A multicenter, open-label, randomized, phase II study of cediranib with or without lenalidomide in iodine 131-refractory differentiated thyroid cancer

BACKGROUND

Multitargeted tyrosine kinase inhibitors (TKIs) of the vascular endothelial growth factor receptor (VEGFR) pathway have activity in differentiated thyroid cancer (DTC). Lenalidomide demonstrated preliminary efficacy in DTC, but its safety and efficacy in combination with VEGFR-targeted TKIs is unknown. We sought to determine the safety and efficacy of cediranib, a VEGFR-targeted TKI, with or without lenalidomide, in the treatment of iodine 131-refractory DTC.

PATIENTS AND METHODS

In this multicenter, open-label, randomized, phase II clinical trial, 110 patients were enrolled and randomized to cediranib alone or cediranib with lenalidomide. The primary endpoint was progression-free survival (PFS). Secondary endpoints included response rate, duration of response, toxicity, and overall survival (OS). Patients (≥18 years of age) with DTC who were refractory to further surgical or radioactive iodine (RAI) therapy as reviewed at a multispecialty tumor board conference, and evidence of disease progression within the previous 12 months and no more than one prior line of systemic therapy were eligible.

RESULTS

Of the 110 patients, 108 started therapy and were assessable for efficacy. The median PFS was 14.8 months [95% confidence interval (CI) 8.5-23.8 months] in the cediranib arm and 11.3 months (95% CI 8.7-18.9 months) in the cediranib with lenalidomide arm (P = 0.36). The 2-year OS was 64.8% (95% CI 43.3% to 86.4%) and 75.3% (95% CI 59.4% to 91.0%), respectively (P = 0.80). The serious adverse event rate was 41% in the cediranib arm and 46% in the cediranib with lenalidomide arm.

CONCLUSIONS

Single-agent therapy with cediranib showed promising efficacy in RAI-refractory DTC similar to other VEGFR-targeted TKIs, while the addition of lenalidomide did not result in clinically meaningful improvements in outcomes.

Early results from a phase 1, multicenter trial of PSCA-specific GoCAR T cells (BPX-601) in patients with metastatic castration-resistant prostate cancer (mCRPC)

140

Background: Prostate stem cell antigen (PSCA) is expressed in >80% of metastatic prostate cancers. BPX-601 is an autologous PSCA-directed chimeric antigen receptor (CAR)-T cell immunotherapy engineered to express a rimiducid-inducible MyD88/CD40 costimulation switch to enhance T cell potency and persistence. Safety and activity of BPX-601 with rimiducid in mCRPC and pancreatic cancer is being assessed in an ongoing, phase 1/2 clinical trial (NCT02744287). Results from the first two prostate cancer cohorts are reported. Methods: Eligible mCRPC patients (pts) had progressed on ≥ 2 prior therapies including an androgen receptor antagonist and taxane. Using a 3+3 design, pts received lymphodepleting chemotherapy followed by a single-dose of 5 x 106 BPX-601 cells/kg and single or weekly doses of 0.4 mg/kg rimiducid infused over 2 hours beginning 7 days following cell infusion. Primary objective of phase 1 is to determine safety, tolerability and MTD or RP2D. Secondary objectives include characterization of clinical efficacy, PK of rimiducid and long-term safety. Biomarkers indicative of GoCAR-T cell expansion in blood, immune cell activity, and infiltration to tumor are being monitored. Results: As of Sept 2022, 8 pts received BPX-601 5x106 cells/kg; 3 and 5 pts received a single or weekly (range: 1-30) doses of rimiducid. Most common ≥ grade 3 adverse events were myelosuppression, attributed to lymphodepletion. All patients developed cytokine release syndrome (6 G1, 2 G3). Immune-effector cell associated neurotoxicity syndrome occurred and resolved in 2 pts (1 G1, 1 G4). One pt experienced a DLT of neutropenic sepsis (G5) with possible hemophagocytic lymphohistiocytosis (eg, IL-18, ferritin, M-CSF, fractalkine, MIP-1β and IL-1RA levels were elevated). Of 7 evaluable pts, PSA50 response was observed in 3 pts at Day 28. Preliminary RECIST-based results demonstrated partial response in 1, stable disease in 3, 1 progressive disease; at data cut off 2 had not reached imaging timepoint. One patient continues on study with SD after >9 months, with persistent evidence of rimiducid responsiveness. Peripheral blood BPX-601 cells expanded to an average of 3466 vector copies / μg DNA +/- 3109 during the first week with continued re-expansion to an average of 30234 copies/ug DNA +/- 67031) following rimiducid treatment. Serum IFN-γ, GM-CSF and IL-6 rapidly increased over 24 hours following rimiducid treatment (mean IFN-γ increase 26.9-fold ± 14.2) and subsequently diminished over 2 days. Conclusions: BPX-601, a PSCA-directed GoCAR-T cell product, has preliminary evidence of biologic activity with toxicity characteristic of previously reported CAR-T studies. Markers of rimiducid-induced GoCAR-T cell activation and proliferation were observed. Exploration of escalating weekly rimiducid doses > 0.4 mg/kg and BPX-601 cell doses is planned. Clinical trial information: NCT02744287 .

PROMISE Registry: A prostate cancer registry of outcomes and germline mutations for improved survival and treatment effectiveness

TPS274

Background: Recent updates to genetic testing recommendations and approved treatment options for prostate cancer (PCa) patients (pts) have clarified the need for comprehensive genetic registries. Germline DNA damage repair (DDR) defects are present in over 10% of pts who develop metastatic castration-resistant prostate cancer (mCRPC) while 5-10% pts with localized PCa have germline pathogenic variants in DDR genes. NCCN guidelines have recently expanded to address genetic testing to include high risk localized, node positive and metastatic disease, in addition to family cancer history criteria. In May 2020, the FDA approved 2 PARP inhibitors for mCRPC treatment. Genetic registries can address the critical need to identify pts for recently approved targeted treatments, understand real-world effects of targeted therapies, and expand clinical trials examining less common mutations. PROMISE is a prospective genetic registry equipped to meet these needs. Methods: 5000 PCa pts will be screened via the online study portal and at-home germline testing to identify and enroll 500 eligible pts with germline pathogenic variants, likely pathogenic variants, and variants of uncertain significance (VUS) in the genes of interest: ATM, ATR, BARD1, BRCA1, BRCA2, BRIP1, CHEK2, FAM175A, GEN1, HOXB13, MRE11A, MLH1, MSH2, MSH6, PALB2, PMS2, PTEN, RAD51C, RAD51D, TP53 and XRCC2. Additional genes may be added as evidence emerges. Eligible pts must be assigned male at birth and have documented PCa through tissue biopsy, and/or PSA >100ng/dL, and/or radiographic evidence of disease. Pts with or without prior genetic testing, including those with known pathogenic variants, are encouraged to enroll. Exclusion criteria are: inability or unwillingness to provide information for eligibility and incomplete inclusion criteria. Following germline testing, pts will be offered genetic counseling and periodic newsletters with updates on treatments and clinical trials. Every 6 months, eligible pts will complete a patient-reported outcome (PRO) survey (EORTC QLQ-C30) and updated medical records will be obtained for clinical data abstraction. Eligible pts will enter long-term follow-up. The primary endpoint is the creation of a prospective genetic registry of PCa pts. Additional endpoints include: frequency of pathogenic or likely pathogenic germline variants of interest, recruitment of a control group with a VUS in the genes of interest, association between disease characteristics and germline testing results, comparison of PROs between disease subpopulations, longitudinal outcomes, and overall survival. Study duration is 20 years (recruitment: 5 years, follow-up: 15 years). PROMISE is recruiting at 23 US sites. 1829 subjects have enrolled in the screening phase with 189 eligible for long-term follow-up. PROMISE is sponsored and managed by the Prostate Cancer Clinical Trials Consortium. Clinical trial information: NCT04995198 .

The treating oncologist as a potential barrier to enrollment in molecular targeted trials

407

Background: It has been hypothesized that the rarity of molecular inclusion criteria hampers trial accrual. In this study, we attempted to address this challenge in the context of a SETD2-mutation targeted trial. Methods: Patients who received molecular sequencing services from Tempus were analyzed for the presence of SETD2 molecular variants that matched trial enrollment criteria, and resided within 50 miles from the treatment center or were receiving treatment at clinical sites with strong referral histories. A written notification was issued to the ordering physician whenever a likely match was identified, and additional phone and email outreach follow up, including reasons for not pursuing the clinical trial, was conducted. Results: Over one year, 38 eligible patients were identified, none of which were enrolled. The most common reason for not being enrolled was cohort closure following initial identification and outreach. More specifically, cohort closure occurred < 2 months, 2-4 months, 4-6 months and > 6 months following identification of the mutation in 5, 8, 2 and 7 patients, respectively. Physicians for additional potential patients cited trial consideration as a future option, presence of prohibitive comorbidities, lack of interest, and patient death in 6, 3, 2 and 1 patients, respectively. Physicians for 4 patients did not respond to multiple follow up attempts. In regards to individual follow up, physicians received 0-1, 2-3, and 4 or more follow up outreach notifications regarding trial availability for 14, 19, and 5 patients respectively. Conclusions: Despite identification of a large number of potential trial candidates for a molecular targeted therapeutic trial through use of matching algorithms and extensive treating physician follow up, no patients were enrolled. This raises the hypothesis that the biggest barrier to enrollment, as in other settings, is treating physician motivation and that AI algorithms for identifying potential subjects are insufficient. Larger target populations than anticipated, better coordination between outreach efforts and enrollment status, and directed patient outreach may be necessary.

A phase II study of sEphB4-HSA in metastatic castration-resistant prostate cancer

84

Background: Ephrin receptors and their membrane-localized ligands induce bidirectional signaling and facilitate tumor-stroma interactions. Expression of EphB4 is increased in prostate cancer tissue and cell lines and retained in castration resistant states, and can promote cell migration, invasion, and metastases. Blocking the EphB4-EphrinB2 pathway, which can be accomplished by soluble EphB4 conjugated to human serum albumin (sEphB4-HSA), has efficacy in preclinical models of aggressive prostate cancer. A phase I clinical trial of sEphB4-HSA led to response or stable disease in 56% of patients, with no grade 4 or 5 related adverse events, and combination pembrolizumab sEphB4-HSA led to a 52% response rate in EphrinB2 expressing urothelial cancer. We hypothesized that targeting the EphB4-EphrinB2 pathway may serve as a therapeutic target in the treatment of metastatic castration resistant prostate cancer (mCRPC). Methods: We conducted a single arm, phase II trial in patients with progressive mCRPC and treatment with at least one second generation androgen receptor (AR)-targeted therapy but no more than three prior therapies for mCRPC. On Day 1 of each cycle patients received sEphB4-HSA 1000 mg IV, with cycle length 14 days cycles 1-6 and cycle length 21 days for cycle 7 and beyond. The primary endpoint was confirmed prostate specific antigen (PSA) response rate (confirmed decrease in PSA by > 50%). We employed a Simon two stage Minimax design, requiring two or more responses among the first 15 patients to enroll an additional ten patients. Results: Fourteen eligible patients enrolled in the study. Median age was 73.5 years (range 52-83), patients had a median baseline PSA value of 65.11 ng/mL (range 7.77-2850 ng/mL) and received a median of three prior therapies (range 1-3) for mCRPC. Ten patients received prior taxane for mCRPC or hormone sensitive prostate cancer. The median length of treatment with sEphB4-HSA was 6.5 weeks (range 2-35 weeks). The potentially treatment-related adverse events (AEs) that occurred in more than 25% of patients were hypertension (10 patients) and fatigue (7 patients). Three patients experienced a serious adverse event potentially related to therapy, including one patient with a grade 5 event (cerebral vascular accident) possibly related to study drug. No patient had a confirmed PSA response, and the study was stopped for futility. Thirteen patients had PSA progression ( > 25% increase in PSA), and one patient withdrew due to toxicity prior to having an evaluable PSA response. The median time to PSA progression was 28 days (95% CI 28-64 days), and median time to radiologic progression was 55 days (95% CI 55 days-NR). Of three patients with measurable disease, two had stable disease and one had progressive disease. Conclusions: In patients with mCRPC who progressed on prior second generation AR-targeted therapy, sEphB4-HSA monotherapy had no discernable anti-tumor activity. Clinical trial information: NCT04033432.

PROMISE Registry: A prostate cancer registry of outcomes and germline mutations for improved survival and treatment effectiveness

TPS191

Background: Recent updates to genetic testing recommendations and approved treatment options for prostate cancer (PCa) patients (pts) have clarified the need for comprehensive genetic registries. Germline DNA damage repair (DDR) defects are present in over 10% of pts who develop metastatic castration-resistant prostate cancer (mCRPC) while 5-10% of pts with localized PCa have germline pathogenic variants in DDR genes. NCCN guidelines have recently expanded to address genetic testing to include high risk localized, node positive and metastatic disease, in addition to family cancer history criteria. In May 2020, the FDA approved 2 PARP inhibitors for mCRPC treatment. Genetic registries can address the critical need to identify pts for recently approved targeted treatments, understand real-world effects of targeted therapies, and expand clinical trials examining less common mutations. PROMISE is a prospective genetic registry equipped to meet these needs. Methods: 5,000 PCa pts will be screened via the online study portal and at-home germline testing to identify and enroll 500 eligible pts with germline pathogenic variants, likely pathogenic variants, and variants of uncertain significance (VUS) in the genes of interest: ATM, ATR, BRCA1, BRCA2, BRIP1, CHEK2, FAM175A, GEN1, HOXB13, MRE11A, MLH1, MSH2, MSH6, NBN, PALB2, PMS2, PTEN, RAD51C, RAD51D, TP53 and XRCC2. Additional genes may be added as evidence emerges. Eligible pts must be assigned male at birth and have documented PCa through tissue biopsy, and/or PSA >100ng/dL, and/or radiographic evidence of disease. Pts with or without prior genetic testing, including those with known pathogenic variants, are encouraged to enroll. Exclusion criteria are: inability or unwillingness to provide information for eligibility and incomplete inclusion criteria. Following germline testing, all pts will be offered genetic counseling and periodic newsletters with updates on treatments and clinical trials. Every 6 months, eligible pts will complete a patient-reported outcome (PRO) survey (EORTC QLQ-C30) and updated medical records will be obtained for clinical data abstraction. Eligible pts will enter long-term follow-up. The primary endpoint is the creation of a prospective genetic registry of PCa pts. Additional endpoints include: frequency of pathogenic or likely pathogenic germline variants of interest, recruitment of a control group with a VUS in the genes of interest, association between disease characteristics and germline testing results, comparison of PROs between disease subpopulations, longitudinal outcomes, and overall survival. Study duration will be 20 years (active recruitment: 5 years, follow-up: 15 years). PROMISE is recruiting at 10 US sites and has 282 subjects enrolled in the screening phase to date. PROMISE is sponsored and managed by the Prostate Cancer Clinical Trials Consortium. Clinical trial information: NCT04995198.

CANTATA: Primary analysis of a global, randomized, placebo (Pbo)-controlled, double-blind trial of telaglenastat (CB-839) + cabozantinib versus Pbo + cabozantinib in advanced/metastatic renal cell carcinoma (mRCC) patients (pts) who progressed on immune checkpoint inhibitor (ICI) or anti-angiogenic therapies

4501

Background: Dysregulated metabolism is a hallmark of RCC, driven by overexpression of glutaminase (GLS), a key enzyme of glutamine metabolism. Telaglenastat (Tela) is an investigational, first-in-class, selective, oral GLS inhibitor that blocks glutamine utilization and critical downstream pathways. Preclinically, Tela synergized w/ cabozantinib (Cabo), a VEGFR2/MET/AXL inhibitor, against RCC tumors. In a Ph 1 study cohort, Tela+Cabo showed encouraging safety/efficacy as 2L+ therapy for mRCC. This trial compared Tela+Cabo vs Pbo+Cabo in previously treated pts w/ clear-cell mRCC (NCT03428217). Methods: Eligible pts had 1-2 prior lines of systemic therapy for mRCC, including ≥1 anti-angiogenic therapy or nivolumab + ipilimumab (nivo/ipi), KPS ≥70%, measurable disease (RECIST 1.1), no prior Cabo or other MET inhibitor. Pts were randomized 1:1 to receive Cabo (60 mg PO QD) with either Tela (800 mg PO BID) or Pbo, until disease progression/unacceptable toxicity, and were stratified by prior PD-(L)1 inhibitor therapy (Y/N) and IMDC prognostic risk group. Primary endpoint was progression-free survival (PFS; RECIST 1.1) by blinded independent radiology review. The study was designed to detect a PFS hazard ratio (HR) of 0.69 w/ alpha 0.05 and 85% power. Data cutoff date: August 31, 2020. Results: 444 pts were randomized (221 Tela+Cabo; 223 Pbo+Cabo). Baseline characteristics were balanced between arms. Median follow-up was 11.7 mo; 276 pts received prior ICI, including 128 w/ prior nivo/ipi. Median PFS (mPFS) was 9.2 mo for Tela+Cabo vs 9.3 mo for Pbo+Cabo (HR = 0.94; 95% CI: 0.74, 1.21; stratified log-rank P= 0.65) with overall response rates (ORR; confirmed) of 31% with Tela+Cabo vs 28% Pbo+Cabo, respectively. Overall survival was not mature at data cutoff. In a prespecified subgroup analysis in pts w/ prior ICI, mPFS was numerically longer w/ Tela+Cabo than Pbo+Cabo (11.1 vs 9.2 mo, respectively; unstratified HR = 0.77; 95% CI: 0.56, 1.06). In the Pbo+Cabo arm, mPFS was 9.2 mo for pts w/ prior ICI exposure and 9.5 mo for pts without, and ORR was 32% and 20%, respectively; if ICI included nivo/ipi, ORR was 37%. Rates of adverse events (AEs) were similar between arms.Grade 3-4 AEs occurred in 71% of Tela+Cabo pts and 79% of Pbo+Cabo pts and included hypertension (17% vs 18%) and diarrhea (15% vs 13%). Cabo was discontinued due to AEs in 10% of Tela+Cabo pts and 15% of Pbo+Cabo pts. Conclusions: The addition of Tela did not improve the efficacy of Cabo in mRCC in this study. Tela+Cabo was well tolerated with AEs consistent with known risks of both agents. The study provides valuable insight on efficacy outcomes of a contemporary population of pts w/ mRCC who receive Cabo in the 2/3L setting. Clinical trial information: NCT03428217.

Biomarker-based phase II study of sapanisertib (TAK-228), an mTORC1/2 inhibitor in patients with refractory metastatic renal cell carcinoma (mRCC)

306

Background: Approved rapalogs inhibit mTORC1 and have limited activity in mRCC, possibly due to compensatory feedback loops. Sapanisertib addresses the incomplete inhibition of the mTOR pathway through targeting of both mTORC1 and mTORC2 with antitumour activity demonstrated in patients with mRCC. In this multicenter, single arm phase II trial, we evaluated the efficacy of sapanisertib in patients with mRCC progressing on standard therapies (NCT03097328). Methods: Eligible mRCC patients had an ECOG performance status of 0-2 and had progressed on standard therapies. Prior therapy with rapalogs (everolimus, temsirolimus) and variant RCC histologies were permitted. Patients had a baseline biopsy and received treatment with sapanisertib 30 mg by mouth weekly until unacceptable toxicity or disease progression. The primary endpoint was overall response rate (ORR) by RECIST 1.1. Tissue biomarkers of mTOR pathway activation were explored. Results: We enrolled 38 mRCC patients (clear cell = 28; variant histology = 10) between August 2017 and November 2019. The majority had intermediate (76%) or poor risk (11%) by IMDC criteria. Twenty (53%) had received ≥ 3 lines of therapy; 13 (34%) patients received prior rapalogs. Median follow-up was 10.4 months (range 1-27.4) and median duration of therapy was 1.6 (range 0.3-13.8) months. ORR by central review was 2 of 38 (5.3% 90%CI: 1%-15.6%). 31.6% of all patients and 30.7% of those with prior rapalog exposure had some tumor shrinkage during course of treatment. Median progression free survival (PFS) was 2.5 months (95% CI 1.8,3.7). Twelve patients (32%) developed treatment-related grade 3 adverse events (AEs) with no grade 4 or 5 toxicity reported; 6 patients (16%) required dose reduction and 4 (11%) discontinued therapy for AEs. Oncopanel tumor sequencing identified alterations in the mTOR pathway in 6 of 29 patients ( MTOR n = 2, PTEN n = 3, TSC1 n = 1.) Reduced PTEN expression by immunohistochemistry was seen in 7 of 19 patients. There was no association between mTOR pathway mutations or PTEN loss and response to sapanisertib. Conclusions: In this study we demonstrate minimal activity of sapanisertib in patients with treatment refractory mRCC with no clear benefit among patients with mTOR/PTEN pathway alterations. Additional treatment strategies are needed for patients with refractory mRCC.

Evaluation of prescribing practices of denosumab and zoledronic acid in breast and prostate cancer patients at University of Chicago Medicine

e24144

Background: Zoledronic acid (ZA) and denosumab are both bone-modifying agents (BMAs) approved for use in patients with bone metastases with breast or prostate cancer as well as patients who are receiving aromatase inhibitors (breast cancer) or androgen deprivation therapy (prostate cancer). There are various frequencies of administration, doses, and duration of these agents depending on indication and extent of disease. Currently there is data to show that ZA can be given every 3 months in patients with metastatic breast and prostate cancer, however, there is no data that clearly indicates that denosumab every 3 months is non-inferior to every 28 days. This study aimed to analyze current prescribing patterns of ZA and denosumab in metastatic breast cancer and metastatic castration resistant prostate cancer patients at The University of Chicago Medicine (UCM). Methods: This was a retrospective study of 80 patients who received at least one dose of ZA or denosumab between July 1st 2018 to June 30th 2019 from UCM outpatient oncology clinic for the purpose of treating metastatic breast cancer or metastatic castration resistant prostate cancer in conjunction with standard antineoplastic therapy. All included patients must have bone metastases. Patients were divided into four groups by disease state (breast or prostate cancer) and BMA agent (ZA or denosumab). The primary outcome was BMA therapy adherence rate, which was defined by those who received greater than or equal to 80% of appropriately scheduled doses. Descriptive statistics were used for skeletal-related events (SREs) and BMA associated adverse effects. Results: Patients who received ZA achieved higher adherence rates (100% breast, 86% prostate) compared to patients that received denosumab (63% breast, 23% prostate). The most common reason for the lower adherence rate in denosumab groups was scheduling convenience. During the study period, there were 3, 0, 2 and 5 patients had SREs in the above four groups respectively. The predominant adverse event across all groups was hypocalcemia and two patients with prostate cancer on denosumab developed osteonecrosis of the jaw. The cost analysis showed using ZA as primary BMA agent might save up to 2.5 million dollars per year at UCM. Conclusions: The use ofZA was associated with higher adherence rates compared to denosumab. Implementing a pharmacy driven protocol for ZA use for patients with metastatic breast and prostate cancer may improve BMA regimen adherence rates and significantly reduce costs.

Optimized management of nivolumab (Nivo) and ipilimumab (Ipi) in advanced renal cell carcinoma (RCC): A response-based phase II study (OMNIVORE)

5005

Background: Nivo + Ipi is an established first-line treatment (tx) for advanced RCC. We hypothesized that the addition of CTLA-4 blockade may not be required for all patients (pts). Furthermore, the optimal duration of Nivo maintenance in responding pts is unknown. In this phase II response-adaptive trial, we investigate the sequential addition of 2 doses of Ipi to induce response in Nivo non-responders (NR) and duration of Nivo in responding pts (NCT03203473). Methods: We enrolled pts with advanced RCC with no prior checkpoint inhibitor exposure. All pts received Nivo alone with subsequent arm allocation based on RECISTv1.1 response within 6 months (mos) of tx. Pts with a confirmed partial response (PR) or complete response (CR) within 6 months (mos) discontinued Nivo and were observed (Arm A). Arm A pts reinitiated Nivo if they developed progressive disease (PD); Ipi was added to Nivo if PD persisted or recurred. Pts with stable disease (SD) or PD after no more than 6 mos of Nivo alone received 2 doses of Ipi (Arm B). The primary endpoints were the proportion with PR/CR at 1-year (yr) after Nivo discontinuation (Arm A) and proportion of Nivo NR who convert to PR/CR after adding Ipi (Arm B). Results: 83 pts initiated tx of whom 99% had ECOG 0-1, 96% clear cell RCC, 51% tx-naïve, and 69% IMDC intermediate/poor risk. Median follow-up was 17.0 mos. 15 pts were not allocated to an arm [7 withdrew for PD, 7 withdrew for toxicity, 1 still on tx with unconfirmed PR (uPR)]. At 6 mos, induction Nivo resulted in a confirmed PR in 11% of pts (n=9/83): 12% (n=5/42) tx-naïve, 10% (4/41) prior tx, 8% (n=1/13) favorable risk, 11% (n=8/70) intermediate/poor risk (Table). 11 pts (13%: 9 PR, 1 uPR, 1 SD) were allocated to Arm A, of whom 5 (45%, 90% CI 20-73%) remained off Nivo at ≥ 1 yr. Of 57 pts (69%) allocated to Arm B, 2 pts converted to a PR (4%, 90% CI 1-11%), both of whom had prior tx and PD as best response to Nivo alone. Grade 3-4 treatment related adverse events (TrAE) occurred in 7% (n=6/83) on induction Nivo and in 23% (n=13/57) on Arm B (Nivo + Ipi). Conclusions: We cannot currently recommend a strategy of Nivo followed by response-based addition of Ipi due to the absence of CR and low PR/CR conversion rate (4%). Though a subset of pts treated with Nivo alone can maintain durable responses off tx at 1-yr, early Nivo discontinuation in the absence of toxicity cannot currently be recommended. Investigation into biomarkers to guide tx is ongoing. Clinical trial information: NCT03203473 . [Table: see text]

Phase I/II trial of enzalutamide (Enz) plus mifepristone (Mif) for metastatic castration-resistant prostate cancer (mCRPC)

91

Background: Resistance to androgen receptor (AR) targeted therapies is common in mCRPC. Glucocorticoid receptor (GR) expression increases with AR inhibition in patients (pts) and blockade of GR signaling inhibits CRPC growth in preclinical models when combined with AR blockade. We thus conducted a phase I/II open label trial of Enz combined with Mif, a GR, AR, and progesterone receptor antagonist for pts with mCRPC to assess the feasibility and impact on disease progression with dual AR/GR antagonism. Methods: The phase I dose escalation portion assessed the safety of the two-drug combination and a recommended phase II dose (R2PD) was determined based on safety, pharmacokinetic and endocrine assessments. In the phase II portion, patients (pts) received 12 weeks of Enz (160mg/day) followed by randomization to Enz alone or Enz plus Mif with PSA-progression free survival (PFS) as the primary endpoint. 42 pts were to randomize to each arm to provide 80% power to detect a hazard ratio of 0.6, with a one-sided alpha of 0.1; there was a planned interim futility analysis after 50% of progression events. Results: 106 pts (18 phase I/88 phase II) were enrolled. Pts had a median age of 70 (range 53-89) and baseline PSA of 12.8 (range 0.1-755). 34% of pts received prior docetaxel. The RP2D was 120mg/day Enz and 300mg/day Mif. In phase II, 33 patients were randomized to each arm, with well-balanced baseline demographics. 22 pts were not randomized (15 due to disease progression, 2 due to toxicity, and 5 due to the interim study analysis). The interim analysis showed no difference between arms in PSA-PFS (hazard ratio = 1.34, p=0.395), 12-month PSA-PFS of 31% in both arms, and per-protocol, the trial was stopped. Toxicities were similar in the arms, e.g. fatigue (12% vs. 14%), hot flashes (6% vs. 5%), and pain (4% vs. 4%). Conclusions: The addition of Mif to Enz following a 12-week Enz lead-in did not delay time to PSA progression. Further analyses of secondary endpoints, including translational biomarkers such as hormone levels, GR/AR-v7 expression in circulating tumor cells and cell free DNA analyses are ongoing. Clinical trial information: NCT02012296.

A phase II study of sEphB4-HSA in metastatic castration-resistant prostate cancer (mCRPC)

TPS274

Background: The EphB4/EphrinB2 pathway is a promising therapeutic target for patients with mCRPC. EphB4 expression is increased in prostate cancer tissue and cell lines, and retained in castration resistant states. EphB4 crosstalks with the PI3K/AKT and MAPK pathways to regulate cell survival and proliferation, and its interaction with the transmembrane ligand EphrinB2 leads to T-cell suppression and immune evasion. A soluble decoy EphB4 receptor-human serum albumin fusion protein (sEphB4-HSA) binds to EphrinB2 and blocks interaction with the cell surface EphB4 receptor to promote immune infiltration and induce tumor cell death. Here we report an ongoing phase II study exploring the preliminary efficacy and safety of sEphB4-HSA in patients with progressive disease after frontline therapy for mCRPC. Methods: Eligibility criteria include mCRPC with disease progression after second generation AR targeted therapy (i.e., abiraterone or enzalutamide), ECOG PS ≤ 2, and adequate renal, hepatic and hematological functions. Pts having received 4 or more prior treatment therapies for mCRPC are excluded. The primary objective is efficacy as reflected by PSA response using PCWG3 criteria. Secondary objectives include safety and tolerability by CTCAE v 5.0, time to PSA progression, overall response by RECIST 1.1 and PCWG3 (bone) criteria, and rPFS. Translational endpoints include expression of EphB4 and EphrinB2 in metastatic tumor samples by immunohistochemistry and correlation with alterations in MYC, PTEN/PI3K, AR, and p53 pathways. sEphB4-HSA is administered as IV infusion over 60 min every 14 days with spacing to every 21 days after 6 cycles. Therapy will continue till disease progression, unacceptable toxicity, treatment delay ≥4 weeks, or patient withdrawal. Preliminary efficacy will be assessed using PSA response rate (PR and CR) with a Simon two stage minimax trial design assuming the undesirable overall response rate (null hypothesis) to be approximately 10% or less, and the alternate hypothesis suggesting success to be approximately 30% or more. Toxicity will be evaluated by the DSMC after the first stage including 15 patients. If 2 or more respond, then an additional 10 patients will be added. Clinical trial information: NCT04033432.

A phase Ib/IIa study of rucaparib (PARP inhibitor) combined with nivolumab in metastatic castrate-resistant prostate cancer

TPS270

Background: Immune checkpoint blockade (ICB) therapies have had a major impact across a wide range of cancers. However, only subsets of patients across all malignancies benefit from ICB. In particular, metastatic castrate-resistant prostate cancers (mCRPC) have shown very limited responses to ICB. While there is ongoing work to identify predictive biomarkers to ICB responsiveness, early preclinical data from our group suggests that targeting fundamental DNA repair pathways could markedly increase the fraction of patients responsive to immunotherapeutic interventions. Based on these preclinical studies, we are conducting an investigator-initiated Phase Ib/IIa co-clinical trial of rucaparib and nivolumab singly and in combination, in mCRPC patients. Methods: Patients are randomized to one of three arms – rucaparib, nivolumab, or both drugs in combination for 4 weeks. Metastatic biopsy samples are collected at baseline and after 4 weeks on treatment, after which all arms switch to combination therapy. The primary objective is to assess feasibility of the combination, and to elucidate changes in T cell infiltration by RNA-seq analysis using established T-cell non-inflamed and inflamed gene signatures. Secondary objectives are to assess changes in immune cell infiltration via flow cytometry, multiplex IHC, transparent tissue tomography (3D mapping) and single-cell RNA-seq. We will correlate changes in the metastatic tumor microenvironment (TME) at baseline and following 4 weeks of treatment, with genomic alterations and clinical responses. We have currently enrolled 12 patients to the study, and collected pre- and 4 week on-treatment biopsies. This study utilizes novel emerging technologies for in-depth TME analysis that will unravel the impact of PARP inhibition, singly and in combination with PD-1 blockade, on specific immune subsets within the TME. The correlative analyses will also lead to the discovery of novel biomarkers of response/resistance, and suggest additional immuno-oncology combinations for specific genomic subsets of mCRPC. Clinical trial information: NCT03572478.

Biomarkers of outcomes in a randomized phase II trial of first-line paclitaxel, ifosfamide, and cisplatin (TIP) versus bleomycin, etoposide, and cisplatin (BEP) for intermediate- and poor-risk germ cell tumors (GCT)

4563

Background: We previously reported no difference in favorable response rate (FRR) or PFS for TIP vs BEP. Here we present results of a pre-planned analysis of biomarkers of outcome. Methods: HCG and AFP were drawn on days 1 and 15 of each cycle and rates of decline classified as satisfactory [S] or unsatisfactory [US] by MSK (Motzer JCO 2007) and GETUG (Fizazi Lancet Oncol 2014) methods. IHC for ERCC1, RAD51, PARP1, HER-2, and p-AKT was performed on pre-treatment tumor samples. An H-score (0 – 300) was calculated for each stain (H = stain intensity [0 – 3] x % positive cells [0-100]). H-score and marker decline category were correlated with FRR (PR + CR) and PFS. Patients (pts) who received disease-stabilizing chemotherapy were excluded from marker analyses. Results: Of 91 pts, 80 did not receive disease-stabilizing treatment with 79 having sufficient marker values for analysis by the MSK method and 75 by GETUG. By MSK, 49 had S decline vs 30 US; by GETUG, 34 S vs 41 US. FRR and PFS were improved for pts with S vs US decline by both methods and remained significant by the MSK method when stratified by IGCCCG group (Table). IHC (n=77) quality was adequate in 71 to 73 pts (varied by stain) and was positive (H >0) for PARP in 68/73, ERCC1 in 54/71, RAD51 in 54/73, p-AKT in 5/72, and HER2 in 4/72. Only PARP1 was associated with outcome with worse PFS for the lowest expression tertile (H < 180; p=0.013). Conclusions: PARP1 expression and tumor marker decline rates, particularly by MSK method, were significantly associated with outcome to initial chemotherapy in int/poor risk GCT. Future trials incorporating marker decline into treatment allocation and validating the prognostic effect of PARP1 expression are warranted. Clinical trial information: NCT01873326. [Table: see text]

A phase Ib/IIa study of rucaparib (PARP inhibitor) combined with nivolumab in metastatic castrate-resistant prostate cancer and advanced/recurrent endometrial cancer

TPS2663

Background: Immune checkpoint blockade (ICB) antibodies have made a major impact in a wide range of cancers. However, only subsets of patients across all malignancies benefit from ICB. In particular, metastatic castrate-resistant prostate cancer (mCRPC) and advanced endometrial cancers (EC) have shown very limited responses to ICB. The central hypothesis of this trial is that the combination of PARP inhibitor (rucaparib) with PD-1 inhibitor (nivolumab) will enhance ICB efficacy in mCRPC and mEC patients. Given that PTEN loss has also been associated with poor response to ICB, a secondary hypothesis of this study is that the combination therapy will have differing efficacy based on the PTEN mutation status of the tumor. Methods: This is an investigator-initiated Phase 1b/IIa clinical trial of rucaparib and nivolumab singly and in combination, in mCRPC and mEC patients. Patients are randomized to one of three arms – rucaparib, nivolumab, or both drugs in combination for 4 weeks. Metastatic biopsy samples are collected at baseline and after 4 weeks on treatment, after which all arms will switch to combination therapy. The primary objective is to assess feasibility of the combination, and to elucidate changes in immune infiltrates by Nanostring RNA sequencing, multiplex immunofluorescence, 3D mapping, IHC, and flow cytometry. Secondary objectives are to assess clinical response, and correlate changes in TME with PTEN status. We have currently enrolled 4 patients to the study, and collected pre- and 4 week on-treatment biopsies. This study presents an opportunity for in-depth TME analysis that will enable the delineation of the effects of PARP inhibition singly and in combination with PD-1 blockade, on immune subsets within the TME. The correlative analyses will also lead to the discovery of novel biomarkers of response/resistance, and suggest additional immunooncology combinations for specific molecular subsets of prostate and endometrial cancers. Clinical trial information: NCT03572478.

CALGB 90601 (Alliance): Randomized, double-blind, placebo-controlled phase III trial comparing gemcitabine and cisplatin with bevacizumab or placebo in patients with metastatic urothelial carcinoma

4503

Background: The combination of gemcitabine (G) and cisplatin (C) is a standard therapy for metastatic urothelial carcinoma (mUC). Based on data that angiogenesis plays a role in UC growth and progression, a randomized placebo-controlled trial was performed. Methods: Patients mUC, no prior chemotherapy for metastatic disease and >12 months from prior (neo)adjuvant chemotherapy and ECOG PS 0-1 were randomized 1:1 to G 1000 mg/m2 IV days 1 and 8 and C IV 70 mg/m2 day 1 with bevacizumab (GCB) 15 mg/kg IV or placebo (GCP) day 1 every 21 days. Randomization was stratified by the presence of visceral metastases and prior chemotherapy. The primary endpoint was overall survival (OS) defined as the time from randomization to death or last follow-up (FU). Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and ≥ grade 3 toxicity. With 445 deaths, the log-rank test had an 87% power to detect a hazard ratio (HR) of 0.74 with a 2-sided α=0.05. The primary analysis was based on the stratified log-rank test adjusting on stratification factors. Alliance Data Safety and Monitoring Board approved the final OS analysis be performed at 420 events due to lower than expected event rates. Results: 506 patients were randomly assigned (252 GCB, 254 GCP) stratified by the presence of visceral disease and prior chemotherapy for UC. The median FU for patients still alive was 46.2 months. Median OS was 14.5 months for patients treated with GCB and 14.3 months for patients treated with GCP with a HR of 0.87 (95%CI 0.72-1.06; 2-sided Wald p=0.17). The HR for PFS was 0.77 (95%CI 0.63-0.93) in favor of GCB (p=0.0074). Grade 3 or greater adverse event rate was 83.5% with GCB compared to 80.7% with GCP. Conclusions: The addition of bevacizumab to GC chemotherapy did not result in improved OS (primary endpoint) in patients with mUC but there was a PFS improvement. The observed median OS of about 14 months is consistent with prior phase III trials of cisplatin-based chemotherapy. Support: U10CA180821, U10CA180882, U10CA180820, U10CA180853, U10CA180888, Genentech https://acknowledgments.alliancefound.org. Clinical trial information: NCT00942331.

Final analysis of a phase II study of MRI based functional imaging of bone metastases in men with metastatic castrate-resistant prostate cancer (mCRPC) receiving cabozantinib

213

Background: Cabozantinib (C) is a small molecule inhibitor of receptor tyrosine kinases including VEGFR-2, c-MET. C trials have shown significant improvements in bone pain and bone scintigraphy in mCRPC patients (pts). We hypothesized that functional imaging using MRI could elucidate underlying biological processes by demonstrating an early decrease in vascular permeability (decrease in transfer consant - Ktrans) and subsequent decrease in cell density (increase in apparent diffusion coefficient - ADC) within bone metastases. Methods: mCRPC pts received C 60 mg daily. The primary endpoint was change in Ktrans at 2 weeks (wks) of treatment. Secondary endpoints included Ktrans and ADC longitudinal changes, and correlation with bone scan, PSA, RECIST, and changes in reported pain. All pts underwent MRI at baseline, day 0, day 15 and every 12 wks. Results: 17 pts were treated at two sites. Median age: 68 yrs (range:51-83), baseline PSA 94.78 ng/mL (7.4-2971), number of prior CRPC therapies 2 (1-8). Median progression free survival was 5.1 months; 5 pts discontinued therapy for adverse events, and 12 for progressive disease. The most common grades 3/4 toxicities were fatigue (24%) and palmarplantar erythrodysesthesia (12%). 14 pts were evaluable for the primary endpoint. At 2 wks, Ktrans decreased an average 35%, 0.074 to 0.048 min-1 (SD=0.016, p<0.0001). There was no change in Ktrans between wk 2 and end of study. There was an increase in median ADC of 150 at wk 12. There were no RECIST or 50% PSA responses. Conclusions: Ktrans decreased significantly after 2 wks of treatment, consistent with antiangiogenic properties of C. Compared to wk 2, K trans at disease progression is unchanged, which could signify that adaptive vascular change is not the primary mechanism of tumor resistance to the drug. Contrary to our hypothesis, ADC increased during the trial, which perhaps correlates with the short median time to progression. Still, MRI of bone metastases could benefit drug development for other agents in mCRPC or interrogation of bone metastases, notoriously challenging for disease response analysis, in other cancers. Clinical trial information: NCT01599793.

IMmotion151: A Randomized Phase III Study of Atezolizumab Plus Bevacizumab vs Sunitinib in Untreated Metastatic Renal Cell Carcinoma (mRCC)

578

Background: Atezolizumab (atezo; anti–PD-L1) + bevacizumab (bev; anti-VEGF) showed first-line (1L) anti-tumor activity with a manageable safety profile in PD-L1+ mRCC pts in a Phase II study (McDermott ASCO-GU 2017). Here we describe the first randomized Phase III trial of a PD-L1/PD-1 pathway inhibitor combined with an anti-VEGF agent in 1L mRCC. Methods: IMmotion151 (NCT02420821) enrolled treatment-naïve pts regardless of prognostic risk group randomized 1:1 to receive atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w or sunitinib (sun) 50 mg PO QD 4 wk on/2 wk off. Pts were stratified by PD-L1 status (< 1% vs ≥ 1% PD-L1 expression on tumor-infiltrating immune cells [IC]; SP142 IHC assay). Coprimary endpoints: progression-free survival (PFS; by investigator per RECIST v1.1) in PD-L1+ pts (≥ 1% IC) and overall survival (OS) in intent-to-treat (ITT) pts. Secondary endpoints included PFS in ITT pts, ORR and DOR. Results: Baseline characteristics were comparable between arms within PD-L1+ (40% of ITT) and ITT pts. Median survival follow-up was 15 mo. PFS HR for atezo + bev vs sun was 0.74 (95% CI 0.57, 0.96) in PD-L1+ pts and 0.83 (95% CI 0.70, 0.97) in ITT pts. OS was immature at first interim analysis. PFS benefit was consistent across analyzed subgroups, including MSKCC risk, liver metastases and sarcomatoid histology. In PD-L1+ pts, ORR was 43% and DOR was not reached for atezo + bev vs 35% and 12.9 mo for sun. 40% of atezo + bev–treated pts and 54% of sun-treated pts had treatment-related Gr 3-4 AEs; 12% and 8% of treatment-related all-Gr AEs led to discontinuation, respectively. Conclusions: The study showed longer PFS for atezo + bev vs sun in PD-L1+ pts. Improved PFS was also observed in ITT pts. Safety was consistent with that of the individual agents. These results support the use of atezo + bev as a 1L treatment option in mRCC. Clinical trial information: NCT02420821. [Table: see text]

IMmotion150: A phase II trial in untreated metastatic renal cell carcinoma (mRCC) patients (pts) of atezolizumab (atezo) and bevacizumab (bev) vs and following atezo or sunitinib (sun)

4505

Background: While inhibiting VEGF improves outcomes in mRCC pts, most develop resistance, often within a year. Here, we report results from a Ph II study of atezo (anti–PD-L1) and bev (anti-VEGF) vs and following atezo or sun (TKI) in mRCC pts. Methods: Pts with untreated mRCC were enrolled in the hypothesis generating IMmotion150 study (NCT01984242) and randomized to atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w, atezo alone or sun 50 mg PO QD 4 wk on/2 wk off. After progression on atezo or sun, crossover to atezo + bev was allowed. PD-L1 status was scored on tumor-infiltrating immune cells (IC, SP142 IHC assay). The primary analysis was modified prior to final analysis to reflect the coprimary endpoints of IRF-assessed PFS (RECIST v1.1) in ITT pts and pts with PD-L1 expression on ≥ 1% of IC (PD-L1+). Results: 54% of pts were PD-L1+. In PD-L1+ pts 1L treatment resulted in a PFS hazard ratio (HR) of 0.64 for atezo + bev vs sun (table). After 1L treatment, 78% of sun and 60% of atezo pts who progressed subsequently received atezo + bev and achieved ORRs of 28% and 24%, respectively (table). Safety was comparable to the known individual profiles of atezo and bev. Additional clinical, safety and biomarker data will be presented. Conclusions: Atezo + bev resulted in encouraging antitumor activity in 1L pts with PD-L1+ mRCC. Preliminary activity in the 2L setting was demonstrated in pts who crossed over to atezo + bev, regardless of prior therapy. 1L atezo + bev vs sun is being evaluated in the ongoing Ph III study IMmotion151 (NCT02420821). Clinical trial information: NCT01984242. [Table: see text]

Abiraterone + prednisone (Abi) +/- veliparib (Vel) for patients (pts) with metastatic castration-resistant prostate cancer (CRPC): NCI 9012 updated clinical and genomics data

5001

Background: In preclinical CRPC models, PARP1 inhibition synergizes with AR targeted therapy, especially in ETS fusion-positive tumors. We hypothesized: 1. Co-targeting PARP-1 + AR is superior to AR inhibition and 2. ETS +ve predicts response. Methods: Pts had metastatic (mets) disease biopsy (bx), stratified by IHC-ETS status and randomized to Abi (Arm A) or Abi + Vel (Arm B). Primary endpoint: PSA response rate (RR > = 50% decline). Secondary endpoints: safety, objective RR (ORR), progression free survival (PFS), and molecular analysis including if DNA repair gene deficiency (DRD: BRCA 1, BRCA 2, ATM, FANCA, PALB2, RAD51B, RAD51C) predicts response. 148 pts stratified by IHC-ETS status were randomized to detect a 20% PSA RR improvement assuming a 5% 1-sided type I error and 80% power. An elastic net multivariable Cox model was used to analyze PFS. Mets bx underwent targeted exon sequencing and capture transcriptome analysis. Results: 72 pts were randomly assigned to Arm A and 76 to Arm B. PSA RR: Arm A 63.9%, Arm B 72.4% (p = 0.27). ORR: Arm A 45%, Arm B 52.2%, p = 0.51. Median PFS: Arm A 10.1 months (m), Arm B 11.3 m, p = 0.95. More Arm-B pts were on therapy for 12+ (45% vs 38%) and 18+ cycles (22% vs 17%). ETS status had no impact. Mets tissue sequencing (N = 80): 42 pts (53%) were ETS +ve, 19 (25%) had DRD, 47 (59%) had AR amplification/copy gain, 32 (40%) had PTEN mutation (mut), 33 (41%) had TP53 mut, 37 (46%) had PIK3CA activation (a) and 12 (15%) had WNT-a. Irrespective of arm pts with DRD had a higher PSA and ORR ( > = 87%) vs wild type (58%, 39%; p = 0.013, p = 0.002, respectively), higher PSA decline rate of > = 90% (74% vs 26%, p = 0.0004) and longer median PFS (95% CI): DRD 16.6 m (11 - NR) vs wild type: 8 m (5.4 – 13.3); p = 0.02. PFS was longer in pts with normal PTEN (13.5 vs 6.2 m, p = 0.02), TP53 (13.3 vs 7.8 m, p = 0.04) and PIK3CA (10.3 vs 8.3 m, p = 0.03). Controlling for clinical factors, DRD, PTEN, TP53 and PIK3CA are associated with PFS in this order of importance. Conclusions: There was a modest trend in favor of Abi + Vel but no difference by ETS. Pts with DRD, normal PTEN,TP53 and PIK3CA had better PFS raising new hypotheses regarding the importance of integrating molecular analysis in therapeutic trials. Clinical trial information: NCT01576172.

Patient Perceptions of Care as Influenced by a Large Institutional Pharmacogenomic Implementation Program

Despite growing clinical use of genomic information, patient perceptions of genomic-based care are poorly understood. We prospectively studied patient-physician pairs who participated in an institutional pharmacogenomic implementation program. Trust/privacy/empathy/medical decision-making (MDM)/personalized care dimensions were assessed through patient surveys after clinic visits at which physicians had access to preemptive pharmacogenomic results (Likert scale, 1 = minimum/5 = maximum; mean [SD]). From 2012-2015, 1,261 surveys were issued to 507 patients, with 792 (62.8%) returned. Privacy, empathy, MDM, and personalized care scores were significantly higher after visits when physicians considered pharmacogenomic results. Importantly, personalized care scores were significantly higher after physicians used pharmacogenomic information to guide medication changes (4.0 [1.4] vs. 3.0 [1.6]; P < 0.001) compared with prescribing visits without genomic guidance. Multivariable modeling controlling for clinical factors confirmed personalized care scores were more favorable after visits with genomic-influenced prescribing (odds ratio [OR] = 3.26; 95% confidence interval [CI] = (1.31-8.14); P < 0.05). Physicians seem to individualize care when utilizing pharmacogenomic results and this decision-making augmentation is perceived positively by patients.

Genetic polymorphisms to predict progression-free survival in patients with metastatic castration-resistant prostate cancer (mCRPC) receiving abiraterone therapy: Results from the NCI 9012 trial

145

Background: Abiraterone is a CYP17 inhibitor approved for treatment of men with mCRPC. The NCI 9012 trial evaluated abiraterone alone with or without the PARP inhibitor veliparib in mCRPC patients. We hypothesized that germline genetic variation in the androgen axis and other metabolic enzymes would predict response to veliparib + abiraterone vs. abiraterone alone. Methods: A randomized trial cohort of (148) men with advanced mCRPC treated with abiraterone with or without veliparib was genotyped for 120 DNA polymorphisms in genes involved in androgen metabolism using Lifetech Open array chips. Blood for pharmacogenomic SNP analysis were collected at pre-treatment from each subject into 10-mL EDTA tube. Polymorphisms were tested using Cox models without treatment for prognostic testing and with treatment arm for predictive testing. Results: Genotyping was completed in 143 of 148 men; all were treated with abiraterone; 72 without veliparib (Median PFS: 10.3m) and 71 with veliparib (Median PFS: 11.3m). Polymorphisms in separate genes (SLCO2B1, KIF3C CYP19A, ESR1) were significantly (P ≤ .025) associated with progression-free survival (PFS) during abiraterone (q-value < 0.69). Polymorphisms in (CYP11A1, HSD17B4, ABHD13;LIG4, CYP19A1, HSD17B4, TRMT11) were predictive for PFS in patients treated with combination of abiraterone/veliparib compared to abiraterone alone (p-value < 0.025; q-value < 0.28). Conclusions: This analysis examines the influence of inherited variations on the efficacy of abiraterone, establishing the importance of pharmacogenomics on individual’s response to this therapy. Genotyping patients at these loci could be predictive of improved PFS to valiparib in combination with abiraterone. Further analysis of the association of more than one polymorphisms compared to zero or one with PFS associated with improved TTP demonstrated a better response to therapy than individuals carrying zero or one is ongoing. Clinical trial information: NCT01576172.

Analysis of overall survival (OS) based on tumor target lesion change in the phase 3 METEOR trial of cabozantinib (cabo) versus everolimus (eve) in advanced renal cell carcinoma (RCC)

522

Background: In the METEOR study (NCT01865747), cabo demonstrated improved progression-free survival (median 7.4 vs. 3.8 mo; HR 0.58, 95% CI 0.45–0.74; p<0.0001), OS (median 21.4 vs. 16.5 mo; HR 0.66, 95% CI 0.53-0.83, p=0.0003), and objective response rate (17% vs. 3%; p<0.0001) compared with eve in patients (pts) with advanced RCC who had received prior VEGFR TKI therapy (Choueiri NEJM 2015, Lancet Oncol 2016). Here we evaluate the impact of changes in target lesion size from baseline on OS. Methods: 658 pts were randomized 1:1 to receive cabo (60 mg qd) or eve (10 mg qd). Stratification factors were MSKCC risk group and number of prior VEGFR TKIs. Target lesion size was assessed per independent radiology review by CT/MRI scans at baseline, every 8 weeks for the first 12 months, and every 12 weeks thereafter. Three subgroups were defined by best change in target lesion size from baseline: decrease ≥30%, decrease <30%, and any increase. Results: The rate of target lesion regression was higher in the cabo arm (75%) compared with the eve arm (48%). A higher fraction of pts had a decrease ≥30% in target lesion size in the cabo arm, while a higher fraction of pts had an increase in target lesion size in the eve arm (Table). Medians for OS with cabo were not estimable (NE) (95% CI, NE‒NE), 20.8 mo (95% CI, 18.1‒NE), and 11.1 mo (95% CI, 7.6‒15.2) for the ≥30% decrease, <30% decrease, and any increase subgroups, respectively. Medians for OS with eve were NE (95% CI, 19.3‒NE), 18.0 mo (95% CI, 15.9‒20.4), and 14.0 mo (95% CI, 10.5‒16.3) for the ≥30% decrease, <30% decrease, and any increase subgroups, respectively. Median duration of follow-up for OS was 18.7 mo (IQR 16.1–21.1) for cabo and 18.8 mo (16.0–21.2) for eve. A higher proportion of pts received subsequent anticancer therapy in the any increase subgroup compared with the other subgroups. Conclusions: Cabo demonstrated a higher rate of tumor target lesion regression than eve, and greater target lesion regression was associated with improved OS in pts with advanced RCC. Clinical trial information: NCT01865747. [Table: see text]

A prospective international randomized phase II study evaluating the food effect on the pharmacokinetics (PK) and pharmacodynamics (PD) of abiraterone acetate (AA) in men with castration-resistant prostate cancer (CRPC)

176

Background: AA is a standard of care for the treatment of metastatic CRPC, with an approximate retail cost of $8000/month. Despite a large food effect (~17-fold increase in CMax with a high-fat meal), AA was administered under fasting conditions in its pivotal trials. There are no randomized continuous dosing studies examining prandial state dosing on AA PK/PD. We sought to test the hypothesis that LOW (250mg w/food) would have similar PK/PD and safety to standard (STD, 1000mg fasting) in patients with progressive CRPC. Methods: Patients (n = 72) with progressive CRPC from seven institutions in the US and Singapore were randomized to treatment with STD or LOW (with low-fat breakfast). Both arms received prednisone 5mg twice daily. PSA was assessed monthly, and testosterone, DHEA/DHEAS were assessed every 12 weeks along with standard disease burden assessments. PK samples were collected at day 1, 8 and months 2, 3, 4. Log change in PSA response rate from baseline to week 12 was examined as the primary endpoint, with a non-inferiority design based on a non-inferiority margin of 15%. This margin corresponds to a 0.51 standard deviation (SD) difference in the mean log changes between the groups. Results: Accrual was completed with n = 36 on STD and n = 36 on LOW. Median (range) age was 74 (52-89) and baseline PSA was 39.2(range 0.6-1789). Mean log-change in PSA at 12 weeks was nominally greater in the LOW arm (-1.59 vs. -1.19). The 95% confidence for the difference (STD-LOW) ranged from -0.40 to 1.19, with lower limit corresponding to -0.24SD. Thus, non-inferiority of LOW was established. Median time to PSA progression was ~14 month in both arms (p = 0.53). Preliminary analysis of PK showed no difference in CMaxbeyond the first cycle with lower PK variability in the LOW arm. Conclusions: Low-dose (250mg/day) abiraterone acetate with a low-fat breakfast is non-inferior to standard dosing in a fasted state with respect to PSA and PK metrics. Although PSA response and progression are not clinically validated surrogates, given the pharmacoeconomic implications, these data warrant consideration by prescribers and payors. Clinical trial information: NCT01543776.

A phase II study of atezolizumab (atezo) with or without bevacizumab (bev) versus sunitinib (sun) in untreated metastatic renal cell carcinoma (mRCC) patients (pts)

431

Background: While targeting VEGF improves outcomes for mRCC pts, resistance invariably develops, often within the first year. Here, we describe the efficacy and safety of atezo (anti-PD-L1) with bev (anti-VEGF) and atezo monotherapy vs sun (TKI) in first-line mRCC. Methods: Treatment-naïve mRCC pts were enrolled in a hypothesis generating Ph II study (IMmotion150; NCT01984242) and randomized to atezo 1200 mg IV q3w + bev 15 mg/kg IV q3w, atezo alone or sun 50 mg PO QD 4 wk on/2 wk off. Crossover to atezo + bev after disease progression was allowed for pts receiving atezo or sun. PD-L1 expression was scored on tumor-infiltrating immune cells (IC, SP142 IHC assay). Coprimary endpoints were PFS (RECIST v1.1 by independent review [IRF]) in ITT pts and pts with PD-L1 expression on ≥ 1% of IC (PD-L1+). Results: Baseline characteristics were comparable across arms and between ITT and PD-L1+ pts. The majority of sun and atezo pts subsequently received atezo + bev. Median survival follow up was 20.7 mo. The PFS HR in ITT pts for atezo + bev vs sun was 1.00 and 1.19 for atezo vs sun. In PD-L1+ pts, the PFS HR for atezo + bev vs sun was 0.64 and 1.03 for atezo vs sun (table). Tx-related Gr 3-4 AEs were seen in 40%, 16% and 57% of pts in the atezo + bev, atezo and sun arms, respectively. AEs leading to death occurred in 3%, 2% and 2% of pts, respectively. Conclusion: Atezo + bev resulted in encouraging antitumor activity in the PD-L1+ subgroup of first-line RCC pts. Atezo + bev safety is consistent with the known profile of atezo and bev individually. The clinical benefit of atezo + bev vs sun will be evaluated in the ongoing Ph III study IMmotion151 (NCT02420821). Clinical trial information: NCT01984242. [Table: see text]

Afatinib activity in platinum-refractory metastatic urothelial carcinoma (UC) patients with ErbB alterations: Results of a phase II trial

459

Background: Metastatic UC has a dismal prognosis, with no FDA-approved second-line therapies. Somatic mutations and copy number (CN) variation in EGFR (ErbB1), HER2 (ErbB2), and ErbB3 are frequent in UC and may represent viable therapeutic targets. We studied whether afatinib, an oral, irreversible Erb family blocker, has activity in UC. Methods: In this single arm, phase II trial, patients (pts) with unresectable platinum-refractory UC received afatinib 40 mg/day continuously until progression or intolerance.The primary endpoint was 3-mo progression-free survival (PFS3) using a Simon two-stage design, with the trial proceeding to stage II if ≥ 30% pts in stage I had PFS3. Pre-specified analysis for EGFR, HER2, ErbB3, and ErbB4 was conducted using targeted next-generation sequencing (Life Technologies) and CN analysis (Taqman) of available archival tumor tissue. Results: The initial enrollment goal of 23 ptswas met: 18 M/5 F, median age 67 (36-82), ECOG 0 in 26%/1 in 74%, Hb < 10 g/dl in 17%, liver metastases in 30%, median time from prior chemotherapy = 3.6 mo. No unexpected toxicities were observed; 2 pts required dose-reduction (grade 3 fatigue, grade 3 rash). 5/23 pts (21.7%) had PFS3 (1 partial response (PR), 4 stable disease). Notably, 5/7 pts (71.4%) with ErbB molecular alterations achieved PFS3 (PFS = 10.3, 7.0, 6.9, 4.6 (ongoing) and 3.9 (ongoing) mo respectively) while 0/16 without alterations reached PFS3 (p < 0.001, Fisher’s exact). The 2 pts with alterations (both HER2 amplified) who did not reach PFS3 had liver metastases. All 3 pts with ErbB3 somatic mutations were responders. One pt with both HER2 amplification and R103G ErbB3 mutation never progressed on therapy, but discontinued after 10.3 mo due to depressed left ventricular ejection fraction. Average time to progression/discontinuation was 4.9 mo in pts with molecular alterations vs 1.7 mo for pts without alterations (p = 0.03). Conclusions: Afatinib demonstrates significant activity in platinum-refractory UC pts with HER2 and/or ErbB3 alterations. The potential contribution of ErbB3 to afatinib sensitivity is novel. A follow-on phase II study of afatinib in marker-selected refractory UC pts is underway. Clinical trial information: NCT02122172.

Physician treatment selection in the prospective Metastatic Renal Cell Cancer (MaRCC) Registry

563

Background: Clinical trials mRCC pts are different from real world pts, resulting in bias in the literature. The MaRCC Registry is designed to survey questions not asked in tri als, such as why physicians make certain management decisions. This analysis describes reasons for physician treatment (tx) selection in the first 109 real world pts enrolled in a multicenter, prospective, observational registry. Methods: MaRCC Registry will enroll 500 pts from up to 60 US academic (ACAD) and community (COMM) sites with ~2 years of recruitment and ≥ 3 years of follow-up. Key inclusion criteria are age ≥ 18 years and diagnosis of mRCC with no prior systemic therapy (STx) for mRCC at study entry. Pts currently not on STx but who are being observed are permitted. Key endpoints include descriptive characteristics of txs, tx and patient outcomes, medication adherence, and health resource utilization. Results: At data cutoff, 105 pts have been accrued with known STx status; median age 64 (Q1-3 range, 56-70); 66% male; 75% ACAD; 87% clear cell histology; and 31% stage IV at diagnosis. Initial management decision was: 40% deferred systemic therapy (DSTx), 22% pazopanib, 18% clinical trial, 10% sunitinib, and 6% other. Among STx pts (N = 61), the most common categories for therapy choice as selected by providers were likelihood of clinical benefit (41%) followed by pt characteristics (30%). Within the clinical benefit category, the most common reason was OS/PFS (31%). Within the pt characteristic category the most common reasons included performance status/frailty (12%) or prognostic factors (12%). Common reasons for DSTx pts (N = 44) were active surveillance (AS) with disease present (39%), AS without disease present following a procedure (11%), or local therapy (7%). ACAD sites had higher percentages of pts with DSTx undergoing AS with disease present and local therapy. Conclusions: This is the first report describing factors driving physician decision making in management of mRCC. Management choices are not captured in other prospective or retrospective studies. Early experience suggests that clinical benefit and pt characteristics were common reasons for initial STx. Side effect profile rarely determined initial STx selection.

Exploring multidisciplinary practice patterns in the management of muscle invasive bladder cancer (MIBC) across the U.S. and Canada in 2015

368

Background: Effective treatment of MIBC requires a multidisciplinary (multiD) approach including surgical, radiation, and chemotherapeutic modalities, which are further supported by pathology, radiology, nursing, social work, nutrition, pharmacy, and psychologic expertise. As surgical and bladder preservation approaches have not been directly compared, practice patterns are heterogeneous. Our primary objective was to catalogue the different styles of multiD approaches or lack thereof in the management of MIBC. Secondary objectives were to assess physician interest, capture examples of successful approaches, and describe barriers to implementation. Methods: We conducted an international online survey regarding the type of multiD approach and available resources used by clinicians managing MIBC. We collaborated with the Bladder Cancer Advocacy Network and the Genitourinary Medical Oncologists of Canada to reach a wide variety of academic and community practices. Results: Of the 101 clinicians surveyed, most practiced at NCI designated comprehensive cancer centers (46%) or Canadian academic institutions (29%). The median number of cases per month was 5 (0-40).Of the different multiD styles, sequential (separate) visits on different days was the most common (60%) followed by sequential same day (41%), concurrent (one visit with all providers, 23%), and none (5%). However, most preferred a sequential same day (44%) or concurrent (28%) approach. Although most academic practices had some form of multiD approach, reported barriers for implementing the preferred strategy were lack of clinic space (63%), funding (46%), staff (46%), and time (34%). The majority felt a multiD approach enriched their practice. Conclusions: Most surveyed practitioners at academic centers integrate a multiD strategy in the management of MIBC. The major barriers are not attitudinal but rather insufficient resources and time. Thus, most physicians employ a sequential rather than a concurrent approach. Future goals include developing strategies to overcome these obstacles and integrating these results with patient preferences to optimize the management of MIBC patients.

Angiogenic markers during bevacizumab-based treatment in metastatic renal cell carcinoma (RCC)

522

Background: Targeting the vascular endothelial growth factor (VEGF) pathway delays progression in mRCC, however innate and acquired resistance limit success. CD105 (endoglin) is a TGFb family receptor which is upregulated after VEGF inhibition, possibly mediating resistance. We studied serum CD105 and TGFb at baseline and after treatment, and tissue levels of TGFbR1 & 2 plus AVCRL, to discover biomarkers for treatment response as part of a randomized trial of bevacizumab (Bev) +/- the anti-endoglin antibody TRC105. Clinical data from the trial were presented at ASCO 2015 (Dorff et al, abstr 4542). Methods: Serum was collected at baseline and before cycles 2&4. ELISA was performed using kits from Abcam. Changes from baseline were evaluated and compared overall and between arms using a general linear mixed effects model. Immunohistochemistry was performed on paraffin embedded tissue samples using antibodies from R&D systems; tissue and baseline ELISA data were evaluated for association with PFS using Kaplan-Meier analysis and the logrank test. Results: 54 subjects (24 on Bev and 28 on Bev+TRC105) had at least one analyzed serum sample; 14 and 19 respectively had both baseline and cycle 2 samples. Mean CD105 was 82.8 (95%CI 64.6, 106.2) at baseline and 59.0 (95%CI 43.2, 80.7) at cycle 2; for 16 patients with cycle 4 data the mean was 39.8, significantly lower than baseline (p = 0.024), but not different between treatment arms. Cycle 2 TGFb levels were not different from baseline (p = 0.66) or between arms (p = 0.17). Baseline serum TGFb below the median ( < 10.6) was associated with higher likelihood of PFS at 12 and 24 weeks; (0.78 vs 0.3 and 0.49 vs 0.19, respectively, p = 0.022); baseline CD105 was not (p = 0.83). Tissue was available for 29 subjects. No tissue markers (TGFbR1 &2 or AVCRL) were associated with longer PFS except, in exploratory analysis, higher TGFbR2 staining in patients treated with TRC105 (p = 0.017). Conclusions: No pharmacodynamics markers for TRC105 therapy were identified. Lower baseline serum TGFb levels may be prognostic of PFS during Bev therapy, supporting the notion that this pathway contributes to resistance. Better PFS in TRC105-treated patients with higher tissue TGFbR2 expression warrants further study. Clinical trial information: NCT01727089.

Front-line management patterns in the prospective metastatic renal cell cancer (MaRCC) registry

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Background: Over the past decade, seven agents were approved for metastatic renal cell carcinoma (mRCC) leading to a rapidly evolving clinical landscape. Clinical trials addressing treatment efficacy, sequencing, and other questions may continue to impact management decisions. Furthermore, our prior retrospective experience indicates a significant proportion of pts may not receive systemic therapy in the first year after diagnosis with metastatic disease. This analysis describes contemporary patterns of care in the first 109 real world pts enrolled in a multicenter, prospective, observational registry. Methods: MaRCC Registry will enroll 500 pts from up to 60 US academic (ACAD) and community (COMM) sites with ~2 years of recruitment and ≥ 3 years of follow-up. Key inclusion criteria are age ≥ 18 years and diagnosis of mRCC with no prior systemic therapy (STx) for mRCC at study entry. Pts currently not on STx but who are being observed are permitted. Key endpoints include descriptive characteristics of treatments (e.g. treatment agents, sequence, duration, reasons for therapy choice and discontinuation), treatment effectiveness (e.g. overall response rate, progression free survival, overall survival), quality of life (PROs), medication adherence, and health resource utilization. Results: At data cutoff, 105 pts have been accrued with known STx status; median age 64 (Q1-3 range, 56-70); 66% male; 75% ACAD; 87% clear cell histology; and 31% stage IV at diagnosis. Initial management strategies are shown in the table. The initial management decision after accrual was to defer systemic therapy (Def STx) in 40% (N=44). In ACAD and COMM sites, Def STx percentages were 38% and 48% respectively. Baseline demographics and clinical characteristics were not notably different between Def STx pts and those treated with STx. Conclusions: In our prospective registry, we have identified a large percentage of pts who initially received Def STx. In the context of contemporary pts undergoing investigational and standard of care STx, we will describe the management and outcomes of the Def STx population. [Table: see text]