Cynthia, X.

534 Background: mTOR plays a critical role in promoting tumor cell growth. In preclinical studies, the anti-tumor activity of mTOR inhibitors is attenuated by feedback up-regulation of AKT mediated by IGF-1R. We designed a phase I trial to determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT) and pharmacodynamic effects of the IGF-1R antibody IMC-A12 in combination with temsirolimus (tem) in patients (pts) with metastatic breast cancer (MBC) where mTOR is frequently activated. Methods: A 3+3 phase I design was chosen. Tem and IMC-A12 were administered IV days (d) 1, 8, 15, and 22 of a 4-week cycle in pts with MBC refractory to standard therapies. Tumor response was evaluated by RECIST. Adverse events (AE) were reported using CTC v3.0. Serum IGF 1 and C-peptide levels on d2 (24h post infusion) and d8 prior to drug infusion were compared to baseline (BL) using paired t-test. Results: Of 26 pts enrolled, 4 did not complete cycle 1 due to progression (3) or co-morbid condition (1). MTD was determined from remaining 22 pts aged 34-72 (median 48) years with ECOG PS 0 (55%) or 1 (45%). 86% had ER+ cancer. Median number of regimens for MBC was 4. Two DLTs at the starting DL (DL 1) necessitated dose de-escalation of tem to 20mg (DL-1), then to 15 mg (DL-2) which was tolerable (Table). Subsequent dose escalation of IMC-A12 led to DLTs in 0 of 6 in DL-2A and 2 of 3 pts in DL-2B. The MTD was defined as DL-2A. Other AEs included gr 1/2 fatigue, neutropenia, anemia, and hyperglycemia. No CR or PR, but 4 SD lasting ≥ 4 months were observed. At DL-2, -2A and -2B, serum IGF 1 levels were significantly elevated on d2 (p <0.002) and d8 compared to BL (p <0.001), but C-peptide levels were not found to differ from BL. Conclusions: The MTD for the combination of IMC-A12 and tem in pts with MBC is lower than that observed for single agents alone. A phase II study is ongoing in MBC. The study is supported in part by ASCO CDA, Komen Craft to CXM, N01-CM62205 and N01-CM-2011-00071. [Table: see text]

Abstract BACKGROUND: nal-IRI is a liposomal formulation of irinotecan (topoisomerase-1 inhibitor). Preclinical data show that nal-IRI accumulates in BMs and prolongs survival in animal models of BM. Findings from a phase 1 expansion study (NCT01770353), evaluating patients with mBC and active BM, are reported. METHODS: This phase 1 expansion study enrolled patients with mBC who received multiple prior lines of cytotoxic therapy in the metastatic setting, including one cohort with mBC and active BM, defined as radiographic evidence of new or progressive central nervous system (CNS) metastases after radiation therapy with ≥1 lesion of ≥1 cm in the longest dimension on gadolinium-enhanced magnetic resonance imaging. Patients received nal-IRI 50 mg/m2 (free-base equivalent; FBE) every two weeks (q2w) as an intravenous infusion over 90 minutes, escalating to 70 mg/m2 FBE q2w, if tolerated. RECIST v1.1 and modified RECIST criteria were used to assses non-CNS and CNS disease, respectively. RESULTS: In total, 30 patients were enrolled (10 with active BM). Median age was 53 years (range 29–70 years) and median number of prior cytotoxic anti-cancer regimens was 3 (range 0–6); 29 patients received ≥1 dose of nal-IRI 50 mg/m2 FBE. Overall, nal-IRI monotherapy appeared to be well tolerated, and achieved ≥30% objective response rates for both CNS and non-CNS disease. Among the 10 patients with active BM, 6 achieved CNS disease control (3 partial responses [PRs] and 3 stable disease [SD]), including one patient with durable CNS SD and non-CNS PR for 2 years. Among 7 patients with serial evaluation of CNS metastases posttreatment, 6 patients achieved a reduction in target CNS lesions compared with baseline. CONCLUSION: Treatment with nal-IRI resulted in CNS disease control among 6 of 10 heavily pretreated patients with mBC and active BM. Further exploration of nal-IRI in patients with mBC and active BM is warranted.

Abstract Background nal-IRI is a liposomal formulation of irinotecan (topoisomerase-1 inhibitor), using intraliposomal stabilisation technology to enable high drug load and in-vivo stability. The expansion of Phase I NCT01770353 evaluated nal-IRI in patients (pts) with mBC. Methods This Phase I expansion study enrolled mBC pts (Cohort 1: ER+ and/or PR+ HER2 BC (C-1); Cohort 2: Triple Negative BC (TNBC, C-2); Cohort 3: BC with active Brain Metastasis (C-3)). Key inclusion criteria: ECOG ≤1; adequate organ function; received &gt;1 to ≤5 prior lines of cytotoxic therapy in metastatic setting, except TNBC pts who could have progressed within 12 months of adjuvant therapy. Pts received nal-IRI 50 mg/m2 (Free-base equivalent, FBE) q2w iv infusion, escalating to 70 mg/m2 FBE q2w, if tolerated. Results 30 pts (10 per cohort) were enrolled: 29 received &gt;1 dose nal-IRI 50 mg/m2 FBE (median age 53 yrs, range 29-70 yrs). Median number of cytotoxic therapies prior to study entry was 3. The most frequent treatment emergent adverse events (TEAEs) were gastrointestinal disorders (all cohorts, 100%), primarily diarrhea (C-1, 100% / C-2, 100% / C-3, 70%), nausea (C-1, 80% / C-2, 56% / C-3, 30%), and vomiting (C-1, 60% / C-2, 33% / C-3, 30%). The incidence of neutropenia was low (C-1, 10% / C-2, 0% / C-3, 10%), all grade 1 / 2. Most common grade 3 TEAEs were diarrhea (28%), nausea (17%), fatigue (14%), hypokalemia (10%) and asthenia (10%), with none reported as grade 4. No grade 5 TEAEs were reported. Partial response (per RECIST) was observed in 10 pts for an objective response rate (ORR) of 35% (C-1, 40% / C-2, 33%) / C-3, 30%). Stable disease was observed in 5 pts (17%). Duration of Response (median, months) was C-1, 7.5 (6.4-13.0) / C-2, 5.6 (3.7-7.4) / C-3, 4.1 (0.0-22.2, extracranial: RECIST) / C-3, 1.8 (0.0-1.9, intracranial: mRECIST). Table 1.Study Demographics, Adverse Events, and Best Overall ResponseDemographicsCohort 1ER+ and/or PR+ Breast Cancern=10Cohort 2Triple Negative Breast Cancern=10Cohort 3Breast Cancer with Active Brain Metastasisn=10Total PopulationN=30Gender, Female, n (%)10 (100%)10 (100%)10 (100%)30 (100%)Age, Years Median (range)56 (49-68)52.5 (37-70)45.5 (29-63)53 (29-70)Race, n (%)WhiteBlack/AfricanOther8 (80%)02 (20%)8 (80%)1 (10%)1 (10%)7 (70%)1 (10%)2 (20%)23(77%)2 (7%)5(16%)Months Since Metastatic diagnosis, Months Median (Range)63.7 (16-87)20.7 (0-34)32.4 (8-55)24.0 (0-87)Number of Prior Cytotoxic Anti-cancer Regimens Median (Range)3.0 (1-6)3.0 (0-5)32.4 (1-6)3.0 (0-6)Safety PopulationCohort 1ER+ and/or PR+ Breast Cancern=10Cohort 2Triple Negative Breast Cancern=9Cohort 3Breast Cancer with Active Brain Metastasisn=10Total PopulationN=29ExposureTreatment Duration, Weeks Median (range)6.1 (0-78)12.3 (0-49)13.9 (1-105)12.3 (0-105)Adverse EventsAny TEAE10 (100%)9 (100%)10 (100%)29 (100%)Grade 38 (80%)6 (67%)10 (100%)20 (69%)Grade 41 (10%)06 (60%)3 (10%)TEAE Related to nal-IRI10 (100%)8 (89%)10 (100%)28 (97%)Grade &gt; 36 (60%)3 (33%)3 (30%)12 (41%)TEAE Related to nal-IRILeading to Dose Adjustment*7 (70%)3 (33%)4 (40%)14 (48%)SAEs6 (60%)4 (44%)7 (70%)17 (59%)SAE Related to nal-IRI4 (40%)1 (11%)1 (10%)6 (21%)Duration of Objective ResponseRECIST 1.1RECIST 1.1RECIST 1.1mRECISTMonths Median (Range)7.5 (6.4-13.0)5.6 (3.7-7.4)4.1 (0.0-22.2)1.84 (0.0-1.9)Best Overall ResponseRECISTRECISTRECISTmRECISTComplete Response (CR)0000Partial Response (PR)4 (40%)3 (33%)3 (30%)3 (30%)Stable Disease (SD)03 (33%)2 (20%)3 (30%)Progressive Disease (PD)5 (50%)2 (22%)3 (30%)2 (20%)Not Evaluable (NE)1 (10%)1 (11%)2 (20%)2 (20%)Objective Response RateCR+PR(95% CI)4 (40%)12.2 -73.83 (33%)7.5-70.73 (30%)6.7-65.33 (30%)(6.7-65.3)*n=1 patient in Cohort 1 discontinued treatment due to TEAE related to treatment with nal-IRI CI, Confidence Interval; nal-IRI, Irinotecan Liposome Injection; SAE, Serious Adverse Event; TEAE, Treatment Emergent Adverse EventSystemic tumor response was evaluated according to RECIST version 1.1CNS tumor response was evaluated according to mRECIST (Anders C. et al., Breast Cancer Res Treat, 2014: 146(3):557-66) Conclusion nal-IRI monotherapy 50g/m2 FBE Q2W appears well tolerated, and achieved &gt;30% ORR for systemic and CNS disease among heavily pre-treated mBC pts regardless of receptor status. Citation Format: Jasgit Sachdev, Pamela Munster, Donald Northfelt, Hyo S. Han, Cynthia MA, Fiona Maxwell, Tiffany Wang, Bruce Belanger, Bin Zhang, Yan Moore, Carey Anders. Phase I expansion study of irinotecan liposome injection (nal-IRI) in patients with metastatic breast cancer (mBC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT048.

e12003 Background: Irinotecan liposome injection (nal-IRI) uses intraliposomal stabilisation technology to enable high drug load and in-vivo stability. This analysis characterizes the PK profile of nal-IRI in pts with mBC. Methods: The expansion of NCT01770353 enrolled 30 pts with mBC over three cohorts (Cohort 1: ER+ and/or PR+ BC [C-1]; Cohort 2: Triple Negative BC [C-2]; and Cohort 3: BC with active Brain Metastasis [C-3]). Key inclusion criteria: ECOG ≤1; adequate organ function; and >1 and ≤5 prior lines of cytotoxic therapy in metastatic setting. Most pts received nal-IRI 60 mg/m2 salt-based equivalent (50 mg/m2 free base equivalent [FBE]) or 80 mg/m2 (70 mg/m2 FBE) q2w by iv infusion, based on tolerance; 2 pts were treated at 40 mg/m2 (35 mg/m2 FBE). Plasma samples were collected over 360h across cycles 1, 2 &3, and analysed using LC-MS/MS for total irinotecan. Data were analysed by a non-compartmental approach using Phoenix Winnonlin, and were compared with values from studies in other tumor types. Results: 21 patients were evaluable for PK analysis (C-1, n=6; C-2, n=7; and C-3, n=8). No trend for accumulation was observed in cycle 2 or 3, when comparing total irinotecan Cmax & exposure (area under the curve at 168 h [AUC168]) versus cycle 1. At 40-80 mg/m2 (35-70 mg/m2 FBE), Cmax of irinotecan tended to increase proportionally with total dose, and was comparable to studies in other tumour types (see Table). Among 29 pts who received nal-IRI, partial response (per RECIST) was observed in 10 pts. The most related TEAEs (≥ 25%) were diarrhea, nausea, vomiting, hypokalaemia, decreased appetite and fatigue. Stable disease was observed in 5 pts. Conclusions: PK parameters in patients with mBC were comparable to historical studies in patients with other tumour types. The safety profile of nal-IRI monotherapy appeared consistent with gastrointestinal and blood disorders. [Table: see text]

591 Background: Both Cb and Bev demonstrate activity when combined with standard chemotherapy in TNBC. CALGB 40603 is a 2x2 randomized trial that previously demonstrated that adding Cb to NACT significantly increased pathologic complete responses in the breast/axilla (pCR), while adding Bev did not (Sikov, JCO 2015). Here we report 5-year LTOs and assess factors that influenced them. Methods: 443 patients with clinical stage II-III previously untreated TNBC received 12 weeks of paclitaxel (wP) +/- Cb then dose-dense AC, +/- Bev before surgery. The primary endpoint was pCR. Analyses of LTOs (event-free survival (EFS), distant recurrence-free interval (DRFI) and overall survival (OS)), impact of residual cancer burden and other variables were secondary. Results: Median follow-up was 5.7 years (y); 5y EFS was 70.9% (95% CI; 66.7%-75.4%), DRFI 76.3% (72.3%-80.5%) and OS 76.9% (72.9%-81.2%). Pretreatment clinical stage and achieving pCR correlated with LTOs, while age, race, subtype (basal-like vs. not) and tumor grade did not. Among pCR 5y EFS was 86.4% vs. 57.5% for non-pCR (HR 0.28, 0.19-0.43), OS was 88.7% vs 66.5% (HR = 0.28, 0.17-0.44). This relationship was similar in all trial arms. Any residual disease conferred poorer outcome; compared with pCR/Residual Cancer Burden (RCB) 0, EFS HRs were 2.29 (1.32-3.97), 3.01 (1.90-4.74), and 9.67 (5.66-16.51) for RCBI, II and III, respectively. There were no improvements in LTOs with Cb (EFS HR 0.99, 0.70-1.40) or Bev (EFS HR 0.91, 0.64-1.29). In an exploratory analysis, receipt of ≥11 doses of wP was associated with better EFS (HR 1.92, 1.33-2.77); this was particularly notable in Cb-treated arms. Conclusions: As expected, regardless of treatment arm pCR was associated with markedly better LTOs, and pts with any residual disease had significantly worse outcomes. The addition of Cb or Bev to standard NACT for TNBC did not improve LTOs in this trial, although it should be noted that the trial was not powered for this endpoint. Omission of chemotherapy doses may result in poorer outcomes, especially among Cb-treated pts, which may warrant further evaluation. Support: U10CA180821; U10CA180882; Genentech; https://acknowledgments.alliancefound.org ; NCT00861705 Clinical trial information: NCT00861705.

TPS592 Background: Persistent cell proliferation (Ki67 > 10%) on tumor biopsies as early as 2-4 weeks (wks) on neo endocrine therapy (ET) identifies resistant tumors in ~20% patients (pts) with early stage ER+ HER2- BC who are at high risk of relapse. Palbo plus ET significantly improves progression free survival in pts with ET naïve or resistant advanced ER+ HER2- BC, and is being evaluated in the adjuvant setting. However, biomarkers predictive of palbo sensitivity are unknown. Ki67 analysis of serial tumor biopsies in the neo palbo and ana (NeoPalAna) trial demonstrated that 2 wks of palbo plus ana potently inhibited Ki67 and induced complete cell cycle arrest (CCCA, Ki67≤2.7%) in tumors with high Ki67 post 4 wks ana run-in. This study is therefore aimed to prospectively investigate the biological activity of palbo plus ana in ET resistant ER+ HER2- BC. Methods: The primary objective is to assess the rate of CCCA (central Ki67 ≤2.7%) after 2 wks of neo palbo and ana. Secondary objectives include analysis of tumor biopsies to explore response biomarkers. Key inclusions include women with clinical stage 2/3 ER+ HER2- BC, central Ki67 > 10% after ≥2 wks of any neo ET, adequate organ function. Key exclusions include prior CDK 4/6 inhibitor, treatment of BC except ET, concomitant use of strong CYP3A4 inhibitor. Pts receive palbo (125mg PO daily, days 1-21, 28-day cycle), ana (1 mg PO daily) and goserelin (if premenopausal). Pts with C1D15 Ki67 > 10% will discontinue study. If C1D15 Ki67 ≤10%, pt will receive 4 cycles of treatment, and additional 10-12 days of palbo if counts normalized within 3 wks post C4D28. Following surgery, pts are eligible for 2 years of adjuvant palbo. A sample size of 37 (stage 1, n = 12, stage 2 n = 25) by simon optimal two stage phase II design will be employed to assess whether the rate of CCCA is ≤5% vs ≥20% (90% power, alpha 0.1). Stage 2 will proceed if ≥1 had CCCA in stage 1. If ≤3 of 37 had CCCA, this regimen will be considered ineffective. The study is active and has enrolled 4 pts. Clinical trial information: NCT01723774.