Strand, Carrie

e22020 Background: The combination of nab-paclitaxel (NP) and bevacizumab (BEV) in patients with MM has shown promising clinical activity. AB160 is a 160 nm nano-immunoconjugate of NP nanoparticles non-covalently coated with BEV for targeted delivery into high VEGF expressing tissues. Preclinical data showed that AB160 improved tumor targeting/ tumor inhibition more than NP followed by BEV. Methods: A 3+3 phase I trial was conducted in patients (pts) with MM who had prior systemic treatment for metastatic disease to determine the maximum tolerated dose of AB160 administered intravenously on days 1, 8 and 15 of a 28-day cycle. Dose level 1 (DL1) was 125 mg/m2 NP /50 mg/m2 BEV. Dose limiting toxicities (DLT) included grade (G) 4 neutropenia or anemia, PLT < 25,000, serum creatinine ≥ 2 times baseline, G2-4 neurologic toxicity or G3-4 non-hematologic toxicities. Tumor evaluations (RECIST) were conducted every 8 weeks. Treatment continued until progression or intolerability. Results: 21 pts (11 ♀) aged 36-78 years old were enrolled. One of the first 3 pts on DL1 developed a G2 colonic perforation; this was considered a DLT. One of the next 3 pts on DL1 had a DLT: G4 neutropenia. Of the 3 pts on DL-1 (100 mg/m2 NP/40 mg/m2 BEV), 2 had no DLTs and 1 died of sepsis after C1D1 dose. Enrollment was suspended until an amendment modifying the eligibility criteria was approved by the IRB. The trial reopened. One of the 4 pts on DL-1 and 1 of the 5 pts on DL1 had a DLT: G3 pain and G3 fatigue, respectively. Enrollment ended after 2 of the 3 pts on DL2 (150 mg/m2 NP/ 60 mg/m2 BEV) developed G4 neutropenia. Thus, MTD is DL1. A median of 3 cycles was administered. Treatment ended due to progression (9), intolerability (9), refusal (2) and death (1). There were no objective tumor responses. Common G3-4 toxicities were: neutropenia (33%) and thromboembolic events (19%). Conclusions: AB160 was found to have insufficient clinical benefit in patients with previously treated MM to justify further development. However, parallel phase I testing in gynecologic cancers suggests clinical benefit (abstract #300225). Clinical trial information: NCT02020707.

e18097 Background: AB160 is a 160 nm nano-immunoconjugate consisting of nab-paclitaxel (NP) nanoparticles non-covalently coated with bevacizumab (BEV) for targeted delivery into tissues expressing high levels of vascular-endothelial growth factor (VEGF). Both taxanes (GOG-0129C, GOG-0126R, GOG-0127V) and BEV (GOG-0229E, AURELIA, GOG-0227C) have demonstrated clinical activity in previously treated metastatic endometrial cancer (EC), ovarian cancer (OC), and cervical cancer (CC), respectively. Methods: A 3+3 phase I trial was conducted in patients with EC, platinum-resistant OC and CC who had prior systemic treatment for metastatic disease to determine the maximum tolerated dose of AB160 administered intravenously on days 1, 8 and 15 of a 28-day cycle. The starting dose level (DL1) was NP at 125 mg/m2 with BEV at 50 mg/m2. There were 2 higher dose levels: DL2 (NP at 150 mg/m2 with BEV at 60 mg/m2) and DL3 (NP at 175 mg/m2 with BEV at 70 mg/m2). Dose limiting toxicities (DLT) included grade (G) 4 neutropenia or anemia, PLT < 25,000, serum creatinine ≥2 times baseline, G2-4 neurologic toxicity or G3-4 non-hematologic toxicities. Disease evaluations were conducted after every 2 treatment cycles using RECIST criteria. Patients were treated until disease progression or intolerability. Samples were collected for pharmacokinetic (PK) studies. Results: Nine women 41 – 74 years of age (median 57) have enrolled (5 with EC and 4 with OC); data are available for the first 8. No DLTs have been observed among the 3 women enrolled on DL1, 3 women on DL2, and 2 women on DL3. All 3 patients on DL3 continue on treatment. The other 6 patients have discontinued due to adverse reactions (3), progression (2), and patient choice (1). The median number of cycles administered is 6 (4-14). The most common severe (G3/4) toxicities include neutropenia (37.5%) and leukopenia (25%). There have been 5 partial responses (62.5%): 1 on DL1 and 2 each on DL2 and DL3. PK evaluation is pending. Conclusions: AB160 therapy is safe and demonstrates promising clinical activity in patients with previously treated metastatic gynecologic malignancies. Further clinical testing is being pursued in this patient population. Clinical trial information: NCT02020707.

e18506 Background: Sapanisertib (SAP) is an oral small molecule dual mTOR complex 1 and 2 (TORC1/2) inhibitor that showed activity in lymphoid neoplasms. It blocks a feedback loop involving mTORC2 activation when TORC1 is selectively inhibited (Yun S et al, Blood 2016). SAP induces apoptosis of malignant lymphoid cells in vitro and in xenografts, with greatest effects in ALL cell lines. We aim to assess potential efficacy of SAP when used as a single agent in relapsed/refractory ALL. Methods: Adults (age ≥18) with ECOG performance status 0-2 and normal organ function (creatinine/total bilirubin <1.5 upper limit of normal) with relapsed and/or refractory ALL (B- or T-cell) were enrolled. Newly diagnosed patients (pts) unfit for aggressive treatments and BCR-ABL+ ALL were allowed if there was no suitable standard treatment. SAP was given at 3 mg orally daily for 21 days every 28 days. Dose escalation was allowed after 2 cycles. Hydroxyurea and corticosteroids were not allowed after starting SAP. The primary end point was complete remission (CR) or CR with incomplete count recovery (CRi). This is a one stage Simon design study with interim analysis after 11 pts completed treatment. Enrollment was continued until interim analysis was done. Results: A total of 16 pts were enrolled on the study with a median age of 46 years old, 56% being males. 1/16 (6%) was treatment naïve. Median number of prior therapies is 3 (range, 1-9). The mean duration on SAP was 14.7 days (range 1-22). Three pts were able to start cycle 2. Safety was evaluable in 14 pts. All 14 pts had at least one G3 AE, while 10 pts had at least one G4 AE. G3/4 related non-hematological adverse events (AE) included 3 mucositis, 1 hepatic failure, 1 sepsis, 3 hyperglycemia, 1 anorexia, 1 seizure, 1 confusion, and 1 pneumonitis. One pt had G5 AE with malignancy. G3/4 hematological AEs included 2 with lymphopenia, 1 thrombocytopenia, 3 with leukopenia, and 1 with neutropenia. No pt achieved a CR/CRi. Best response was stable disease in 2 (12.5%) pts. Five pts had progressive disease while 9 were not evaluable because of early removal. Conclusions: SAP exhibited the expected safety profile. Although several pts developed cytopenias on drug, there was no evidence of clinically meaningful single-agent activity against ALL. Analysis of paired bone marrow aspirates from this trial is being performed to assess whether mTOR was substantially inhibited at therapeutically achievable drug concentrations. Clinical trial information: NCT02484430.

Abstract Purpose: The surface receptor MET is highly expressed on primary uveal melanoma; MET inhibitors demonstrated early clinical signals of efficacy in slowing uveal melanoma growth. The primary objective of our study was to compare the progression-free survival rate at 4 months (PFS4) of patients with uveal melanoma treated with cabozantinib or chemotherapy. Patients and Methods: Patients with metastatic uveal melanoma and RECIST measurable disease were randomized 2:1 to receive either cabozantinib (arm 1) versus temozolomide or dacarbazine (arm 2) with restaging imaging every two cycles. Cross-over from arm 2 to cabozantinib after progression was allowed (arm 2X). Available tumor specimens were analyzed by whole-exome sequencing (WES) and results were correlated with outcome. Results: Forty-six eligible patients were accrued with 31, 15, and 9 in arms 1, 2, and 2X, respectively. Median lines of prior therapy, including hepatic embolization, were two. Rates of PFS4 in arm 1 and arm 2 were 32.3% and 26.7% (P = 0.35), respectively, with median PFS time of 60 and 59 days (P = 0.964; HR = 0.99). Median overall survival (OS) was 6.4 months and 7.3 months (P = 0.580; HR = 1.21), respectively. Grade 3–4 Common Terminology Criteria for Adverse Events were present in 61.3%, 46.7%, and 37.5% in arms 1, 2, and 2X, respectively. WES demonstrated a mean tumor mutational burden of 1.53 mutations/Mb and did not separate OS ≤ or &gt;1 year (P = 0.14). Known mutations were identified by WES and novel mutations were nominated. Conclusions: MET/VEGFR blockade with cabozantinib demonstrated no improvement in PFS but an increase in toxicity relative to temozolomide/dacarbazine in metastatic uveal melanoma.

9506 Background: Survival is poor in mUM and treatment options are limited. MET kinase is over-expressed on UM and the MET inhibitor cabo showed activity in an early trial. Methods: A091201 was a 2:1 randomized phase II study testing progression-free survival (PFS) of cabo (60 mg daily) vs chemo (DTIC/TMZ). We studied baseline metastatic tumor samples (n = 19; 1 lung, 18 liver) by whole exome sequencing (WES) and RNAseq. We correlated data with OS and made comparisons for mUM vs. primary tumors from TCGA (n = 80). Results: 46 patients were accrued with 96% and 63% with liver metastases and elevated LDH, respectively. Toxicities were similar to prior reports of cabo and chemo. The trial stopped at interim analysis due to no difference in PFS (p = 0.964; HR = 0.99) or OS (p = 0.580; HR = 1.21). WES showed tumor mutational burden of 46±4 (mean±SEM) and did not separate OS at 1 year (p = 0.14, two-sided Wilcoxon rank sum test) in A091201. Recurrent known mutations included GNAQ/11, SF3B1, BAP1; novel mutations included GOLGA6L10, PKD1L3, and FAM228B. Gene expression signatures differed significantly between A091201 and TCGA cohorts including MET signaling (p = 7.87e-22), T cell-inflamed (p = 0.004), homologous recombination deficiency (p = 0.004), proliferation (p = 0.009) and hypoxia (p = 5.2e-10) (two-sided Student’s t-test). Tumor immune cell enrichment analysis revealed significant differences with lower M1:M2 macrophage (p = 1.2e-10) and higher Tregs (p = 6.0E-21) in mUM relative to TCGA (two-sided Wilcoxon rank sum test). Epithelial-mesenchymal transition gene expression signature was significantly associated with worse OS in A091201 (p = 0.02) with angiogenesis signature trending toward significance (p = 0.21) (log-rank test). OS separated by differentially expressed genes with OS ≤ 1 year associating with increased expression of the angiogenesis/immune-associated molecule neuropilin 1. Conclusions: These results provide insights between primary and mUM indicating potential novel therapeutic approaches. Support: U10CA180821, U10CA180882, T32GM007019, Exelixis. https://acknowledgments.alliancefound.org ; Clinical trial information: NCT01835145.

A vaccine that could expand melanoma-specific T cells might reduce the risk of recurrence of resected melanoma and could provide an alternative or adjunct to standard immunotherapy options. We tested the safety and immunogenicity of a vaccine coupling a melanoma-associated peptide with a xenogenic peptide (to promote epitope spreading) and/or resiquimod (to activate antigen-presenting cells). HLA-A2-positive patients with resected stage II, III, and IV melanoma were assigned to treatment on one of three schedules. All patients received three subcutaneous doses of the peptide MART-1a mixed with Montanide. In addition, patients on schedule 1 received the xenoantigen peptide Gag267–274, patients on schedule 2 received topical resiquimod, and patients on schedule 3 received both Gag267–274 and resiquimod. Blood samples were tested for the frequency of antigen-specific T cells by tetramer assay, as well as immune cell subtypes and plasma cytokine levels. Patients enrolled from October 2012 to December 2014, with 10 patients enrolling to each schedule. The most common adverse events were injection site reaction (26 patients) and fatigue (15 patients). Tetramer analysis revealed antigen-specific responses (defined as doubling of MART-1a-specific T cells from pretreatment to post-treatment) in 20, 60, and 40% of patients treated on schedules 1, 2, and 3, respectively. Vaccine treatment consisting of MART-1a peptide, Gag267–274, Montanide, and topical resiquimod was well-tolerated. The addition of the Gag267–274 xenoantigen was not associated with an increase in the response to MART-1a, whereas use of topical resiquimod was associated with a higher frequency of MART-1a-specific T-cell responses that did not meet statistical significance.

33 Background: Pathologic complete response (pCR) is an important prognostic indicator and surrogate endpoint, particularly for patients with hormone receptor-negative breast cancer. Previous studies have suggested differential response to pre-operative therapy by age and body mass index (BMI), though no association has been seen by race. We assessed associations of age at diagnosis, BMI and race with pCR accounting for breast cancer subtype. Methods: Women enrolled in four clinical trials of neoadjuvant chemotherapy (CALGB 40601 and 40603; ACOSOG Z1031 and Z1041) were eligible for this analysis. Age, race, and BMI were abstracted from patient records at baseline. Tumor subtype was assessed using immunohistochemical staining and/or fluorescence in situ hybridization. Logistic regression models were used to determine the association of race/ethnicity and age at diagnosis with pCR, the absence of residual invasive disease in the breast after neoadjuvant chemotherapy, adjusting for subtype (HER2+, ER+/ HER2-, triple negative), age, study arm, lymph node status, tumor size, and tumor grade. Results: 1,146 women with a mean age of 51.5 years were included. 156 (13.6%) were of black race. 590 (51.5%) of tumors were HER2+, 169 (14.7%) were ER+/HER2- and 387 (33.8%) were triple negative. In multivariate analyses controlling for tumor characteristics and other factors, black race (OR: 1.07, 95% CI: 0.67-1.70), age (OR: 0.99, 95% CI: 0.97-1.00) and BMI (OR: 0.99, 95% CI: 0.96-1.01) were not significant predictors of pCR. Similar associations we observed when stratified by subtype, and we found no interaction between age and black race (p=0.06), black race and BMI (p=0.54) or age and BMI (p=0.73). Conclusions: After accounting for tumor characteristics, we observed no differences in pCR rates according to race, age or BMI.