1. AD-4 Status Report 2010 Biological Effects of Antiprotons Are Antiprotons a Candidate for Cancer Therapy? January 20, 2011 University of Aarhus University Hospital of Aarhus University of New Mexico, Albuquerque University of Athens Queen’s University Belfast CERN, Geneva Hôpital Universitaire de Geneve German Cancer Research Center, Heidelberg Max Planck Institute for Nuclear Physics, Heidelberg University of Montenegro, Podgorica 32 Scientists from 10 Institutions

2. Dose to Target Rationale for Conformal Radiotherapy Dose (and tumor control) are limited due to tolerance of organs at risk Better conformity of dose to target enables application of higher doses & higher tumor control without increasing normal tissue complication rate January 20, 2011

3. Particles deposit LESS physical dose in front of the tumor and NO dose beyond the distal edge of the Bragg peak! Particle Therapy offers Reduced Integral Dose to Body January 20, 2011

4. Physical Advantage of Antiprotons January 20, 2011

5. Potential Clinical Advantages? January 20, 2011 Each Particle Type shows distinct features  Protons are well known and easy to plan (RBE = 1) which is the reason they are most widely adopted.  Antiprotons have lowest entrance dose for the price of an extended isotropic low dose halo.  Carbon ions have sharpest lateral penumbra but comparatively higher entrance dose than even protons (no RBE included here), but show forward directed tail due to in beam fragmentation. Detailed dose plans (including RBE) will need to be developed to assess applicability of particle types for different tumor types and locations!

6. INGREDIENTS:  V-79 Chinese Hamster cells embedded in gelatin  Antiproton beam from AD (126 MeV) ANALYSIS:  Study cell survival in peak (tumor) and plateau (skin) and compare the results to protons (and carbon ions) METHOD:  Irradiate cells with dose levels to give survival in the peak is between 0 and 90 %  Slice samples, dissolve gel, incubate cells, and look for number of colonies The AD-4 Experiment at CERN January 20, 2011

7. Irradiate sample tube with living cells suspended in gel. Slice sample tube in  1 mm slices and determine survival fraction for each slice.  Repeat for varying (peak) doses. Biological Analysis Method Example: SOBP of Carbon Ions at GSI January 20, 2011

8. Example: Protons at Triumf Plot “peak” and “plateau” survival vs. relative dose to extract the Biological Effective Dose Ratio BEDR = F RBE peak /RBE plateau (F = ratio of physical dose in peak and plateau region) Biological Analysis Method January 20, 2011 RBE peak = Co-60 Dose Peak Dose =1.15 RBE plat = Co-60 Dose Plateau Dose =1.0 Plot “peak” or “plateau” survival vs. absolute dose and compare to 60 Co irradiation comparing dose values needed for Iso-Effect for peak, plateau, and 60 Co irradiation: Relative Biological effectiveness RBE

9. Carbon Ions – SOBP at GSI January 20, 2011 note: clinical beams with precise dosimetry and fast dose delivery …….. Energy to achieve same clinical relevant depth and form SOBP as at CERN….

10. RBE for Carbon Ions January 20, 2011 Extract survival vs. dose plot for each depth slice and calculate RBE SF=10% RBE plateau = 1.2RBE peak = 2.0 RBE distal = 1.5

11. Physical Dose Calculations requires exact Knowledge of Beam Parameters Biological Variability necessitates multiple Independent Experiments under Identical Conditions Most important result is NOT Peak-to-Plateau ratio but Variation of RBE with Depth January 20, 2011 RBE Analysis for Antiprotons

12. CERN DATA 2008 January 20, 2011 note: good control over dose planning for SOBP…….. RBE plateau = 1.2 RBE peak = 1.73 – 2.2

13. CERN DATA 2009 January 20, 2011 note: attempt to collect data in tail for RBE analysis…….. difficult task – long irradiation times – very little effect

14. January 20, 2011 CERN DATA 2010 Additional data set in Plateau and Peak (preliminary analysis) ……detailed dose calculations and error analysis still ongoing

15. New Beam Monitor Purpose: Shot-to-shot monitoring of beam spot shape, size, and position for precise dose calculations to replace Gafchromic film, facilitate alignment, and have instant feed back on beam changes Solution: Solid state pixel detector (Monolithic Active Pixel Sensor) January 20, 2011  Dedicated MAPS design to beam monitoring  pixel 153×153 µm 2 squares  two 9×9 interdigited arrays of n-well/p-epi diodes + two independent read-out circuits – avoiding dead time  In-pixel storage capacitors – choice ~0.5 pF or ~5 pF to cope with signal range Mimotera, Massimo Caccia (Universita’ dell’Insumbria Como, Italy) Long term goal: Measure LET distributions in 2D/3D

16. Complete Info on Beam Shot January 20, 2011 Integral, Width in X and Y for each shot at a glance

17. Online Display of Beam January 20, 2011

18. Beam Shift!! January 20, 2011 Mimotera allows immediate response to Accelerator Problems Failure of quadrupole was detected and repaired within 1 hour, and 12 hour irradiation of cell samples (half way completed) was saved!

19. Real Time Imaging - Simulation January 20, 2011  Use 4 x 3 layers of (virtual) silicon pixel detectors 40x40 cm 2 / 5 cm spacing 30 cm from origin   Pixel Resolution  = 100  m  Track charged pions and photons  Overall detector efficiency  = 1%  Define vertex as approach of two tracks closer than 2 mm  If more than 2 tracks per particle are detected use meta-center of vertices of any two tracks

20. Results of Simulation January 20, 2011 Beam Eye View Side View Achievable Precision: +/- 1mm

21. Proof of Principle Experiment Q: How to minimize material and cost A: Instead of 3 layers use one layer and look at grazing incidence. Q: What detector to use for first test? A: Turn to our friends in ALICE and use one (spare) module of the Alice Silicon Pixel Detector (SPD) January 20, 2011

22. First Experimental Realization January 20, 2011  grazing incidence of pions produce long tracks  length distribution changes with angle  stopping distribution along z-axis can be inferred  Future work: Expansion to 3 - D pbar π±π± Water phantom 289.5° Bragg Peak293.0° distal fall-off

23. January 20, 2011 First Results Distal Edge of Depth Dose Profile is detected Resolution is limited due to distance from target and pion scattering red: Simulation blue: Experiment

24. January 20, 2011 Monte Carlo for Clinical Beams Monte Carlo for Clinical Example: Distance beam to detector = 30 cm Continuous spill 1 x 10 9 antiprotons (blue: 1x10 8 ) Detection of distal edge possible with precision of 1 – 2 millimeter

25. DNA Damage and Repair Quantify DNA damage in human cells along and around a 126 MeV antiproton beam at CERN. Investigate immediate and longer term DNA damage. Investigate non-targeted effects outside the beam path due to secondary particles or bystander signaling. January 20, 2011

26. DNA Damage and Repair Assays January 20, 2011 There is more to biology than just clonogenics – especially outside the targeted area:  Immediately after attack on DNA proteins are recruited to the site  This event signals cell cycle arrest to allow repair  If damage is too extensive to repair programmed cell death (apoptosis) is induced  Cells also deficient of cell cycle check point proteins may enter mitosis (cancer cells are often deficient in repair proteins and continue dividing)  -H2AX: Phosphorylation of H2AX in the presence of Double Strand Breaks Micronuclei: Fluorescent detection of micronuclei (parts of whole chromosomes) formed due to DNA damage, which are indicating potential of tumorigenesis  -H2AX and Micronucleus assays are typically used to study immediate and long term DNA damage respectively

27. January 20, 2011 Results  -H2AX Assay γ-H2AX foci in cells irradiated with up 1.1x10 9 antiprotons in the plateau (blue) or SOBP (red).

28. Results for  -H2AX January 20, 2011 SOBP antiprotons generate larger DNA double strand breaks than either plateau antiprotons or X-rays. 60 minutes after radiation no difference is detected anymore

29. Results Micronuclei Assay January 20, 2011 Mean number of micronuclei for two replicate experiments for antiproton plateau and SOBP data sets. Sub lethal damage seems to be LET dependent.

30. Summary and Outlook Achievements 2010 Extended data set on Biological Effect of Antiprotons for preliminary dose planning studies Confinement of RBE Enhancement to Bragg peak only has been confirmed (preliminary analysis) DNA damage assays for studies of late effects achieved higher resolution Fast Beam Monitoring implemented Real Time Imaging of Stopping Distribution – Proof of principle experiment performed January 20, 2011

31. Recent Publications Bassler, N., Holzscheiter, M.H., Petersen, J.B., 'Neutron Fluence in Antiproton Radiotherapy, Measurements and Simulations', submitted to Acta Oncologica (2010) Bassler, N., Kantemiris, I., Karaiskos, P., Engelke, J., Holzscheiter, M.H., Petersen, J.B. 2010; Comparison of optimized single and multifield irradiation plans of antiproton, proton, and ion beams, Radiotherapy & Oncology (2010) vol. 95, pp. 87 – 93 Kantemiris, I., Angelopoulos, A., Bassler, N., Giokaris, N., Holzscheiter, M., Karaiskos, P., Kalogeropoulos, T.E., 'Real-time imaging during antiproton radiotherapy', Phys. Med. Biol. (2010) vol. 55, pp. N1–N9 J.N. Kavanagh, F.J. Currell, D.J. Timson, M.H. Holzscheiter, N. Bassler, R. Herrmann, G. Schettino; ‘Induction of DNA Damage by Antiprotons for a Novel Radiotherapy Approach’; European Physical Journal D D 60 (2010) pp. 209- 214 January 20, 2011 Summary and Outlook

32. Future Work Continue increasing precision of RBE determination Add more independent data sets (identical conditions) Improving biological protocols and error analysis. Increase data density for sets to stabilize fits Detailed dose planning studies on specific cancers Continue DNA damage studies to assess risk of secondary primary malignancies (SPM’s) Develop 2D LET measuring system (mostly off line) Transfer technology between HIT and AD-4 - Protons, Carbon ions, Antiprotons January 20, 2011

33. Beam Time Request 2 weeks of 126 MeV (500 MeV/c) antiprotons Survival measurements on V-79 cell lines Augment or complete data set on RBE Improve error analysis Study of DNA damage using  -H2AX and MN Increasing statistical significance and complete measurement from 2010 (beam time loss) Liquid ionization chamber measurements Two dose rate method on pulsed beams January 20, 2011