ETCTN 10476: A randomized phase 2 study of combination atezolizumab and varlilumab (CDX-1127) with or without addition of cobimetinib in previously treated unresectable biliary tract cancer

TPS639

Background: The combination of the MEK inhibitor, Cobimetinib, with the PD-L1 antagonist, Atezolizumab, significantly improved progression-free survival (PFS) compared to Atezolizumab monotherapy in patients with advanced biliary tract cancer (BTC) following first-line chemotherapy (NCT03201458). Interrogation of biospecimens from this trial and parallel pre-clinical work showed that the addition of MEK inhibition enhanced tumor immunogenicity but simultaneously had detrimental effects on host T-cell activation and priming. The addition of immune co-stimulants rescues T-cell function in the setting of systemic MEK inhibition in vivo. Unlike other immune co-stimulatory markers, CD27 is one of the most positively differentially expressed receptors in the TME post-treatment with combined MEK inhibition and PD-L1 blockade. We hypothesize that addition of CD27 immune agonism to the combination of PD-L1 and MEK inhibition can improve immunotherapy outcomes in patients with BTC. Methods: We are conducting an open-label, randomized ph 2 trial evaluating a PD-L1 inhibitor (atezolizumab) in combination with a CD27 immune agonist (CDX-1127 [Varlilumab]) with or without addition of a MEK inhibitor (Cobimetinib) in patients with unresectable, previously treated, BTC. Key inclusion criteria include: adults with pathologically-confirmed BTC, s/p 1-2 lines of systemic therapy (including any FDA-approved targeted therapies) in the metastatic setting, measurable disease, ECOG performance status ≤1, adequate baseline organ and marrow function. Patients who have received gem-cis-durvalumab, and/or prior FGFR2/IDH1 targeted therapy are eligible for enrollment. The study is planned for 64 evaluable subjects (32 subjects per treatment arm) randomized in a 1:1 ratio, stratified by site of BTC location, to either Atezolizumab + CDX-1127 or Atezolizumab + CDX-1127 + Cobimetinib. During the 28-day treatment cycles, all patients receive Atezolizumab (840mg flat dose) and CDX-1127 (3mg/kg) infusions on D1 and D15. For those randomized to the triplet regimen arm, the additional Cobimetinib will be dosed orally at 60mg daily on days 1-21. Overall response rate and PFS are co-primary endpoints. A clinically meaningful improvement in ORR warranting further study is 20%. The primary correlative outcome is treatment-related changes in CD8+ infiltrating T cells. After an initial safety lead-in, a planned interim efficacy analysis will take place following enrollment of the first 18 patients in each treatment arm. Currently, 14 participants (n=6 [triplet arm], n=8 [doublet arm]), have been enrolled & treated on protocol. This study is sponsored by the NCI Cancer Therapy Evaluation Program and is open nationally at designated NCI Experimental Therapeutics Clinical Trials Network sites. Clinical trial information: NCT04941287 .

Using light scattering to assess how phospholipid-protein interactions affect complex I functionality in liposomes

Complex I is an essential membrane protein in respiration, oxidising NADH and reducing ubiquinone to contribute to the proton-motive force that powers ATP synthesis. Liposomes provide an attractive platform to...

Phase II study of vismodegib in patients with SMO or PTCH1 mutated tumors: Results from NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol T

3010

Background: NCI-MATCH (EAY131) is a platform trial enrolling patients (pts) with solid tumors, lymphomas, or multiple myeloma to targeted therapies based on matching genomic alterations (NCT02465060). Subprotocol Arm T evaluated vismodegib (GDC0449), a hedgehog signaling pathway inhibitor with anti-tumor activity in pts with tumors harboring PTCH1 and SMO mutations. Methods: Pts whose tumors had SMO or PTCH1 mutations were eligible; results were confirmed by NCI-MATCH central labs if possible. Pts received oral vismodegib (150 mg daily) for 4-week cycles until progression/toxicity. Tumor response was assessed every 2 cycles. Primary endpoint was ORR; secondary endpoints included PFS, 6-month PFS, OS, and predictive biomarkers. Cutaneous basal cell carcinomas were excluded. Results: Of 34 pts enrolled (6/20/16 – 9/22/20); 2 were ineligible and 1 did not start therapy. The 31 analyzable pts’ demographics were primary tumor sites/histology [gastrointestinal (n = 9), skin/soft tissue (n = 7), gynecologic (n = 5), lung (n = 4), unknown primary (n = 4), ductal breast (n = 1), meningioma (n = 1)]; median age 64 (range 19-81); 48.4% women; 61.3% (19/31) > 3 lines of prior therapy; 74% (23/31) > 1 co-occurring mutation [median 2 co-alterations (range 1-20)]. 8/31 > 4 co-occurring alterations. 9 pts had SMO mutant tumors (all SNVs); 5/9 had > 1 co-occurring gene alterations. 22 pts had PTCH1 alterations (7 SNVs and 15 indels); 18/22 pts had > 1 additional gene alteration. Of 31 analyzable pts, 22 were MATCH-confirmed (i.e. had central confirmation of tumor PTCH1/SMO mutations). MATCH-confirmed pts had ORR 9.1% (2/22) while all analyzable pts had ORR 6.5% (2/31). 2 PRs were seen in pts with a skin/soft tissue sarcoma ( PTCH) and a meningioma ( SMO) with a median duration of response 14 months. The 6-month PFS rate was similar in MATCH-confirmed and analyzable pts (22.4% and 23.2% respectively) and median PFS was identical at 1.8 months. Median OS was 9.1 months in MATCH-confirmed and 7.3 months in analyzable pts. Within analyzable SMO variants: 1 PR, 3 SD, 4 PD, and 1 unevaluable responses were documented. Within analyzable PTCH1 variants: 1 PR, 7 SD, 10 PD, and 4 unevaluable responses were seen. 4 pts (12.9%) discontinued therapy due to AE. Among 33 pts starting therapy, 18 (54.5%) had grade 1-2 toxicity, while 2 (6.1%) had grade 3 treatment-related toxicity. Most common toxicities: grade 1-2 fatigue (n = 11), anorexia (n = 8), weight loss (n = 7), alopecia (n = 7), and dysgeusia (n = 6). There were 4 on-study deaths, but none were treatment related. Conclusions: Although the primary endpoint was not reached, vismodegib was well-tolerated with mostly grade 1-2 toxicities and substantial responses were seen in patients with SMOPro641Ala and PTCHGlu947Ter alterations. Further study of the impact of concomitant molecular alterations may yield additional insights into vismodegib mechanisms of response. Clinical trial information: NCT02465060.

The growth of cognition: Free energy minimization and the embryogenesis of cortical computation

The assumption that during cortical embryogenesis neurons and synaptic connections are selected to form an ensemble maximising synchronous oscillation explains mesoscopic cortical development, and a mechanism for cortical information processing is implied by consistency with the Free Energy Principle and Dynamic Logic. A heteroclinic network emerges, with stable and unstable fixed points of oscillation corresponding to activity in symmetrically connected, versus asymmetrically connected, sets of neurons. Simulations of growth explain a wide range of anatomical observations for columnar and non-columnar cortex, superficial patch connections, and the organization and dynamic interactions of neurone response properties. An antenatal scaffold is created, upon which postnatal learning can establish continuously ordered neuronal representations, permitting matching of co-synchronous fields in multiple cortical areas to solve optimization problems as in Dynamic Logic. Fast synaptic competition partitions equilibria, minimizing "the curse of dimensionality", while perturbations between imperfectly partitioned synchronous fields, under internal reinforcement, enable the cortex to become adaptively self-directed. As learning progresses variational free energy is minimized and entropy bounded.

A randomized phase II study of cabozantinib and nivolumab versus nivolumab in recurrent endometrial cancer

6010

Background: The efficacy of treatment for recurrent endometrial cancer (EC) remains limited. Vascular endothelial growth factor and inflammatory chemokines are proangiogenic factors and immune modulators involved in immune suppression. Reprogramming the tumor microenvironment by combining antiangiogenic and immunotherapy (IO) could enhance antitumor responses. Methods: A 2:1 randomized phase 2 trial compared the combination of cabozantinib and nivolumab (Arm A) versus nivolumab (Arm B) in recurrent EC. Primary endpoint was progression free survival (PFS) assessed by RECIST 1.1 (NCT03367741). Women with recurrent measurable EC were eligible. There were no limits on prior therapy, but at least one prior platinum-based chemotherapy was required. Patients (pts) were stratified according to MSI status and assessed by CT every 8 weeks. Cabozantinib was given at 40 mg daily (Arm A) and nivolumab at 240 mg, on D1 and D15 of a 28-day cycle for 4 cycles, followed by 480 mg every 4 weeks (Arms A & B). Pts with carcinosarcoma or prior IO were enrolled in an exploratory cohort and received combination treatment (Arm C). A baseline biopsy was required for all pts. CyTOF analysis was performed on fresh biopsies. Results: 76 evaluable pts were enrolled (Arm A: 36, Arm B: 18, Arm C: 9 carcinosarcoma, and 20 post IO including 7 pts crossed over from Arm B). 55% of pts had received ≥3 prior lines of therapy. Two pts were MSI high in Arm A and none in Arm B. The Kaplan-Meier estimated median PFS was 5.3 (95% CI: 3.5-9.5) months in Arm A and 1.9 (95% CI: 1.6-3.8) months in Arm B, with a log-rank p = 0.07, which met the significance level of 0.1 used for sample size calculation. Objective response rate (ORR) was 25% for Arm A and 16.7% for Arm B; stable disease (SD) was seen in 44.4% vs 11.1%, respectively. Clinical benefit (ORR+SD) was significantly higher in arm A vs B (p < 0.001). In Arm C-carcinosarcoma, one patient had a partial response (11.9 months duration) and four SD. In Arm C-prior IO, six pts responded and eight had SD. The most common related AEs in Arm A were diarrhea (47.2%), elevated liver enzymes (44.4%), fatigue (38.9%), anorexia, hypertension, and nausea (30.6%), mainly grade 1/2. Preliminary CyTOF analysis across treatment arms identified multiple immune subsets for further interrogation including activated CD8+ and CD4+ T cells. Conclusions: Cabozantinib plus nivolumab demonstrates improved PFS compared to nivolumab in heavily pre-treated women with recurrent EC. In-depth CyTOF analysis of the tumor microenvironment to identify predictive immune biomarkers of response is ongoing. Clinical trial information: NCT03367741.

Phase II study of copanlisib in patients with tumors with PIK3CA mutations (PTEN loss allowed): NCI MATCH EAY131-Z1F

3506

Background: The NCI-MATCH (EAY131) is a platform trial that enrolls patients (pts) with solid tumors, lymphomas, or multiple myeloma to targeted therapies based on matching genomic alterations of interest (NCT02465060). Arm Z1F evaluated copanlisib, a highly selective, pan-Class 1 PI3K inhibitor with predominant activity against both the δ and α isoforms in pts with PIK3CA mutations. Methods: Pts received copanlisib (60 mg IV) on days 1, 8, and 15 in 28-day cycles until progression/toxicity. Tumor assessment was every 2 cycles. The primary endpoint was objective response rate (ORR); secondary endpoints were PFS, 6-month PFS, and predictive biomarkers. Pts with KRAS mutations, HER2+ve breast cancers, lymphomas were excluded. Results: 35 pts were enrolled (from 8/2/18 to 12/27/18), of which, 28 pts were available for analysis (7 patients, not eligible or did not start therapy). Multiple histologies were enrolled with gynecologic (n = 7), gastrointestinal (n = 6), and genitourinary (n = 5) the most common tumors. Median age 61 (range 42-78). 75% of pts had ≥ 3 lines of prior therapy. 54% of PIK3CA mutations were located in the helical domain, 32% in kinase domain and 14% in other domains. Twenty-six pts had co-occurring gene alterations (median 3; range 1-9), with 9 patients having 4 or more gene alterations. The ORR was 11% (3/28, 90% CI: 3%-25%). Partial responses were seen in uterine cancer, clear cell carcinoma of anterior abdominal wall, and liposarcoma. 6 pts had > 6 months of stable disease and clinical benefit rate was 32% (9/28). Two pts are still on treatment. The most common reason for protocol discontinuation was disease progression (n = 18, 69%). Thirty pts were included for toxicity analysis. Ten pts (33%) had grade 1 or 2 toxicities, 16 pts (53%) had grade 3 toxicities, and one patient (3%) had grade 4 toxicity (CTCAE v5.0). Most common toxicities include hyperglycemia (n = 19), fatigue (n = 11), hypertension (n = 10), diarrhea (n = 10), and nausea (n = 9). Total of 5 deaths were reported, none related to treatment. Conclusions: Copanlisib showed meaningful clinical activity across various tumors with PIK3CA mutation in the late-line refractory setting. Further study either alone or in combinations in select tumors is warranted. G3/4 toxicities observed were consistent with reported toxicities for PI3K pathway inhibition. Clinical trial information: NCT02465060 .

A new diminutive genus and species of catfish from Lake Tanganyika (Siluriformes: Clariidae)

The examination of material representing one of Lake Tanganyika's six previously recognized endemic catfish lineages, has revealed the presence of an additional genus of clariid, described here as Pseudotanganikallabes new genus. This genus is represented by a single species, Pseudotanganikallabes prognatha sp. nov., which is distinguished from all other clariids by its lack of an infraorbital series, the presence of multiple osseous connections between the swim bladder capsules and elements of the neurocranium, the absence of an ethmoid notch, the presence of a very large, egg-shaped occipital fontanelle and the extension of the lower lip beyond the margin of the upper jaw. A combination of additional external and molecular characters serves to further distinguish this taxon from all currently recognized clariid species. Phylogenetic analysis of mitochondrial (cytb) and nuclear (18S-ITS1-5.8S-ITS2-28S) sequence data supports the creation of a new genus for this species, as it appears to represent an independent, monophyletic lineage within the family Clariidae.

Exploratory phase II evaluation of cabozantinib in recurrent/metastatic uterine carcinosarcoma (CS): A study of the Princess Margaret, Chicago, and California phase II consortia

5587

Background: Carcinosarcoma (CS) is a rare ( < 5%) aggressive subtype of endometrial cancer (EC). Patients (pts) with progression on platinum-based chemotherapy (CTX) have limited options, there is no standard 2ndline treatment and median progression-free survival (PFS) is < 2months (mt), 6-mt PFS less than 20%. Limited molecular data on CS aligns with epithelial EC, providing rationale for evaluating similar strategies such as targeting MET and angiogenesis. Cabozantinib (cabo) is multi-targeted tyrosine kinase inhibitor against MET, VEGFR, TIE2, RET, AXL and KIT. Methods: PHL-86 (NCI#9322/NCT01935934) is a multi-centre, non-randomized, phase II trial of cabo (60 mg oral daily dose on a 28-day cycle) in EC pts recurring within a year of adjuvant CTX or with progression after 1stline of CTX for metastatic disease. Pts with rare histology including CS, were enrolled in an exploratory cohort. Activity of interest for further evaluation was defined as 4 responses (either partial response [PR] or 12-wk PFS) out of 10 pts of a given histotype. CT scans were performed after cycle 3 and every 2 cycles thereafter. Results: From 2013 to 2016, 32 pts were treated in the exploratory cohort, 19 pts with CS. Median age was 66 years (range 25-75); prior treatment included CTX (17: 1 line, 6: 2 lines) and/or radiation (11). Fifteen pts were evaluable for response, with 1 PR (7%) and 8 pts with 12-wk PFS (53%). Median PFS was 3 mt (95% CI: 2.7 – 4.6) with estimated 6-mt PFS of 13% (2 to 33%). Toxicity evaluation is available for 19 pts. Common events were fatigue and GI upset. Most frequent > Grade3 toxicities were hypertension (5), anemia (4), diarrhea (2). Four pts had GI fistula (2) or perforation (2). Mutation profiling in archival tissue showed TP53 (73%), PIK3CA (40%), KRAS (27%), PTEN(13%) with > 1 mutation present in 14/15 pts analyzed. The 1 pt with no somatic mutations had a PR (31% decrease) on cabo (PFS 6.7mt). Conclusions: Cabo in CS cohort met the predefined endpoint for further evaluation and compares favourably with other agents in this poor prognosis disease. Larger studies are required to define depth and durability of response and identify relevant biomarkers. Clinical trial information: NCT01935934.

A randomized, phase II efficacy assessment of multiple MET kinase inhibitors in metastatic papillary renal carcinoma (PRCC): SWOG S1500

TPS4599

Background: PRCC constitutes approximately 15% of RCC cases, and no standard of care exists for metastatic disease. Approved VEGF- and mTOR-directed therapies for clear cell RCC in metastatic PRCC (mPRCC) have generally been ineffective. Trials assessing sunitinib and everolimus in non-clear cell RCC show a numerical advantage in progression-free survival (PFS) with sunitinib therapy. Prospective studies evaluating sunitinib in mPRCC show a broad range of efficacy, with PFS ranging from 1.6-6.6 months. Another possible approach to treating mPRCC is to target the MET protooncogene, which is frequently altered across both type I and type II disease. SWOG 1500 is a randomized, phase II study which will compare sunitinib to three MET-directed therapies in pts with mPRCC. Methods: Eligible pts will have PRCC (type I, type II or NOS), Zubrod performance status 0-1, and measurable metastatic disease. Pts may have received up to 1 prior systemic therapy, with the exception of prior VEGF-directed treatments. Treated brain metastases are allowed. Tissue must be available for central pathologic review of papillary subtype. Pts will receive either oral sunitinib, cabozantinib, crizotinib or savolitinib in a 1:1:1:1 randomization, with stratification by (1) prior therapy (0 vs 1) and (2) PRCC subtype (type I vs type II vs NOS). The primary endpoint of the study is to compare PFS with sunitinib to PFS with MET-directed therapies. Secondary endpoints in the study include comparison of response rate, overall survival and safety profile. Translational aims of the study include correlation of clinical outcome with MET mutation, copy number and other markers of MET signaling. Radiographic assessment will be performed every 12 wks. Interim analyses are planned for each arm. A total of 275 pts will be enrolled, with 26 pts registered as of Jan 30, 2017. Clinical trial information: NCT02761057.

Phase II study of cabozantinib (cabo) in patients (pts) with recurrent/metastatic endometrial cancer (EC): A study of the Princess Margaret, Chicago, and California phase II consortia

5524

Background: Recurrent/metastatic EC has a poor prognosis with no standard 2ndline therapy. Cabo is a multi-targeted kinase inhibitor of MET, VEGFR, TIE2, AXL & KIT, relevant in epithelial-stromal cross-talk. The role of MET/HGF in aggressive EC biology, where transient benefit of VEGF-targeting is due to MET/HGF, TIE2 & AXL, provides rationale for MET targeting in EC. Methods: PHL86 (NCI#9322/NCT01935934) is a multi-centre, phase II trial of cabo (60mg oral daily dose) in pts with EC recurring within a year of adjuvant chemotherapy (ctx), or with progression after 1 line of ctx for metastatic disease. Experimental (E) cohort was stratified by histology (serous (SER) vs endometroid (END)) in a Simon two-stage design for co-primary endpoints of response rate ( > 30%) & 12-week progression-free-survival (PFS) ( > 55%). Activity was defined as > 7 partial responses (PRs) or > 15 instances of 12 wk-PFS in 36 pts. Pts with rare histology EC were treated in a parallel exploratory (Ex) cohort. Results: From May 2013 to Nov 2016, 102 pts (E: 71; Ex: 31) have been treated with cabo after prior radiation (59) and/or ctx (no. lines: 1(77); 2(22)). Cabo was well tolerated with common toxicities of fatigue, nausea, diarrhea & hand-foot syndrome. Most frequent Grade 3/4 toxicity was hypertension (32/101 pts). Fistula/perforation occurred in 4 of 71 SER/END pts & 4 of 31 Ex pts; no risk factors were identified. In 33 END pts, 6 PRs & 24 instances of > 12-wk PFS were observed; median PFS is 4.8 mths (95% CI: 4.4 – 6.4) with estimated 6-mth PFS of 43% (95% CI: 27 to 59%). In 34 SER pts, 4 PRs & 20 instances of > 12-wk PFS were observed; median PFS is 4.0 mths (95% CI: 2.7 – 4.7) with estimated 6-mth PFS of 30% (95% CI: 15 to 46%). 4 pts have had PFS > 12 mths, 1 SER pt remains on study after 25mths. Mutational analysis demonstrated presence of KRAS with PTEN or PIK3CA mutations in 9 (SER/END) pts, of whom 8/9 pts met 12-wk PFS endpoint, with a median PFS 5.9 mth (4.1 to 15.4). Conclusions: Cabo has single agent activity in END and SER EC with durable disease control. Concurrent mutation in KRAS/PTEN/PIK3CA may enrich for response. The current data support further evaluation of cabo in EC. Clinical trial information: NCT01935934.

A phase I study of cabozantinib plus nivolumab (CaboNivo) and ipilimumab (CaboNivoIpi) in patients (pts) with refractory metastatic urothelial carcinoma (mUC) and other genitourinary (GU) tumors

293

Background: We report the safety and clinical activity of CaboNivo and CaboNivoIpi in pts with mUC and other GU tumors. Methods: Part I included 4 dose levels (DLs) (Cabo PO daily and Nivo IV q2wk): DL1 Cabo40/Nivo1, DL2 Cabo40/Nivo3, DL3 Cabo60/Nivo1, DL4 Cabo 60/Nivo3. Part II included 3 DLs (Cabo PO daily, plus NivoIpi IV q3 wk x 4 doses then Nivo q2wk): DL5 Cabo 40/Nivo1/Ipi1, DL6 Cabo40/Nivo3/Ipi1, DL7 Cabo 60/Nivo3/Ipi 1. Tumors were assessed for overall response rate (ORR) by RECIST 1.1. Adverse events (AEs) were graded (G) by NCI-CTCAE v4.0. Results: From 7/22/15-10/14/16, 40pts [mUC N=14/(plasmacytoid N=1); bladder urachal N=4; bladder squamous cell carcinoma (bSCC) N=2; germ cell tumor (GCT) N=4; castrate-resistant prostate cancer (CRPC) N=9/(neuroendocrine prostate N=1); sarcomatoid renal cell carcinoma (sRCC) N=1; trophoblastic tumor N=1); sertoli cell tumor N=1; and penile SCC N=4] were treated. Median age was 58 (range 31-77); 36 (90%) were male. AEs related to study drugs with [1] CaboNivo included G3 hyponatremia 4/24 (17%), hypophosphatemia 4/24 (17%), lipase increase 3/24 (13%), dehydration 2/24 (8%), diarrhea 2/24 (8%), fatigue 2/24 (8%), HTN 2/24 (8%), thromboembolic event 1/24 (4%), rash 1/24 (4%), chest pain 1/24 (4%), amylase increase 1/24 (4%), hyperthyroid 1/24 (4%), proteinuria 1/24 (4%), thrombocytopenia 1/24 (4%); and G4 pyelonephritis 1/24 (4%); [2] CaboNivoIpi included G3 hypophosphatemia 2/16 (13%), lipase increase 2/16 (13%), fatigue 1/16 (6%), ALT increase 1/16 (6%), and HTN 1/16 (6%). There were 2/40 (5%) G3 immune-related AEs: 1 aseptic meningitis/CaboNivo; and 1 colitis/CaboNivoIpi. There were no G5 toxicities, or DLTs. 38 pts were evaluable for response. ORR was 12/38 (32%): 1 CR (bSCC); 11 PRs (5 mUC, 1 sRCC, 1 urachal, 1 bSCC, 1 CRPC, 2 penile). SD 20/38 (53%); 9/11 responses were ongoing and 26/39 (67%) pts remain on study. Conclusions: CaboNivo and CaboNivoIpi were well tolerated with no DLTs. Responses were seen at all DLs. The recommended dose for Part I is Cabo40/Nivo3 and for Part II is Cabo40/Nivo3/Ipi1. Rare tumors such as bSCC, urachal, and penile cancer demonstrated responses. Clinical trial information: NCT02496208.

Cabozantinib (C) plus docetaxel (D) and prednisone (P) in metastatic castrate-resistant prostate cancer (mCRPC)

235

Background: Docetaxel (D) improves overall survival in metastatic castrate-resistant prostate cancer (mCRPC), but benefits remain short-lived. Clinical data suggests patients (pts) with mCRPC treated with anti-androgen therapy like abiraterone (AA) or enzalutamide (ENZA) have decreased responses to subsequent therapy due to cross-resistance in the androgen pathway targeted by D, AA, or ENZA(van Soest et al, Eur J Cancer 49:18, 2013). Combining D with other agents, like cabozantinib (C), could target different cellular signaling pathways potentially minimizing tumor resistance. Methods: D naive pts receive 75 mg/m2 IV on day 1 of a 21 day cycle, and prednisone (P) 5 mg po q12 hours with C at 3 dose levels: 20, 40, or 60 mg po daily until maximum tolerated dose (MTD) is defined. In phase 2, pts who have progressed on AA or ENZA, enroll on a randomized 2 arm cohort comparing D plus C to D alone. Results: 20 pts have been accrued; 4 at 20 mg C, 8 at 40 mg C, and 7 at 60 mg C. On phase 2, 1 pt is randomized to D alone. Median age is 68 (44-84 yrs). Median baseline PSA is 94.7 (0.01-754.1 ng/mL). Gleason score is 9 (7-10). Median cycles is 9.5 (1-33). 8 pts have bone only disease, 12 pts have bone and soft tissue disease. Common grade 2 and grade 3 adverse events possibly related to C: hand/foot syndrome (4/16), oral mucositis (4/16), hypophosphatemia (4/16), and fatigue (3/16). The MTD of C is 40 mg daily with D. 15 pts were previously treated with AA or ENZA. In 13 patients previously treated with AA, median PFS has not been reached, with a median potential follow up of 12.4 months. Six month PFS is 77.8% and 9 month PFS is 60.5%. Conclusions: D plus P may have limited benefits after disease progression on AA as seen in 3 retrospective analyses demonstrating a median PFS survival of 4.6 months or less (Mezynski J, et al. Ann Oncol 23;11, 2012) (Aggarwal R, et al. Clin Genitourin Cancer 12;5, 2014) (Schweizer MT, et al. Eur Urol 66;4, 2014). PFS results seen in this trial compare favorably to previously published data of treatment with D after AA in mCRPC, suggesting the addition of C to D may help overcome acquired resistance. Further randomized trials will determine if C in combination with D will enhance clinical outcomes. Clinical trial information: NCT01683994.

Phase II randomized, double-blind, placebo-controlled study of tivantinib in men with asymptomatic or minimally symptomatic metastatic castrate-resistant prostate cancer (mCRPC)

146

Background: Tivantinib is a putative non-ATP competitive inhibitor of c-MET receptor tyrosine kinase that has additional cytotoxic mechanisms including tubulin inhibition. Prostate cancer demonstrates higher c-MET expression as the disease progresses to more advanced stages and to castration resistance. Methods: 80 patients (pts) with asymptomatic or minimally symptomatic mCRPC were assigned (2:1) to either tivantinib 360 mg PO BID or placebo (P). The primary endpoint was progression free survival. PCWG2 guidelines were utilized for determining eligibility and progression. Results: Of the 80 pts enrolled, 78 (52 tivantinib, 26 P) received treatment and were evaluated. Median age was 67 yrs (range: 43 to 85). Baseline characteristics were balanced between arms for ECOG PS, Gleason score, PSA, LDH, hemoglobin, Alk Phos, prior treatment, bone and organ involvement. More African Americans and those with lymph node involvement were randomly assigned to placebo. Median follow up is 8.2 months (range: 1.4 to 27.6). To date 59 patients have progressed. Patients treated with tivantinib had significantly better PFS vs. those treated with placebo (medians: 5.6 mo vs 3.8 mo, respectively; HR = 0.53, 95% CI: 0.32 to 0.89; p=0.015). Toxicity was mild overall. Grade 3 febrile neutropenia was seen in 1 patient on tivantinib while grade 3 and 4 neutropenia were recorded in 1 patient each on tivantinib and placebo. Grade 3 sinus bradycardia was recorded in two men on the tivantinib arm. 8 deaths (3 P and 5 tivantinib) have been recorded and were all considered unrelated to therapy. Conclusions: Tivantinib significantly improved PFS in men with asymptomatic or minimally symptomatic mCRPC. Given the favorable toxicity profile and evidence of anti-tumor activity, investigation of tivantinib with other agents may be a rational strategy. Clinical trial information: NCT01519414.

Sorafenib dose escalation is not uniformly associated with blood pressure elevations in normotensive patients with advanced malignancies

Hypertension with vascular endothelial growth factor (VEGF) receptor inhibitors is associated with superior treatment outcomes for advanced cancer patients. To determine whether increased doses of sorafenib cause incremental increases in blood pressure (BP) we measured 12-hour ambulatory BP in 41 normotensive advanced solid tumor patients in a randomized dose escalation study. After 7 days’ sorafenib (400mg BID) mean diastolic BP (DBP) increased in both study groups. After dose escalation, group A (400mg TID) had marginally significant further increase in 12-hour mean DBP (p=0.053) but group B (600mg BID) did not achieve statistically significant increases (p=0.25). Within groups, individuals varied in BP response to sorafenib dose escalation, but these differences did not correlate with changes in steady state plasma sorafenib concentrations. These findings in normotensive patients suggest BP is a complex pharmacodynamic biomarker of VEGF inhibition. Patients have intrinsic differences in sensitivity to the BP elevating effects of sorafenib.

A phase II study of cabozantinib in patients (pts) with relapsed or refractory metastatic urothelial carcinoma (mUC)

307

Background: Translational studies have shown that shed MET levels in serum and urine of pts with UC correlate with stage and visceral metastases and that cabozantinib reverses HGF-driven UC cell growth and invasion. These data support the evaluation of cabozantinib in pts with mUC. Methods: In this phase II study, pts receive cabozantinib 60 mg daily in 28-day cycles. There are 3 study cohorts (1) mUC, (2) bone only mUC (3) metastatic rare bladder histology. The primary objective is to determine the response rate (RR) by RECIST. Response is assessed every 2 cycles. Tissue, blood, and urine were collected on all pts to test for MET/HGF and immune subsets. Results: 26 out of 55 pts have enrolled (19 M, 7 F): median age 62 (42-82) and median KPS of 80%. Primary sites include bladder (77%) and upper tract UC (23%). Prior therapy includes 30% pts with 1 regimen, 39% with 2, 15% with 3, 8% with 4 and 8% with 6. 81% of pts had visceral metastases (lung, liver and bone) and 19% lymph node only metastases. 23 pts (19 in cohort 1, 3 in cohort 2 and 1 in cohort 3) were evaluable for response after completing at least 4 weeks of therapy. In cohort 1, 2 pts achieved PR (1 remained on study for 10 months and 1 remains on study after >12 months of therapy); 7 pts had SD for at least 16 weeks (1 remained on study for 11 months); 10 had PD; 1 is too early to assess for response; 1 was removed before restaging for toxicity and 1 was removed for not meeting eligibility. The objective RR is 11% and SD 37% for a clinical benefit of 48%. In cohort 2, 1 of 3 pts had a near resolution of bone lesions on NaF PET/CT for 11 months. In cohort 3, only pt enrolled (squamous cell carcinoma of the bladder) achieved SD for 16 weeks. Mixed responses with regression of lung, bone or lymph nodes were observed in 30% of pts with PD. Grade 3/4 toxicities included: fatigue (8%), hyponatremia (8%), hypophosphatemia (8%) diarrhea (4%), thromboembolism (4%), transaminitis (4%), hypothyroidism (4%), thrombocytopenia (4%), dysphonia (4%), hypomagnesemia (4%), creatinine increase (4%) and proteinuria (4%). Conclusions: Cabozantinib has clinical activity in pts with relapsed or refractory mUC with manageable toxicities. Further studies are underway to correlate response to therapy with MET expression. Clinical trial information: NCT01688999.

A phase I study of the multikinase inhibitor cabozantinib (C) plus docetaxel (D) and prednisone (P) in metastatic castrate-resistant prostate cancer (mCRPC)

108

Background: Cabozantinib (C) is a multikinase inhibitor of c-Met, vascular endothelial growth factor receptor two and RET. C has shown activity in metastatic castrate resistant prostate cancer (mCRPC), with resolution of bone lesions on bone scan (BS), regression of soft tissue/visceral disease (STD), reductions in circulating tumor cells and bone biomarkers. Combining docetaxel (D) with other agents, without overlapping toxicities, can target different cellular signaling pathways necessary for tumor survival. Methods: Patients (pts), with no prior D for CRPC, receive a fixed dose of D (75 mg/m2 IV day one of each 21 day cycle) and prednisone (P) (5 mg po q12 hours) with C at three escalating dose levels: 20 mg, 40 mg, or 60 mg (all po daily). Using a standard three-plus-three design, three to six pts are treated at each dose level until the maximum tolerated dose (MTD) has been defined. Results: Thirteen pts have been accrued; four on dose level one, six on dose level two, and three on dose level three. Median age 69 (45 to 84). Four pts have an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of zero and nine pts have a PS of one. Median Gleason score is nine (7 to 10). Median on-study prostate-specific antigen (PSA) is 129.2 ng/mL (0.01-508.5 ng/mL). Median cycles is six (1 to 17). Grade 1 adverse events (AEs), possibly related to C; dysgeusia (4/12), oral mucositis (4/12), increased ALT (3/12), and epistaxis (3/12). Grade 2 AEs; nausea (2/12), hand/foot syndrome (2/12), fatigue (2/12), dysgeusia (2/12), oral mucositis (2/12), hypophosphatemia (2/12), and anemia (2/12). Grade 3 AE is hypophosphatemia (2/12). Grade 4 AE is neutropenia (1/12). MTD of C is 60 mg. Of nine evaluable pts, six have bone only disease. Of these six, three pts have PSA declines of less than 30% with improvement on BS (two pts) or stable BS (one pt). The other three pts have PSA declines of greater than 30% and bone scan improvement. Three pts have STD and bone disease; one patient had a PSA decline of greater than 30% with improvement on BS and SD by CT scan. One patient had an increase in PSA of less than 30% with improvement on BS and CT. The third pt had PD by CT and an increase in PSA equal to 30%. PFS probability at six months is 90.0% and is 67.5% at eight months and beyond. Conclusions: The addition of C to D and P, has an acceptable toxicity profile. CT scan and BS improvements did not correlate with PSA declines in all pts. An expansion cohort will combine D plus P with C at the MTD (60 mg) to determine clinical benefit. Clinical trial information: NCT01683994.

Phase I trial of FOLFIRI in combination with sorafenib and bevacizumab in patients with advanced gastrointestinal malignancies

551

Background: Sorafenib inhibits various pro-angiogenesis pathways including PDGFR-B, a factor associated with resistance to anti-VEGF therapy. A previous phase II trial in patients with chemorefractory metastatic CRC demonstrated a 63% disease control rate with a combination of bevacizumab (BEV) and sorafenib. This phase I trial sought to determine the MTD of BEV and sorafenib combined with standard cytotoxic therapy for advanced gastrointestinal (GI) cancers. Methods: Patients with advanced GI malignancies appropriate for irinotecan-based therapy were enrolled (14 with CRC, 3 gastroesophageal). A standard 3 + 3 design was used with 3 escalating sorafenib dose levels (DL): (1) 200 mg po daily, days 3-7, 10-14; (2) 200 mg po twice daily, days 3-6, 10-13; and (3) 200 mg po twice daily, days 3-7, 10-14. FOLFIRI: irinotecan 180 mg/m2 d1, leucovorin 400 mg/m2 d1, 5-fluorouracil (FU) bolus 400 mg/m2 d1, 5-FU infusion 2400 mg/m2d1-2 and BEV 5 mg/kg d1. 1 cycle = 14 days. Results: Seventeen pts were enrolled, median age of 56 (range 32 and 81). Two pts were replaced, as they did not complete DLT evaluation, leaving 15 evaluable pts. Four evaluable pts at DL1 and 6 pts at DL2 had no DLTs. At DL 3, the first cohort of 3 pts did not experience any DLTs. In the second cohort of 3 pts, 2 pts experienced DLTs (asymptomatic G3 hypophosphatemia, G3 dehydration and diarrhea). MTD was determined to be DL2: sorafenib 200 mg PO twice daily, days 3-6, 10-13 combined with FOLFIRI and BEV at standard doses. Of the 15 evaluable pts, 4 pts had PR, 8 pts had SD as best response, 1 pt had PD, and 2 pts discontinued treatment prior to first tumor assessment. The median number of cycles was 10 (range 1-37). Three pts with CRC had disease control > 12 months. Conclusions: The MTD of this regimen is sorafenib 200 mg PO twice daily, days 3-6,10-13 combined with standard doses of FOLFIRI and BEV. Dual VEGF inhibition combined with cytotoxic therapy may provide prolonged disease stabilization for select patients with advanced GI malignancies. Supported by CA69912 and CA15083. Clinical trial information: NCT01383343.

A phase I trial of cixutumumab (C) (IMC-A12) and sorafenib (S) for treatment of advanced hepatocellular carcinoma (HCC)

293

Background: The insulin growth factor (IGF) pathway is activated in hepatocarcinogenesis. C is a monoclonal antibody against human insulin-like growth factor-1 receptor (IGF-1R). In vivo HCC models show activated IGF signaling and antitumor effects due to C. Given the cross-talk between the IGF and VEGF pathways, the combination of C and S was chosen for study. Methods: This study evaluated the safety of C (2, 4 or 6 mg/kg) IV weekly with standard doses of S (400 mg po bid) in patients (pts) with HCC without standard curative options. Eligibility criteria included: no prior systemic therapy, Child-Pugh score of A or B7, ECOG 0 or 1, platelets > 75,000/mm3, and albumin > 2.8 g/dl. The study used a standard 3+3 design. One cycle was 28 days. Results: A total of 21 pts (17 males and 4 females) were enrolled; mean age was 63 years (43-85); 10 Asian, 4 Hispanic, 5 White, 1 Black, and 1 Native American. There were 3 dose limiting toxicities (DLTs); grade 3 hyperglycemia, grade 3 hypophosphatemia, and grade 5 peritonitis (table). The maximum tolerated dose (MTD) was C 4 mg/Kg and S 400 mg BID. Eighteen of 21 (86%) pts had ≥ grade 3 toxicities attributable to treatment. Grade 3 adverse events that occurred in ≥ 2 pts were: diarrhea (4; 19%), hypertension (4; 19%), thrombocytopenia (3; 14%), palmar-plantar erythrodysesthesia (2; 10%), hyperglycemia (2; 10%), and fatigue (2; 10%). There was one grade 4 colonic perforation and one grade 5 peritoneal infection in the same pt. The median number of cycles completed was 4 (0-19 cycles). Sixteen of the 21 pts completed 2 cycles and were evaluated for response. Thirteen of the sixteen (81%) (95% CI: 54%-96%) achieved stable disease. The median event-free survival was 3.8 months (95%CI: 1.9, 11.3). The median OS was 13.1 months (95% CI: 7.6, undefined). Conclusions: The majority of adverse events in pts treated with the combination of C and S were typical of sorafenib toxicity. There was preliminary evidence of efficacy as seen in the median OS. Analysis of biomarker correlative data is on-going. Clinical trial information: NCT01008566. [Table: see text]

Use of supportive measures to improve outcome and decrease toxicity in docetaxel-based antiangiogenesis combinations in metastatic castrate resistant prostate cancer (mCRPC)

e16017

Background: We have completed accrual of 63 patients (pts) to our study combining lenalidomide (L), with bevacizumab (B), docetaxel (D), and prednisone (P) (ART-P) in mCRPC. Due to the lack of improved survival and the increased toxicity of anti-angiogenic docetaxel combinations in the MAINSAIL and CALGB 90401 trials, we attempted to compare and contrast our studies with these failed phase III trials. Methods: Among the first 52 pts on ART-P, 3 received L 15 mg daily, 3 received 20 mg daily, and the others received 25 mg daily for 14 days of every 21−day cycle (C). We then enrolled 11 pts at L 15 mg. All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily. Pegfilgrastim was given on day 2. Patients on CALGB 90401 received D 75 mg/m2 and B 15 mg/kg on day 1, with P 10 mg. On MAINSAIL, pts received D 75 mg/m2, L 25 mg daily for 14 days of every 21−day cycle with daily P. Patients on CALGB 90401 and MAINSAIL did not receive enoxaparin or pegfilgrastim prophylactically. Results: The median number of Cs on ART-P is 18 (1-52). Median PFS is 19.1 months. Twenty-seven pts had a PR, and one pt with measurable disease had a CR. Two patients (3%) had deep vein thromboses. Of 1,334 Cs given, 14 cycles were complicated by febrile neutropenia (FN) (1%). There were no treatment related deaths. In comparison, median number of Cs in MAINSAIL L+DP arm was 6, with a PFS of 45 weeks and an OS of 77 weeks. Thirty-four pts (6.5%) developed pulmonary emboli and there were 2 deaths due to toxicity in the experimental arm. Nearly 12% of Cs were complicated by FN. In the experimental arm of CALGB 90401 trial, median OS was 22.6 months with median PFS of 9.9 months. The median number of Cs were 8 and 19 pts developed thrombosis/emboli (3.6%). In addition, 37 patients developed FN and treatment related deaths were reported at 4%. Conclusions: The use of supportive care allowed longer treatment duration with the ART-P combination as compared to D+L (MAINSAIL) and D+B (CALGB 90401), potentiating a longer PFS, RR and possibly OS with an improved safety profile. This data demonstrates the potential importance of supportive measures and is hypothesis generating for future combination studies. Clinical trial information: NCT00942578.

A phase I study of cabozantinib (Cabo) plus docetaxel (D) and prednisone (P) in metastatic castrate resistant prostate cancer (mCRPC)

TPS5095

Background: In mCRPC, two randomized trials demonstrated an overall survival (OS) benefit with the chemotherapeutic agent D. However, the survival improvement is modest and new strategies are needed to enhance clinical response. D-based combinations have been evaluated as one alternative strategy. Cabo targets multiple tyrosine kinases including c-Met, vascular endothelial growth factor receptor 2 (VEGFR2) and RET. Cabo has shown activity in mCRPC, with resolution of bone lesions on bone scan, regression of soft tissue/visceral disease, and reductions in circulating tumor cells and bone biomarkers (Smith, et al, J Clin Oncol 30, 2012 [suppl; abstr 4513]). We hypothesize the addition of Cabo to D and P, in patients (pts) with mCRPC, will have an acceptable toxicity profile and could lead to improved survival by targeting different cellular pathways simultaneously. This combination therapy may represent a safe and effective strategy to improve the outcome of mCRPC pts treated with D-based chemotherapy. Methods: This is a phase I trial to determine the safety profile and the recommended phase II dose of Cabo in combination with D and P. Pts receive a fixed dose of D (75 mg/m2 IV day 1 of each 21 day cycle) and P (5 mg po q12 hours) in combination with Cabo at three escalating doses: dose level 1 is 20 mg, level 2 is 40 mg, and level 3 is 60 mg (all po qdaily). Using a standard 3 + 3 design, three patients will initially be treated at each dose level until the maximum tolerated dose (MTD) has been defined. An expansion cohort will then be enrolled at the MTD. The accrual ceiling for the study, including both the dose escalation and the expansion phases, is set at 24 pts. Secondary objectives include assessments of pharmacokinetics of each agent, evaluation of antitumor activity of the combination therapy, and assessment of changes in molecular biomarkers for receptor tyrosine kinase and angiogenesis pathways, as well as biomarkers for bone metabolism. Restaging with bone and CT scan will be undertaken every 3 cycles. Enrollment at dose level 1 has been completed without dose-limiting toxicity. Accrual is ongoing at the second dose level. Clinical trial information: NCT01683994.

Application of MET pharmacodynamic assays to compare effectiveness of five MET inhibitors to engage target in tumor tissue

11103

Background: Several MET inhibitors are currently being developed that block aberrant HGF/MET signaling in different cancers. We utilized validated MET pharmacodynamic (PD) assays to compare time course, magnitude, and reversal of MET suppression by 5 MET inhibitors in preclinical models. Methods: Immunoassays (total MET, pY1234/35MET, and pY1356MET) were developed and validated to measure modulation of MET by 5 MET inhibitors (crizotinib, tivantinib, cabozantinib, foretinib, and EMD1214063). The comparison was implemented in 3 sequential stages: 1) establish time course and magnitude of MET inhibition after single drug administration of 4 different doses; 2) determine dose(s) and schedule for sustained MET inhibition and downstream signaling at optimal levels; and 3) compare efficacy of MET inhibitors at MTD and equal MET inhibition. The preclinical models include an autophosphorylation gastric tumor (SNU5) model and a paracrine MET activation model in hHGF knock-in mice. Plasma and tumor exposures were measured using LC-MS/MS to correlate with PD effects. Results: We completed phase one in the SNU5 model and determined inhibition of pY1234/35MET and total MET in tumor tissues after single administration of MET inhibitors. Time course and magnitude of pY1234/35MET inhibition varied considerably among MET inhibitors, with the most rapid (>80% suppression in 30 min) and sustained inhibition (up to 48 h) observed with EMD1214063 at a dose of 30 mg/kg. The maximal inhibition of pY1234/35MET and time taken for biomarker recovery were wide-ranging among MET inhibitors. Tumor drug exposures were concomitantly higher than plasma for all drugs and correlated inversely with pY1234/35MET, except for tivantinib which, unlike other drugs, is not ATP competitive inhibitor. Conclusions: We applied validated PD assays to directly compare similarities and differences in extent and duration of MET inhibition by 5 MET inhibitors. Our results provide important foundation for head-to-head comparison of efficacies of MET inhibitors at MTD and equal MET inhibition. Funded by NCI Contract No HHSN261200800001E.

A phase I-II study of tipifarnib plus weekly paclitaxel (P) followed by dose-dense doxorubicin/cyclophosphamide (AC) in stage IIb-IIIc breast cancer (BC)

1118

Background: Tipifarnib (T) is an orally bioavailable farnesyl transferase inhibitor (FTI) that has activity in metastatic BC (J Clin Oncol 2003; 21:2492-9). We previously showed that adding T (200 mg PO BID days 2-7) to preoperative AC was associated with a higher pathologic complete response (pCR) than expected compared with historical data (Clin Cancer Res. 2009;15;2942-8), and preclinical data suggest that FTIs enhance the antineoplastic effects of P (Cancer Res 2005; 65:3883-93). Methods: Eligible pts with HER2-negative clinical stage IIB-IIIC BC received 12 weekly doses of P (80 mg/m2) followed by AC (60/600 mg/m2 every 2 weeks and pegfilgrastim), plus T 100 mg or 200 mg on days 1-3 of each P dose in cohorts of 3-6 pts in the phase I (and T 200 mg PO BID on days 2-7 each AC cycle in both the phase I and II). Simon two-stage design used for the phase II in two strata generally resistant to neoadjuvant chemotherapy. The trial was powered to detect an improvement in breast pathologic complete response (pCR) from 15% to 35% in each stratum (alpha 0.10, beta 0.10), which required breast pCR in at least 4/19 eligible pts in stage I to proceed to stage II, and at least 8/33 pts in stage I and II to be considered promising. Results: Sixty patients accrued in both the phase I and II. Two patients were non evaluable. There were no DLTs in the first 6 evaluable patients treated at dose level 1 and 2.The recommended phase II dose of T identified in the phase I trial was 200 mg BID.All protocol therapy was completed in 43/55 pts (78%) in the phase II, and one pt died of pneumonitis during therapy of uncertain cause. The prespecified efficacy endpoint was not met for either stratum. Conclusions: The addition of the FTI tipifarnib to neoadjuvant sequential weekly paclitaxel followed by dose-dense AC did not result in a higher breast pCR rate compared with historical data. Clinical trial information: NCT00049114. [Table: see text]

A phase II study of trebananib (AMG 386) and abiraterone in metastatic castration resistant prostate cancer

TPS5102

Background: Preclinical studies support the use of an antiangiogenic approach in the treatment of prostate cancer. Trebananib is a novel peptide-Fc fusion protein that sequesters angiopoeitin 1 and angiopoeitin 2, thereby preventing their interaction with their common receptor Tie2, and inhibiting tumor endothelial cell proliferation and tumor growth. Trebananib is currently in Phase 3 trials for the treatment of ovarian carcinoma and has been shown to have clinical activity in multiple tumor types. Previous studies have demonstrated that in vivo alterations of testosterone levels regulate the expression of vascular endothelial growth factor, fibroblast growth factor, and angiopoietin associated factors. Dual inhibition of the androgen and angiogenic axis represents a novel strategy of combined targeted therapy for patients with metastatic castration-resistant prostate cancer (mCRPC). We hypothesize that the addition of trebananib to CYP17 inhibitor abiraterone and prednisone will increase the median progression free survival (PFS) in chemotherapy-naïve mCRPC. Methods: This phase 2 study will evaluate the treatment effect as measured by progression free survival in patients treated with trebananib plus abiraterone/prednisone relative to abiraterone/prednisone alone. 72 patients with progressive, mCRPC will be randomized 1:1 to either study arm. Trebananib is administered intravenously every week, on days 1, 8, 15 and 22 of each 28-day cycle. Abiraterone acetate is taken once daily with prednisone 5 mg twice daily. We have completed the initial run-in phase of trebananib at 15mg/kg and 30mg/kg. The randomized phase of the study will use the 30 mg/kg dose of trebananib with the standard dose (1000 mg) of abiraterone. The primary end point is radiographic PFS. Secondary end points include overall survival, changes in genetic biomarkers related to the androgen and angiogenesis signaling axis, molecular markers of angiogenesis, circulating tumor cells and androgen receptor signaling status in circulating tumor cells before and after treatment. This combination of angiogenesis inhibition and abiraterone has the potential to improve clinical outcomes in front-line therapy for mCRPC. Clinical trial information: NCT01553188.

A phase II study of cabozantinib (XL184) in patients with advanced/metastatic urothelial carcinoma

TPS4589

Background: Accumulating evidence supports MET as a therapeutic target in urothelial carcinoma. Activated MET can promote angiogenesis and tumor growth by upregulating VEGF and may play a role in urothelial carcinoma pathogenesis. Cabozantinib inhibits primarily VEGFR2 and MET pathways. Cabozantinib has been approved by the FDA for the treatment of progressive metastatic medullary thyroid cancer, is in Phase 3 trials for metastatic castration-resistant prostate cancer and has demonstrated clinical activity in multiple solid tumors. We previously reported that shed MET levels in serum and urine of patients with urothelial carcinoma correlate with stage, presence of visceral metastases and urinary source and that cabozantinib is effective in reversing HGF-driven urothelial carcinoma cell growth and invasion. These data support the evaluation of cabozantinib in patients with metastatic urothelial carcinoma. Methods: This is a phase II study of oral cabozantinib 60mg daily given continuously in 28-day cycles. There are three study cohorts: [1] metastatic urothelial carcinoma [2] bone only metastatic urothelial carcinoma [3] metastatic non-urothelial carcinoma of the bladder, urethra, ureter, or renal pelvis. A maximum of 55 subjects will be enrolled. Up to 45 patients will be accrued to cohort 1.The remainder will be enrolled on exploratory cohorts 2 & 3. A two-stage single-arm phase II design will be employed. The primary objective is to determine the objective response rate in patients with metastatic urothelial carcinoma who have progressed on prior chemotherapy. Secondary objectives include progression free survival, safety and toxicity, and overall survival. Exploratory objectives include tumor tissue Met expression, shed MET levels in serum and urine, immune subsets, genetic biomarkers, molecular markers of angiogenesis and circulating tumor cells, correlation with clinical response parameters. Finally we will explore treatment evaluation with FDG and NaF PET/CT compared to standard imaging. This study is supported by the Cancer Therapy Evaluation Program (CTEP). NCT01688999 Clinical trial information: NCT01688999.

Use of supportive measures to improve outcome and decrease toxicity in docetaxel-based antiangiogenesis combinations

128

Background: We have recently completed accrual of 63 patients (pts) to our study combining lenalidomide (L), with bevacizumab (B), docetaxel (D), and prednisone (P) (ART-P). Due to the lack of improved survival and the increased toxicity of anti-angiogenic docetaxel combinations in the MAINSAIL and CALGB 90410 trials we attempted to contrast and compare our studies with the failed phase III trials. Methods: Among the first 52 pts on the ART-P, 3 received L 15 mg daily, 3 had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). We later enrolled 11 more pts at L 15 mg. All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. Patients on CALGB 90410 received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and on MAINSAIL received D 75 mg/m2, L 25 mg daily for 14 days of every 21−day cycle with daily P. Patients on CALGB 90410 and MAINSAIL did not receive enoxaparin or pegfilgrastim prophylactically. Results: Median number of Cs in ART-P was 16 (3−38). PFS was 22 months and median OS has not been reached. Pts with measurable disease had 1 CR and 25 PR (86.7% RR). Two patients (3%) had deep vein thromboses. Of 1,219 cycles given, 14 cycles were complicated by febrile neutropenia (FN) (1.1%). There were no treatment related deaths. In comparison, median number of Cs in MAINSAIL L+DP arm was 6, with a PFS of 45 weeks and an OS of 77 weeks. Thirty-four pts (6.5%) developed pulmonary emboli and there were 2 deaths due to toxicity in the experimental arm. Nearly 12% of Cs were complicated by FN. In the experimental arm of CALGB 90410 trial, median OS was 22.6 months with median PFS of 9.9 months. Median number of Cs was 8, and 19 pts developed thromboses/emboli (3.6%). In addition, 7% of patients developed FN and treatment related deaths were reported at 4%. Conclusions: The use of supportive care allows the ART-P combination to be given for more cycles than were given in MAINSAIL and CALGB 90401 potentiating a longer PFS, RR and possibly OS with an improved toxicity profile. This data demonstrates the potential importance of supportive measures and is hypothesis generating for future combination studies. Clinical trial information: NCT00942578.

Dual antiangiogenic therapy using lenalidomide and bevacizumab with docetaxel and prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC)

4569

Background: Previously, we had shown the potent anti−tumor activity of dual anti-angiogenic therapy by combining bevacizumab (B) and thalidomide (T) with docetaxel (D) and prednisone (P) in mCRPC (Ning JCO 2010). We hypothesized that combining lenalidomide (L), an analogue of T, with B, D, and P would have a more favorable efficacy/toxicity profile. Methods: All patients (pts) had chemotherapy−naïve mCRPC. Among the first 52 pts, 3 received L 15 mg daily, 3 had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). The protocol was recently amended to enroll 11 more pts at L 15 mg; 2 pts have now been enrolled in this expansion cohort. All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. PSA each C with imaging after C2 and after every 3C. Dental exams with mandible CT scan at baseline, after C5, and every 6C. Results: 54 of 62 pts have been enrolled. Median age 65.5 (51−82), Gleason score 8 (5−10), on−study PSA 85.2 ng/ml (0.15−3520), and pre−study PSA doubling time 1.49 months (0.52−6.73). Median number of Cs was 16 (3−38). PFS was 22 months and probability of survival at 12 months was 90%. Forty-six (85.2%) and 42 (77.8%) pts had PSA declines of ≥50% and ≥75%, respectively. Of 30 pts with measurable disease there were 1 CR and 25 PR (86.7% overall RR). 17/54 pts were off study for radiographic disease progression and 8/54 for other reasons. Grade ≥2 toxicities included neutropenia (34/54), anemia (23/54), thrombocytopenia (7/54), hypertension (12/54), perianal fistula (3/54), rectal fissure (1/54), myocardial infarction (1/54), and osteonecrosis of the jaw (ONJ) (12/54, 22.0%). At the time of diagnosis of ONJ, 7/12pts were on bisphosphonates (BP), 2/12 had used BP previously, and 3/12 never used BP. The incidence of ONJ was comparable to 18.3% reported by Ning et al. A recent study of carboplatin plus weekly docetaxel reported an incidence of 29.3%. Conclusions: Dual anti-angiogenic therapy with, B and L, plus D and P was associated with high PSA (85.2%) and tumor (86.7%) responses in mCRPC, with manageable toxicities. The incidence of ONJ is comparable to other studies.

A phase I trial of riluzole and sorafenib in patients with advanced solid tumors and melanoma

TPS3112

Background: Metabotropic glutamate receptor 1 (GRM1) has been identified as a potential therapeutic target in melanoma. Over 60% of human melanomas express this cell surface glutamate receptor and excitation of GRM1 results in the activation of MAPK and PI3K/AKT pathways. Riluzole, an oral GRM1 blocking agent, results in growth arrest of melanoma cells in vitro and in vivo. We previously reported that administration of riluzole to melanoma patients suppressed activity of the PI3K/AKT and MAPK pathways in paired tumor samples (Yip Clin Cancer Res 2009). In preclinical studies, the efficacy of riluzole was attenuated in melanoma cells harboring BRAFV600E mutations, but sorafenib, a RAF kinase inhibitor, enhanced the effect of riluzole on these cells. The combination of riluzole and sorafenib was additive or synergistic in both BRAF mutant and BRAF wildtype melanoma cells in vitro and in BRAF wildtype cells in a xenograft model (Lee HJ Clin Cancer Res 2011). We thus designed a phase I trial to test the combination of riluzole with sorafenib in patients with solid tumors and advanced melanoma. Methods: The primary objective of this trial is identification of the maximum tolerated dose (MTD). An expansion cohort at the MTD is planned for patients with advanced melanoma to examine the correlation of clinical or radiographic response with signaling through the MAPK and PI3K/AKT pathways and with GRM1 receptor status of individual tumors. Eligible patients must have advanced solid tumors (phase I) or stage III unresectable/stage IV melanoma with biopsiable tumor (expansion cohort) and ECOG PS ≤ 2. Riluzole will be administered at 100 mg twice daily combined with sorafenib beginning at 200 mg daily and escalating in subsequent cohorts at 200 mg increments. Correlative studies: Tumors will be assessed for BRAF and NRAS mutational status. Pretreatment tumor blocks will be examined for GRM1 receptor status by immunohistochemistry. Pre and post treatment levels of pERK and pAKT will be measured in paired tumor samples to assess effects of treatment on MAPK and PI3K signaling. Limited sampling pharmacokinetic studies will be performed. Progress: Accrual to three cohorts is complete without DLT. Accrual to the final planned cohort is in progress.

Phase I pharmacokinetic (PK) and pharmacodynamic (PD) study of intravenous dimethane sulfonate (DMS612, NSC 281612) in advanced malignancies

2553

Background: DMS612 is a dimethane sulfonate compound that was identified as preferentially cytotoxic to renal cell carcinoma (RCC) cell lines in a chemical screen of the NCI-60 panel. DMS612 has bifunctional alkylating activity in vitro. Objectives of this first-in-human phase I study included determining the dose-limiting toxicity (DLT), maximum tolerated dose (MTD), recommended phase 2 dose (RP2D), PK and PD of DMS612 administered by 10 minute intravenous infusion on day 1, 8 and 15 of a 28 day cycle. Methods: Eligibility criteria included adults with advanced solid malignancies or lymphoma with ECOG performance status 0-2, life expectancy > 3 months and adequate organ and marrow function. Patients were enrolled using a standard “3+3” dose escalation scheme. Plasma PK of DMS612 and metabolites was assessed by LC-MS/MS. DNA damage PD was assessed by γ-H2AX immunofluorescence. Results: 35 subjects were enrolled (22 male, 13 female) with median age 59 years (41-75). Tumor types included colorectal (8), RCC (4), cervix (2), and urothelial (2). Doses administered were 1.5, 3, 5, 7, 9 and 12 mg/m2. The MTD was determined to be 9 mg/m2, with only one DLT of grade 4 thrombocytopenia in 12 subjects enrolled. The maximum administered dose of 12 mg/m2 was considered to be intolerable after 1 of 3 subjects had grade 4 neutropenia and 1 had prolonged grade 3 thrombocytopenia. Prolonged thrombocytopenia in later cycles was observed in other subjects, including one patient naïve to prior cytotoxic chemotherapy. One subject with RCC had a confirmed partial response at 7 mg/m2. DMS612 was rapidly converted into carboxy, chloroethyl and hydroxyethyl analogues and their glucuronides, some of which retained alkylating activity in vitro. Dose-dependent pharmacodynamic evidence of DNA damage induced by DMS612 in vivo was observed by γ-H2AX immunofluorescance in both peripheral blood lymphocytes and plucked scalp hairs. Conclusions: The MTD of DMS12 administered by intravenous infusion on day 1, 8 and 15 of a 28-day cycle was 9 mg/m2. Pre-clinical and clinical observations suggest that further study of DMS612 in RCC is warranted.

Phase II trial of bevacizumab and lenalidomide with docetaxel and prednisone in patients with metastatic castration-resistant prostate cancer (mCRPC)

207

Background: Angiogenesis may be vital to mCRPC. Previously, we had shown the potent anti−tumor activity of dual antiangiogenic therapy by combining thalidomide (T) and bevacizumab (B) with docetaxel (D) and prednisone (P) in mCRPC (Ning JCO 2010). We hypothesized that combining lenalidomide (L), an analogue of T, with B, D, and P would have a more favorable efficacy/toxicity profile.

Methods: All patients (pts) had chemotherapy−naïve mCRPC. 3 pts received R 15 mg daily, 3 pts had 20 mg daily, and the rest had 25 mg daily for 14 days of every 21−day cycle (C). All pts received D 75 mg/m2 and B 15 mg/kg on day 1 with P 10 mg and enoxaparin daily throughout each C. Pegfilgrastim was given on day 2. PSA was assayed each C with imaging after C2 and then after every 3C.

Results: 47 of the planned 51 pts have been enrolled. Median age was 66 (51−82), Gleason score 8 (5−10), on−study PSA 91.6 ng/ml (0.15−3520), pre−study PSA doubling time 1.43 months (0.52−6.73), number of Cs 14 (1−31), and PFS was 19.3 months as of this analysis. Among 45 pts who have completed ≥2 cycles, 39 (86.7%) and 30 (66.7%) had PSA declines of ≥50% and ≥75%, respectively. Of 29 pts with measurable disease there were 2 CR, 21 PR, and 6 SD (79.3% overall RR). 10/47 pts were taken off study for radiographic disease progression and 5/47 for other reasons. Grade ≥3 toxicities included neutropenia (24/47), anemia (9/47), thrombocytopenia (5/47), weight loss (1/47), hypertension (3/47), and febrile neutropenia (4/47). Other toxicities included perianal fistula (3/47), rectal fissure (1/47), myocardial infarction (1/47), and osteonecrosis of the jaw (ONJ) (16/47, 34.0%). At the time of diagnosis of ONJ, 9/16 pts were on bisphosphonates and 3/16 had used bisphosphonates previously. Although the incidence of ONJ was higher than the 18.3% reported by Ning, a recent study of carboplatin plus weekly docetaxel reported an incidence of 29.3%.

Conclusions: Dual antiangiogenic therapy with, B and L, plus D and P was associated with high PSA (86.7%) and tumor (79.3%) responses with manageable toxicities. Further studies are underway to explore the high incidence of ONJ.

Phase II trial of the farnesyltransferase inhibitor tipifarnib plus fulvestrant in hormone receptor-positive metastatic breast cancer: New York Cancer Consortium Trial P6205

BACKGROUND

Fulvestrant produces a clinical benefit rate (CBR) of approximately 45% in tamoxifen-resistant, hormone receptor (HR)-positive metastatic breast cancer (MBC) and 32% in aromatase inhibitor (AI)-resistant disease. The farnesyltransferase inhibitor tipifarnib inhibits Ras signaling and has preclinical and clinical activity in endocrine therapy-resistant disease. The objective of this study was to determine the efficacy and safety of tipifarnib-fulvestrant combination in HR-positive MBC.

PATIENTS AND METHODS

Postmenopausal women with no prior chemotherapy for metastatic disease received i.m. fulvestrant 250 mg on day 1 plus oral tipifarnib 300 mg twice daily on days 1-21 every 28 days. The primary end point was CBR.

RESULTS

The CBR was 51.6% [95% confidence interval (CI) 34.0% to 69.2%] in 31 eligible patients and 47.6% (95% CI 26.3% to 69.0%) in 21 patients with AI-resistant disease. A futility analysis indicated that it was unlikely to achieve the prespecified 70% CBR. Tipifarnib dose modification was required in 8 of 33 treated patients (24%).

CONCLUSIONS

The target CBR of 70% for the tipifarnib-fulvestrant combination in HR-positive MBC was set too high and was not achieved. The 48% CBR in AI-resistant disease compares favorably with the 32% CBR observed with fulvestrant alone in prior studies and merit further clinical and translational evaluation.

Generation and control of cortical gamma: findings from simulation at two scales

A continuum model of electrocortical activity was applied separately at centimetric and macrocolumnar scales, permitting analysis of interaction between scales. State equations included effects of retrograde action potential propagation in dendritic trees, and kinetics of AMPA, GABA and NMDA receptors. Parameter values were provided from independent physiological and anatomical estimates. Realistic field potentials and pulse rates were obtained, including resonances in the alpha/theta and gamma ranges, 1/f(2) background activity, and autonomous gamma activity. Zero-lag synchrony and travelling waves occurred as complementary aspects of cortical transmission, and lead/lag relations between excitatory and inhibitory cell populations varied systematically around transition to autonomous gamma oscillation. Properties of the simulations can account for generation and control of gamma activity. All factors acting on excitatory/inhibitory balance controlled the onset and offset of gamma oscillation. Autonomous gamma was initiated by focal excitation of excitatory cells, and suppressed by laterally spreading trans-cortical excitation, which acted on both excitatory and inhibitory cell populations. Consequently, although spatially extensive non-specific reticular activation tended to suppress autonomous gamma, spatial variation of reticular activation could preferentially select fields of synchrony.

An outline of functional self-organization in V1: synchrony, STLR and Hebb rules

A model of self-organization of synapses in the striate cortex is described, and its functional implications discussed. Principal assumptions are: (a) covariance of cell firing declines with distance in cortex, (b) covariance of stimulus characteristics declines with distance in the visual field, and (c) metabolic rates are approximately uniform in all small axonal segments. Under these constraints, Hebbian learning implies a maximally stable synaptic configuration corresponding to anatomically and physiologically realistic ''local maps'', each of macro-columnar size, and each organized as Möbius projections of a "global map" of retinotopic form. Convergence to the maximally stable configuration is facilitated by the spatio-temporal learning rule. A tiling of V1, constructed of approximately mirror-image reflections of each local map by its neighbors, is formed. The model supplements standard concepts of feed-forward visual processing by introducing a new basis for contextual modulation and neural network identifications of visual signals, as perturbation of the synaptic configuration by rapid stimulus transients. On a long time-scale, synaptic development could overwrite the Möbius configuration, while LTP and LTD could mediate synaptic gain on intermediate time-scales.

The maximum range and timing of excitatory contextual modulation in monkey primary visual cortex

Contextual modulations of receptive field properties by distal stimulus configurations have been shown for a variety of stimulus paradigms. A survey of excitatory contextual modulation data for V1 shows the maximum scale of interactions, measured in terms of distance in V1, to be between 10 mm and 30 mm. Different types of excitatory contextual modulation in V1 occur throughout the interval of 40-250 ms after stimulus delivery. This window provides opportunity for global propagation of visual contextual information to a subset of V1 neurons, via several routes within the visual system. We propose a number of experiments and analyses to confirm the results from this empirical survey.