Maarten van der Doelen

TARGETED ALPHA-RADIONUCLIDE THERAPIES IN METASTATIC PR STATE CANCER

MAARTEN VAN DER DOELEN

TARGETED ALPHA-RADIONUCLIDE THERAPIES IN METASTATIC PROSTATE CANCER

Maarten van der Doelen

COLOPHON

Targeted alpha-radionuclide therapies in metastatic prostate cancer © Maarten J. van der Doelen, Nijmegen, The Netherlands, 2023.

All rights reserved. The copyright of the articles that have been published has been transferred to the respective journals. No parts of this thesis may be reproduced or transmitted in any formor by any means, without prior written permission of the author.

Cover design and layout:

James Jardine | www.jamesjardine.nl Ridderprint | www.ridderprint.nl

Printing:

ISBN:

978-94-93108-34-9

The work presented in this thesis was carried out within the Departments of Medical Oncology and Urology, Radboud Institute for Health Sciences, Radboud university medical center, Nijmegen, the Netherlands. Parts of the research described in this thesis were funded by Bayer Health Care, the Paul Speth Society, the Swedish Cancer Society, the Cancer Society of Stockholm, the King Gustav V Jubilee Fund, and the Stockholm County Council.

Printing of this thesis was supported by the Radboud University Nijmegen.

TARGETED ALPHA-RADIONUCLIDE THERAPIES IN METASTATIC PROSTATE CANCER

Proefschrift ter verkrijging van de graad van doctor aan de Radboud Universiteit Nijmegen op gezag van de rector magnificus prof. dr. J.H.J.M. van Krieken, volgens besluit van het college voor promoties in het openbaar te verdedigen op

donderdag 19 januari 2023 om 14.30 uur precies

door

Maarten Johannes van der Doelen geboren op 20 augustus 1989 te Den Dungen

Promotor prof. dr. W.R. Gerritsen Copromotoren dr. I.M. van Oort dr. N. Mehra Manuscriptcommissie prof. dr. S. Heskamp (voorzitter) prof. dr. J.H.A.M. Kaanders dr. D.E. Oprea-Lager (Amsterdam UMC)

Table of CO NTENTS

Chapter 1

9

General introduction and outline of the thesis Based on:

Patient selection for radium-223 therapy in patients with bone metastatic castration resistant prostate cancer: new recommendations and future perspectives. Clinical Genitourinary Cancer. 2019; 17: 79-87 .

PART I

EFFECT EVALUATION OF TARGETED ALPHA RADIONUCLIDE THERAPIES

Chapter 2

27

Clinical outcomes and molecular profiling of advanced metastatic castration-resistant prostate cancer patients treated with 225 Actinium labeled prostate-specific membrane antigen targeted alpha-radiation therapy. Urologic Oncology. 2021; 39: 729 e7-e16 . Immunophenotyping reveals longitudinal changes in circulating immune cells during radium-223 therapy in patients with metastatic castration resistant prostate cancer. Frontiers in Oncology. 2021; 11: 667658. Health-related quality of life, psychological distress and fatigue in metastatic castration-resistant prostate cancer patients treated with radium-223 therapy. Prostate Cancer and Prostatic Diseases. 2022.

Chapter 3

53

Chapter 4

87

PART II

PROGNOSTIC PARAMETERS IN PATIENTS TREATED WITH TARGETED ALPHA-RADIONUCLIDE THERAPIES

Chapter 5

133

Radium-223 therapy in patients with advanced castration-resistant prostate cancer with bone metastases. Lessons from daily practice. Clinical Nuclear Medicine. 2018; 43: 9-16.

Chapter 6

153

Early alkaline phosphatase dynamics as a biomarker of survival in metastatic castration-resistant prostate cancer patients treated with radium-223. European Journal of Nuclear Medicine and Molecular Imaging. 2021; 48: 3325-34. Impact of DNA damage repair defects on response to radium-223 and overall survival in metastatic castration-resistant prostate cancer. European Journal of Cancer. 2020; 136: 16-24 .

Chapter 7

175

PART III EPILOGUE

Chapter 8

199

General discussion and future perspectives Based on:

Patient selection for radium-223 therapy in patients with bone metastatic castration resistant prostate cancer: new recommendations and future perspectives. Clinical Genitourinary Cancer. 2019; 17: 79-87.

Chapter 9

Summary Samenvatting

231 235

PART IV APPENDICES

243 245 249 253 255 257 261

List of abbreviations List of contributing authors List of publications and presentations Research data management PhD portfolio Curriculum vitae Dankwoord

1 General introduction and outline of the thesis

Based on:

Patient selection for radium-223 therapy in patients with bone metastatic castration resistant prostate cancer: new recommendations and future perspectives Maarten J. van der Doelen, Niven Mehra, Rick Hermsen, Marcel J.R. Janssen, Winald R. Gerritsen, Inge M. van Oort

Clinical Genitourinary Cancer. 2019; 17: 79-87.

General introduction and outline of the thesis

GENERAL INTRODUCTION Prostate cancer

1

Globally, prostate cancer is the second most frequently diagnosed cancer in men, with an estimated 1.4 million new cases in 2020. (1) Prostate cancer is the fifth cause of cancer-related death in men worldwide. In the Netherlands, prostate cancer is the most commonly diagnosed cancer in men. In 2019, 13,500 patients were diagnosed with prostate cancer and nearly 3,000 men died from prostate cancer. (2, 3) Prostate cancer is usually diagnosed in men above 60 years of age. The majority of patients presents with localized prostate cancer. Depending on the grade and stage of the disease, treatment options for localized prostate cancer include active surveillance, focal and brachytherapy, external beam radiotherapy, and radical prostatectomy. (4) These therapies are often successful, resulting in long-term disease control and increased prostate cancer-specific survival. (5, 6) However, when the disease metastasizes, the prognosis is worse. In case of newly diagnosed metastatic prostate cancer, the median overall survival (OS) is limited to approximately 42 months. (7) In addition, metastatic prostate cancer may cause considerable pain, impaired mobility, bone marrow failure and skeletal-related events, including pathological fractures and spinal cord compression. (8, 9) Treatment of metastatic prostate cancer Androgen deprivation therapy (ADT) with bilateral orchiectomy or luteinizing hormone releasing hormone agonists or antagonists is standard of care for patients with metastatic prostate cancer, based on benefit in terms of quality of life and reduction of disease-associated morbidity. (10, 11) Although most patients initially respond to ADT, the disease eventually progresses to castration-resistant prostate cancer (CRPC), as a result of extragonadal (e.g. commensal intestinal microbiota) and intratumoral androgen synthesis and altered androgen receptor signaling. (12, 13) The transition to CRPC is known to be inevitably lethal, although survival has improved significantly since the approval of several novel life-prolonging agents following positive outcomes of pivotal phase 3 trials. (14) In 2004, docetaxel, a taxane-based chemotherapeutic drug, was the first agent that was shown to prolong survival in metastatic CRPC (mCRPC) patients. (15, 16) In 2010, cabazitaxel chemotherapy was registered for the treatment of men with disease progression after docetaxel chemotherapy. (17) Also in 2010, the autologous immunotherapeutic agent sipuleucel-T was shown to provide survival advantage in

11

Chapter 1

patients with asymptomatic or minimally symptomatic mCRPC. (18) However, two years after approval, the drug was withdrawn from the European market at the request of the marketing authorization holder. Next, two second generation androgen-signaling inhibitors, enzalutamide and abiraterone acetate, were registered for the treatment of both chemotherapy-naïve mCRPC patients and mCRPC patients who underwent prior docetaxel chemotherapy. (19-22) Radium-223 dichloride (radium-223) therapy, an alpha particle emitting radionuclide, was added to the therapeutic landscape of mCRPC in 2013. (23) More recently, the poly (adenosine diphosphate–ribose) polymerase (PARP) inhibitors rucaparib and olaparib were approved for treatment of pretreated mCRPC patients with a deleterious germline or somatic homologous recombination repair gene alteration. (24, 25) Furthermore, in 2015, the CHAARTED and STAMPEDE trials showed that the combination of continuous ADT plus six courses of docetaxel chemotherapy resulted in improved survival when compared to ADT alone in patients with an initial diagnosis of metastatic prostate cancer. (26, 27) Subsequently, the combination of ADT plus abiraterone and prednisone was also found to be life-prolonging in patients with metastatic hormone sensitive prostate cancer. (28, 29) The upfront use of docetaxel or abiraterone already in the hormone-sensitive setting has resulted in a change in the treatment paradigm of metastatic prostate cancer patients and the expanding number of treatment options has made the sequencing of life-prolonging agents more complex. Therefore, optimization of treatment strategies to improve survival and postpone disease-associated morbidity are of utmost importance. These strategies include combinatory therapy in patients with newly diagnosed metastatic hormone-sensitive prostate cancer, concomitant use of bone protective agents, and personalized medicine in patients with mCRPC. Targeted alpha-radionuclide therapy Radionuclides, also known as radioisotopes, are unstable atomswith excess of energy. By radioactive decay, the atoms lose their excess of energy in the form of energy particles. Based on the type of the emitted particles, radionuclides are classified as alpha, beta or gamma-emitting radionuclides. The therapeutic effectiveness of specific radionuclides is determined by their specificity of targeting and the innate characteristics of the particles emitted, including the range, effective travel distance in surrounding tissue, and the magnitude of emitted energy. (30) An alpha particle is identical to the nucleus of a Helium atom and consists of two protons and two neutrons. Alpha particles have a high linear energy transfer (50-230 keV/µm) and short radiation range in tissue (40-100 µm). In beta decay, an electron or

12

General introduction and outline of the thesis

positron is emitted. When compared to alpha particles, beta particles have lower linear energy transfer (0.2 keV/µm) and considerable longer range (1,000-10,000 µm). Figure 1 illustrates the difference between alpha and beta particle radiation ranges. Due to the high linear energy radiation, alpha particles have the ability to cause numerous ionization events, leading to irreparable double-strand deoxyribonucleic acid (DNA) breaks within the cell nucleus and subsequent apoptosis. Together with the short path-length, this potentially enables alpha particles to deliver localized tumor cell killing. However, to minimize unwanted toxicity from alpha particles to normal healthy tissues, targeted delivery to the sites of cancer cells is desirable. Based on the method of delivery, targeted alpha-radionuclide therapy (TAT) is categorized as mechanism mediated TAT and molecule-guided TAT. (31) In mechanism-mediated TAT, the targeting of the alpha-emitting radionuclide relies solely upon the innate physicochemical nature of the element and no specific vehicles are necessary to deliver nuclear energy to the tumor cells. In molecule-guided TAT, alpha-emitting radionuclides are coupled with monoclonal antibodies, peptides, small molecules or nanoparticles, which target tumor-associated antigens that are aberrantly present on the cancer cells and thereby selectively deliver cytotoxic radiation, while minimizing toxicity to surrounding healthy tissues. (32, 33)

1

In this thesis, two targeted alpha-particle emitting radionuclides were evaluated for therapy of mCRPC: actinium-225 and radium-223.

A

B

Figure 1. Schematic overview showing the difference between radiation ranges when a bone metastasis located at the border of bone matrix (yellow) and bone marrow (red) is irradiated by a alpha or a beta particle. A . Short radiation range by an alpha particle (2 to 10 cell diameters). B . Long radiation range by a beta particle (10 to 1000 cell diameters), which might lead to bone marrow toxicity. Figure adapted from slide deck Bayer Health Care, based on Henriksen G, et al. (Cancer Res. 2002;62:3120–3125) and Brechbiel MW. (Dalton Trans. 2007;43:4918–4928). (34, 35)

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Actinium-225 Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein showing significant overexpression in high-grade and advanced stage prostate cancer. (36) Expression is further upregulated in mCRPC state and following treatment with second generation androgen-signaling inhibitors (37, 38). By the use of PSMA-targeting vehicles, such as antibodies (e.g. monoclonal antibody J591) or small molecule ligands (e.g. PSMA-617), that are labeled with a radionuclide, targeted imaging and radioligand therapy (RLT) can be obtained. (39) Actinium-225 is an alpha-emitter with a physical half-life of 9.9 days and decays to stable bismuth-209 by net production of four alpha particles with energies of 5.8-8.4 MeV. Targeted delivery of actinium-225 to the prostate cancer cells may be accomplished via actinium-225 labeled PSMA-617 ( 225 Ac-PSMA). Since PSMA is known to be highly expressed on prostate cancer cells at the primary tumor and within lymph node, bone and visceral metastases, the alpha particles may be directed to PSMA expressing cells regardless of their location. First results of 225 Ac-PSMA RLT in small cohorts of mCRPC patients are promising, with high rates of biochemical and radiological responses. (40, 41) Radium-223 Radium-223 (Xofigo®) is a radioactive isotope of the alkaline earth metal radium and has a physical half-life of 11.4 days. During its decay to stable lead-207, four alpha particles are emitted, with an average energy of 5.8-7.6 MeV. In addition, small amounts of beta radiation (3.6%) and gamma radiation (1.1%) are emitted. Complete decay to stable lead-207 results in a combined energy of 28.2 MeV. (42) Radium-223 naturally acts as a bone-seeking radionuclide. Radium-223 behaves as a calcium mimetic and is actively incorporated into the bone matrix via binding to hydroxyapatite at osteoblastic bone sites, but it also passively binds in areas of high bone turnover. There it affects both cancer cells and the tumor microenvironment. (43) The short range of high-energy alpha-radiation from radium-223 therapy (40-80 µm, <10 cell diameters) induces targeted tumor cell killing at sites of osteoblastic bone activity, while minimizing damage to the surrounding tissue, such as bone marrow. (34) Since 2013, radium-223 is approved as an alpha-emitting radiopharmaceutical for mCRPC patients with symptomatic bone metastases and no visceral metastases. The registration of radium-223 is based on an OS benefit of 3.6 months when compared to placebo, demonstrated in the phase 3, randomized, double-blind, placebo-controlled

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General introduction and outline of the thesis

Alpharadin in Symptomatic Prostate Cancer Patients (ALSYMPCA) trial. (23) The OS benefit of radium-223was found to be irrespective of previous docetaxel chemotherapy, baseline opioid use and bisphosphonate use. (23, 44, 45) Radium-223 also prolonged the time to first symptomatic skeletal event and patients experienced meaningful health related quality of life improvement during treatment as compared to placebo. (46, 47) Radium-223 has a low myelosuppression incidence and tolerable side effects, and is deemed safe on the long term, with no evidence of radiation-induced hematological malignancies described so far. (23, 48-50) Radium-223 is injected intravenously at a dose of 55 kBq per kilogram bodyweight and repeated every four weeks for a maximum of six injections. (51)

1

GAPS IN KNOWLEDGE Effect evaluation of targeted alpha-radionuclide therapies

Assessing treatment response during systemic therapies for mCRPC is important, as it will inform physicians and patients whether there is a therapeutic benefit. Most often, response is assessed by a combination of imaging tests, serum biochemical markers and symptom assessments. TheALSYMPCA trial didnotmandate radiological evaluationduring radium-223 therapy. Although bone progression during radium-223 therapy is rare, extraskeletal disease progression following radium-223 has been reported in up to 46% of the patients. (52) This underlines the importance of meticulous evaluation of solid lesions before therapy and effect evaluation during therapy. Standard of care during radium-223 therapy currently includes monthly biochemical tests and imaging with bone scintigraphy and computer tomography (CT) of thorax, abdomenandpelvisbeforeandafter radium-223therapy. (51)However, intheALSYMPCA trial, a 30 percent or greater reduction in prostate-specific antigen (PSA) was found in only 16% of patients after three radium-223 injections. (23) Alkaline phosphatase (ALP), a recognized marker of osteoblast activity due to bone metastases, might be a better biomarker for the effect evaluation of radium-223 therapy. (53) For evaluation of PSMA targeted RLT, both PSA and ALP might be useful response markers. Furthermore, since radiation may induce immunological changes, evaluation of immune cell subsets in patients treated with TAT may also provide information on response to therapy.

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In addition to biochemical and radiological responses, patient-reported outcomes are important in the evaluation of therapies. Patient-reported outcomes can inform health care professionals on the efficacy and tolerability of treatment, increase patient satisfaction, improve symptom control, and provide prognostic information. (54) Patient selection for targeted alpha-radionuclide therapies TheALSYMPCA trial benchmarked the criteria for patients to receive radium-223 therapy. These criteria necessitate progressive CRPC with symptomatic bone metastases, with bone-only disease, or with concomitant lymph node metastases with a largest diameter less than 3 cm on the short-axis, no (history of ) visceral metastases, no imminent or established spinal cord compression, and adequate hematological, liver and kidney function. (23) However, in the ALSYMPCA trial, a statistically significant OS benefit of treatment could not be demonstrated in some subgroups, including patients with low baseline alkaline phosphatase levels (< 220 U/L), Eastern Cooperative Oncology Group performance score ≥ 2 and very low or extremely high number of bone metastases on baseline bone scintigraphy. (23) These findings raise the question whether radium-223 should be used in these subgroups. To evaluate the efficacy of radium-223 in patients with these characteristics, largeobservational studieswith real-worlddataarewarranted. Earlier utilization of radium-223 therapy in castrate-resistant state is more likely to result in completion of therapy and potentially better patient outcomes, partly because in later disease stage, patients exhibit more symptoms and are more likely to experience disease progression as a result of more aggressive cancer biology following resistance to antihormonal drugs and taxane-based chemotherapy. (55) In addition, radium-223 therapy should be withheld in patients with (a history of ) visceral metastases, necessitating baseline CT of thorax, abdomen and pelvis to exclude visceral disease and disease progression in lymph node metastases before initiation of radium-223. Particularly when radium-223 is initiated after one line of second-generation hormonal therapy and after docetaxel chemotherapy, the prevalence of baseline visceral metastases increases. (55, 56) This again underlines the importance of early initiation of radium-223 in the treatment paradigm of mCRPC. In the ALSYMPCA trial, symptomatic bone metastases were defined as bone metastases in patients who either use regular analgesic medication for cancer-related bone pain or receive external-beam radiation therapy for bone pain prior to initiation of radium-223. (23) Experiencing pain without daily use of analgesics or deriving a limitation in the performance of daily (strenuous) activities may also be considered as symptomatic disease, and these patients therefore should be considered as potential candidates for

16

General introduction and outline of the thesis

radium-223 therapy. One may also argue that radium-223 may be beneficial in patients with bone metastatic disease not yet being symptomatic, but having radiographic signs of bone-progression. (55) For PSMA-targeted RLT, selection criteria are disease progression on registered mCRPC therapies, sufficient expression of PSMA in all metastatic lesions on a pretherapeutic PSMA-ligand positron emission tomography (PET) scan, and adequate bone marrow and kidney function. (57) However, genotypic and phenotypic characteristics, such as histological PSMA expression or DNA damage repair alterations, might also be important selection criteria. OUTLINE OF THE THESIS The aim of this thesis was to evaluate radium-223 therapy and 225 Ac-PSMA RLT in mCRPC in daily clinical practice, with a focus on effect evaluation and the identification of prognostic parameters, in order to optimize patient selection for these therapies in the future. Part I of this thesis focuses on the effect evaluation of radium-223 therapy and 225 Ac PSMA RLT in mCRPC patients. In chapter 2 , we describe the findings of an observational cohort study which evaluated the efficacy, impact on quality of life and safety of 225 Ac-PSMA RLT in advanced mCRPC patients. Furthermore, this study explored predictive biomarkers on pretherapeutic tissue biopsies. In chapter 3 , we evaluate the immunological changes in mCRPC patients by phenotyping their peripheral blood mononuclear cells before, during, and after treatment with radium-223. In chapter 4 , we present the outcomes of a prospective Dutch multicenter study on health-related quality of life, psychological distress and fatigue in mCRPC patients who were treated with radium-223 therapy. Part II of this thesis describes studies that used real-world data to explore prognostic parameters in mCRPC patients treated with radium-223 therapy. In chapter 5, we describe the outcomes of a retrospective cohort study which aimed to identify pretherapeutic parameters that predict overall survival and treatment completion in mCRPC patients who were treated with radium-223 therapy in an academic care setting. The aim of the multicenter retrospective cohort study described in chapter 6 was to investigate whether ALP dynamics after the first radium-223 injection can act as

1

17

Chapter 1

surrogate marker for overall survival. In chapter 7 , the potential of DNA damage repair mutation status as a biomarker of efficacy of radium-223 therapy and overall survival of mCRPC patients is described. Part III contains the general discussion in chapter 8 , in which the main findings are discussed and future perspectives are described. Finally, chapter 9 provides a summary of this thesis in both English and Dutch.

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General introduction and outline of the thesis

REFERENCES

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1. Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin. 2021;71(3):209-49. 2. Nederlandse Kankerregistratie, Integraal Kankercentrum Nederland. Incidentiecijfers prostaatkanker in Nederland. 2019. 3. Centraal Bureau voor de Statistiek. Sterftecijfers prostaatkanker in Nederland. 2019. 4. Mottet N, van den Bergh RCN, Briers E, Van den Broeck T, Cumberbatch MG, De Santis M, et al. EAU-EANM-ESTRO-ESUR-SIOG Guidelines on Prostate Cancer-2020 Update. Part 1: Screening, Diagnosis, and Local Treatment with Curative Intent. Eur Urol. 2021;79(2):243-62. 5. Hamdy FC, Donovan JL, Lane JA, Mason M, Metcalfe C, Holding P, et al. 10-Year Outcomes after Monitoring, Surgery, or Radiotherapy for Localized Prostate Cancer. N Engl J Med. 2016;375(15):1415-24. 6. Wilt TJ, Jones KM, BarryMJ, Andriole GL, Culkin D,Wheeler T, et al. Follow-up of Prostatectomy versus Observation for Early Prostate Cancer. N Engl J Med. 2017;377(2):132-42. 7. James ND, Spears MR, Clarke NW, Dearnaley DP, De Bono JS, Gale J, et al. Survival with Newly Diagnosed Metastatic Prostate Cancer in the “Docetaxel Era”: Data from 917 Patients in the Control Arm of the STAMPEDE Trial (MRC PR08, CRUK/06/019). Eur Urol. 2015;67(6):1028-38. 8. Carlin BI, Andriole GL. The natural history, skeletal complications, and management of bone metastases in patients with prostate carcinoma. Cancer. 2000;88(12 Suppl):2989-94. 9. Saad F, Lipton A, Cook R, Chen YM, Smith M, Coleman R. Pathologic fractures correlate with reduced survival in patients with malignant bone disease. Cancer. 2007;110(8):1860-7. 10. Pagliarulo V, Bracarda S, Eisenberger MA, Mottet N, Schröder FH, Sternberg CN, et al. Contemporary role of androgen deprivation therapy for prostate cancer. Eur Urol. 2012;61(1):11-25. 11. Cornford P, van den Bergh RCN, Briers E, Van den Broeck T, Cumberbatch MG, De Santis M, et al. EAU-EANM-ESTRO-ESUR-SIOG Guidelines on Prostate Cancer. Part II-2020 Update: Treatment of Relapsing and Metastatic Prostate Cancer. Eur Urol. 2021;79(2):263-82. 12. Scher HI, Sawyers CL. Biology of progressive, castration-resistant prostate cancer: directed therapies targeting the androgen-receptor signaling axis. J Clin Oncol. 2005;23(32):8253-61. 13. Pernigoni N, Zagato E, Calcinotto A, Troiani M, Mestre RP, Calì B, et al. Commensal bacteria promote endocrine resistance in prostate cancer through androgen biosynthesis. Science. 2021;374(6564):216-24. 14. Sartor O, de Bono JS. Metastatic Prostate Cancer. N Engl J Med. 2018;378(7):645-57. 15. Tannock IF, de Wit R, Berry WR, Horti J, Pluzanska A, Chi KN, et al. Docetaxel plus prednisone or mitoxantrone plus prednisone for advanced prostate cancer. N Engl J Med. 2004;351(15):1502-12. 16. Petrylak DP, Tangen CM, Hussain MH, Lara PN, Jr., Jones JA, Taplin ME, et al. Docetaxel and estramustine compared withmitoxantrone and prednisone for advanced refractory prostate cancer. N Engl J Med. 2004;351(15):1513-20.

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17. De Bono JS, Oudard S, Ozguroglu M, Hansen S, Machiels JP, Kocak I, et al. Prednisone plus cabazitaxel or mitoxantrone for metastatic castration-resistant prostate cancer progressing after docetaxel treatment: a randomised open-label trial. Lancet. 2010;376(9747):1147-54. 18. Kantoff PW, Higano CS, Shore ND, Berger ER, Small EJ, Penson DF, et al. Sipuleucel-T immunotherapy for castration-resistant prostate cancer. N Engl J Med. 2010;363(5):411-22. 19. Ryan CJ, Smith MR, de Bono JS, Molina A, Logothetis CJ, de Souza P, et al. Abiraterone in metastatic prostate cancer without previous chemotherapy. N Engl J Med. 2013;368(2):138 48. 20. De Bono JS, Logothetis CJ, Molina A, Fizazi K, North S, Chu L, et al. Abiraterone and increased survival in metastatic prostate cancer. N Engl J Med. 2011;364(21):1995-2005. 21. Beer TM, Armstrong AJ, Rathkopf DE, Loriot Y, Sternberg CN, Higano CS, et al. Enzalutamide in metastatic prostate cancer before chemotherapy. N Engl J Med. 2014;371(5):424-33. 22. Scher HI, Fizazi K, Saad F, Taplin ME, Sternberg CN, Miller K, et al. Increased survival with enzalutamide in prostate cancer after chemotherapy. N Engl J Med. 2012;367(13):1187-97. 23. Parker C, Nilsson S, Heinrich D, Helle SI, O’Sullivan JM, Fossa SD, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J Med. 2013;369(3):213-23. 24. de Bono J, Mateo J, Fizazi K, Saad F, Shore N, Sandhu S, et al. Olaparib for Metastatic Castration-Resistant Prostate Cancer. N Engl J Med. 2020;382(22):2091-102. 25. Abida W, Patnaik A, Campbell D, Shapiro J, Bryce AH, McDermott R, et al. Rucaparib in Men With Metastatic Castration-Resistant Prostate Cancer Harboring a BRCA1 or BRCA2 Gene Alteration. J Clin Oncol. 2020;38(32):3763-72. 26. Sweeney CJ, Chen YH, Carducci M, Liu G, Jarrard DF, Eisenberger M, et al. Chemohormonal Therapy in Metastatic Hormone-Sensitive Prostate Cancer. N Engl J Med. 2015;373(8):737-46. 27. James ND, Sydes MR, Clarke NW, Mason MD, Dearnaley DP, Spears MR, et al. Addition of docetaxel, zoledronic acid, or both to first-line long-termhormone therapy in prostate cancer (STAMPEDE): survival results from an adaptive, multiarm, multistage, platform randomised controlled trial. Lancet. 2016;387(10024):1163-77. 28. Fizazi K, Tran N, Fein L, Matsubara N, Rodriguez-Antolin A, Alekseev BY, et al. Abiraterone plus Prednisone in Metastatic, Castration-Sensitive Prostate Cancer. N Engl J Med. 2017;377(4):352-60. 29. James ND, de Bono JS, Spears MR, Clarke NW, Mason MD, Dearnaley DP, et al. Abiraterone for ProstateCancerNot PreviouslyTreatedwithHormoneTherapy. NEngl JMed. 2017;377(4):338 51. 30. De Vincentis G, Gerritsen W, Gschwend JE, Hacker M, Lewington V, O’Sullivan JM, et al. Advances in targeted alpha therapy for prostate cancer. Ann Oncol. 2019;30(11):1728-39. 31. Dizdarevic S, McCready R, Vinjamuri S. Radium-223 dichloride in prostate cancer: proof of principle for the use of targeted alpha treatment in clinical practice. Eur J Nucl Med Mol Imaging. 2020;47(1):192-217. 32. Sartor O, Sharma D. Radium and other alpha emitters in prostate cancer. Transl Androl Urol. 2018;7(3):436-44.

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33. Makvandi M, Dupis E, Engle JW, Nortier FM, Fassbender ME, Simon S, et al. Alpha-Emitters and Targeted Alpha Therapy in Oncology: from Basic Science to Clinical Investigations. Target Oncol. 2018;13(2):189-203. 34. Henriksen G, Breistol K, Bruland OS, Fodstad O, Larsen RH. Significant antitumor effect from bone-seeking, alpha-particle-emitting (223)Ra demonstrated in an experimental skeletal metastases model. Cancer Res. 2002;62(11):3120-5. 35. Brechbiel MW. Targeted alpha-therapy: past, present, future? Dalton Trans. 2007(43):4918 28. 36. Silver DA, Pellicer I, Fair WR, Heston WD, Cordon-Cardo C. Prostate-specific membrane antigen expression in normal and malignant human tissues. Clin Cancer Res. 1997;3(1):81-5. 37. Wright GL, Jr., Grob BM, Haley C, Grossman K, Newhall K, Petrylak D, et al. Upregulation of prostate-specific membrane antigen after androgen-deprivation therapy. Urology. 1996;48(2):326-34. 38. Meller B, Bremmer F, Sahlmann CO, Hijazi S, Bouter C, Trojan L, et al. Alterations in androgen deprivation enhanced prostate-specific membrane antigen (PSMA) expression in prostate cancer cells as a target for diagnostics and therapy. EJNMMI Res. 2015;5(1):66. 39. Farolfi A, Fendler W, Iravani A, Haberkorn U, Hicks R, Herrmann K, et al. Theranostics for Advanced Prostate Cancer: Current Indications and Future Developments. Eur Urol Oncol. 2019;2(2):152-62. 40. Kratochwil C, Bruchertseifer F, Giesel FL, Weis M, Verburg FA, Mottaghy F, et al. 225Ac PSMA-617 for PSMA-Targeted alpha-Radiation Therapy of Metastatic Castration-Resistant Prostate Cancer. J Nucl Med. 2016;57(12):1941-4. 41. Kratochwil C, Bruchertseifer F, Rathke H, Bronzel M, Apostolidis C, Weichert W, et al. Targeted alpha-Therapy of Metastatic Castration-Resistant Prostate Cancer with (225)Ac-PSMA-617: Dosimetry Estimate and Empiric Dose Finding. J Nucl Med. 2017;58(10):1624-31. 42. Bruland OS, Nilsson S, Fisher DR, Larsen RH. High-linear energy transfer irradiation targeted to skeletal metastases by the alpha-emitter 223Ra: adjuvant or alternative to conventional modalities? Clin Cancer Res. 2006;12(20 Pt 2):6250s-7s. 43. Suominen MI, Fagerlund KM, Rissanen JP, Konkol YM, Morko JP, Peng Z, et al. Radium-223 Inhibits Osseous Prostate Cancer Growth by Dual Targeting of Cancer Cells and Bone Microenvironment in Mouse Models. Clin Cancer Res. 2017;23(15):4335-46. 44. Hoskin P, Sartor O, O’Sullivan JM, Johannessen DC, Helle SI, Logue J, et al. Efficacy and safety of radium-223 dichloride in patients with castration-resistant prostate cancer and symptomatic bone metastases, with or without previous docetaxel use: a prespecified subgroup analysis from the randomised, double-blind, phase 3 ALSYMPCA trial. Lancet Oncol. 2014;15(12):1397-406. 45. Parker C, Finkelstein SE, Michalski JM, O’Sullivan JM, Bruland O, Vogelzang NJ, et al. Efficacy and Safety of Radium-223 Dichloride in Symptomatic Castration-resistant Prostate Cancer Patients With or Without Baseline Opioid Use From the Phase 3 ALSYMPCA Trial. Eur Urol. 2016;70(5):875-83.

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Chapter 1

46. Sartor O, Coleman R, Nilsson S, Heinrich D, Helle SI, O’Sullivan JM, et al. Effect of radium-223 dichloride on symptomatic skeletal events in patients with castration-resistant prostate cancer and bone metastases: results from a phase 3, double-blind, randomised trial. Lancet Oncol. 2014;15(7):738-46. 47. Nilsson S, Cislo P, Sartor O, Vogelzang NJ, Coleman RE, O’Sullivan JM, et al. Patient-reported quality-of-life analysis of radium-223 dichloride from the phase III ALSYMPCA study. Ann Oncol. 2016;27(5):868-74. 48. Dizdarevic S, Petersen PM, Essler M, Versari A, Bourre JC, la Fougere C, et al. Interim analysis of the REASSURE (Radium-223 alpha Emitter Agent in non-intervention Safety Study in mCRPC popUlation for long-teRm Evaluation) study: patient characteristics and safety according to prior use of chemotherapy in routine clinical practice. Eur J Nucl Med Mol Imaging. 2019;46(5):1102-10. 49. Vogelzang NJ, Coleman RE, Michalski JM, Nilsson S, O’Sullivan JM, Parker C, et al. Hematologic Safety of Radium-223 Dichloride: Baseline Prognostic Factors Associated With Myelosuppression in the ALSYMPCA Trial. Clin Genitourin Cancer. 2017;15(1):42-52 e8. 50. Parker CC, Coleman RE, Sartor O, Vogelzang NJ, Bottomley D, Heinrich D, et al. Three-year Safety of Radium-223 Dichloride in Patients with Castration-resistant Prostate Cancer and Symptomatic Bone Metastases from Phase 3 Randomized Alpharadin in Symptomatic Prostate Cancer Trial. Eur Urol. 2018;73(3):427-35. 51. Poeppel TD, Handkiewicz-Junak D, Andreeff M, Becherer A, Bockisch A, Fricke E, et al. EANM guideline for radionuclide therapy with radium-223 of metastatic castration-resistant prostate cancer. Eur J Nucl Med Mol Imaging. 2018;45(5):824-45. 52. Keizman D, Fosboel MO, Reichegger H, Peer A, Rosenbaum E, Desax MC, et al. Imaging response during therapy with radium-223 for castration-resistant prostate cancer with bone metastases-analysis of an international multicenter database. Prostate Cancer Prostatic Dis. 2017;20(3):289-93. 53. Heinrich D, Bruland O, Guise TA, Suzuki H, Sartor O. Alkaline phosphatase in metastatic castration-resistant prostate cancer: reassessment of an older biomarker. Future Oncol. 2018;14(24):2543-56. 54. Kotronoulas G, Kearney N, Maguire R, Harrow A, Di Domenico D, Croy S, et al. What is the value of the routine use of patient-reported outcome measures toward improvement of patient outcomes, processes of care, and health service outcomes in cancer care? A systematic review of controlled trials. J Clin Oncol. 2014;32(14):1480-501. 55. Heinrich D, Bektic J, Bergman AM, Caffo O, Cathomas R, Chi KN, et al. The Contemporary Use of Radium-223 in Metastatic Castration-resistant Prostate Cancer. Clinical Genitourinary Cancer. 2018;16(1):e223-e31. 56. Pezaro CJ, Omlin A, Lorente D, Nava Rodrigues D, Ferraldeschi R, Bianchini D, et al. Visceral disease in castration-resistant prostate cancer. Eur Urol. 2014;65(2):270-3. 57. Kratochwil C, Fendler WP, Eiber M, Baum R, Bozkurt MF, Czernin J, et al. EANM procedure guidelines for radionuclide therapy with (177)Lu-labelled PSMA-ligands ((177)Lu-PSMA RLT). Eur J Nucl Med Mol Imaging. 2019;46(12):2536-44.

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PART I EFFECT EVALUATION OF TARGETED ALPHA-RADIONUCLIDE THERAPIES

2 Clinical outcomes and molecular profiling of advanced metastatic castration-resistant prostate cancer patients treated with 225 Ac-PSMA-617 targeted alpha-radiation therapy

Maarten J. van der Doelen, Niven Mehra, Inge M. van Oort, Monika G. Looijen-Salamon, Marcel J.R. Janssen, José A.E. Custers, Peter H.J. Slootbeek, Leonie I. Kroeze, Frank Bruchertseifer, Alfred Morgenstern, Uwe Haberkorn, Clemens Kratochwil, James Nagarajah, Winald R. Gerritsen

Urologic Oncology. 2021; 39: 729 e7-e16.

Chapter 2

ABSTRACT Introduction

Targeted alpha-radiation therapy (TAT) with 225 Ac-labeled prostate-specific membrane antigen (PSMA) ligands is a promising novel treatment option for metastatic castration resistant prostate cancer (mCRPC) patients. Limited data is available on efficacy, quality of life (QoL) and pretherapeutic biomarkers. Aim of this study was to evaluate the efficacy of 225 Ac-PSMA TAT and impact on QoL in advanced mCRPC, and to explore predictive biomarkers on pretherapeutic metastatic tissue biopsies. Methods Observational cohort study including consecutive patients treated with 225 Ac-PSMA TAT between February 2016 and July 2018. Primary endpoint was overall survival (OS). Furthermore, prostate-specific antigen (PSA) changes, radiological response, safety, QoL and xerostomia were evaluated. Biopsies were analyzed with immunohistochemistry and next-generation sequencing. Results Thirteen patients were included. Median OS was 8.5months for the total cohort and 12.6 months for PSMA radioligand therapy-naïve patients. PSA declines of ≥90% and ≥50% were observed in 46% and 69% of patients, respectively. Six patients were radiologically evaluable; 50% showed partial response. All patients showed >90% total tumor volume reduction on PET imaging. Patients experienced clinically relevant decrease of pain and QoL improvement in physical and role functioning domains. Xerostomia persisted during follow-up. Patients with high baseline immunohistochemical PSMA expression or DNA damage repair (DDR) alterations tended to have longer OS. Conclusions TAT with 225 Ac-PSMA resulted in remarkable survival and biochemical responses in advanced mCRPC patients. Patients experienced clinically relevant QoL improvement, although xerostomia was found to be non-transient. Baseline immunohistochemical PSMA expression and DDR status are potential predictive biomarkers of response to 225 Ac-PSMA TAT.

28

Actinium-225 labeled PSMA radioligand therapy in mCRPC patients

INTRODUCTION Prostate cancer is the most commonly diagnosed cancer in men, and development of metastatic castration-resistant prostate cancer (mCRPC) is associated with a poor prognosis. Despite registration of life-prolonging chemotherapeutic agents and androgen-receptor targeting therapies (ARTs), there is an ongoing need for additional effective therapeutic strategies with different mechanisms of action. Prostate-specific membrane antigen (PSMA) is a transmembrane glycoprotein showing significant overexpression in high grade and advanced stage prostate cancer, which makes it an attractive target for diagnostic and therapeutic approaches (1-3). Several retrospective cohort studies have described the potential of beta particle emitting 177 Lu PSMA-617 ( 177 Lu-PSMA) radioligand therapy (RLT) in mCRPC (4). A recent prospective phase 2 study investigated 177 Lu-PSMA RLT in mCRPC patients after prior chemotherapy and ARTs and reported ≥50% PSA declines in 57% of the patients and median overall survival (OS) of 13.5 months (5). Beta emitters like 177 Lu show therapeutic efficacy in large tumor masses due to long radiation range and the ability to induce a cross-fire effect (6, 7). Targeted alpha radiation therapy (TAT) with 225 Ac may be more effective in patients with disseminated metastatic disease, due to the shorter radiation range coupled with high-linear-energy transfer that induces targeted tumor cell killing by causing higher number of double strand DNA breaks compared to 177 Lu , while minimizing damage to surrounding tissues such as red bone marrow (7-9). In addition, 225 Ac-PSMA-617 ( 225 Ac-PSMA) TAT is able to overcome refractory disease after 177 Lu-PSMA RLT (10-12). Limited data is available on the effect on quality of life (QoL) and side effects of 225 Ac PSMA TAT. Additionally, pretherapeutic biomarkers are needed to guide clinicians to select the most susceptible patients for 225 Ac-PSMA TAT to improve outcome. The aim of this observational cohort study was to evaluate the efficacy, impact on QoL and safety of 225 Ac-PSMA TAT in advanced mCRPC patients. Furthermore, we explored predictive biomarkers on pre-therapeutic tissue biopsies.

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29

Chapter 2

PATIENTS AND METHODS Study design and patient population

This was an observational cohort study including consecutive patients with advanced mCRPCwhowere referred to receive 225 Ac-PSMATAT at the nuclearmedicine department of the Heidelberg University Hospital, Germany. We performed retrospective analyses of a prospectively maintained database. Screening and eligibility assessment, as well as patient follow-up were performed at the Radboudumc, Nijmegen, The Netherlands. Patients were eligible if they had an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 and PSMA expression of metastatic lesions above the physiologic background liver uptake at 68 Ga-PSMA-HBED-CC ( 68 Ga-PSMA-11) PET/ CT. Laboratory requirements were baseline hemoglobin level >8.0 g/dL, white blood cell count >2.0 x 10 9 /L, platelet count >75 x 10 9 /L, and creatinine clearance <2 mg/ dL. Permitted therapies during 225 Ac-PSMA TAT were luteinizing hormone-releasing hormone analogues, low-dose steroids, bone protective therapies (bisphosphonates or RANK-ligand inhibitors) and analgesics. Concomitant systemic anti-prostate cancer therapies, including abiraterone and enzalutamide, were not allowed during TAT. Application of 225 Ac-PSMA TAT PSMA-617 was labeled with 225 Ac as published previously (10, 11). The radioligand was produced in-house using the PSMA-617 precursor from ABX (Radeberg, Germany) and 225 Ac was provided from the European Commission’s Joint Research Centre (Karlsruhe, Germany). 225 Ac-PSMA was injected intravenously every eight weeks up to four cycles, with an initial activity of 8 MBq, thereafter reduced to 6 MBq per subsequent cycle. Patients were hospitalized for 48 hours with external cooling of the salivary glands and received dexamethasone to reduce radiation inflammation. Therapy was discontinued at evidence of disease progression, deterioration of clinical condition, treatment-related adverse events or patient refusal to continue. Outcome measures Primary endpoint was OS, defined as the time interval from first 225 Ac-PSMA TAT cycle to the date of death or last follow-up. Secondary endpoints were clinical, biochemical, and radiological efficacy, safety, and patient-reported outcomes. Clinical disease progression was defined as the moment of no longer clinically benefiting according to Prostate Cancer Working Group 3 (PCWG3) criteria, start of a new systemic treatment or best supportive care, or death (13). PSA response was defined as ≥50% decrease from baseline, according to PCWG3 criteria (13). In addition, ≥90% confirmed PSA decline was

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Actinium-225 labeled PSMA radioligand therapy in mCRPC patients

included. Changes in alkaline phosphatase (ALP) levels were calculated as percentage change from baseline. Radiological evaluation by 68 Ga-PSMA-11 PET with contrast enhanced high-dose CT from skull base to mid-thigh was performed eight weeks after end of therapy and during follow-up based on clinical indications. Scans were evaluated according to RECIST 1.1 and PERCIST by two nuclear medicine physicians (14, 15). In addition, whole body tumor volume was measured using the semi-automatic 3D ROI Visualisation, Evaluation and Image Registration software (ROVER, ABX, Radeberg, Germany). We used a maximum standardized uptake value of 15 as threshold to automatically select PSMA positive lesions and removed of areas with physiologic uptake manually. Treatment-emergent adverse events were scored using the Common Terminology Criteria for Adverse Events, version 5.0. Skeletal related events (SREs) were defined according to PCWG3 criteria (13). Patients were asked to complete the European Organization for Research and Treatment of Cancer (EORTC) QoL questionnaires Core 30 (QLQ-C30) and Bone Metastases-22 (BM-22) (16, 17) and the Xerostomia Inventory (18) at baseline, at end of therapy and during follow-up at 12 and 18 months. Exploratory biomarker analyses Patients underwent CT-guided metastatic tissue biopsies before and after 225 Ac-PSMA TAT for immunohistochemistry (IHC) and next-generation sequencing (NGS), to explore predictive biomarkers. Patients underwent a 68 Ga-PSMA-11 PET/CT prior to bone biopsy to improve the success rate (19). Archival prostate specimens were utilized when baseline metastatic biopsies were unavailable or not evaluable. IHC assessment by two independent urological pathologists included revision of prostate cancer diagnosis and staining for neuroendocrinemarkers (CD56 antigen, chromogranin and synaptophysin), PSMA, the androgen receptor and Ki-67 expression. Membranous PSMA expression heterogeneity was assessed semiquantitatively by H-scores (scale 0-300), defined as the product of the percentage of immunopositive tumor cells (0-100%) and the staining intensity (0=negative; 1+=weak; 2+=moderate; 3+=intense). Other IHC results were expressed as the percentage of immunopositive tumor cells (0-100%). Specimens that showed different staining intensities were scored for the most prevalent intensity. Tumor samples were sequenced by non-profit institutes (Center for Personalized Cancer Treatment; CPCT), by fee-for-service providers (FoundationOne), and by a custom in house NGS panel (20). The pathogenicity of alterations was assessed according to the guidelines for the interpretation of sequence variants. Statistical methods Descriptive statistical methods were used to characterize the cohort and to analyze changes in QoL. Survival curves were estimated using Kaplan-Meier statistics. QoL data

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Chapter 2

are presented as median scale scores plus interquartile ranges. Clinically relevant QoL changes were defined as small (5-10 points), moderate (10-20 points), or large (>20 points), according to Osoba et al (21). Alterations in the Xerostomia Inventory scores were tested using the Wilcoxon signed-rank test for paired data. Two-sided P-values <0.05 were considered statistically significant. Ethics This study was approved by the medical ethics review committee and it was performed in accordance with the principles of the 1964 Declaration of Helsinki and its later amendments. 225 Ac-PSMA TAT was applied in accordance to the German pharmaceuticals law as salvage therapy for mCRPC patients, presenting progressive disease after approved therapies. Patients were informed about the experimental nature of 225 Ac-PSMA TAT and gave written informed consent. Biomarker assessment was performed following informed consent to the urology biobank (CWOM 9803-0060) and NGS protocol by FoundationOne and CPCT-02 (NCT01855477). Between February 2016 and July 2018, thirteen consecutive mCRPC patients received 225 Ac-PSMA TAT. Median age was 71 years (Table 1). All patients received prior taxane based chemotherapy and eleven (85%) patients previously received ARTs. Two (15%) patients had progressed on previous 177 Lu-PSMA RLT. Patients received a median of four prior systemic therapies (range 1-5) (Supplementary table 1). All patients had bone metastases, eleven (85%) patients had lymph node metastases and visceral metastases were present in eight (62%) patients. Median PSA and ALP at baseline were 878 μg/L and 356 U/L, respectively. Overall survival Eleven (85%) patients had deceased at time of analysis. For the total cohort, median OS was 8.5 months (Figure 1A). Median OS was 12.6 months for PSMA RLT-naïve patients versus 1.3 months in patients who underwent prior 177 Lu-PSMA RLT (Figure 1B). Two (15%) patients were alive, 29 and 34 months since first 225 Ac-PSMA TAT injection; one of them is having an ongoing response to PSMA RLT. RESULTS Baseline patient characteristics

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Actinium-225 labeled PSMA radioligand therapy in mCRPC patients

Table 1. Baseline patient demographics and clinical characteristics. Characteristic

Total cohort (N = 13)

Age, years, median (IQR)

71 (64-77)

Time CRPC to 225 Ac-PSMA-617 TAT, months, median (IQR)

35 (17-64)

Gleason score ≥8, n (%)

6 (46.2)

2

Extent of disease on 68 Ga-PSMA-11 PET/CT Bone metastases, n (%)

13 (100.0)

Bone metastases only, n (%)

3 (23.1)

Locoregional lymph node metastases, n (%)

10 (76.9)

Visceral metastases, n (%)

8 (61.5)

Prior systemic therapies Number of different systemic therapies, median [range]

4 [1-5]

Docetaxel, n (%)

13 (100.0)

Cabazitaxel, n (%)

8 (61.5)

Abiraterone, n (%)

11 (84.6)

Enzalutamide, n (%)

10 (76.9)

223 Ra-dichloride, n (%)

4 (30.8)

177 Lu-PSMA-617 RLT, n (%)

2 (15.4)

Opioid use, n (%)

7 (63.6)

ECOG performance status ECOG 0, n (%)

3 (23.1)

ECOG 1-2, n (%)

10 (76.9)

Hemoglobin level, g/dL, median (IQR)

10.1 (9.0-11.2)

Platelet count, x10 9 /l, median (IQR)

314 (177-405)

Prostate-specific antigen level, ng/ml, median (IQR)

878 (203-1611)

Alkaline phosphatase level, U/l, median (IQR)

356 (155-671)

Lactate dehydrogenase level, U/l, median (IQR)

294 (239-858)

Prostate-specific antigen doubling time, months, median (IQR) 1.9 (1.1-2.2) CRPC, castration-resistant prostate cancer; ECOG, Eastern Cooperative Oncology Group; IQR, interquartile range; PSMA, prostate specific membrane antigen; RLT, radioligand therapy; TAT, targeted alpha-radiation therapy.

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