Nanus, David M.

5074 Background: PC commonly expresses PSMA and has dose-responsive radiosensitivity. 177Lu-based radioligands usually use an empiric dosing regimen. This 1st dose-escalation study of 177Lu-PSMA-617 employed a dose-dense fractionation schedule intended to allow delivery of higher total doses to overcome radioresistance due to repopulation. Here, we report mature results of the study. Methods: Progressive mCRPC following > 1 potent ARPI (e.g., abi/enza) and chemo (or unfit/refuse taxane) without limit of # prior therapies provided adequate organ function and ECOG PS 0-2. Treatment: single cycle of fractionated dose 177Lu-PSMA-617 on D1 and D15. In Ph I dose-escalation, patients (pts) received one cycle of 7.4 - 22 GBq followed by Simon 2-stage Ph II at 22.2 GBq. PSMA expression was not required for treatment, but pre- and post-treatment 68Ga-PSMA11 PET/CT and/or 177Lu-PSMA-617 SPECT done. Primary efficacy by PSA changes with 2ndary outcomes with CT/bone scans, PSMA PET, circulating tumor cell (CTC; CellSearch) counts, plasma DNA (PCF_SELECT), and survival. Results: Between 1/2017 – 2/2021, 50 pts treated with median PSA 164.3, 35 (70%) CALGB (Halabi) poor risk. 47 (94%) bone, 38 (76%) nodal, 12 (24%) lung, 5 (10%) liver mets (4 additional pts with PSMA PET+ liver mets not apparent on CT). 29 (58%) with prior >2 ARPI, 29 (58%) with >1 chemo, 14 (28%) with Ra-223, 2 (4%) with 177Lu-J591. 27 (54%) treated at 22 GBq. No dose-limiting toxicity during Ph I. 38 (76%) with any PSA decline, 27 (54%) with >50% PSA. Median rPFS 8.3 mo [5.6-16.7], and OS 15.7 mo [10.9-20.6]. Of 17 RECIST measurable, 6 (35.3%) responded, 7 (41.2%) stable, 4 (23.5%) progressed. Of 31 with paired CTC counts, 16 (52%) decreased, 5 (16%) were stable; 10 (32.3%) converted to favorable/undetectable. Plasma DNA with high allele-specific ploidy and ARcopy number gain associated with OS (univariate). Treatment emergent adverse events (TEAE): 32 (64%) dry mouth, 22 (44%) pain flare, 22 (44%) fatigue, 19 (38%) nausea, 15 (30%) anemia, 15 (28%) thrombocytopenia (plts), 9 (18%) neutropenia (ANC). All TEAEs restricted to grade (Gr) 1-2 except 6 (12%) with Gr 3 anemia, 2 (4%) Gr 3/4 plts, 1 (2%) Gr 3 ANC. TEAE incidence and Gr were not related to dose. On multivariable analysis, 177Lu dose administered (p=0.09), CALGB risk (p=0.04), prior chemo (p=0.009), associated with OS; dose (p=0.1), CALGB risk (p=0.2), and AR copy number (p=0.2) associated with PSA50 decline. Baseline PSMA imaging (by imaging score or SUVmax) was not associated with OS or response. Conclusions: A single-cycle of fractionated-dose 177Lu-PSMA-617 is safe. Despite no pre-selection for PSMA expression, most had PSA decline with favorable PFS and OS compared to historical controls and similar to PSMA-selected targeted radionuclide studies administering multiple cycles in a less dose-intense approach. Clinical trial information: NCT03042468 .

Abstract Background: We have previously reported that 177Lu-PSMA-617 given as a single-cycle, dose-intense regimen for patients (pts) with pretreated mCRPC is efficacious even without selection by PSMA (ESMO 2021). Quantitative analyses of pre-treatment PSMA PET may allow for better patient selection and prediction of toxicities. Analyses of sequential PET images may also provide insights that may be associated with longer term outcomes. Our previous analysis of 13 patients demonstrated association of PSMA PET signal with overall survival (OS) and PSA responses, as well as trends with adverse events (Nauseef GU ASCO 2022). Here we present long-term follow up data and expanded imaging correlatives from our completed phase I/II study. MethodsEntry criteria: progressive mCRPC after at least one prior potent AR pathway inhibitor and prior chemotherapy (excepting men ineligible for or refusing of chemotherapy) with allowance for prior radionuclides (incl. Ra223 and PSMA-TRTs). Treatment was fractionated-dose (D1 and D15) 177Lu-PSMA-617 (7.4-22.2 GBq). TRAQinform IQ (AIQ Solutions) was used to identify, track, and quantify regions of interest suspicious of cancer (lesion-ROI) on PSMA PET/CT images and quantify uptake in normal organs outside of lesion-ROI. Measurements included SUVmean across all lesion-ROI, volume of lesion-ROI, and SUVtotal (sum of SUV in all lesion-ROI), as well as changes after treatment, including in PSMA-expressing healthy tissues. Associations with survival were tested via Cox proportional hazard models in univariate analyses and associations with adverse events (AEs) and PSA responses were via assessed via Wilcoxon rank sum tests. Results32 pts (of 50 total in the study between 1/2017-2/2021) had pre- and post-treatment imaging suitable TRAQinform IQ analysis and associated survival analyses. Baseline characteristics were similar to the entire study cohort. PSA response of 50% was observed in 21/32 (66%) of which 16 were confirmed. No imaging variable predicted PSA30 or PSA50, although an association was observed in pretreatment SUVmean and lesion-ROI volume reduction. No imaging variable was significantly associated with OS (e.g., pretx SUVmean HR 0.9, p=0.10, pretx Volume HR 1.00, p=0.052). Pretx SUVmean was associated with mPFS (HR 0.85, 95% CI 0.74, 0.98, p=0.023). Among select AEs, anemia was associated with non-lesion-ROI skeleton SUVtotal in pre- (p=0.027) and post-tx (p=0.007). Higher pre-treatment salivary gland uptake (SUVmean) was associated with more xerostomia (p=0.11). Fatigue was associated with a variety of variables including salivary SUVs (mean, max, and total) and post-tx bowel SUVmax (p=0.030). ConclusionsPre-treatment and pre- to post-treatment 68Ga-PSMA11-PET data analyzed may be associated with outcome. While a strength of this study is the prospective nature of patient enrollment and fixed imaging timepoints, our associations are limited by small sample size. Expansion of this analysis to larger datasets may improve our ability to predict treatment response and toxicity by body-wide PSMA detection. Citation Format: Jones Trevor Nauseef, Charlene Thomas, Michael Sun, Nicole Jacobs, Andrés Ricaurte Fajardo, Sam Ruder, Escarleth Fernandez, Zachary Davidson, Amie Patel, A. Oliver Sartor, Shankar Vallabhajosula, Ana Molina, Cora N. Sternberg, David M. Nanus, Sandra Huicochea Castellanos, Joseph Osborne, Neil H. Bander, Timothy Perk, Scott Tagawa. Quantitative assessment of PSMA imaging before and after 177Lu-PSMA-617 treatment in a Ph I/II trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT225.

Abstract Background: Advanced prostate cancer is defined as metastatic hormone-sensitive prostate cancer (mHSPC) or castration-resistant prostate cancer (CRPC). Newer and aggressive treatments are leading to increasing lifespans in this population. As such, studying quality of life could have a large impact on the survivorship experience. An important component of quality of life is financial toxicity, defined as the financial burden and distress that can arise for patients and their families because of cancer treatment. Objectives: To understand the prevalence and predictors of financial toxicity in advanced prostate cancer. Methods: IRONMAN (International Registry of Men with Advanced Prostate Cancer) is a prospective cohort of patients with newly diagnosed mHSPC or CRPC enrolling in 15 countries. Financial toxicity was collected using the EORTC QLQ-C30 (“has your physical condition or medical treatment caused you financial difficulties?”) at enrollment and every three months thereafter. For this analysis, we studied 997 patients cared for at 37 US sites enrolled from 7/2017 to 7/2023. We examined baseline and longitudinal reports of financial toxicity across clinical and demographic factors: age at enrollment, race and ethnicity, disease state, marital status, education, employment, military status, and type of health center. We conducted adjusted risk difference analysis and multivariable regression modeling to identify predictors of financial toxicity using a generalized estimating equations approach to calculate odds ratios (OR and 95% confidence intervals, CI). Results: At enrollment, 125 (13%) patients reported experiencing “quite a bit” or “very much” financial toxicity. 21% of Black patients experienced toxicity compared to 10% of White patients. Even after incorporating all other predictors, Black patients experienced 5% (95% CI: 0, 11) greater toxicity than White patients. Independently of other predictors, patients >75 experienced 11% (CI: -17, -4) lower toxicity compared to those <65 years (while patients in the 65-74 group experienced 6% less, CI: -12, 1). Toxicity was 6% greater in patients with mHSPC (CI: 2, 10) than in patients with CRPC, and disabled or unemployed patients were at substantially higher risk. In the multivariable longitudinal analyses, older age (> 75) remained associated with significantly lower odds for financial toxicity (OR: 0.30, 0.15-0.61) while mHSPC (OR: 1.91, 1.14-3.20) and being unemployed (OR: 2.69, 1.03-6.99) or disabled (OR: 5.14, 2.29-11.6) were associated with higher odds. Conclusions: Financial toxicity is prevalent in advanced prostate cancer, especially in patients who are Black, younger than 75, diagnosed with mHSPC, or unemployed/disabled. These results may inform identification of patients at high risk for financial toxicity to support delivery of patient-situation-informed care by clinicians and targeted aid for patients at highest risk. Citation Format: Isani Singh, Bailey Vaselkiv, Emily Rencsok, Karen Autio, Deborah Enting, Alicia Morgans, Joel Nowak, Kevin Kensler, David Nanus, Robert Dreicer, Brian Lewis, Oliver Sartor, Elisabeth Heath, Phillip Kantoff, Deborah Kaye, Daniel George, Lorelei Mucci. Financial toxicity among patients with advanced prostate cancer in the United States [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3410.

265 Background: UC response to CT is not durable. Angiogenesis may play a role in the progression of UC. We evaluated whether maintenance sunitinib delays progression after response to CT. Methods: Pts with ECOG PS 0-2, adequate organ function, stable disease, partial or complete response (SD, PR, CR) after 4-6 cycles of CT for advanced UC were randomized to oral sunitinib 50 mg/day, 28 days on, 14 days off (6-week cycle) or placebo. Disease was assessed every 12 wks. At progression, placebo pts were offered open label sunitinib. Primary endpoint: progression rate at 6 months (ms); secondary endpoints: safety, objective response rate, survival, VEGF/sVEGFR2 serum level changes. Using a randomized selection design 42 pts/arm has 90% probability of selecting sunitinib if true reduction in 6-ms progression rate is 15% (from 50% to 35%). Results: Study was closed early due to slow accrual. 54 pts with median age 69 years, median ECOG PS 1, 70% with bladder primary, 26 with SD, 23 with PR, 5 with CR to CT were randomized to sunitinib (26) or placebo (28). The median number of cycles was 2/arm (sunitinib 0-15, placebo 0-13). The 6-ms progression rate was 81% (95%CI 61-93%), median time-to-progression (TTP) 5 ms (0.3-22.2, 95%CI 2.4-6.3) for sunitinib and 75% (95%CI 55-89%), 2.7 ms (0.8-19.6, 95%CI 2.5-7.4) for placebo. Response rate in pts with SD at enrollment was 9% for sunitinib and 7% for placebo. Most common G3/4 AEs on sunitinib were diarrhea (15.4%/0%), fatigue (15.4%/3.8%), thrombocytopenia (15.4%/7.7%), hypertension (11.5%/0%). 16 placebo pts received sunitinib with best response 1 PR (6.25%), 6 SD (37.5%), 5 PD (31.25%); 4 not response evaluable. Median TTP was 3.4 ms (0.1-22, 95%CI 1.6-5.5). 11 pts had G3/4 AEs, 5 pts discontinued sunitinib due to AEs (4 related, 1 unrelated). Placebo pts had no change in VEGF/sVEGFR2 over time. Sunitinib pts had no change in VEGF but sVEGFR2 significantly decreased after 1 cycle (p<0.0001) and at progression (p=0.0002). VEGF/sVEGFR2 did not correlate with TTP. Conclusions: Maintenance sunitinib was feasible but did not improve 6-ms progression rate; open label sunitinib had limited activity. sVEGFR-2 decreased on sunitinib.

BACKGROUNDAngiogenesis contributes to the progression of urothelial carcinoma (UC). In the current study, the authors investigated the role of maintenance sunitinib in patients with advanced UC.METHODSPatients with locally recurrent/metastatic UC and adequate organ function who achieved stable disease or a partial or complete response after 4 to 6 chemotherapy cycles were randomized to sunitinib at a dose of 50 mg/day (28 days on and 14 days off) or placebo. The primary endpoint was the 6‐month progression rate. Secondary endpoints were safety, survival, change in serum vascular endothelial growth factor (VEGF)/soluble VEGF receptor‐2 (sVEGFR2), and the activity of sunitinib in patients who developed disease progression while receiving placebo. A total of 38 eligible patients per treatment arm were required to select better therapy with 90% probability (α = .05).RESULTSA total of 54 eligible patients were randomized to either the sunitinib arm (26 patients) or the placebo arm (28 patients). The median number of cycles received was 2 cycles per treatment arm. The most common grade 3 to 4 adverse events (graded according to version 3.0 of the National Cancer Institute Common Terminology Criteria for Adverse Events) among patients receiving sunitinib were thrombocytopenia, diarrhea, mucositis, fatigue, and hypertension. There were no grade 3 or 4 adverse events noted among > 5% of patients receiving placebo. The 6‐month progression rate was 72% versus 64%. The median progression‐free survival (PFS) was 2.9 months (range, 0.5 months‐32.5 months) versus 2.7 months (range, 0.8 months −65 months) for the sunitinib versus placebo arms, respectively. Patients receiving placebo were found to have no changes in their serum VEGF/sVEGFR2 levels over time. Patients treated with sunitinib had no significant change in their VEGF level, but the sVEGFR2 level significantly decreased after cycles 1 and 2 (P < .0001) and at the time of disease progression (P = .0002). A baseline VEGF level that was at or greater than the median was found to be correlated with a longer PFS. Sixteen patients who were receiving placebo received sunitinib at the time of disease progression, with the best responses being 1 partial response (6.3%), 6 cases of stable disease (37.5%), and 5 cases of progressive disease (31.3%); 4 patients were not evaluable for response. The median PFS was 3.7 months (range, 0.1 months‐22 months).CONCLUSIONSThe current multicenter study was limited by premature closure and a small sample size. Maintenance sunitinib did not appear to improve the 6‐month progression rate. Open‐label sunitinib was found to have only modest activity. The sVEGFR2 level decreased among patients receiving sunitinib. Cancer 2014;120:692–701. © 2013 American Cancer Society.