Bone Scan Response Research Articles

A randomized phase IIa study of quantified bone scan response in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 dichloride alone or in combination with abiraterone acetate/prednisone or enzalutamide

BackgroundIn metastatic castration-resistant prostate cancer (mCRPC), assessing treatment response and bone lesions with technetium-99m is limited by image resolution and subjectivity. We evaluated bone scan lesion area (BSLA), a quantitative imaging assessment of response in patients with mCRPC receiving radium-223 alone or in combination with androgen receptor pathway inhibitors (abiraterone/prednisone or enzalutamide).Patients and methodsThis randomized, non-comparative phase IIa three-arm trial (NCT02034552) evaluated technetium-99m-based BSLA response rate (RR), safety, radiologic progression-free survival (rPFS), and time to first symptomatic skeletal event (SSE) in men with mCRPC and bone metastases receiving radium-223 with/without abiraterone/prednisone or enzalutamide. The primary endpoint was week 24 BSLA RR.ResultsOverall, 63 patients received treatment (abiraterone/prednisone combination, n = 22; enzalutamide combination, n = 22; radium-223 monotherapy, n = 19). Median treatment duration (first to last dose of any study treatment) was 12 months (abiraterone/prednisone combination), 10 months (enzalutamide combination), and 3 months (radium-223 monotherapy). Week 24 BSLA RR was 58% [80% confidence interval (CI) 41% to 74%; one-sided P < 0.0001; 11/19 patients] with abiraterone/prednisone combination, 50% (32% to 68%; one-sided P < 0.0001; 8/16 patients) with enzalutamide combination, and 22% (10% to 40%; one-sided P = 0.0109; 4/18 patients) with radium-223 monotherapy. Median rPFS was not evaluable for combination arms and 4 months (80% CI 4 to 12) for monotherapy. SSEs were reported in 32% of patients; median time to first SSE was not estimable. Fatigue and back pain were the most commonly reported treatment-emergent adverse events (TEAEs); more patients receiving combination therapy than monotherapy had TEAEs. Fractures were reported in 18% receiving abiraterone/prednisone, 32% receiving enzalutamide, and 11% receiving radium-223 monotherapy. Fracture rates were lower in patients taking bone health agents versus not taking bone health agents at baseline.ConclusionsTechnetium-99m imaging BSLA may offer objective, quantifiable assessment of isotope uptake changes, and potentially treatment response, in patients with mCRPC and bone metastases treated with radium-223 alone or in combination with abiraterone/prednisone or enzalutamide. In this largely treatment-naive population, BSLA RR was numerically lower with radium-223 monotherapy versus combination therapy, indicating a limited role as first-line treatment. Use of radium-223 should follow evidence-based treatment guidelines and the licensed indication.

A phase II trial of cabozantinib in hormone receptor-positive breast cancer with bone metastases.

1062 Background: We assessed the antitumor activity of cabozantinib, a potent multi-receptor oral tyrosine kinase inhibitor with activity against MET, RET, VEGFR2, and AXL, in patients with hormone-receptor positive (HR+) breast cancer with bone metastases. Methods: In this single-arm multicenter phase II study, patients with HR+, HER2- metastatic breast cancer and ≥ 1 prior line of therapy received an initial starting dose of 100 mg cabozantinib, later reduced to 60 mg per day. The primary endpoint was bone scan response rate determined by independent central review and defined as percent change of bone scan area from baseline. The target bone scan response rate was 30% compared to a null response rate of 10%. Secondary endpoints included objective response rate (ORR) by RECIST v1.1, progression free (PFS) and overall survival (OS). Bone scan and CT were obtained every 12 weeks. Results: Among 52 enrolled patients, median age was 55, and 54% and 42% had &gt; 2 lines prior endocrine and chemotherapy, respectively and 18 (35%) had bone-only disease. 20 (38%) experienced a partial bone scan response and 6 (12%) had stable disease (SD). 16 (31%) patients discontinued study prior to week 12 assessment for early clinical progression or toxicity, and three (6%) had missing follow-up scans. Best extra-osseous overall response revealed SD in 26 (50%), but no objective responses. In 25 patients with bone scan disease control at 12 weeks, only 3 (12%) developed extra-osseous progression. Median PFS was 4.3 months (90% CI 2.8 - 5.5) and OS was 19.6 months (90% CI 18.0 – 26.8). In a landmark analysis, patients with bone scan disease control at 12 weeks had longer OS (median 24.2 months, 90% CI 16.4 – 31.7) than those without (median OS 13.3 months, 90% CI 9.5 – 18.2), with a hazard ratio of 0.37 (90% CI 0.21 – 0.65). Most common grade 3 or 4 toxicities were hypertension (10%), anorexia (6%), diarrhea (6%), fatigue (4%) and hypophosphatemia (4%). Dose reduction or delay occurred in 42 (81%) patients. Conclusions: This study met its primary endpoint with bone scans improved in 38% of patients with metastatic HR+ breast cancer and remained stable in an additional 12% with cabozantinib treatment. Bone scan response correlated with improved OS. This is the first reported study in breast cancer to use bone scan response as a primary endpoint. Further studies with cabozantinib in HR+ breast cancer and additional validation of bone scan response as a surrogate for clinical benefit in breast cancer are warranted. Clinical trial information: NCT01441947 .

Radium-223 in patients with metastatic castration-resistant prostate cancer: Efficacy and safety in clinical practice.

Radium-223 has improved overall survival (OS) and reduced symptomatic skeletal events (SSE) in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases (ALSYMPCA trial). Our aim was to assess clinical and biochemical factors related to survival, safety and survival outcomes of Radium-223 in a clinical practice setting. We retrospectively analysed 32 mCRPC patients treated with Radium-223, assessing bone scan, pain reduction, alkaline phosphatase (ALP) and prostate-specific antigen (PSA) response (≥30% reduction). At scintigraphic assessment, 41% had partial response with a disease control rate of 91%; 56% had ALP response and 25% had PSA response; 41% had pain reduction with pain control of 72%. Scintigraphic response and stability were correlated with longer median progression-free survival (mPFS) (13 and 12 vs. 6 months; P=0.002) and mOS (16 and 12 vs. 6 months; P=0.003). ALP response was associated with longer mPFS (13 vs. 12 months; P=0.2) and mOS (16 vs. 12 months; P=0.2). PSA response was associated with longer mPFS (13 vs. 12 months; P=0.02), whereas mOS could not be computed. Pain response and stability were associated with survival benefit according to mPFS (13 and 12 vs. 9 months) and mOS (both 16 vs. 12 months) without statistical significance. Baseline ALP <220 UI/l, Eastern Cooperative Oncology Group (ECOG) performance status 0 and absence of previous chemotherapy correlated with statistically significantly longer survival outcomes. Skeletal-related events (SRE) occurred in three patients and median time to first SRE was 9.5 months, mPFS was 12 months and mOS 14 months. G3-G4 toxicities developed in 16% of patients. Our results are in line with those reported in the pivotal trial and in other retrospective studies. In conclusion, Radium-223 was associated with high scintigraphic, biochemical and pain response rates and was tolerated well by most patients. Response to Radium-223 and better baseline factors correlated to longer survival in clinical practice experience as in the clinical trial setting.

Patterns of bone scan and pain response following treatment with Ra-223 in metastatic castrate resistant prostate cancer (mCRPC).

e17011Background: Overall survival was improved in men with mCRPC treated with radium-223 (Ra-223) in the phase 3 ALSYMPCA trial; however, bone scans were not performed in this study, and retrospec...

Cabozantinib, a New Standard of Care for Patients With Advanced Renal Cell Carcinoma and Bone Metastases? Subgroup Analysis of the METEOR Trial.

Purpose Cabozantinib, an inhibitor of tyrosine kinases including MET, vascular endothelial growth factor receptors, and AXL, increased progression-free survival (PFS), overall survival (OS), and objective response rate (ORR) in patients with advanced renal cell carcinoma (RCC) after previous vascular endothelial growth factor receptor-targeted therapy in the phase III METEOR trial. Because bone metastases are associated with increased morbidity in patients with RCC, bone-related outcomes were analyzed in METEOR. Patients and Methods Six hundred fifty-eight patients were randomly assigned 1:1 to receive 60 mg cabozantinib or 10 mg everolimus. Prespecified subgroup analyses of PFS, OS, and ORR were conducted in patients grouped by baseline bone metastases status per independent radiology committee (IRC). Additional end points included bone scan response per IRC, skeletal-related events, and changes in bone biomarkers. Results For patients with bone metastases at baseline (cabozantinib [n = 77]; everolimus [n = 65]), median PFS was 7.4 months for cabozantinib versus 2.7 months for everolimus (hazard ratio, 0.33 [95% CI, 0.21 to 0.51]). Median OS was also longer with cabozantinib (20.1 months v 12.1 months; hazard ratio, 0.54 [95% CI, 0.34 to 0.84]), and ORR per IRC was higher (17% v 0%). The rate of skeletal-related events was 23% with cabozantinib and 29% with everolimus, and bone scan response per IRC was 20% versus 10%, respectively. PFS, OS, and ORR were also improved with cabozantinib in patients without bone metastases. Changes in bone biomarkers were greater with cabozantinib than with everolimus. The overall safety profiles of cabozantinib and everolimus in patients with bone metastases were consistent with those observed in patients without bone metastases. Conclusion Cabozantinib treatment was associated with improved PFS, OS, and ORR when compared with everolimus treatment in patients with advanced RCC and bone metastases and represents a good treatment option for these patients.

Efficacy of cabozantinib (C) vs everolimus (E) in patients (pts) with advanced renal cell carcinoma (RCC) and bone metastases (mets) from the phase III METEOR study.

4558Background: In pts with metastatic RCC, bone mets are prognostic for poor outcomes and represent an unmet medical need. The Phase 3 METEOR trial (NCT01865747) assessed the efficacy and safety of C vs E in pts with RCC and ≥1 prior VEGFR TKI. The trial met its primary endpoint of improving progression-free survival (PFS; HR 0.58, 95% CI 0.45–0.75; P<0.001) (Choueiri NEJM 2015). As C has shown clinical activity in bone mets in prostate cancer pts (Smith JCO 33 2015 abs 139), we evaluated clinical outcomes in RCC pts with bone mets in METEOR. Methods: 658 pts were randomized (stratified by MSKCC risk group and number of prior VEGFR TKIs) 1:1 to receive C (60 mg qd) or E (10 mg qd). Clinical outcome measures included PFS, ORR, overall survival (OS), and safety. Exploratory endpoints included bone scan response (BSR) in pts with bone scan lesions at baseline (Brown Nucl Med Commun 2012 33:384), incidence of skeletal-related events (SRE), and changes in bone turnover markers. Results: 142 pts had bone mets ...

Final analysis of COMET-2: Cabozantinib (Cabo) versus mitoxantrone/prednisone (MP) in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) with moderate to severe pain who were previously treated with docetaxel (D) and abiraterone (A) and/or enzalutamide (E).

141 Background: Cabo inhibits tyrosine kinases including MET and VEGFRs. In a phase 2 study in mCRPC pts, Cabo was associated with improvements in pain, bone scans, measurable disease, and circulating tumor cells. COMET-2 compared the effects of Cabo versus MP on pain palliation in men with progressive mCRPC. Methods: In this double-blind, controlled phase 3 study (NCT01522443), pts with moderate to severe pain and disease progression following D, and A and/or E were randomized 1:1 to receive Cabo (60 mg qd) or MP (12 mg/m2 q3wk and 5 mg bid, resp). All pts were required to have a 7-day average of 4+ pain per Brief Pain Inventory (BPI) item 3 while on an optimized narcotics regimen at baseline. Randomization was stratified by prior cabazitaxel and ECOG performance status. The primary endpoint was pain response (≥30% reduction in BPI item 3) at week 6, confirmed at week 12, without increase in narcotics. The original sample size (N = 246) was selected to achieve at least 90% power to detect an increase in pain response with Cabo (25%) vs. MP (8%) using a two-sided α = 0.05 chi-squared test. The secondary efficacy endpoints were bone scan response (BSR) and overall survival (OS). Results: 119 pts were randomized between March 2012 and July 2014. Randomization was concluded prior to reaching the planned sample size because the companion study COMET-1 did not show a significant OS benefit compared to P in a similar population. Pain response rates were 15% for Cabo vs 17% for MP (P = 0.773). BSR rates were 31% for Cabo vs 5.2% for MP. Median OS was 9 months for Cabo vs 7.9 months for MP. Most frequent G3/4 AEs in the Cabo arm were anemia (22% vs 26% MP), hypertension (22% vs 0% MP), fatigue (18% vs 8.8% MP), and AST increased (10% vs 1.8% MP), with fewer pts discontinuing study treatment for AEs in the Cabo arm (16% vs 26% MP). Conclusions: The primary endpoint of improving pain response was not achieved in this heavily pretreated population. The key secondary endpoints of BSR and OS showed trends favoring the Cabo arm, and no new safety signals were observed at the dose of 60 mg. Clinical trial information: NCT01522443.

Final analysis of COMET-1: Cabozantinib (Cabo) versus prednisone (Pred) in metastatic castration-resistant prostate cancer (mCRPC) patients (pts) previously treated with docetaxel (D) and abiraterone (A) and/or enzalutamide (E).

139 Background: Cabo inhibits tyrosine kinases including MET and VEGFRs. In a phase 2 study in mCRPC pts, Cabo was associated with improvements in bone scans, pain, measurable disease, and circulating tumor cells. COMET-1 compared the effects of Cabo versus Pred on overall survival (OS) in men with progressive mCRPC and prior D and A and/or E. Methods: In this randomized, double-blind, controlled phase 3 study (NCT01605227), pts with mCRPC and prior D and A and/or E were randomized 2:1 to receive Cabo (60 mg qd) or Pred (5 mg bid). Pts were stratified by prior treatment with cabazitaxel, ECOG status, and presence of moderate to severe pain. The primary endpoint was OS. The study was designed to observe 578 deaths to provide 90% power to detect a hazard ratio (HR) of 0.75. A secondary endpoint was bone scan response at Week 12 (BSR) determined by central independent radiology committee, defined as a ≥30% decrease in the bone scan lesion area compared to baseline. Exploratory endpoints include PFS and OS subgroup analyses. Results: 1,028 pts were randomized between Jul 2012 and Nov 2013. In the final analysis after 614 deaths, the estimated median OS was 11.0 months for Cabo vs 9.8 months for Pred (HR 0.90; 95% CI: 0.0.76-1.06; P = 0.212). The secondary endpoint of BSR was 41% for Cabo vs 3% for Pred (P &lt;0.001). Median PFS per investigator was 5.5 months for Cabo vs 2.8 months for Pred (HR 0.50; P &lt;0.001). For 191 pts with visceral disease median OS was 7.1 months for Cabo vs 4.8 months for Pred (HR 0.65; P = 0.0215). 371 (54.4%) and 233 (67.3%) pts received salvage therapy in the Cabo and Pred arms, respectively. Subsequent cabazitaxel and/or D was reported in 107 (15.7%) and 104 (30.1%) Cabo and Pred pts, respectively. Serious adverse events of pulmonary embolism, nausea, dehydration and fatigue were more frequent with Cabo. Conclusions: Compared to prednisone, Cabo improved BSR and PFS but did not significantly increase OS. The improvement in OS was greatest in the subset of patients with visceral metastases. The activity and safety profile of Cabo was similar to that observed in phase 2 studies in mCRPC. Clinical trial information: NCT01605227.

Association of changes in biomarkers with treatment with cabozantinib (Cabo) in metastatic castration-resistant prostate cancer (mCRPC): A post-hoc analysis of the 100mg nonrandomized expansion cohort of a randomized discontinuation trial.

196 Background: Cabo, an oral inhibitor of receptor tyrosine kinases (RTK) including MET and VEGFR2, showed activity in early clinical studies in mCRPC, and is being investigated in phase 3 trials. Our primary aim was to retrospectively study the potential association between plasma concentrations of known markers of hypoxia, RTK cell signaling, inflammation, bone metabolism, chemo-attraction and epithelial-mesenchymal transition with response to Cabo in patients (pts) who received 100mg daily as part of a phase 2 non-randomized expansion cohort (NCT00940225). Methods: Our cohort of mCRPC pts with available plasma samples comprised of 81 pts with bone lesions assessed for bone scan response (BSR, defined as ≥30% decrease in lesion area compared to baseline). Thirty three pts also had measurable disease and were assessed for RECIST response. Plasma samples were available for all pts at baseline, at 6 weeks and at time of best response. Levels of 27 plasma biomarkers were measured in duplicate using ELISA. Spearman correlation coefficients were calculated for the association between response and biomarker levels at each time point. Results: Sixty six of 81 pts (81%) had a BSR, and 6 of 33 pts (18%) had a partial response by RECIST. No significant associations were found between the levels of any of the biomarkers at baseline or subsequent time points and either BSR or response by RECIST. Over time, the plasma concentrations of soluble VEGFR2 were significantly decreased during treatment with Cabo, consistent with the known effects of VEGFR inhibition on soluble VEGFR2. The plasma concentrations of nine markers (VEGFA, CA9, clusterin, FLT3L, Gas6A, Bone Alkaline phosphatase, and the soluble forms of the RTKs MET, IGF1R and AXL) were significantly increased during treatment with Cabo irrespective of response. Conclusions: These results demonstrate that metabolic alterations occur following treatment with Cabo in pts with mCRPC. Changes in certain biomarkers during treatment with Cabo could suggest potential co-targeting approaches with Cabo or other RTK inhibitors in mCRPC.

A dose-ranging study of cabozantinib in men with castration-resistant prostate cancer and bone metastases.

Cabozantinib is an oral MET/VEGFR2 inhibitor. A recent phase II study of cabozantinib (100 mg daily) showed improved bone scans in subjects with metastatic castration-resistant prostate cancer (mCRPC), but adverse events (AE) caused frequent dose reductions. This study was designed to determine the efficacy and tolerability of cabozantinib at lower starting doses. An adaptive design was used to determine the lowest active daily dose among 60, 40, and 20 mg. The primary endpoint was week 6 bone scan response, defined as ≥30% decrease in bone scan lesion area. The secondary endpoint was change in circulating tumor cells (CTC). Among 11 evaluable subjects enrolled at 40 mg, there were 9 partial responses (PR), 1 complete response, and 1 stable disease (SD). Of 10 subjects subsequently enrolled at 20 mg, there were 1 PR, 5 SDs, and 4 with progressive disease. Among 13 subjects enrolled on the 40 mg expansion cohort, there were 6 PRs and 7 SDs. No subjects required dose reduction or treatment interruption at 6 or 12 weeks; 3 subjects at dose level 0 discontinued due to AEs by 12 weeks. At 40 mg, median treatment duration was 27 weeks. 58% of subjects with ≥5 CTCs/7.5 mL at baseline converted to <5. Cabozantinib 40 mg daily was associated with a high rate of bone scan response. Cabozantinib 40 mg daily was associated with better tolerability than previously reported for cabozantinib 100 mg daily. These observations informed the design of phase III studies of cabozantinib in mCRPC.

897O - Cabozantinib (XL184) At 40 Mg in Patients with Metastatic Castration Resistant Prostate Cancer (MCRPC): Results of a Phase 2 Non-Randomized Expansion Cohort (NRE)

ABSTRACT Background Cabozantinib (cabo) inhibits MET & VEGFR2. In a phase 2 NRE cohort of patients (pts) with mCRPC, cabo at 100 mg daily was associated with high rates of bone scan resolution, pain relief & overall disease control, independent of PSA changes. We now report the activity & safety of cabo 40 mg daily. Methods Docetaxel (D)-pretreated (≥225 mg/m) CRPC pts with bone metastasis were required to have progressed within 6 months of last dose of D. Tumor response was assessed q6 wks. Bone scan response used computer-aided assessment of bone scan lesion area (BSLA). Diffusion Weighted MRI was performed in some pts. Pain intensity (worst pain over the past 24 hrs; BPI scale 0-10) & interference with sleep & daily activity were prospectively assessed using an IVR system (7 day intervals). Analgesic use was collected by diary. Bone turnover markers & circulating tumor cells (CTCs) were assessed. Results 51 pts were enrolled. Among 30 pts who had ≥6 wks f/u, the median age was 66 yrs. 20% received cabazitaxel, 70% abiraterone, & 20% had visceral disease. 47% (14/30) had pain (BPI ≥4) at baseline (bsl) of which 86% (12/14) were using narcotics. Median bsl CTC count was 17 & 73% had ≥5. Median f/u was 84 days (range, 44-141). 55% (11/20 pts) with a f/u bone scan showed BSLA reduction (range, 1-70%). Increases in Apparent Diffusion Coefficient (suggestive of tumor necrosis) & enhancement reduction were observed in bone & soft tissue metastases. 10/14 pts (71%) evaluable for pain response had a ≥30% reduction from bsl; 7/12 (58%) pts decreased narcotics. Sleep & daily activity improved in pts with pain relief. Among pts with elevated bsl serum levels of CTx, NTx & bALP, 57%, 60% & 33% respectively, had declines ≥30%. In 22 pts with CTCs ≥5, 59% had a decrease of ≥30% at wks 6 or 12, & 23% converted to Conclusions Cabo 40 mg was well tolerated & demonstrated bone scan resolution, substantial pain relief with a narcotic sparing effect, & reductions in bone turnover markers & CTCs in heavily pretreated mCRPC pts. MRI results are consistent with an anti-tumor effect. Disclosure M.R. Smith: Consultant to Exelixis. O.A. Sartor: Consultant for Exelixis. All other authors have declared no conflicts of interest.

Investigator-sponsored trial of efficacy and tolerability of cabozantinib (cabo) at lower dose: A dose-finding study in men with castration-resistant prostate cancer (CRPC) and bone metastases.

4566 Background: Cabo (XL184) is an oral inhibitor of MET and VEGFR2. In a randomized discontinuation trial of cabo 100mg daily, 76% of men with CRPC and bone metastases had partial or complete resolution of bone scan lesions as early as week (wk) 6. However, treatment was limited by adverse events (AEs), with dose reductions in 51% of patients (pts), and discontinuations in 10%. The current study was designed to determine the efficacy and tolerability of cabo at lower starting doses. Methods: An adaptive response scheme was used to determine the lowest active daily cabo dose among dose levels +1 (60mg), 0 (40mg), and -1 (20mg). The primary endpoint was wk 6 bone scan response (BSR) assessed with an automated FDA 510(k) approved computer-aided detection system. A ≥30% decrease in total bone scan lesion area (BSLA) was defined as a response. The first cohort was treated at dose level 0. The number of responses (≥8 vs. &lt;8 among 11 evaluable pts) was used to select the dose level (-1 vs. +1) for the second cohort. Based on the observed BSR rate in the second cohort of 11 pts, a dose was selected for expansion to treat 13 more pts. Results: The study completed planned enrollment of 36 pts. Median age was 66; 44% were docetaxel-pretreated. Among 12 pts enrolled at dose level 0, there were 10 BSRs at wk 6 including 1 complete response (CR), and 1 pt with stable disease (SD). The median decrease in BSLA was 62%. Ten pts evaluated at wk 12 included 9 BSRs (3 CRs), and 1 sustained SD. Among 11 pts then treated at dose level -1, 10 pts were evaluable at wk 6: 1 BSR, 5 SD, and 4 had progressive disease. No pts in the 2 cohorts required dose reduction or treatment interruption at 12 wks; 1 pt discontinued due to grade 3 AEs (anorexia, fatigue). 6/12 pts with ≥6 months follow-up remain on study. 5/5 pts enrolled at 40mg with CTCs ≥5 per 7.5mL converted to &lt;5. Thirteen pts accrued to the expansion cohort at 40mg daily had confirmed high BSR rate. Conclusions: Cabo 40mg daily achieves a high BSR rate in men with CRPC and bone metastases, and is associated with better tolerability than previously reported for cabo 100mg daily.

Cabozantinib (XL184) in chemotherapy-pretreated metastatic castration resistant prostate cancer (mCRPC): Results from a phase II nonrandomized expansion cohort (NRE).

4513 Background: Cabozantinib (cabo) inhibits MET and VEGFR2. High rates of bone scan resolution, pain relief and overall disease control, independent of PSA changes, were previously reported in a phase II study in mCRPC patients (pts). This is a NRE cohort in docetaxel (D)-pretreated pts with a novel primary endpoint of bone scan response based on computer-aided quantitative assessment of bone scan lesion area (BSLA) and a double-reader, independent, blinded review (Nucl Med Commun, in press). Methods: D-pretreated (≥225 mg/m2) CRPC pts with bone metastasis were required to have progressed in soft-tissue or bone within 6 months of last dose of D. Pts received 100 mg cabo qd. Tumor response was assessed q6 wks. Bone scan response (BSR) was defined by a ≥30% decline in BSLA. Pain intensity (worst pain over the past 24 hrs; BPI scale 0-10) and interference with sleep and daily activity were prospectively assessed using an IVR system. Analgesic use was collected by diary. Bone turnover markers and CTCs were assessed. Results: 93 D-pretreated pts were enrolled (89 evaluable with ≥6 wks f/u). Median age was 67, 46% received cabazitaxel and/or abiraterone, 32% had visceral disease, 51% had fatigue, and 18% had anemia. 44% had worst pain ≥4 of which 95% were taking narcotics. Median CTC count was 49 and 80% had ≥5. Median f/u was 125 days (range, 23-305). Of 85 pts evaluable for BSR, 51 (60%) had a PR, 24 (28%) SD, 5 (6%) PD and 5 (6%) d/c’d prior to f/u scan. 21/30 pts (70%) had reduction of measurable disease.16/33 pts (49%) with BPI ≥4 and ≥12 wks f/u had pain reduction durable for ≥6 wks; 46% had decreased narcotic use, including 27% who discontinued use. Sleep and daily activity were improved in pts with pain relief. Among pts with elevated serum levels, 74%, 67% and 47% had declines on treatment of ≥30% in CTx, NTx and bALP, respectively. In 59 pts with CTCs ≥5, 92% had a decrease of ≥30% and 39% converted to &lt;5 CTCs at weeks 6 or 12. 12% discontinued cabo due to AEs. Most common Gr 3/4 AEs were fatigue (19%), nausea (10%) and anemia (10%). Conclusions: Cabo treatment resulted in high rates of bone scan response, durable pain relief, and reductions in bone turnover markers and CTCs in D-pre-treated CRPC pts with bone metastases.

Abstract A90: Efficacy and tolerability of cabozantinib at lower dose: A dose finding study in men with castration-resistant prostate cancer and bone metastases.

Abstract Background: Cabozantinib is an orally available inhibitor of MET and VEGFR2. In a randomized discontinuation trial of cabozantinib (100 mg daily), 86% of men with mCRPC and bone metastases had partial or complete resolution of lesions on bone scan as early as week 6; dose reductions for AEs occurred in 51% of pts, and discontinuations in 10%.[1] The current study is designed to determine the efficacy and safety of cabozantinib at lower doses. Methods: The study uses an adaptive response scheme based on Sargent one-stage design [2] to determine the lowest effective cabozantinib dose among three dose levels: dose level +1 (60 mg daily), dose level 0 (40 mg daily), and dose level −1 (20 mg daily). Bone scan responses were assessed by comparison of baseline and week 6 bone scans using an automated FDA 510(k) approved computer-aided detection (CAD) system.[3] A decrease in total bone scan lesion area of ≥ 30% was defined as a response The first cohort was treated at dose level 0 (40 mg po QD). Using the adaptive design, the number of bone scan responses at dose level 0 (≥8 responses versus &amp;lt;8 responses among 11 evaluable subjects) was used to select the dose level (−1 versus +1) for the second cohort. By this design, subjects will be treated at two of the three dose levels (dose level 0 and −1, or dose level 0 and +1). Based on the observed bone scan response rate in the second cohort of 11 subjects, a dose level will be selected for expansion to treat an additional 13 subjects. Results: The study has enrolled a total of 23 subjects. Twelve subjects were enrolled in the first study cohort and treated with cabozantinib 40 mg daily. Median followup is 14 weeks. One subject discontinued the study at week 2 because of anorexia and fatigue. Another subject discontinued at week 6 after experiencing a hip fracture. The remaining 10 subjects remain on treatment without dose reduction. Baseline and week 6 bone scans have been centrally reviewed for the first 10 evaluable subjects. There were 9 confirmed bone scan responses at week 6 including complete response. Median decrease in bone lesion area at week 6 was 69%. Eleven subjects were accrued to the second cohort and treated with cabozantinib 20 mg daily; all subjects remain on study. Conclusions: Cabozantinib 40 mg daily results in high rates of bone scan response in men with CRPC and bone metastases. Cabozantinib 40 mg daily is associated with improved tolerability compared to cabozantinib 100 mg daily. Evaluation of the efficacy and tolerability of cabozantinib 20 mg daily is ongoing.

Abstract B114: Cabozantinib effects on bone metastasis: Computer-aided quantitative bone scan assessment of prostate cancer treatment response.

Abstract Background: Cabozantinib is an oral inhibitor of MET and VEGFR2 and at a dose of 100 mg qd has demonstrated high rates of partial or complete bone scan resolution in CRPC patients with bone metastases, as assessed by manual visual reads. No accepted approach exists for the assessment of bone scan response in prostate cancer patients. An FDA 510(k) approved image analysis package has been developed that includes a computer-aided detection (CAD) system to detect pixels associated with bone lesions on bone scan with high accuracy, thus facilitating quantitative assessment of tumor burden with advantages of objectivity and consistency over manual approaches. A change in total Bone Scan Lesion Area of 30% or greater has been previously established as a cutoff point to distinguish responders from non-responders [1]. Methods: Original Digital Imaging and Communications in Medicine (DICOM) format images of baseline and week 6 bone scan assessments were collected and analyzed by the automated CAD system then reviewed by a physician experienced with bone scan interpretation as part of an ongoing clinical study of single agent cabozantinib at a lower starting dose of 40 mg qd in CRPC subjects with evidence of bone metastases. All subjects had undergone standard of care whole body scintigraphy, 2–4 hours post-injection of 20–25 mCi of Tc MDP. All images underwent intensity normalization to a bone scan reference to account for differences in radiotracer dosing levels and scan timing to improve reproducibility. Lesions consistent with metastatic foci of disease were automatically segmented based on anatomic region-specific intensity thresholds. Each segmented image was reviewed by a nuclear medicine physician for removal of any remaining false positive regions (e.g. areas of degenerative joint disease). Quantitative assessment of lesion burden was then determined. Results: 10 CRPC subjects showing evidence of bone metastasis were treated in an ongoing dose-ranging study with cabozantinib and were evaluable for bone scan response assessment at week 6. Reductions in the following parameters (median and range) were observed at week 6 relative to baseline: total Bone Scan Lesion Area (168.5 cm2 [20, 864] to 54 cm2 [0, 431]; 68% reduction), Bone Scan Lesion Count (34 [3, 74] to 3 [0, 64]; 91% reduction), and mean normalized Bone Scan Lesion Intensity (92.2 [56.5, 155.0] to 57.0 [0, 90.5]; 38% reduction). All 10 subjects had a reduction in Bone Scan Lesion Area, with 9 achieving a bone scan response at the week 6 timepoint as assessed by both the CAD system and visual review by the investigator. Conclusion: A significant reduction in apparent bone scan abnormality was demonstrated by the automated CAD system. The results demonstrate the potential for objective measurement of cabozantinib treatment effects in bone, laying the foundation for further validation against other clinically relevant outcome measures such as pain and overall survival. Reference: 1. G. H. Chu, M. S. Brown, H. J. Kim, M. Auerbach, C. Poon, B. Ramakrishna, A. Vidovic, D. W. Gjertson, M. J. Morris, S. M. Larson, J. G. Goldin, H. I. Scher. Initial analytic validation of automated bone scan measures for treatment response assessment in patients with metastatic castration-resistant prostate cancer (CRPC). J Clin Oncol 29: 2011 (suppl; abstr e15174). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B114.

Phase II study of XL184 in a cohort of patients (pts) with castration-resistant prostate cancer (CRPC) and measurable soft tissue disease.

127 Background: XL184 is an oral, potent inhibitor of MET and VEGFR2. MET pathway activation promotes tumor growth, invasion and metastasis. Overexpression of MET and/or its ligand HGF are associated with prostate cancer metastasis. In preclinical studies, androgen ablation upregulates MET signaling. Preliminary data from the open label Lead-in Stage of an ongoing adaptive design phase II randomized discontinuation trial are presented. Methods: Eligible pts had CRPC, measurable disease with or without bone metastasis, and disease progression on ≤1 prior non-hormonal systemic treatment. XL184 was administered orally for 12 weeks (wks). Tumor (RECIST) and bone scan response (complete or partial resolution) were assessed every 6 wks. Primary endpoint is objective response rate at wk 12. Pts with SD at wk 12 will enter a placebo-controlled randomized phase. Results: As of 10/4/10, 72 pts have been enrolled. Median time on study was 50 days (range, 6+-350+ days). Median age was 69 yrs; 45% of pts were docetaxel-pretreated. All pts had measurable disease, including 69% with visceral metastases. To date, there are 24 response evaluable pts, defined as enrolled ≥12 wks prior to data cutoff. 5/24 (21%) pts had a partial response (≥30% reduction) in measurable disease with 3 responses confirmed at 12 wks and 2 unconfirmed responses ongoing. 6/24 (25%) had PSA declines of ≥50%. 13 of 15 (87%) pts with known bone metastases had either complete or partial resolution of lesions on bone scan. Bone scan responses were associated with investigator-reported improvement in bone pain in 11/15 (73%) with pain at baseline. Effects on osteoclast and osteoblast activity were observed: plasma C-telopeptide declined ≥50% in 8/12 (66%) pts and serum total alkaline phosphatase (tALP) declined ≥50% in 5/8 (63%) pts with bone metastases and baseline elevated tALP. The most common AEs ≥Grade 3 severity (related) were fatigue (10%), diarrhea (3%) and elevated AST (3%). Conclusions: XL184 results in tumor responses, partial or complete resolution of lesions on bone scan, and symptom relief in pts with metastatic CRPC, including those pretreated with docetaxel. XL184 also decreased biomarkers of both osteoblast and osteoclast activity. [Table: see text]

Salvage chemotherapy for hormone-refractory prostate cancer: Association of Adriamycin and ifosfamide

Prostate carcinoma is the most common cancer in men. Hormone-resistance is the natural history of this metastatic disease and requires the use of docetaxel as the standard chemotherapy. At present, there is no approved second-line treatment. Here, we report a combination of treatment with Adriamycin and ifosfamide in a series of 7 relatively young patients with an average age of 57 years at the time of diagnosis. Chemotherapy was administered over 3 days with the following schedule: 20 mg/m(2) Adriamycin per day and 1-1.5 mg/m(2) ifosfamide per day, in association with Uromitexan. Treatment was repeated every 3 weeks. Three biological responses, one CT scan response, one bone scan response and two CT scan stabilizations, were obtained. Mean survival following this combination was 6.6 months, and over 26 months after first-line chemotherapy. Tolerance was good with the use of granulocyte-colony stimulating factors. Our observations clearly show that the use of this type of salvage therapy for relatively young patients in good physical condition should be further assessed in a clinical trial, particularly when different lines of chemotherapy are required.

Phase II trial of docetaxel (D) and high-dose celecoxib (C) in patients (Pts) with hormone resistant prostate cancer (HRPC)

4616 Background: COX-2 is an inducible enzyme, which converts arachidonic acid to prostaglandins. COX-2 is over expressed in 89.3% of our pts with prostate cancer and is an independent predictor of survival (Cogswell et al; Proc ASCO 2003, #1675). Both D and C are angiogenesis inhibitors and induce apoptosis; their combination could be synergistic. In an ongoing pilot trial we determined the effects on PSA, Overall Response(OR), toxicity, and survival. Methods: Eighteen (18) pts with HRPC progressing by rising PSA and radiographic manifestations were treated with D 30mg/m2 IV over 30min,weekly for 3 wks and C 400mg po bid daily of each 4wk cycle. All pts were assessed by PSA and radiological tests every 2 cycles. Dose modifications for hematologic, hepatic and renal toxicity were made. Detailed renal function tests were assessed by a nephrologist. The RECIST criteria and PSA decline by ≥50% were used. Sample size was determined by Simon's Optimal Two-Stage design. Results: The median age was 73.5 years(55–94), ECOG PS 1(0–1),LDH 180.5 U/L(125–899 ), Hgb 11.9g/dL (8.6–14.6), PSA 215.8 ng/dL (28.5–2675). The median number of cycles was 3(2–6).The median follow up was 6 mos (2–11+). Soft tissue metastases were present in 15 pts (83.3%) and bone metastases in 17 pts (94.4 %). Seventeen(17)pts are evaluable for response. Of these, 11 pts(64.7%) had PSA responses and the PSA normalized in 4pts (23.5%).Soft tissue responses were seen in 5(2CR's + 3PR's)pts(29.4%)and SD in 5pts(29.4%). One pt(5.9%) had an impressive bone scan response. The OR for 11pts was 64.7%. One pt withdrew due to abdominal pain, 2pts(11.7%) had grade III diarrhea and one had grade III nail changes. There was excellent renal tolerance (Yudd et al; Proc ASCO 2004 subm ). Conclusions: The combination of D and C is well tolerated. The OR rate was 64.7%. PSA decline by≥50%, PSA normalization, soft tissue, and bone scan responses were demonstrated. Further accrual and longer follow up will determine its full impact in pts with HRPC. (Supported by Aventis and Pfizer). Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Pfizer Aventis