCa-2 cells showed the highest TfR expression, followed by AsPC-1 and BxPC-3 cells. ¹¹¹In-TSP-A01 and ¹¹¹In-TSP-A02 bound specifically to the three cell lines according to TfR expression. The dissociation constants for TSP-A01, DOTA-TSP-A01, TSP-A02, and DOTA-TSP-A02 were 0.22, 0.28, 0.17, and 0.22 nM, respectively. ¹¹¹In-TSP-A01 was highly accumulated in tumors, especially in MIAPaCa-2, but this was not true of ¹¹¹In-TSP-A02. The absorbed dose for ⁹⁰Y-TSP-A01 was estimated to be 8.3 Gy/MBq to BxPC-3 and 12.4 Gy/MBq to MIAPaCa-2. MIAPaCa-2 tumors treated with 3.7 MBq of ⁹⁰Y-TSP-A01 had almost completely disappeared around 3 weeks after injection and regrowth was not observed. Growth of BxPC-3 tumors was inhibited by 3.7 MBq of ⁹⁰Y-TSP-A01, but the tumor size was not reduced.</p><p>Conclusion</p><p>⁹⁰Y-TSP-A01 treatment achieved an almost complete response in MIAPaCa-2 tumors, whereas it merely inhibited the growth of BxPC-3 tumors. ⁹⁰Y-TSP-A01 is a promising RIT agent for pancreatic cancer, although further investigation is necessary to improve the efficacy for the radioresistant types like BxPC-3.</p></div

Biodistribution of ¹¹¹In-TSP-A01 and ¹¹¹In-TSP-A02 in nude mice bearing BxPC-3 and MIAPaCa-2 xenografts at day 1 (black bars), day 2 (diagonal line bars), day 4 (gray bars), day 7 (white bars), and day 10 (horizontal line bars) after intravenous injection of 37 kBq of ¹¹¹In-TSP-A01 (A) and ¹¹¹In-TSP-A02 (B).

<p>Biodistribution of ¹¹¹In-TSP-A01 and ¹¹¹In-TSP-A02 in nude mice bearing BxPC-3 and MIAPaCa-2 xenografts at day 1 (black bars), day 2 (diagonal line bars), day 4 (gray bars), day 7 (white bars), and day 10 (horizontal line bars) after intravenous injection of 37 kBq of ¹¹¹In-TSP-A01 (A) and ¹¹¹In-TSP-A02 (B).</p