5012 Background: NEPC is an aggressive form of prostate cancer with poor prognosis and no standard treatment approach. NEPC can be characterized by late, treatment-emergent transformation from ...adenocarcinoma to high-grade neuroendocrine carcinoma (NEC), in 10–15% of mCRPC patients (pts). DLL3 is overexpressed in high-grade NECs, including NEPC, and minimally expressed on normal tissue. Tarlatamab, a bispecific T-cell engager immunotherapy with clinical activity in small cell lung cancer (SCLC), binds DLL3 and CD3 resulting in T-cell mediated tumor lysis. Here, we report primary analysis data of tarlatamab in NEPC (NCT04702737). Methods: This is an open-label phase 1b study evaluating tarlatamab monotherapy in adult (≥18 years y) pts with metastatic de novo or treatment-emergent NEPC by histologic, genomic, or immunohistochemistry (IHC) criteria. The starting dose was the highest safe and tolerable dose in the phase 1 SCLC trial (NCT03319940). Safety was the primary objective; anti-tumor activity and pharmacokinetics were secondary objectives. Exploratory analysis of DLL3 expression was assessed by IHC using the Ventana SP347 assay. Results: As of 28 March 2023, 40 pts received ≥1 tarlatamab dose (1 mg step dose, 100 mg target dose). Median (range) age was 64.5 (43–83) y, prior lines of therapy was 3 (1–9), prostate specific antigen at baseline was 0.2 (0.0–5000.0) μg/L. Treatment-related adverse events (TRAE) occurred in all patients, with no fatal TRAE. Most common TRAEs were cytokine-release syndrome (CRS; 65.0%), pyrexia (52.5%) and dysgeusia (42.5%). CRS occurred primarily in treatment cycle 1; events were mostly grade 1–2 (one grade 3 event). Treatment discontinuation due to TRAE was low (7.5%). Tarlatamab serum exposures were consistent with tarlatamab SCLC studies. Objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) was 10.5% (95% CI, 2.9, 24.8); median progression free survival (mPFS) was 1.9 months (m) (95% CI, 1.7, 3.5). Retrospective DLL3 IHC analysis showed that 18 of 32 (56.3%) biopsy evaluable pts had ≥1% DLL3 tumor positivity (DLL3+). As of 24 January 2024, ORR in DLL3+ pts was 22.2% (95% CI, 6.4, 47.6); durations of response in the 4 pts with response were 25.8 m, 9.2 m, 5.5 m, 3.7 m; mPFS in DLL3+ pts was 3.75 m (95% CI, 1.87, 11.01). Efficacy is shown in Table. Conclusions: Findings from this phase 1 study of tarlatamab in pts with NEPC demonstrated manageable safety with encouraging anti-tumor activity in DLL3 expressing NEPC. Further investigation is ongoing. Clinical trial information: NCT04702737 . Table: see text
TPS5109 Background: Progression to metastatic castration-resistant prostate cancer (mCRPC) occurs in most patients treated with androgen receptor signaling inhibitors (ARSi) for advanced disease. ...Preclinical studies demonstrate that AR and PI3K - AKT - mTOR (PAM) pathways interact through reciprocal negative feedback, whereby inhibition of one pathway activates the other. Thus, combining a PAM inhibitor with an ARSi may deliver improved anti-cancer activity in patients with mCRPC. A Phase 2 trial in 129 patients with mCRPC who progressed on abiraterone demonstrated improved median radiographic progression-free survival (rPFS) when samotolisib, a dual PI3K-mTOR inhibitor, was added to enzalutamide. These results form the basis for this clinical trial of gedatolisib, a potent PAM inhibitor, in combination with darolutamide in men with mCRPC who have previously progressed on ARSi. Methods: This open-label, multicenter, Phase 1/2 study will evaluate the safety and efficacy of gedatolisib in combination with darolutamide in men with mCRPC who have progressed on ARSi. In Phase 1, 36 patients will be randomized to one of two dose arms to evaluate dose limiting toxicities (DLTs) and determine the recommended Phase 2 dose (RP2D). Gedatolisib will be administered once weekly for 3-weeks-on/1-week-off: Arm 1 – 120 mg and Arm 2 – 180 mg, with darolutamide 600 mg orally administered twice daily. Arm 2 may be dose de-escalated depending on the number of DLTs observed. In Phase 2, 12 additional patients will be enrolled at the RP2D (n= 30). Key inclusion criteria include adult males (≥ 18 years) with mCRPC who have progressed on or after treatment with one next-generation ARSi. Key exclusion criteria include males with adenocarcinoma with a small cell component and with ≥10% neuroendocrine type cells; prior treatment with PI3K, AKT, or mTOR inhibitor; prior chemotherapy or radiopharmaceutical therapy for mCRPC; uncontrolled type 1/2 diabetes; or active brain or leptomeningeal metastases. Primary endpoints for Phase 1 are safety and tolerability (incidence of DLTs, adverse events, and determination of maximum tolerated dose) determination of the recommended Phase 2 dose (RP2D), PK, and Bayesian Optimal Interval utility score. Primary endpoints for Phase 2 are rPFS rate at 6 months based on Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 with modifications as specified in Prostate Cancer Working Group 3 criteria. Secondary endpoints include rPFS rates at 9 and 12 months, overall rPFS, prostate-specific antigen response of ≥50% decrease from baseline at 4, 8, 12, and 16 weeks, overall response rate, duration of response, clinical benefit rate, overall survival rate at 18 and 24 months, and safety. The trial is currently open for enrollment (NCT06190899). Clinical trial information: NCT06190899 .
5057
Background: Activating AR mutations ensure a continued AR activation by non-androgen steroid ligands, e.g. progesterone and glucocorticoids. CYP11A1 is the only enzyme that catalyzes the ...conversion of cholesterol to pregnenolone, from which all steroid hormones (glucocorticoids, mineralocorticoids, and sex steroids) are subsequently derived. ODM-208, an oral, selective inhibitor of CYP11A1, is being evaluated for safety and efficacy as a treatment of mCRPC in the ongoing CYPIDES phase I/II trial in men previously treated with both novel hormonal therapies and taxanes (ClinicalTrials.gov identifier: NCT03436485). Preliminary phase 1 results were previously reported (Fizazi K et al., ASCO GU 2022). Here we confirm that the in-vitro sensitivity of common AR mutations to ODM-208 treatment is mirrored in patient response in CYPIDES phase 1. Methods: ODM-208 was administered at daily doses between 6-150 mg (phase 2 dose: 10 mg) with dexamethasone and fludrocortisone, resulting in maximal suppression in all measured steroids at all doses. AR ligand-binding domain (LBD) mutations (L702H, V716M, W742L, W742C, H875Y, F877L, T878A, T878S, M896T, M896V) were assessed using a BEAMing assay (Sysmex Inostics) from plasma circulating cell-free DNA (cfDNA) collected before the first dose of ODM-208. The activation of wild-type (wt) and LBD mutated AR with various ligands was also studied in vitro using a luciferase reporter assay in AR negative PC3 cells. Results: 17 of 44 patients had at least one AR activating mutation, the most frequent being L702H (n = 11), T878A (n = 10), and H875Y (n = 6). Eleven out of the 16 evaluable patients (68%) with an AR LBD mutation achieved ≥50% reduction in serum PSA compared with 2 out of the 24 evaluable patients (8%) without an AR LBD mutation (P <.0001). The in vitro sensitivity of each of these common AR mutations to a variety of non-androgenic steroids will be presented, along with detailed PSA responses, duration of responses, and safety in mCRPC patients bearing the same mutations. Conclusions: AR activating mutations may permit continued hormone dependence in mCRPC, related to actions of non-androgenic steroid hormones. Treatment with ODM-208 blocked all steroid hormone production and resulted in frequent ≥50% PSA reductions in this group of heavily pretreated mCRPC pts with various AR LBD mutations, some being long-lasting. cfDNA AR mutations are a promising predictive biomarker for ODM-208 efficacy. Dexamethasone did not activate mutated ARs, supporting its selection for glucocorticoid replacement therapy in combination with ODM-208. Clinical trial information: NCT03436485.
Criteria based on measurements of lesion diameter at CT have guided treatment with historical therapies due to the strong association between tumor size and survival. Clinical experience with immune ...checkpoint modulators shows that editing immune system function can be effective in various solid tumors. Equally, novel immune-related phenomena accompany this novel therapeutic paradigm. These effects of immunotherapy challenge the association of tumor size with response or progression and include risks and adverse events that present new demands for imaging to guide treatment decisions. Emerging and evolving approaches to immunotherapy highlight further key issues for imaging evaluation, such as dissociated response following local administration of immune checkpoint modulators, pseudoprogression due to immune infiltration in the tumor environment, and premature death due to hyperprogression. Research that may offer tools for radiologists to meet these challenges is reviewed. Different modalities are discussed, including immuno-PET, as well as new applications of CT, MRI, and fluorodeoxyglucose PET, such as radiomics and imaging of hematopoietic tissues or anthropometric characteristics. Multilevel integration of imaging and other biomarkers may improve clinical guidance for immunotherapies and provide theranostic opportunities.
221
Background: AR ligand binding domain (LBD) activating somatic point mutation is a known mechanism of resistance to androgen-receptor signaling inhibitor (ARSI) treatment in mCRPC, leading to a ...persistent addiction to steroid hormones. Two early phase trials investigating CYP11A1 inhibitors - CYPIDES (ODM208, NCT03436485) and STESIDES (ODM209, NCT03878823) - recruited mCRPC patients with and without pre-specified AR LBD mutation. In CYPIDES Part 1, AR LBD mutations (ARm) strongly predicted for PSA decline with ODM-208 (Fizazi, ASCO GU 2021). Here, we evaluated clinical and genomic data associated with ARm in patients with mCRPC. Methods: We reviewed clinical and molecular data from patients with mCRPC who progressed after ≥1 ARSI and ≥1 line of taxane-based chemotherapy or were ineligible to chemotherapy, pre-screened in CYPIDES and STESIDES trials at our center. Circulating tumor DNA (ctDNA) was tested for AR LBD mutation (Guardant360 CDx and Sysmex OncoBEAM) and for genomic analysis (FoundationOne Liquid CDx, STING trial, NCT04932525) to screen for actionable targets. Results: From March 2020 to January 2022, 272 men were screened. Median age was 62y. Overall, 212 (78%), 202 (74%), and 240 (88%) patients had received previous abiraterone, enzalutamide, and docetaxel respectively. Median PSA at screening was 59 ng/mL (IQR 11; 246). ARm was found in 69 patients (25%). The most frequent mutations were L702H (15%), T878A (12%), H875Y (7%), V716M (2%), F877L (2%), W742C (1%), globally consistent with previous reports. Associations of ARm with relevant baseline characteristics of patients are summarized. Duration of enzalutamide exposure was correlated with the number of AR mutations per patient (p = 0.006) whereas no correlation was found for abiraterone exposure duration (p=0.71). In 173 (64%) patients with available genomic testing, no alterations were found to be mutually exclusive with ARm, including in DNA repair alteration. Conclusions: AR LBD mutations were detected in ctDNA in 25% of men with advanced mCRPC treated with at least one ARSI. Their incidence was associated with a longer duration of treatment with enzalutamide and a longer time from CRPC and prostate cancer diagnosis. Table: see text
BACKGROUNDGenomic stratification may help improve the management of patients with metastatic urothelial cancer (mUC), given the recent identification of targetable alterations. However, the ...collection of tissue samples remains challenging. Here, we assessed the clinical utility of plasma circulating tumour DNA (ctDNA) sequencing in these patients.METHODSPatients with mUC were prospectively enroled in the STING trial (NCT04932525), in which ctDNA was profiled using the Foundation One Liquid CDx Assay (324 genes, blood tumour mutational burden bTMB, microsatellite instability status). Each genomic report was reviewed by a multidisciplinary tumor board (MTB).RESULTSBetween January 2021 and June 2022, 140 mUC patients underwent molecular profiling. The median time to obtain the assay results was 20 days ((confidence interval) CI95%: 20,21). The ctDNA analysis reproduced the somatic genomic landscape of previous tissue-based cohorts. Concordance for serial ctDNA samples was strong (r = 0.843 CI95%: 0.631-0.938, p < 0.001). At least one actionable target was detected in 63 patients (45%) with a total of 35 actionable alterations, including bTMB high (≥10 mutations/Mb) (N = 39, 21.1%), FGFR3 (N = 20, 10.8%), and Homologous recombination deficiency (HRD) alterations (N = 14, 7.6%). MTB recommended matched therapy in 63 patients (45.0%). Eight patients (5.7%) were treated, with an overall response rate of 50% (CI95%: 15.70-84.30) and a median progression-free survival (PFS) of 5.2 months (CI95%: 4.1 - NR). FGFR3 alterations were associated with a shorter PFS in patients treated with immunotherapy.CONCLUSIONOverall, we demonstrated that genomic profiling with ctDNAs in mUC is a reliable and feasible approach for the timely initiation of genotype-matched therapies.
Despite metastatic renal cell carcinoma (mRCC) expanded treatment options, disease progression ultimately occurs for most patients. Rechallenge may be a compelling strategy in a refractory setting. ...Cabozantinib is the standard of care in first and later lines of therapy, but its activity in rechallenge is unknown.
This retrospective study assessed the efficacy and safety of cabozantinib rechallenge, as defined by a second exposure after an interval of ≥3 months without treatment or ≥1 other treatment line, in patients with mRCC. The primary endpoint was median progression-free survival (PFS) at rechallenge. Secondary endpoints included overall survival, objective response rate, and safety at rechallenge.
We included 51 mRCC patients who received cabozantinib in a rechallenge setting between 2017 and 2022. Median age at diagnosis was 54 years, 78% were male, 90% had clear cell mRCC, and 92% had prior nephrectomy. 15 patients (29%) were rechallenged after a pause in treatment, whereas 36 (70.6%) had ≥1 other treatment lines between first cabozantinib exposure (CABO-1) and rechallenge (CABO-2). Median PFS was 15.1 months (mo, 95% Confidence interval 11.2–22.1) at CABO-1 and 14.4mo (95%CI 9.8-NR) at CABO-2. Median overall survival was 67.6mo for CABO-1 (95% CI 52.2-NR) and 27.4mo for CABO-2 (95%CI 17.2-NR); objective response rate was 70.6% for CABO-1 and 60% for CABO-2. CABO-2 PFS was higher for patients with CABO-1 PFS > 12 months, and for those who discontinued CABO-1 because of toxicity, without statistical significance. There were no unexpected adverse events.
Cabozantinib rechallenge is a feasible treatment option with potential clinical benefit for mRCC patients.
•This is the first study evaluating the concept of cabozantinib rechallenge to date.•The population was highly selected with heavily pretreated patients.•At rechallenge, median PFS and OS were 14.4 and 27.4 months, and ORR was 59%.•Safety did not show unexpected adverse events at rechallenge.
159
Background: MK-5684 (previously ODM-208) is a first-in-class, oral, non-steroidal, selective inhibitor of CYP11A1, the first and rate-limiting enzyme of steroid biosynthesis. MK-5684 suppresses ...the production of all steroid hormones and precursors that may activate the androgen receptor (AR) signaling pathway. Initial phase 1 (ASCO-GU 2022) and phase 2 results in AR-LBD mutation-positive (ESMO 2022) mCRPC patients were previously presented. Now we report phase 2 results for both AR-LBD mutation-positive and negative patients. Methods: MK-5684 5mg BID (with dexamethasone and fludrocortisone) was evaluated in an open-label expansion cohort in patients with progressing mCRPC who had previously received ≥1 line of 2
nd
generation AR pathway inhibitor and ≥1 line of taxane-based chemotherapy. An initial expansion cohort enrolled 45 patients with an activating AR-LBD mutation identified in cell-free DNA (Guardant360 assay, 74-gene panel), a subsequent extension cohort included mainly AR-LBD mutation-negative patients to attain comparable groups of about 60 patients each, with and without AR-LBD mutations. Study objectives were safety and preliminary efficacy assessed by PSA and RECIST response and standard safety measures. MK-5684 treatment was continued until subsequent disease progression. The study was conducted at 18 sites in France, Finland, UK and USA. Data are based on a 17 July 2023 data cut-off. Results: A total of 66 AR-LBD mutation-positive and 68 AR-LBD mutation-negative patients (median age 68.3 years) were enrolled and received MK-5684 treatment. 53% and 33.8% of patients had previously received both abiraterone and enzalutamide, and 63.6% and 55.9% patients had received cabazitaxel in AR-LBD mutation positive and negative groups respectively. MK-5684 profoundly suppressed androgen synthesis resulting in PSA
50
responses in 55.6% and 16.7% of patients and PSA
30
responses in 69.8% and 30.0% of patients, with and without AR-LBD mutations respectively. At the time of abstract data cut-off, objective responses by RECIST had occurred in 8 patients, all with AR-LBD mutations (ORR 20.5% for AR-LBD positive). MK-5684 was well-tolerated: the most common treatment-related adverse events were related to adrenal suppression with the rate of hospitalization for adrenal insufficiency being much lower than in phase 1 when typically higher MK-5684 doses were administered (3.0% vs. 33% respectively). Data with a minimum follow up of approximately 4 months after last patient enrolment will be presented. Conclusions: Administration of MK-5684 to heavily pre-treated mCRPC patients showed promising antitumor activity. PSA
50
responses were most frequent among patients harboring activating AR-LBD mutations. Clinical trial information: NCT03436485 .
Abstract only
18
Background: ODM-208 is a novel, oral, non-steroidal and selective inhibitor of CYP11A1, the first and rate-limiting enzyme of steroid biosynthesis. ODM-208 suppresses the production ...of all steroid hormones and their precursors that may activate the androgen receptor (AR) signalling pathway. This is particularly relevant in patients with AR ligand binding domain (LBD) activating somatic point mutations, a mechanism of resistance to hormone-based therapies in metastatic castration-resistant prostate cancer (mCRPC). We report the first results of the first-in-man phase I CYPIDES trial. Methods: ODM-208 was examined in a dose finding phase 1 trial with a 3+3 design in patients with progressive mCRPC who had previously received ≥1 line of AR signalling inhibitor and ≥1 line of taxane-based chemotherapy. ODM-208 was administered up to 150 mg/day with glucocorticoid (GC) and mineralocorticoid replacement therapy and androgen deprivation therapy (ADT). The phase 1 endpoints included dose-limiting toxicities (DLTs), adverse events, pharmacokinetics, pharmacodynamics, PSA and RECIST response, and exploratory genetic profiling. Results: By Jan 22 2021, 41 patients (median age 70 yrs.) had received ODM-208. The dose finding was completed and included doses ranging from 10 to 150 mg/day. 22 (54%) patients had previously received both abiraterone and enzalutamide, and 23 (56%) patients both docetaxel and cabazitaxel. Although tolerated by most patients, the main safety finding was adrenal insufficiency (AI). Overall, 15/41 (37%) patients experienced Grade 3 AI requiring short-term high-dose GC treatment. ODM-208 plasma exposure was dose proportional. Serum testosterone was undetectable after 4 weeks of start of ODM-208 in almost all patients, as were serum DHEA sulphate, androstenedione, 11β-hydroxyandrostenedione, 11-ketotestosterone and pregnenolone. Overall 12/36 (33%) evaluable patients achieved a PSA decline of ≥50%. In evaluable patients with AR LBD mutation 10/15 (67%) achieved a PSA decline of ≥50%. Clinical improvement in symptoms such as pain was also observed in some men. Conclusions: Administration of ODM-208 to mCRPC men pretreated with abiraterone/enzalutamide and taxanes was highly effective in blocking the production of steroid hormones and showed promising antitumor activity, especially in men with AR mutation-positive cancers. The phase 2 dose expansion part of CYPIDES is ongoing. Clinical trial information: NCT03436485.
4576
Background: Genomic stratification may help to improve the management of patients with metastatic urothelial cancer (mUC) given the recent identification of targetable molecular alterations in ...this disease. However, collecting tissue samples in mUC remains challenging. We assessed the clinical utility of plasma circulating tumor DNA (ctDNA) sequencing in mUC. Methods: mUC patients were prospectively enrolled in the STING trial (NCT04932525) whereby ctDNA was profiled using the FoundationOne Liquid CDx Assay (324 genes, tumor mutational burden TMB, microsatellite instability status). Each individual genomic report was reviewed and discussed weekly by a multidisciplinary tumor board (MTB). Actionable targets were classified by ESCAT tier leading to molecular-based treatment suggestions whenever it was possible. Results: Between January 2021 and June 2022, 140 mUC patients underwent molecular profiling. Median time to assay results was 20 days. ctDNA abundance was correlated with number of prior lines and number of metastatic sites. ctDNA analysis reproduces the somatic genomic landscape reported by previous tissue-based cohorts. Concordance for serial tumor tissue was moderate (r=0.545 CI95: 0.121-0.801, p= 0.016). At least one actionable target was detected in 63 patients (45 %) with a total of 35 actionable alterations including TMB high (≥12 mutations/Mb) (N= 39, 21.1%), FGFR3 (N= 20, 10.8%) and HRD alterations (N= 14, 7.6%). The MTB recommended a matched therapy for 63 patients (45.0%). In total, 8 patients (5.7 %) were treated with an overall response rate of 50% (95%: 15.70-84.30) and a median PFS of 5.2 months (CI95%: 4.1 - NR). FGFR3 alterations were associated with lower progression-free survival in patients treated with immunotherapy. Conclusions: Overall, our analysis demonstrates that genomic profiling with a large panel of ctDNA in mUC is a reliable and feasible approach to timely initiate genotype-matched therapies. Clinical trial information: NCT04932525 .
