Erlichman, Charles

259 Background: Vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) are produced by bladder cancer cell lines in vitro and expressed in human tumor tissues. Preclinical studies have also shown that bladder cancer cell lines express VEGF receptor 1 and 2 on their surface membrane. Pazopanib is a vascular endothelial receptor tyrosine kinase inhibitor with anti-angiogenesis and antitumor activity in several preclinical models. A two-stage phase II study was conducted to assess the activity and toxicity profile of pazopanib administered to patients with metastatic, urothelial carcinoma. Methods: Patients with one prior systemic therapy for recurrent, metastatic urothelial carcinoma were eligible. Patients received pazopanib at a dose of 800 mg orally daily for 4 week cycle. Results: Nineteen patients were enrolled. Median age was 66 years, with > 89% of patients presenting poorly differentiated bladder cancer. Adverse event data is available on 18 patients. No grade 4 or 5 events have been experienced. Nine patients have experienced 11 grade 3 adverse events of which 7 were deemed at least possibly related to treatment. Most common toxicities were anemia, thrombocytopenia, leucopenia and fatigue. For stage 1, none of the first 16 evaluable patients were deemed success (CR or PR) by the RECIST criteria during the first four 4-week cycles of treatment. Median progression- free survival was 1.9 months. This met the futility stopping rule of interim analysis, and therefore, the trial was recommended to be permanently closed. Correlative studies including measurement of VEGF levels in archived tissues and blood are pending. Conclusions: Pazopanib did not show activity in urothelial carcinoma patients. The role of anti-VEGF therapies in urothelial carcinoma may need further evaluation in rational combination strategies. [Table: see text]

260 Background: Recent placebo-controlled phase III trials of the mTOR inhibitor everolimus and the VEGF/ PDGF receptor inhibitor sunitinib in PNET noted improved progression-free survival (PFS). However, objective response rates (RR) with these agents are <10%. Preclinical studies suggest enhanced anti-tumor effects with combined mTOR and VEGF targeted therapy. Methods: We conducted a phase II trial of the mTOR inhibitor TEM (25 mg IV q week) and the VEGF-A monoclonal antibody BEV (10 mg/kg IV q 2 weeks) in patients (pts) with well or moderately differentiated PNET and progressive disease by RECIST within 7 months of study entry. Co-primary endpoints were RR and 6-month PFS. Planned enrollment is 50 patients, with interim analysis after the first 25 evaluable pts. Pts had no prior mTOR or VEGF targeted agents, ECOG PS 0-1, and adequate hematologic and organ function. Continued octreotide was allowed, but not required. Prior interferon, embolization, and ≤ 2 chemotherapy regimens were allowed. Results: Confirmed PR was documented in 11 of the first 25 (44%) evaluable patients. 20 of 25 (80%) patients were progression-free at 6 months. Both endpoints exceeded pre-defined criteria to continue enrollment. For 35 evaluable patients, the most common grade 3-4 adverse events attributed to therapy were leukopenia (12%), hypertension (12%), hyperglycemia (12%), mucositis (9%), and fatigue (9%). Conclusions: The combination of TEM/BEV has substantial activity in a multi-center phase II trial with RR of 44%, well in excess of single targeted agents in PNET. 6-month PFS was a notable 80% in a population of patients with RECIST criteria progression within 7 months of study entry. Accrual is ongoing. Supported by NCI N01 Contracts: 662205, 62203, 62208, 62209, 62206, 62204, 62207, 62201.

259 Background: Belinostat is a novel histone deactylase inhibitor which demonstrates preclinical activity in HCC. We report the results of a phase I/II study on belinostat in patients (pts) with unresectable HCC. Methods: Major eligibility criteria included histologically confirmed HCC not amenable to curative treatment; PS ≤ 2; adequate organ function; prior systemic therapy was allowed. In the phase I portion, belinostat was given i.v. on D1-5 every 3 weeks with dose levels of 600, 900, 1200 and 1400 mg/m2/day. In the phase II portion, belinostat was tested at the MTD. Primary endpoint was PFS and secondary endpoints were RR according to RECIST and OS. CT assessment was done every 8 weeks. Results: Phase I portion: a total of 18 pts were accrued; no DLTs were observed at 1400mg/m2/day for 5 days, and this dose was selected for phase II development. Phase II portion: 42 pts were accrued; Median age = 57.5 years; 41 had Child’s A function, and 24 pt had ECOG 0. Sixteen (38%) had previous systemic therapy, and 21 (50%) had previous transarterial therapy. Median follow-up was 20.0 months. The PR and SD rate was 2.4% (1/42) and 45.2% (19/42). Median PFS was 2.64 months (95%C.I. 1.55-3.17) and OS was 6.60 months (95%C.I. 4.53-11.60). Grade 3 or higher toxicities (>5% rate) were abdominal pain (9.5%), (9.5%) hyperbilirubinemia (9.5%), raised ALT (9.5%); anemia (7.1%) and vomiting (7.1%). Conclusions: Belinostat demonstrates disease stabilization in a predominantly pretreated population of pts with unresectable HCC with an acceptable safety profile. Further randomized studies are warranted.Supported in part by N01-CM-62205.

Abstract Background: The combination of a microtubule stabilizing agent and an mTOR inhibitor has been identified as a synergistic combination in preclinical models. Additional studies have further evaluated the impact of treatment sequence with paclitaxel and rapamycin where administration of rapamycin after paclitaxel was associated with synergy. In our preclinical studies, apoptosis was greater with the combination of ixabepilone and temsirolimus than with either single agent. Thus, a Phase I study of the combination of Ixabepilone (IXB) and Temsirolimus (TEM) was performed to determine the maximum tolerated dose (MTD), describe the toxicity profile and characterize the pharmacokinetics of each agent in patients with advanced cancer. Methods: Eligible patients included adults with a histologically confirmed solid tumor malignancy that was metastatic or unresectable who have received ≤ 2 chemotherapy regimens and had ECOG PS ≤ 2 with adequate bone marrow, renal and hepatic function. Using a standard 3+3 design, patients were treated with IXB IV over 3 hours on day 1 and TEM IV over 0.5 hours on days 2 and 9 (schedule A) or days 1 and 8 (schedule B) every 21 days. Pharmacokinetics (PK) was performed in patients on schedule B. Results: 22 evaluable patients were enrolled between August 24, 2011 and November 7, 2014. The final 7 patients were treated on schedule B. Patients were treated at 3 dose levels of IXB (mg/m2)/TEM (mg): DL1- 24/15 (A- 6 pts, B- 2 pts); DL2- 32/15 (A- 3 pts, B- 5 pts); DL3- 32/20 (A- 6 pts). One patient had DLT (grade 3 hypophosphatemia) and 1 patient expired due to disease progression in DL1A. No DLTs were seen in DL2A. The dose was escalated to DL3 and 1 patient had DLT (grade 3 hypokalemia). Following a change to schedule B, 5 patients were enrolled to DL2B and 1 experienced DLT (grade 4 neutropenia, grade 4 thrombocytopenia, grade 4 sepsis). The dose was reduced to DL1B and 2 more patients were enrolled, both of whom experienced DLTs (grade 5 bronchopulmonary hemorrhage and grade 4 neutropenia). Grade 4 events considered at least possibly related to treatment occurred in 6 of 22 patients (27%) and included cardiac arrest, dyspnea, hypokalemia, hypoxia, multi-organ failure, decreased platelets, acute renal failure, neutropenia, neutropenic fever, sepsis, and decreased WBCs. Patients received a median of 4 cycles (range, 1-10+). Partial response was noted in 1 patient and stable disease was noted in 11 patients. One patient remains on treatment after 11 cycles. IXB (plasma), TEM (whole blood) and sirolimus (whole blood) concentrations were measured by a sensitive, specific lc/ms/ms assay. A 24 and 32 mg/m2 IXB dose yields Cmax of 159 and 312 ng/ml, respectively. The IXB CLp and t1/2 values were 31 L/h and 76 h, respectively. The Cmax, Cl and t1/2 values after a 15 mg TEM dose were 518 ng/ml, 6.4 L/h and 11 h, respectively. The Cmax and t1/2 values of sirolimus after a 15 mg TEM dose were 37.6 ng/ml and 49 h, respectively. The PK of IXB and TEM in combination were similar to those reported for each drug alone. Conclusions: The reasons for the unpredictable, severe toxicity of the IXB/TEM combination are unclear. The MTD could not be determined, and enrollment was discontinued. This trial exemplifies challenges associated with development of drug combinations with mTOR inhibitors. Supported in part by UM1 CA186686 and P30 CA15083. Clinical trial information: NCT01375829 Citation Format: Joel M. Reid, Michael E. Menefee, Felix Boakye-Agyeman, Chad A. Walden, Charles Erlichman, Keith C. Bible. Phase I and pharmacokinetic study of ixabepilone and temsirolimus in adult patients with advanced solid tumors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B113.

Abstract Background: AI's are more effective than TAM in ER+ breast cancer. In AI refractory MBC, the response rate to TAM is 0% (Osborne 2011). Z-Endx is an active metabolite of TAM and among TAM treated women in the adjuvant and metastatic settings, reduced CYP2D6 metabolism and low Endx concentrations (Css &lt;20 nM) have been associated with increased likelihood of disease recurrence. Preclinical studies have demonstrated greater Z-Endx exposure and anti-tumor activity with oral Z-Endx compared to equivalent doses of oral TAM (Reid 2014) Methods: We conducted a phase I trial to determine the maximum-tolerated dose (MTD) and evaluate the toxicities, clinical activity, and pharmacokinetics (PK) of Z-Endx in patients (pts) with ER+, AI refractory MBC. Unlimited prior endocrine regimens were allowed. An accelerated titration schedule was applied (2 pts/dose level) until moderate toxicity or DLT, followed by a 3+3 design and then to expansion cohorts (40, 80, and 100 mg/day). Z-Endx was administered orally once daily (28 day cycle). Eye exams were performed at baseline, and end of cycles 2 and 6. PK was performed during cycle 1 and prior to subsequent cycles. For pts in the expansion cohorts, tumor biopsies were obtained at baseline for DNA sequencing (Foundation Medicine). Plasma cholesterol levels were obtained at baseline and after 1 cycle. Results: From March 2011 to Dec 2014, 41 pts (38 evaluable), median age 60, received Z-Endx once daily encompassing 7 dose levels (20-160 mg/daily). The median number of prior hormonal regimens was 2 and 3 for the dose escalation and expansion cohorts, respectively. Dose escalation was stopped at 160 mg/day given MTD not reached and attainment of mean Endx Css of 3.6 uM. Cycle 1 DLT (PE) was observed in one patient (60 mg). No eye toxicity was observed. PK demonstrated mean Endx Css of &gt; 1 uM at all dose levels ≥ 40 mg/day. Antitumor activity was observed at multiple dose levels including 3 confirmed partial responses and an additional 7 with stable disease for ≥6 cycles. Of these 10 pts, 9 had prior progression on both AI and fulvestrant and 3 additionally on TAM. After 1 cycle, total and LDL cholesterol decreased &gt; 20 points in 54% and 40% of pts, respectively. Tumor sequencing in the expansion cohorts (n=14) did not identify ESR1 mutations; however, ESR1 amplification was identified in 1 pt with prolonged stable disease (&gt;200 days). Of 6 pts with rapid progression (≤2 cycles), 4/6 had either CCND1 amplification (n=1) or at least one of the following activating mutations: ERBB2 L755S (n=1), AKT1 E17K (n=1), MTOR E1799K (n=1). Conclusions: The direct administration of Z-END provides substantial drug exposure, acceptable toxicity, and "proof of principle" antitumor activity in endocrine resistant MBC. While the MTD was not determined, the goal of achieving Endx Css concentrations of &gt; 1 uM was achieved. Tumor sequencing identified pts with predicted and confirmed endocrine resistance. A randomized phase II comparing endoxifen (80 mg/day) with TAM in AI refractory MBC was recently activated (NCT02311933). Supported in part by CA 133049, CA186686, CA15083, CA116201, and CA15083. Citation Format: Goetz MP, Suman VJ, Reid JM, Northfelt DW, Mahr MA, Dockter T, Kuffel M, Buhrow SA, Safgren SL, McGovern RM, Collins JM, Streicher H, Hawse JR, Haddad TC, Erlichman C, Ames MM, Ingle JN. Final results of a first-in-human phase I study of the tamoxifen (TAM) metabolite, Z-Endoxifen hydrochloride (Z-Endx) in women with aromatase inhibitor (AI) refractory metastatic breast cancer (MBC) (NCT01327781). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD2-03.

Abstract Background Activating mutations in PIK3CA occur in approximately 40% ER+BC. MK-2206 (M), a pan-AKT inhibitor, induced apoptosis of ER+ BC under estrogen deprivation in preclinical studies. We conducted this neoadjuvant trial to determine the pathologic complete response (pCR) rate of M plus anastrozole (A) for PIK3CA mutant (Mut) ER+ BC. Methods This single arm open label study of M+A used a 2-stage Simon phase II design (stage 1, n=16; stage 2, n=13, alpha=0.10, power=0.90) to test whether pCR rate &lt;1% (based on historical data with A alone), against the alternative that pCR rate ≥15% in PIK3CA Mut ER+ BC. At least 1 pCR in stage 1 was required to proceed to stage 2. Eligible patients (pts) with clinical stage II or III ER+HER2- BC were pre-registered and proceeded to a research tumor biopsy for PIK3CA sequencing, followed by treatment with daily A monotherapy for 28 days (cycle 0). Pts with PIK3CA Mut BC were subsequently registered, underwent a second biopsy, and started M (150mg PO weekly) with daily A on cycle 1 day 1 (C1D1) for a maximum of four 28-day cycles followed by surgery. Goserelin was added for premenopausal pts. A tumor biopsy on C1D17, 17 days post the start of M, was performed. Those with C1D17 Ki67 &gt;10% discontinued study treatment. pCR was defined as no invasive cancer in the breast and the lymph nodes. Tumor specimens collected at all timepoints are being analyzed for markers of proliferation, apoptosis, and PI3K pathway activity, gene expression microarray, intrinsic subtypes, and next generation sequencing of 83 genes. Results Of the 51 pts pre-registered, 35 pts did not register due to no PIK3CA mutation (n=22), inadequate specimen for testing (n=6), physician/pt decision (n=7). The remaining 16 pts (median age: 58, range: 40-77 years) received combination therapy. Three pts did not complete 4 cycles due to C1D17 Ki67 &gt;10% (n=2) and intolerability (grade (Gr) 4 transaminase elevation in C1, n=1). Other severe toxicities possibly related to M included Gr 3 rash (25%) and pruritus (12.5%). Of the 13 pts completed study therapy and underwent surgery, all had residual disease in the breast and 7 also had positive nodes. Table 1 summarized changes in Ki67 during treatment. ComparisonsnAbsolute changes in Ki67 median (range)Wilcoxon signed rank p-valueC1D1 relative to pre-registration11-17.0% (-49.8 to 4.1%)0.0020C1D17 relative to pre-registration14-16.4% (-51.4 to 4.1%)0.0004C1D17 relative to C1D112-1.5% (-18.6 to 15.8%)0.9697C1D1, biopsy post 28 days of A alone; C1D17 biopsy post 17 days on combination therapy Although Ki67 levels post A monotherapy (C1D1) or M+A (C1D17) were significantly lower than that of pre-registration samples, Ki67 did not differ between C1D17 and C1D1 samples. Other correlative studies are ongoing and results will be presented. Conclusion Despite the small sample size, biomarker analysis on serial biopsy specimens demonstrated that M+A is unlikely to be more effective than A alone in PIK3CA Mut ER+ BC. This trial demonstrated the feasibility of genomic sequencing for pt selection and the value of a small, well-designed proof-of-principle neoadjuvant trial for the evaluation of targeted agents. Citation Format: Ma CX, Suman VJ, Goetz M, Northfelt D, Burkard M, Ademuyiwa F, Naughton M, Margenthaler J, Aft R, Gray R, Tavaarwerk A, Wilke L, Haddad T, Moynihan T, Loprinzi C, Hieken T, Hoog J, Guo Z, Han J, Vij K, Mardis E, Sanati S, Al-Kateb H, Doyle L, Erlichman C, Ellis MJ. A phase II neoadjuvant trial of MK-2206, an AKT inhibitor, in combination with anastrozole for clinical stage 2 or 3 PIK3CA mutant estrogen receptor positive HER2 negative (ER+HER2-) breast cancer (BC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-13-04.

Abstract Purpose: PI3K/AKT pathway activation is an important endocrine resistance mechanism in estrogen receptor–positive (ER+) breast cancer. After promising preclinical modeling of MK-2206, an allosteric pan-AKT inhibitor, with either estrogen deprivation or fulvestrant, we conducted a phase I trial in patients with metastatic ER+HER2− breast cancer to determine the recommended phase II treatment dose (RPTD) of MK-2206 when combined with either anastrozole, fulvestrant, or anastrozole/fulvestrant. Experimental Design: ER+ breast cancer cell lines were exposed in vitro to MK-2206 plus estrogen deprivation with or without fulvestrant and monitored for apoptosis. A standard 3+3 design was employed to first determine the maximum tolerated dose (MTD) of MK-2206 plus anastrozole based on cycle 1 toxicity. Each cycle was 28 days. The RPTD was determined on the basis of toxicities observed at MTD level during the first 3 cycles. Subsequent patients received MK-2206, at the RPTD determined above, plus fulvestrant or anastrozole/fulvestrant to define RPTD for these additional regimens. Results: MK-2206 induced apoptosis in parental ER+ but not in long-term estrogen-deprived cell lines, for which fulvestrant was required for apoptosis induction. Thirty-one patients enrolled. The RPTD was defined as MK-2206 150 mg orally weekly with prednisone prophylaxis for each combination. Grade 3 rash was dose limiting. 42% (95% CI, 23%–63%) patients derived clinical benefit without progression within 6 months. Response was not associated with tumor PIK3CA mutation. Conclusions: MK-2206 plus endocrine treatments were tolerable. MK-2206 in combination with anastrozole is being further evaluated in a phase II neoadjuvant trial for newly diagnosed ER+HER2− breast cancer. Clin Cancer Res; 22(11); 2650–8. ©2016 AACR. See related commentary by Jansen et al., p. 2599