Riikka Oksala

Discovery of ODM-201, a new-generation androgen receptor inhibitor targeting resistance mechanisms to androgen signaling-directed prostate cancer therapies.

Activation of androgen receptor (AR) is crucial for prostate cancer growth. Remarkably, also castration-resistant prostate cancer (CRPC) is dependent on functional AR, and several mechanisms have been proposed to explain the addiction. Known causes of CRPC include gene amplification and overexpression as well as point mutations of AR. We report here the pharmacological profile of ODM-201, a novel AR inhibitor that showed significant antitumor activity and a favorable safety profile in phase 1/2 studies in men with CRPC. ODM-201 is a full and high-affinity AR antagonist that, similar to second-generation antiandrogens enzalutamide and ARN-509, inhibits testosterone-induced nuclear translocation of AR. Importantly, ODM-201 also blocks the activity of the tested mutant ARs arising in response to antiandrogen therapies, including the F876L mutation that confers resistance to enzalutamide and ARN-509. In addition, ODM-201 reduces the growth of AR-overexpressing VCaP prostate cancer cells both in vitro and in a castration-resistant VCaP xenograft model. In contrast to other antiandrogens, ODM-201 shows negligible brain penetrance and does not increase serum testosterone levels in mice. In conclusion, ODM-201 is a potent AR inhibitor that overcomes resistance to AR-targeted therapies by antagonizing both overexpressed and mutated ARs. ODM-201 is currently in a phase 3 trial in CRPC.

Castration Induces Up-Regulation of Intratumoral Androgen Biosynthesis and Androgen Receptor Expression in an Orthotopic VCaP Human Prostate Cancer Xenograft Model

Androgens are key factors involved in the development and progression of prostate cancer (PCa), and PCa growth can be suppressed by androgen deprivation therapy. In a considerable proportion of men receiving androgen deprivation therapy, however, PCa progresses to castration-resistant PCa (CRPC), making the development of efficient therapies challenging. We used an orthotopic VCaP human PCa xenograft model to study cellular and molecular changes in tumors after androgen deprivation therapy (castration). Tumor growth was monitored through weekly serum prostate-specific antigen measurements, and mice with recurrent tumors after castration were randomized to treatment groups. Serum prostate-specific antigen concentrations showed significant correlation with tumor volume. Castration-resistant tumors retained concentrations of intratumoral androgen (androstenedione, testosterone, and 5α-dihydrotestosterone) at levels similar to tumors growing in intact hosts. Accordingly, castration induced up-regulation of enzymes involved in androgen synthesis (CYP17A1, AKR1C3, and HSD17B6), as well as expression of full-length androgen receptor (AR) and AR splice variants (AR-V1 and AR-V7). Furthermore, AR target gene expression was maintained in castration-resistant xenografts. The AR antagonists enzalutamide (MDV3100) and ARN-509 suppressed PSA production of castration-resistant tumors, confirming the androgen dependency of these tumors. Taken together, the findings demonstrate that our VCaP xenograft model exhibits the key characteristics of clinical CRPC and thus provides a valuable tool for identifying druggable targets and for testing therapeutic strategies targeting AR signaling in CRPC.

Sexual incentive motivation in male rats requires both androgens and estrogens

In Experiment 1 castrated male rats were implanted with a Silastic capsule containing either E or cholesterol (CHOL) 35 days after castration. They were then tested for sexual incentive motivation and copulatory behaviors every 5th day for 3 weeks. None of the treatments affected sexual incentive motivation. After the last test, all subjects were implanted with DHT-containing Silastic capsules, and tests continued for another 3 weeks. While E+DHT enhanced sexual incentive motivation and copulatory behavior, DHT alone failed to do so. In Experiment 2 the aromatase inhibitor fadrozole (F) was combined with testosterone (T). T restored all behaviors to the level seen in intact rats, and F significantly reduced these effects. In fact, T+F was not different from DHT. T and DHT restored the weight of the prostate and seminal vesicles to levels close to those of intact rats. In Experiment 3 a lower dose of E was employed. Also this dose of E failed to affect sexual incentive motivation while E+DHT restored it to the level of intact animals. Castration enhanced the serum concentrations of LH and FSH. E alone caused a marked reduction, and E+DHT brought both gonadotropins back to the level of intact animals. It was concluded that the doses of E and DHT employed in these experiments were within or close to the physiological range, and that such doses of E completely fail to enhance sexual incentive motivation in castrated animals. DHT has small or no effects. It appears that sexual incentive motivation and copulation require simultaneous stimulation of androgen and estrogen receptors.

ODM-201, a new generation androgen receptor inhibitor for castration-resistant prostate cancer: Preclinical and phase I data.

65^ Background: Castration resistant prostate cancer (CRPC) is characterized by persistent, high level androgen receptor (AR) expression and resistance to conventional AR inhibitors. ODM-201 is a novel AR inhibitor with unique pharmacologic properties that has shown promising results in preclinical and clinical studies. METHODS AR binding affinity of ODM-201 to wild type AR was determined in cytosolic lysates obtained from ventral prostates of castrated rats using a competition binding assay. Additionally, effects of ODM-201 on the growth of castration resistant VCaP tumors was evaluated. Tumors were established by subcutaneous injection of VCaP prostate cancer cells into male nude mice. After initial tumor growth, mice were castrated. ODM-201 (50 mg/kg QD or BID orally) was initiated upon tumor regrowth. Since the risk of seizures has been reported for some second generation AR inhibitors, ODM-201 concentrations in mouse brain homogenates were studied after repeated oral administration to assess the risk. The clinical effects of ODM-201 (100, 200, 300, 500, 700, 900 mg BID) was examined in a Phase I/II dose-escalation trial in patients (N=24) with progressive metastatic CRPC. RESULTS ODM-201 binds to wild type AR with superior affinity compared to enzalutamide (Ki of 9 and 39 nM, respectively). In the VCaP CRPC model, ODM-201 significantly (p<0.001 compared to castrated control), and more efficiently than enzalutamide, inhibited tumor growth. After oral administration, tissue/plasma ratio of ODM-201 in mouse brain homogenates was negligible in all studied doses. In the Phase I/II clinical study, ODM-201 (100 to 700 mg results available) was well tolerated, and most commonly reported adverse events were asthenia, diarrhea and nausea. A PSA response (defined as ≥ 50% decrease) was obtained in 13/15 patients evaluable at 12 weeks with all patients achieving partial response or stable disease by RECIST/PCWG2 criteria. CONCLUSIONS ODM-201 is a new generation AR inhibitor with superior preclinical efficacy compared to enzalutamide and bicalutamide, it does not enter the brain in preclinical studies, and it shows very promising activity and no significant toxicity in patients with CRPC. CLINICAL TRIAL INFORMATION NCT01317641.

Optimized design and analysis of preclinical intervention studies in vivo.

Recent reports have called into question the reproducibility, validity and translatability of the preclinical animal studies due to limitations in their experimental design and statistical analysis. To this end, we implemented a matching-based modelling approach for optimal intervention group allocation, randomization and power calculations, which takes full account of the complex animal characteristics at baseline prior to interventions. In prostate cancer xenograft studies, the method effectively normalized the confounding baseline variability, and resulted in animal allocations which were supported by RNA-seq profiling of the individual tumours. The matching information increased the statistical power to detect true treatment effects at smaller sample sizes in two castration-resistant prostate cancer models, thereby leading to saving of both animal lives and research costs. The novel modelling approach and its open-source and web-based software implementations enable the researchers to conduct adequately-powered and fully-blinded preclinical intervention studies, with the aim to accelerate the discovery of new therapeutic interventions.

Discovery and development of ODM-204: A Novel nonsteroidal compound for the treatment of castration-resistant prostate cancer by blocking the androgen receptor and inhibiting CYP17A1

We report the discovery of a novel nonsteroidal dual-action compound, ODM-204, that holds promise for treating patients with castration-resistant prostate cancer (CRPC), an advanced form of prostate cancer characterised by high androgen receptor (AR) expression and persistent activation of the AR signaling axis by residual tissue androgens. For ODM-204, has a dual mechanism of action. The compound is anticipated to efficiently dampen androgenic stimuli in the body by inhibiting CYP17A1, the prerequisite enzyme for the formation of dihydrotestosterone (DHT) and testosterone (T), and by blocking AR with high affinity and specificity. In our study, ODM-204 inhibited the proliferation of androgen-dependent VCaP and LNCaP cells in vitro and reduced significantly tumour growth in a murine VCaP xenograft model in vivo. Intriguingly, after a single oral dose of 10-30 mg/kg, ODM-204 dose-dependently inhibited adrenal and testicular steroid production in sexually mature male cynomolgus monkeys. Similar results were obtained in human chorionic gonadotropin-treated male rats. In rats, leuprolide acetate-mediated (LHRH agonist) suppression of the circulating testosterone levels and decrease in weights of androgen-sensitive organs was significantly and dose-dependently potentiated by the co-administration of ODM-204. ODM-204 was well tolerated in both rodents and primates. Based on our data, ODM-204 could provide an effective therapeutic option for men with CRPC.

Abstract 4968: Importance of tumor microenvironment in the preclinical estrogen receptor positive breast cancer- Primary tumor and bone metastasis models

Estrogen receptor positive (ER+) breast cancer has ability to metastasize to bone in high frequency. Bone is known to be fertile soil for metastasized cancer cells to survive and in turn, metastasized tumor cells alter normally balanced bone environment. Prevention and treatment of bone metastasis is challenging and better understanding why bone metastasis are resistant to current therapies is needed. Aim of the present study was to explore the role of tumor microenvironment and estrogen supplementation on growth of primary breast cancer tumor and bone metastasis to establish predictive ER+ breast cancer models for drug development. ER+ human breast cancer MCF-7 cells were inoculated into mammary fat pad and in the tibia of female athymic nude mice. Mice received either hormonal supplementation (17-beta estradiol pellet, E2) or placebo. Tumor growth was followed for 5 and 9 weeks. From one group, E2 supplementation was removed on study week 5 and tumor growth was followed for 4 weeks. During the study, blood samples were collected for serum steroid concentration measurements and at the end, histopathological evaluation and immunohistochemical (IHC) stainings were performed to examine tumor steroid hormone receptor expression. Orthotopic MCF-7 tumor growth was clearly hormone dependent. E2 supplementation, that increased serum estradiol for app. 3-fold, supported tumor growth and when E2 was removed, tumor size decreased and no tumor growth was observed thereafter. In the full absence of E2 supplement, no orthotopic tumor growth was observed. In contrast, when MCF-7 cells were inoculated into tibia, tumor growth was observed both with and without E2 supplement. IHC stainings confirmed orthotopic tumor to express ER, PR and AR when animals received E2. After E2 removal, orthotopic tumors expressed still ER and AR but no longer PR. Also intratibial tumors expressed ER and PR in the presence of E2, but no PR in the absence of E2 supplement. E2 is needed to support MCF-7 tumor growth when cancer cells are inoculated orthotopically into mammary fat pad. No orthotopic tumor growth is observed in the absence of E2 supplement. In contrast, in the bone microenvironment, MCF-7 cells form tumor even in the absence of E2 supplement. Results highlight importance of tumor microenvironment in the breast cancer progression and also refer why tumor in the different sites may be resistant to therapy. Taking together, when developing new therapies against breast cancer, focus should be addressed not only on primary tumor growth but also on bone metastasis where cancer cells are under influence of bone environment. Citation Format: Jenni Bernoulli, Mari I. Suominen, Tiina Kahkonen, Jenni Maki-Jouppila, Jussi M. Halleen, Riikka Oksala. Importance of tumor microenvironment in the preclinical estrogen receptor positive breast cancer- Primary tumor and bone metastasis models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4968. doi:10.1158/1538-7445.AM2017-4968

ODM-204, a Novel Dual Inhibitor of CYP17A1 and Androgen Receptor: Early Results from Phase I Dose Escalation in Men with Castration-resistant Prostate Cancer

BACKGROUND Most prostate cancer patients develop castration-resistant prostate cancer (CRPC) after androgen deprivation therapy treatment. CRPC growth is mediated mostly by androgen receptor signalling driven by primary androgens synthesised largely by the CYP17A1 enzyme. OBJECTIVE To evaluate the safety profile and dose-limiting toxicities of ODM-204. DESIGN, SETTING, AND PARTICIPANTS In this open, uncontrolled, nonrandomised, multicentre, tolerability and pharmacokinetic first-in-man phase I dose escalation study, patients with metastatic CRPC were randomised to receive ODM-204 in sequential cohorts of five dose levels (ie, 50, 100, 200, 300, and 500mg twice daily) concomitantly with prednisone. INTERVENTION ODM-204, a novel, orally administered, investigational, nonsteroidal dual inhibitor of CYP17A1 and androgen receptor. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS ODM-204 plasma concentrations, serum testosterone, and prostate-specific antigen (PSA) levels were evaluated and imaging of lesions was performed. RESULTS AND LIMITATIONS Of the 23 patients enrolled into the study, 60.9% experienced mild adverse effects considered to be related to the study treatment, which were fatigue, increased/decreased appetite, nausea, asthenia, diarrhoea, and weight decrease. ODM-204 area under the curve (AUC0-12) values increased dose dependently until the 300mg dose. The AUC was lower on day 8 after repeated dosing compared with day 1 from the 200mg dose upwards. Decreases in testosterone levels were seen with ODM-204 treatment confirming androgen deprivation. Of the patients, 13% also demonstrated a >50% decrease in PSA at week 12 and continued ODM-204 treatment for over a year. CONCLUSIONS ODM-204 was well tolerated up to the highest evaluated dose. There were decreases in both testosterone and PSA levels, suggesting preliminary antitumour activity in the treatment of CRPC. The pharmacokinetic properties of the molecule, however, prevent further development. PATIENT SUMMARY This study looked at the safety of ODM-204, a novel dual inhibitor of CYP17A1 and the androgen receptor, in castration-resistant prostate cancer patients. ODM-204 treatment was found to be well tolerated, and it also reduced both serum testosterone and prostate-specific antigen levels, but the properties of the molecule prevent further development.

Abstract 4133: ODM-203, a novel, selective and balanced FGFR and VEGFR inhibitor with strong activity on primary and metastatic tumor growth in FGFR-dependent and angiogenic cancer models

Genomic alterations in fibroblast growth factor receptors (FGFR) and upregulation of vascular endothelial growth factor receptors (VEGFR) are often found in the same cancer types such as gastric, lung and breast and these alterations correlate with patient survival and disease progression. In addition, both FGFR and VEGFR signaling promote tumor angiogenesis. Activation of FGFR signaling has also been described to function as a compensatory angiogenic signal following development of resistance to VEGF inhibition. ODM-203 is a novel and selective inhibitor of the FGFR and VEGFR families exhibiting equal potency to both receptors both in vitro and in vivo. In recombinant kinase assays, ODM-203 inhibits both the FGFR and VEGFR family kinases in the low nanomolar range (IC50 6-35 nM). In cells, ODM-203 suppresses FGFR and VEGFR signaling with similar potency. It also inhibits VEGF-induced endothelial cell (HUVEC) proliferation (IC50 33 nM) with similar potency as it inhibits proliferation in FGFR-dependent cell lines (IC50 50-150 nM). In vivo, ODM-203 shows strong anti-tumor activity in FGFR-dependent xenograft models and in angiogenic xenograft models with similar well tolerated doses. In addition ODM-203 inhibits metastatic tumor growth in angiogenic xenograft models. Lack of activity in a FGFR and VEGFR independent tumor models further supports the selective mode of action of ODM-203. Oral administration of ODM-203 was well tolerated with only FGFR or VEGFR inhibition related physiological events observed in vivo in rat and dog. Based on our findings, ODM-203 has a unique profile with equal potency for both FGFR and VEGFR kinase families which correlates with with strong activity on primary and metastatic tumor growth in FGFR-dependent and angiogenic tumor models. Therefore, a clinical trial with ODM-203 is ongoing in patients with solid tumors (NCT 02264418). Citation Format: Tim Holmstrom, Anu Moilanen, Mari Bjorkman, Tero Linnanen, Gerd Wohlfahrt, Stefan Karlsson, Riikka Oksala, Timo Korjamo, Susanta Samajdar, Srinivasan Rajagopalan, Shekar Chelur, Kishore Narayan, Raghuveer Ramachandra, Thomas Anthony, Samiulla DS, Murali Ramachandra, Pekka Kallio. ODM-203, a novel, selective and balanced FGFR and VEGFR inhibitor with strong activity on primary and metastatic tumor growth in FGFR-dependent and angiogenic cancer models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4133. doi:10.1158/1538-7445.AM2015-4133

Abstract LB-31: Castration induces upregulation of intratumoral androgen biosynthesis and androgen receptor expression in orthotopic VCaP human prostate cancer xenograft model

Androgens are key factors involved in the development and progression of prostate cancer (PCa), and the growth of PCa can be suppressed by androgen deprivation therapy (ADT). In a significant proportion of men receiving ADT, PCa progresses to castration-resistant prostate cancer (CRPC), which is a major challenge in the development of efficient therapies. The aim of the study was to characterize the cellular and molecular changes in tumors after ADT (castration), by using orthotopic VCaP human prostate cancer xenograft model. VCaP cells were inoculated in the dorsolateral prostate of immunodeficient mice, and tumor growth was followed by weekly serum PSA measurements. Mice with recurrent tumors after castration were randomized to treatment groups. Serum PSA concentrations showed significant correlation with the tumor volume, confirming that PSA is a reliable indicator of the tumor volume in the orthotopic VCaP xenograft model. Tumor and serum samples were collected and concentrations of androgens were measured by LC-MS/MS. Castration-resistant tumors retained their intratumoral androgen (androstenedione, testosterone, 5α-dihydrotestosterone) concentrations at levels similar to those in tumors growing in intact hosts. Accordingly, castration induced upregulation of enzymes involved in androgen biosynthesis (CYP17A1, AKR1C3 and HSD17B6), as well as expression of full-length androgen receptor (AR) and AR splice variants (AR-V1 and AR-V7). Furthermore, AR target gene expression was maintained in castration-resistant xenografts. AR antagonists, MDV3100 and ARN-509, suppressed the PSA production of castration-resistant tumors, confirming their androgen-dependency. In conclusion, we demonstrated that VCaP xenograft model exhibits the key characteristics of clinical CRPC, thus providing a valuable tool to identify druggable targets and for testing therapeutic strategies targeting AR signaling in CRPC. Citation Format: Matias Knuuttila, Emrah Yatkin, Jenny Kallio, Saija Savolainen, Teemu Daniel Laajala, Tero Aittokallio, Riikka Oksala, Merja Hakkinen, Pekka Keski-Rahkonen, Seppo Auriola, Matti Poutanen, Sari Makela. Castration induces upregulation of intratumoral androgen biosynthesis and androgen receptor expression in orthotopic VCaP human prostate cancer xenograft model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-31. doi:10.1158/1538-7445.AM2014-LB-31