Citations

5564 Background: Cabozantinib (C) may enhance response to immune checkpoint inhibitors (ICIs) by promoting an immune-permissive microenvironment and has shown encouraging activity in combination with ICIs in tumor types including RCC and HCC. C and atezolizumab (A) have shown low objective response rates as monotherapy in metastatic castration-resistant prostate cancer (mCRPC) (Smith JCO 2012; Kim JCO 2018). COSMIC-021 (NCT03170960), a multinational phase 1b study, is evaluating the combination of C + A in various solid tumors. We report results for Cohort 6 in mCRPC. Methods: Eligible patients (pts) were required to have radiographic progression in soft tissue after enzalutamide and/or abiraterone, measurable disease, and an ECOG PS of 0 or 1. Prior chemotherapy for mCSPC was permitted. Pts received C 40 mg PO QD and A 1200 mg IV Q3W. CT/MRI scans were performed Q6W for the first year and Q12W thereafter. The primary endpoint is ORR per RECIST 1.1. Other endpoints include safety, ORR per irRECIST, duration of response (DOR), PFS, and OS. Results are presented for the first 44 pts enrolled. Results: Median follow-up as of Dec 20, 2019 was 12.6 mo (range 5, 20) for the 44 mCRPC pts. Median age was 70 y (range 49, 90), 50% had ECOG PS 1, 34% had visceral metastases, and 61% had extrapelvic lymph node metastases. 27% had prior docetaxel and 52% had 2 prior novel hormonal therapies. The most common any grade treatment-related adverse events (TRAEs) were fatigue (50%), nausea (43%), decreased appetite (39%), diarrhea (39%), dysgeusia (34%), and PPE (32%). One grade 5 TRAE of dehydration was reported in a 90 y/o. Median duration of treatment was 6.3 mo. ORR per RECIST 1.1 among all 44 pts was 32% (2 CRs [4.5%] and 12 PRs [27%]); 21 (48%) pts had SD resulting in a disease control rate of 80% in all pts. One pt with PD per RECIST 1.1 had an irPR per irRECIST. ORR per RECIST 1.1 was 33% in 36 pts with high-risk disease (visceral and/or extrapelvic lymph node metastases). Median DOR for all pts with response per RECIST 1.1 was 8.3 mo (range 2.8, 9.8+). 17 (50%) of 34 pts with post-baseline PSA evaluation had a decrease in PSA. In 12 responders with post-baseline PSA evaluation, 8 (67%) had a PSA decrease ≥50%. Tumor PD-L1 expression will also be reported. Conclusions: The combination of C + A had a tolerable safety profile and demonstrated clinically meaningful activity with durable responses in men with mCRPC. Given the encouraging activity in these pts, especially in those with high-risk disease, further evaluation of C + A in men with mCRPC is being pursued. Clinical trial information: NCT03170960 .

5013 Background: Cabozantinib (C), an inhibitor of MET, AXL, and VEGFR, has been shown to promote an immune-permissive environment and has shown promising clinical activity in combination with immune checkpoint inhibitors (ICIs) in solid tumors including renal cell carcinoma and urothelial carcinoma (UC). ICI monotherapy is approved for patients (pts) with locally advanced or metastatic UC with disease progression after platinum-containing chemotherapy. COSMIC-021, a multi-center phase 1b study, is evaluating the combination of C with atezolizumab (A) in various solid tumors (NCT03170960). We report results from Cohort 2 in UC pts with prior platinum-containing chemotherapy. Methods: Eligible pts had ECOG PS 0-1 and had progressed on or after a platinum-containing chemotherapy (including pts with disease recurrences < 12 months after the end of perioperative chemotherapy). Pts received C 40 mg PO QD and A 1200 mg IV Q3W. CT/MRI scans were performed Q6W for first year and Q12W thereafter. The primary endpoint is objective response rate (ORR) per RECIST v1.1 by investigator. Other endpoints include safety, duration of response (DOR), PFS, and OS. Results: As of Dec 20, 2019, 30 pts with advanced UC were enrolled with a median follow-up of 16.5 mo (range 12, 21). Median age was 66 yrs (range 44, 84), 73% were male, and 60% had ECOG PS 1. Primary tumor sites were bladder (80%), renal pelvis (10%), and ureter (10%); the most frequent metastatic sites included lung (40%) and liver (27%). Fourteen pts (47%) had received ≥2 prior systemic anticancer therapies. The most common treatment-related AEs (TRAEs) of any grade were asthenia (37%), diarrhea (27%), decreased appetite (23%), increased transaminases (23%), and mucosal inflammation (20%). Grade 3/4 TRAEs occurred in 57% of pts, with no grade 5 TRAEs. Confirmed ORR per RECIST v1.1 was 27% (8 of 30 pts), including 2 pts with CR. DCR (CR+PR+SD) was 64%. Median DOR was not reached, with the longest DOR ongoing at 14.3+ mos. Median PFS was 5.4 mo (range 0.0+, 17.3+). Conclusions: C in combination with A demonstrated encouraging clinical activity in pts with advanced UC with an acceptable safety profile. Additional cohorts of pts with advanced UC are being explored in the study. Clinical trial information: NCT03170960 .

Objective To evaluate patient‐reported outcome (PRO) data from the IMmotion150 study. The phase 2 IMmotion150 study showed improved progression‐free survival with atezolizumab plus bevacizumab vs sunitinib in patients with programmed death‐ligand 1 (PD‐L1)+ tumours and suggested activity of atezolizumab monotherapy in previously untreated metastatic renal cell carcinoma (mRCC). Patients and methods Patients with previously untreated mRCC were randomised to atezolizumab 1200 mg intravenously (i.v.) every 3 weeks ( n = 103), the atezolizumab regimen plus bevacizumab 15 mg/kg i.v. every 3 weeks ( n = 101), or sunitinib 50 mg orally daily (4 weeks on, 2 weeks off; n = 101). The MD Anderson Symptom Inventory (MDASI) and Brief Fatigue Inventory (BFI) were administered on days 1 and 22 of each 6‐week cycle. Time to deterioration (TTD), change from baseline in MDASI core and RCC symptom severity, interference with daily life, and BFI fatigue severity and interference scores were reported for all comers. The TTD was the first ≥2‐point score increase over baseline. Absolute effect size ≥0.2 suggested a clinically important difference with checkpoint inhibitor therapy vs sunitinib. Results Completion rates were >90% at baseline and ≥80% at most visits. Delayed TTD in core and RCC symptoms, symptom interference, fatigue, and fatigue‐related interference was observed with atezolizumab (both alone and in combination) vs sunitinib. Improved TTD (hazard ratio [HR], 95% confidence interval [CI]) was more pronounced with atezolizumab monotherapy: core symptoms, 0.39 (0.22–0.71); RCC symptoms, 0.22 (0.12–0.41); and symptom interference, 0.36 (0.22–0.58). Change from baseline by visit, evaluated by the MDASI, also showed a trend favouring atezolizumab monotherapy vs sunitinib. Small sample sizes may have limited the ability to draw definitive conclusions. Conclusion PROs suggested that atezolizumab alone or with bevacizumab maintained daily function compared with sunitinib. Notably, symptoms were least severe with atezolizumab alone vs sunitinib (IMmotion150; ClinicalTrials.gov Identifier: NCT01984242).

139 Background: C may enhance response to immune checkpoint inhibitors by promoting an immune-permissive microenvironment. COSMIC-021 (NCT03170960), a multinational phase 1b study, is evaluating the combination of C with A in various solid tumors. We report interim results from Cohort 6 in mCRPC. Methods: Eligible pts were required to have radiographic progression in soft tissue after enzalutamide and/or abiraterone, measurable disease, and an ECOG PS of 0 or 1. Prior chemotherapy for mCSPC was permitted. Pts received C 40 mg PO qd and A 1200 mg IV q3w. CT/MRI scans were performed q6w for 52w and q12w thereafter. Bone scans were performed q12w. The primary endpoint is ORR per RECIST 1.1. Other endpoints include safety, ORR per irRECIST, duration of response (DOR), PFS, and OS. Results: As of Oct 2019, 44 mCRPC pts were enrolled with a median follow-up of 10.6 mo (range 3.4+, 17.9). Median age was 70 y (range 49, 90), 50% had ECOG PS 1, 34% had visceral metastases, and 61% had extrapelvic lymph node metastases. 27% of pts had prior docetaxel and 52% had ≥2 prior novel hormonal therapies. The most common any grade TEAEs were fatigue (57%), nausea (48%), decreased appetite (45%), diarrhea (39%), PPE (32%), and vomiting (32%). One Grade 5 TRAE of dehydration was reported in a 90 y/o. Median duration of treatment was 5.3 mo. The ORR per RECIST 1.1 among all pts was 32% (2 CRs [4.5%] and 12 PRs [27%]); 21 (48%) pts had SD giving a disease control rate of 80% in all pts. One pt with initial PD per RECIST 1.1 had an irPR per irRECIST. ORR per RECIST 1.1 was 33% in 36 pts with high-risk clinical features (visceral and/or extrapelvic lymph node metastases). Median DOR for all pts with response per RECIST 1.1 was 8.3 mo (range 1.38+, 9.76+). In 12 responders with at least 1 post-baseline PSA evaluation, 8 (67%) had a PSA decline ≥50%. Conclusions: The combination of C+A had a tolerable safety profile and demonstrated clinically meaningful activity with durable responses in men with mCRPC. Given the encouraging activity in these pts, especially in those with visceral and/or extra pelvic lymph node metastases, further evaluation of C+A in men with mCRPC is being pursued. Clinical trial information: NCT03170960.

Objectives: Immunotherapy (IO) has become standard of care (SOC) for many advanced malignancies, although identifying patients likely to benefit remains difficult. We sought to assess whether demographic factors are associated with response to IO, compared with SOC systemic therapy, using stratified meta-analysis. Methods: A systematic review of MEDLINE, PubMed, Embase, and Scopus from inception to October 2, 2018. Randomized controlled trials comparing IO to SOC in patients with advanced solid organ malignancies were included if results were stratified by age, performance status (PS), or race, assessing overall survival (OS). Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for each group using random-effects models independently. Results: We identified 21 eligible randomized controlled trials, including 20 stratified by age, 17 by PS, and 4 by race. Patients with PS 0 (HR, 0.74; 95% CI, 0.63-0.86) and PS≥1 (HR, 0.75; 95% CI, 0.68-0.83) had similar OS benefits from IO compared with SOC (P=0.80). There was no difference on the basis of patient race (white vs. nonwhite) (P=0.46). IO demonstrated an OS benefit for younger (below 65 y: HR, 0.73; 95% CI, 0.65-0.82) and older (65 y and above: HR, 0.79; 95% CI, 0.71-0.88) patients with no difference between age groups (P=0.27). Among prespecified subgroup analyses, there was significant effect modification in 2 subgroups: younger patients in the first-line setting (P=0.03) and those receiving anti-CTLA-4 drugs (P=0.05). Conclusions: When examining OS using stratified meta-analysis, we did not demonstrate significant differences in IO efficacy according to patient age, PS or race, though data on race were sparse.

4515 Background: The phase 2 IMmotion150 study showed improved PFS with atezo + bev vs sun in patients (pts) whose tumors were PD-L1+ and corroborated the activity of atezo monotherapy in previously untreated mRCC. This study offers an opportunity to evaluate PROs with immunotherapy and VEGF-directed therapy alone and in combination. Methods: Pts randomized to atezo 1200 mg IV q3w alone or with bev 15 mg/kg IV q3w, or sun 50 mg po qd for 4 wk on/2 wk off completed the MD Anderson Symptom Inventory (MDASI) and Brief Fatigue Inventory (BFI) q3w of each 6-wk cycle until progression (RECIST 1.1). Time to deterioration (TTD; first ≥ 2-point score increase over baseline [BL]) and change from BL (effect size [ES] ≥ 0.2 suggests a clinically important difference vs sun) in MDASI symptom severity and interference and BFI fatigue severity and interference scores are reported for all-comers. Results: Completion rates were > 90% at BL and ≥ 80% at most visits across arms. BL PRO scores indicating mild symptoms and interference were similar across arms. Delayed TTD of symptom severity and interference with daily life was seen with atezo vs sun and atezo + bev vs sun and was longest with atezo alone (Table). Pts reported milder symptoms and less interference during the first 6 cycles with atezo vs sun: ES mean (range) was 0.36 (0.07-0.68) for core symptom severity and 0.36 (0.04-0.83) for symptom interference. The 5 worst pt-reported symptoms during tx (dry mouth, fatigue, rash, drowsiness, lack of appetite) were all in the sun arm; all 16 symptoms measured were milder with atezo vs sun. Conclusions: PROs suggest that atezo alone or with bev maintained daily function with minimal symptom interference vs sun. Clinical activity, safety and PRO data for atezo support its investigation in adjuvant tx of high-risk RCC pts (IMmotion010; NCT03024996). Clinical trial information: NCT01984242. [Table: see text]

4502 Background: Patients with no evidence of disease (NED) after metastasectomy for metastatic renal cell carcinoma (mRCC) are at high risk of recurrence, but no systemic therapy has been shown to benefit this population. Pazopanib is an inhibitor of VEGFR and other kinases that improves progression-free survival in patients with measurable RCC metastatic disease. We performed a randomized, double-blind, placebo-controlled multicenter study to test the hypothesis that pazopanib would improve disease-free survival in patients with mRCC rendered NED after metastasectomy Methods: Patients with NED following metastasectomy were randomized 1:1 to receive pazopanib starting at 800 mg daily vs. placebo for 52 weeks. Patients were stratified by 1 vs. > 1 site of resected disease, and by disease-free interval ≤ vs. > 1 year. Clinical assessment for toxicity and patient-reported outcomes were performed every 4 weeks, and restaging scans every 12 weeks. The study was designed to observe a 42% improvement in disease-free survival (DFS) from 25% to 45% at 3 years. Results: From August 2012 to July 2017, 129 patients were enrolled. The study was unblinded after 83 DFS events had been observed (92% information). The median follow-up from randomization was 30 months (range 0.4 – 66.5 months). The study did not meet the primary endpoint: hazard ratio (95% CI) for DFS was 0.85 (0.55, 1.31) p= 0.47 in favor of pazopanib. At the time of unblinding, 22/129 (17%) of subjects had died. The HR for overall survival (OS) was 2.65 (1.02, 6.9) in favor of placebo ( p= 0.05). Patient-reported outcomes and laboratory correlates will be reported separately. Conclusions: 52 weeks of pazopanib did not improve DFS compared to blinded placebo in patients with mRCC who were NED after metastasectomy. There was a trend toward worse overall survival with pazopanib. Clinical trial information: NCT01575548.