Multidimensional Molecular Profiling of Metastatic Triple-Negative Breast Cancer and Immune Checkpoint Inhibitor Benefit

PURPOSE

In metastatic triple-negative breast cancer (mTNBC), consistent biomarkers of immune checkpoint inhibitor (ICI) therapy benefit remain elusive. We evaluated the immune, genomic, and transcriptomic landscape of mTNBC in patients treated with ICIs.

METHODS

We identified 29 patients with mTNBC treated with pembrolizumab or atezolizumab, either alone (n = 9) or in combination with chemotherapy (n = 14) or targeted therapy (n = 6), who had tumor tissue and/or blood available before ICI therapy for whole-exome sequencing. RNA sequencing and CIBERSORTx-inferred immune population analyses were performed (n = 20). Immune cell populations and programmed death-ligand 1 expression were assessed using multiplexed immunofluorescence (n = 18). Clonal trajectories were evaluated via serial tumor/circulating tumor DNA whole-exome sequencing (n = 4). Association of biomarkers with progression-free survival and overall survival (OS) was assessed.

RESULTS

Progression-free survival and OS were longer in patients with high programmed death-ligand 1 expression and tumor mutational burden. Patients with longer survival also had a higher relative inferred fraction of CD8+ T cells, activated CD4+ memory T cells, M1 macrophages, and follicular helper T cells and enrichment of inflammatory gene expression pathways. A mutational signature of defective repair of DNA damage by homologous recombination was enriched in patients with both shorter OS and primary resistance. Exploratory analysis of clonal evolution among four patients treated with programmed cell death protein 1 blockade and a tyrosine kinase inhibitor suggested that clonal stability post-treatment was associated with short time to progression.

CONCLUSION

This study identified potential biomarkers of response to ICIs among patients with mTNBC: high tumor mutational burden; presence of CD8+, CD4 memory T cells, follicular helper T cells, and M1 macrophages; and inflammatory gene expression pathways. Pretreatment deficiencies in the homologous recombination DNA damage repair pathway and the absence of or minimal clonal evolution post-treatment may be associated with worse outcomes.

Abstract CT129: A multicohort, open-label, phase 2 basket study of the coformulation of vibostolimab with pembrolizumab, with or without other anticancer therapies, in select solid tumors

Background: T-cell immunoreceptor with Ig and ITIM domains (TIGIT) is coexpressed with PD-1 on both CD4+ and CD8+ T cells in tumors. Preclinical models and early clinical data have shown enhanced antitumor activity when an anti-TIGIT antibody is co-administered with an anti-PD-1 antibody. The efficacy and safety of a novel coformulation of the anti-TIGIT antibody vibostolimab and the anti-PD-1 antibody pembrolizumab (vibostolimab/pembrolizumab), alone or in combination with other anticancer therapies, will be investigated in select advanced solid tumors in a multicohort, open-label, phase 2 basket trial (NCT05007106).

Trial Design: Key eligibility criteria are histologically or cytologically confirmed advanced (locally recurrent unresectable or metastatic) solid tumor naive to anti-PD-1/PD-L1 therapy (Table 1). Patients will be assigned to treatment randomly (cohort A1) or nonrandomly (cohorts A2-G) by tumor type and biomarker status (Table 1). All patients will be treated until disease progression, unacceptable toxicity, patient/physician decision to withdraw, or 35 cycles of vibostolimab/pembrolizumab or pembrolizumab alone. Primary end points are objective response rate (all cohorts) and progression-free survival (PFS; cohort A1) per RECIST v1.1 by blinded independent central review (cohort A1) or investigator (cohorts A2-G). Secondary end points include PFS per RECIST v1.1 assessed by the investigator (cohorts A2-G), quality of life (cohort A1), and duration of response, overall survival, and safety (all cohorts). Enrollment is ongoing.

Table 1. Patient Population and Treatment by Cohort Cohort Patient Population Treatmenta A1b PD-L1-positive (CPS ≥1) cervical cancer that progressed on ≥1 line of therapy Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV Pembrolizumab 200 mg Q3W IV A2 PD-L1-negative (CPS <1) cervical cancer that progressed on ≥1 line of therapy Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV B1 dMMR endometrial cancer that progressed after 1 prior systemic, platinum-based chemotherapy Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV B2 pMMR endometrial cancer that progressed after 1 prior systemic, platinum-based chemotherapy Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV + lenvatinib 20 mg QD PO C PD-L1-positive (CPS ≥1) head and neck squamous cell carcinoma (previously untreated) Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV D Biliary tract cancer that progressed after 1 prior systemic therapy Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV E Esophageal cancer (previously untreated) Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV + 5-FU 800 mg/m2/day on days 1-5 Q3W IV + cisplatin 80 mg/m2 Q3W IV for ≤6 cycles F Triple-negative breast cancer (previously untreated) Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV + paclitaxel 90 mg/m2 on days 1, 8, and 15 Q4W IV G Hepatocellular carcinoma (previously untreated) Vibostolimab 200 mg/pembrolizumab 200 mg Q3W IV + lenvatinib 12 mg/8 mg QD PO 5-FU, fluorouracil; CPS, combined positive score; dMRR, mismatch repair-deficient; IV, intravenously; pMRR, mismatch repair-proficient; PO, orally; Q3W, every 3 weeks; Q4W, every 4 weeks; QD, once daily. aAll treatments are ≤35 cycles unless otherwise indicated. bPatients in cohort A1 will be randomly assigned 1:1 to receive one of the 2 treatments; analysis will be stratified by prior bevacizumab use.

Citation Format: Iwona Lugowska, Carlos Rojas, Alejandro Falcon Gonzalez, Lucia Gonzalez Cortijo, Chih-Hung Hsu, Chia-Jui Yen, Sun Young Rha, Kan Yonemori, Daneng Li, Ravit Geva, Pamela Salman, Eduardo Yanez Ruiz, Qi Liu, Tanya Keenan, Jane Healy, Mariusz Kwiatkowski. A multicohort, open-label, phase 2 basket study of the coformulation of vibostolimab with pembrolizumab, with or without other anticancer therapies, in select solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT129.

Abstract CT180: Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) and coformulation of vibo/pembro in ovarian cancer naive to PD-1/PD-L1 inhibitors

Background: The anti-TIGIT antibody vibo in combination with pembro has shown promising antitumor activity in anti-PD-1/PD-L1-naive NSCLC. In the ongoing phase 1 trial (NCT02964013), we evaluated the safety and efficacy of these drugs given in combination (vibo + pembro) or as a coformulation (vibo/pembro) for the treatment of ovarian cancer naive to PD-1/PD-L1 inhibitors.

Methods: Patients had locally advanced unresectable or metastatic ovarian cancer naive to PD-1/PD-L1 inhibitors that progressed after ≥1 line of therapy, including platinum therapy. Patients were nonrandomly assigned to receive vibo (200 mg IV Q3W) + pembro (200 mg IV Q3W) or as the coformulation (vibo/pembro) at the same dose for ≤35 cycles (~2 years) or until disease progression (PD), toxicity, or patient withdrawal. Primary end points were safety and tolerability. Secondary and exploratory end points included PK, objective response rate (ORR), duration of response (DOR), and progression-free survival (PFS) by investigator review per RECIST v1.1. PD-L1 positivity was defined as a combined positive score (CPS) of ≥1 or when CPS was missing, as a tumor proportion score of ≥1% or as a mononuclear immune cell density score of ≥2.

Results: Of 61 patients enrolled, 21 received vibo + pembro, and 40 received vibo/pembro. Median age was 58 years; 48% of patients had ECOG performance status 1, 15% had BRCA1 and/or BRCA2 mutations, 87% received ≥2 lines of prior therapy (66%, bevacizumab; 41%, PARP inhibitor), and 74% had platinum-resistant disease (PD <6 months after platinum). PD-L1 status was positive in 21 patients, negative in 31 patients, and unknown in 9 patients. Median follow-up was 13 months (range, 9-15). Treatment-related adverse events (TRAEs) occurred in 79% of all patients; 13% were grade 3 or 4. No deaths due to TRAEs were reported. The most common TRAEs (≥20%) were fatigue (23%), pruritus (23%), and rash (20%). PK exposure was similar between treatment groups. ORR was 8% (95% CI, 3-18) in all patients and 24% (95% CI, 8-47) in patients with PD-L1-positive tumors. Median DOR was 19 months (range, 4-19). The disease control rate at 6 months was 11% (95% CI, 5-22) in all patients and 24% (95% CI, 8-47) in patients with PD-L1-positive tumors. Median PFS was 2 months (95% CI, 2-2) in all patients and 2 months (95% CI, 2-8) in patients with PD-L1-positive tumors.

Conclusions: Safety and PK were comparable with vibo + pembro combination and the vibo/pembro coformulation in patients with platinum-resistant locally advanced unresectable or metastatic ovarian cancer naive to PD-1/PD-L1 inhibitors. Antitumor activity was equivalent between the combination and coformulation, with responses limited to PD-L1-positive tumors. Vibo/pembro coformulation may offer a safe and convenient treatment option in these patients; further investigations of antitumor activity by PD-L1 status are needed.

Citation Format: Ruth Perets, Martin Gutierrez, Sun Young Rha, Sarah Taylor, Brian Stein, Antonio Jimeno, Ira Winer, Diana Chen, Tanya Keenan, Mohini Rajasagi, Mallika Lala, Jane Healy, Ronnie Shapira-Frommer. Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) and coformulation of vibo/pembro in ovarian cancer naive to PD-1/PD-L1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT180.

Abstract CT508: Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) in patients (pts) with cervical cancer naive to PD-1/PD-L1 inhibitors

Background: The anti-TIGIT antibody vibo in combination with pembro was well tolerated across all doses in the dose-escalation phase of the ongoing phase 1 study in pts with advanced solid tumors (NCT02964013); promising antitumor activity of vibo + pembro was observed in anti-PD-1/PD-L1-naive NSCLC. We present initial results of the dose-expansion phase in pts with advanced cervical cancer naive to PD-1/PD-L1 inhibitors.

Methods: Pts with histologically confirmed, locally advanced, or metastatic cervical cancer who failed prior standard-of-care chemotherapy or who experienced early progression on definitive chemoradiation and were naive to PD-1/PD-L1 inhibitors were randomly assigned 1:1 to receive 1 of 2 doses of vibo (200 or 700 mg) + pembro (200 mg) Q3W for ≤35 cycles (~2 y) or until PD, toxicity, or pt withdrawal. Primary end points were safety and tolerability. Secondary and exploratory end points included ORR, DOR, and PFS by investigator review per RECIST v1.1.

Results: Median age of the 80 pts with cervical cancer was 49 y; 58% had an ECOG PS of 1; 53% received ≥2 prior lines of therapy; and 61% had PD-L1-positive tumors. 41 pts received vibo 200 mg, and 39 received vibo 700 mg. Median follow-up was 12 mo (range, 5-26). Treatment-related AEs (TRAEs) occurred in 27 pts in each treatment group (66%, vibo 200 mg; 69%, vibo 700 mg). The most frequent TRAEs (≥15%) were rash (22%), increased lipase (17%), and pruritus (17%) with vibo 200 mg + pembro and pruritus (28%), pyrexia (21%), rash (15%), and fatigue (15%) with vibo 700 mg + pembro. Grade 3 or 4 TRAEs occurred in 29% (vibo 200 mg + pembro) and 18% (vibo 700 mg + pembro). No deaths due to TRAEs were reported. Efficacy is reported in the Table.

Conclusions: Vibo + pembro was safe in pts with advanced cervical cancer. Antitumor activity was comparable between the 2 doses of vibo studied and responses were observed irrespective of PD-L1 status. Based on these data, the RP2D for vibo remains 200 mg Q3W.

Efficacy By Treatment Group By PD-L1 Statusa Vibo 200 mg + Pembro n = 41 Vibo 700 mg + Pembro n = 39 PD-L1-positive n = 49 PD-L1-negative n = 21 Confirmed ORR, % (95% CI) 15 (6-29) 23 (11-39) 20 (10-34) 14 (3-36) CR, n (%) 2 (5) 5 (13) 6 (12) 1 (5) PR, n (%) 4 (10) 4 (10) 4 (8) 2 (10) SD, n (%) 12 (29) 7 (18) 14 (29) 3 (14) PD, n (%) 18 (44) 19 (49) 20 (41) 12 (57) Median DOR, months (range)b Not reached (10 to 31+) Not reached (4+ to 35+) Not reached (4+ to 35+) Not reached (21 to 27+) Median PFS, months (95% CI) 2 (2-4) 2 (2-4) 4 (2-4) 2 (1-4) CR, complete response; DOR, duration of response; PD, progressive disease; ORR, objective response rate; PFS, progression-free survival; PR, partial response; SD, stable disease. aPD-L1 status was unknown in 10 patients; data were pooled across treatment groups. PD-L1 positivity was defined as combined positive score (CPS) ≥1 or when CPS was missing, as tumor proportion score ≥1% or mononuclear immune cell density score ≥2. b“+” indicates no PD present at the time of the last disease assessment.

Citation Format: Ronnie Shapira-Frommer, Ruth Perets, Mark Voskoboynik, Kathryn Mileham, Adnan Nagrial, Brian Stein, Vincent Chung, Martin Gutierrez, Diana Chen, Tanya Keenan, Mohini Rajasagi, Jane Healy, Sun Young Rha. Safety and efficacy of vibostolimab (vibo) plus pembrolizumab (pembro) in patients (pts) with cervical cancer naive to PD-1/PD-L1 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT508.

Abstract P2-14-18: A randomized phase II trial of carboplatin with or without nivolumab in metastatic triple-negative breast cancer

Background: Platinum agents induce DNA crosslinking and cause accumulation of genotoxic stress, which leads to immune activation via IFN-γ signaling, making the combination with nivolumab (PD-1 antibody) an attractive strategy to enhance the benefit of either agent alone in metastatic triple-negative breast cancer (mTNBC). Methods: In this phase II open-label, investigator-initiated, multicenter trial, patients with unresectable locally advanced or mTNBC treated with 0-1 prior lines of chemotherapy in the metastatic setting were randomized 1:1 to carboplatin (AUC 6) with or without nivolumab (360 mg) IV every 3 weeks. Stratification factors included: germline BRCA (gBRCA) status, prior neo/adjuvant platinum, and number of prior lines of metastatic therapy. After approval of PD-L1 inhibition for mTNBC, the study was amended to include first-line mTNBC only and PD-L1 status was added as a stratification factor. Patients randomized to carboplatin alone were allowed to crossover at progression to receive nivolumab (+ nab-paclitaxel post-amendment). The primary objective was to compare progression-free survival (PFS) per RECIST 1.1 criteria of carboplatin with or without nivolumab in first-line mTNBC in the intent-to-treat (ITT) population. Key secondary objectives were objective response rate (ORR), overall survival (OS), clinical benefit rate, and duration and time to objective response. PD-L1 status was confirmed centrally using the SP142 Ventana assay (positive, ≥1% IC). Paired research biopsies at baseline, on-treatment and at progression were performed, if safely accessible. The trial closed to accrual prior to reaching target accrual due to approval of PD-1 inhibition in combination with platinum-based chemotherapy for PD-L1+ mTNBC. Results: Between 1/30/2018 and 12/9/2020, 78 patients enrolled. Three patients did not receive protocol treatment, and the safety analysis was conducted among the 75 that received any treatment; 37 received carboplatin + nivolumab (Arm A), 38 received carboplatin alone (Arm B). Median age was 59.1 yrs (range: 25.4-75.8). Four patients (5.3%) had a known gBRCA1/2 mutation. Sixty-two (82.7%) patients received 0 prior lines (ITT population) and 13 (17.3%) 1 prior line of metastatic therapy. Sixty-seven patients (89.3%) experienced any grade ≥2 treatment-related adverse event (AE). The most frequent AE were platelet count decrease (n=40; 53.3%), anemia (n=36; 48.0%), neutrophil count decrease (n=33; 44.0%) and fatigue (n=24; 32.0%). Grade 3/4 AE were observed in 46 (61.3%) patients, and there was one grade 5 AE (COVID19 pneumonia). Any grade ≥2 immune-related AE (irAE) were observed in 25 of the 37 (67.6%) patients treated with carboplatin + nivolumab. Grade 3/4 irAE were observed in 11 (29.7%) patients. In the ITT population (32 on Arm A; 30 on Arm B), median PFS was 4.2 months with carboplatin + nivolumab, and 5.5 months with carboplatin (stratified HR 0.98, 95% CI [0.51 - 1.88]; p=0.95). ORR was 25% vs. 23.3%, respectively. At a median follow-up of 23.5 months, median OS was 17.5 months vs. 10.7 months (stratified HR 0.63, 95% CI [0.32 - 1.24]; p=0.18). In patients with PD-L1+ mTNBC (13 on Arm A; 11 on Arm B), median PFS was 8.3 months and 4.7 months, respectively (stratified HR 0.63, 95% CI [0.21 - 1.89]; p=0.41). ORR was 23.1% vs. 27.3%, respectively. Median OS was 17.5 months vs. 9.6 months (stratified HR 0.59, 95% CI [0.20 - 1.75]; p=0.34). Conclusions: Addition of nivolumab to carboplatin in patients with previously untreated mTNBC, unselected by PD-L1 status, did not significantly improve PFS. A trend toward improved PFS and OS was observed in patients with PD-L1+ mTNBC. Tissue, blood and intestinal microbiome biomarker analyses are planned; bulk tumor and single-cell sequencing, and TCR sequencing in peripheral blood are ongoing. Clinical trial information: NCT03414684.

Citation Format: Ana C Garrido-Castro, Noah Graham, Kevin Bi, Jihye Park, Jingxin Fu, Tanya Keenan, Edward Thomas Richardson, Ricardo Pastorello, Paulina Lange, Victoria Attaya, Robert Wesolowski, Natalie Sinclair, Zarah Lucas, Steve Lo, Nadine Tung, Meredith Faggen, Peter A Kaufman, Caroline C Block, Fred Briccetti, Madhavi Toke, Wendy Chen, Kai Wucherpfennig, Sascha Marx, Ye Tian, Judith Agudo, Jennifer L Guerriero, Stuart Schnitt, Nancy U Lin, Eric P Winer, Elizabeth A Mittendorf, Nabihah Tayob, Eliezer Van Allen, Sara M Tolaney. A randomized phase II trial of carboplatin with or without nivolumab in metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-14-18.

Integrating molecular profiles into clinical frameworks through the Molecular Oncology Almanac to prospectively guide precision oncology

Tumor molecular profiling of single gene-variant ('first-order') genomic alterations informs potential therapeutic approaches. Interactions between such first-order events and global molecular features (for example, mutational signatures) are increasingly associated with clinical outcomes, but these 'second-order' alterations are not yet accounted for in clinical interpretation algorithms and knowledge bases. We introduce the Molecular Oncology Almanac (MOAlmanac), a paired clinical interpretation algorithm and knowledge base to enable integrative interpretation of multimodal genomic data for point-of-care decision making and translational-hypothesis generation. We benchmarked MOAlmanac to a first-order interpretation method across multiple retrospective cohorts and observed an increased number of clinical hypotheses from evaluation of molecular features and profile-to-cell line matchmaking. When applied to a prospective precision oncology trial cohort, MOAlmanac nominated a median of two therapies per patient and identified therapeutic strategies administered in 47% of patients. Overall, we present an open-source computational method for integrative clinical interpretation of individualized molecular profiles.

The Immunology of Hormone Receptor Positive Breast Cancer

Immune checkpoint blockade (ICB) has revolutionized the treatment of cancer patients. The main focus of ICB has been on reinvigorating the adaptive immune response, namely, activating cytotoxic T cells. ICB has demonstrated only modest benefit against advanced breast cancer, as breast tumors typically establish an immune suppressive tumor microenvironment (TME). Triple-negative breast cancer (TNBC) is associated with infiltration of tumor infiltrating lymphocytes (TILs) and patients with TNBC have shown clinical responses to ICB. In contrast, hormone receptor positive (HR+) breast cancer is characterized by low TIL infiltration and minimal response to ICB. Here we review how HR+ breast tumors establish a TME devoid of TILs, have low HLA class I expression, and recruit immune cells, other than T cells, which impact response to therapy. In addition, we review emerging technologies that have been employed to characterize components of the TME to reveal that tumor associated macrophages (TAMs) are abundant in HR+ cancer, are highly immune-suppressive, associated with tumor progression, chemotherapy and ICB-resistance, metastasis and poor survival. We reveal novel therapeutic targets and possible combinations with ICB to enhance anti-tumor immune responses, which may have great potential in HR+ breast cancer.

Abstract PS4-25: Comprehensive genomic analysis reveals molecular correlates of response to immune checkpoint inhibitors (ICI) in metastatic triple-negative breast cancer (mTNBC)

Background: Genomic mechanisms associated with response to ICI in mTNBC are largely unknown. The aim of this work is to assess the genomic and immune profiles of mTNBC samples collected from patients (pts) treated with ICI. Methods: We identified 31 women with mTNBC treated with ICI (pembrolizumab, n=6, NCT02447003; atezolizumab, n=4, NCT01375842; nivolumab + cabozantinib, n = 6, NCT03316586; pembrolizumab + eribulin, n=8, NCT02513472; atezolizumab + nab-paclitaxel, n=7, NCT01633970) who had tumor tissue or blood available for sequencing obtained before and after ICI. Clinical benefit (CB), here defined as any objective response or stable disease (SD) for > 24 weeks, was observed in 20 pts (65%). An extraordinary responder was defined as having CB ≥ 2 yrs; 5 pts were considered extraordinary responders (range 26-60months). Whole exome sequencing (WES) was done on each tumor and on germline DNA from blood (23 pts had successful WES performed on samples collected before ICI; 5 of these had WES on samples taken after disease progression). RNA sequencing (RNAseq) was successfully performed in 18 of the tumors with WES performed on samples before ICI; and 3 of these had RNAseq on samples taken after disease progression. 18 pts had tumors assessed by multiplex immunofluorescence (mIF) panels encompassing CD4, CD8, PD-1, PD-L1, and cytokeratin on samples collected before ICI. WES, deep targeted panel and low coverage whole genome sequencing were performed on serially collected plasma samples from 22 pts to evaluate tumor fraction and specific mutations. The association between biomarkers and clinical benefit to ICI was assessed. Results: 21 of 31 pts (67%) had received ≥1 prior lines of systemic therapy in the metastatic setting before starting ICI. Among the most frequently mutated genes at baseline are: TP53 (57%); PIK3CA (18%); DNAH5, MYH8 (both 13%); KMT2C, AKT1, LAMA2 (all 9%). Pts with CB had a higher tumor mutational burden (TMB) than pts with no CB (p=0.018). Differential expression analysis of RNAseq data revealed an upregulation of several immune-related genes in pts with CB, indicating increased immune infiltration in that group. Gene set enrichment analysis of this expression data using hallmark and canonical pathway gene sets from MSigDB (nominal p-val < 0.05) showed that, compared to samples from pts without CB, extraordinary responders had elevated transcriptional signatures of several cancer-related pathways associated with cell survival, proliferation and metabolism, as well as genes associated with increased immune infiltration and upregulation of inflammatory response programs. The mIF showed that the tumor microenvironment (TME) of pts with CB were enriched in Cytokeratin-negative/PD-L1-positive cells compared to those without CB (p=0.014). Expression of CD4, CD8 and PD-1 was not significantly different between pts with and without CB. Genomic analysis of circulating tumor DNA, and tumor evolutionary analysis for pts with both pre- and post-ICI samples (acquired resistance) will be presented. Conclusions: Clinical benefit to ICI in mTNBC was associated with upregulation of immune-related pathways, enrichment of non-tumoral PD-L1-positive cells in TME, and high TMB.

Citation Format: Romualdo Barroso-Sousa, Juliet Forman, Zachary T. Weber, Katherine Collier, Katrina Z. Kao, Edward T. Richardson, III, Tanya Keenan, Ofir Cohen, Michael P. Manos, Ryan C. Brennick, Patrick Ott, F. Steve Hodi, Deborah A. Dillon, Nancy U. Lin, Eliezer E. Van Allen, Scott Rodig, Eric P. Winer, Elizabeth A. Mittendorf, Catherine J. Wu, Daniel Stover, Nikhil Wagle, Sachet Shukla, Sara Tolaney. Comprehensive genomic analysis reveals molecular correlates of response to immune checkpoint inhibitors (ICI) in metastatic triple-negative breast cancer (mTNBC) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-25.

A standardized head-fixation system for performing large-scale, in vivo physiological recordings in mice

BACKGROUND

The Allen Institute recently built a set of high-throughput experimental pipelines to collect comprehensive in vivo surveys of physiological activity in the visual cortex of awake, head-fixed mice. Developing these large-scale, industrial-like pipelines posed many scientific, operational, and engineering challenges.

NEW METHOD

Our strategies for creating a cross-platform reference space to which all pipeline datasets were mapped required development of 1) a robust headframe, 2) a reproducible clamping system, and 3) data-collection systems that are built, and maintained, around precise alignment with a reference artifact.

RESULTS

When paired with our pipeline clamping system, our headframe exceeded deflection and reproducibility requirements. By leveraging our headframe and clamping system we were able to create a cross-platform reference space to which multi-modal imaging datasets could be mapped.

COMPARISON WITH EXISTING METHODS

Together, the Allen Brain Observatory headframe, surgical tooling, clamping system, and system registration strategy create a unique system for collecting large amounts of standardized in vivo datasets over long periods of time. Moreover, the integrated approach to cross-platform registration allows for multi-modal datasets to be collected within a shared reference space.

CONCLUSIONS

Here we report the engineering strategies that we implemented when creating the Allen Brain Observatory physiology pipelines. All of the documentation related to headframe, surgical tooling, and clamp design has been made freely available and can be readily manufactured or procured. The engineering strategy, or components of the strategy, described in this report can be tailored and applied by external researchers to improve data standardization and stability.

Integrated molecular drivers coordinate biological and clinical states in melanoma

We performed harmonized molecular and clinical analysis on 1,048 melanomas and discovered markedly different global genomic properties among subtypes (BRAF, (N)RAS, NF1, Triple Wild-Type), subtype-specific preferences for secondary driver genes, and active mutational processes previously unreported in melanoma. Secondary driver genes significantly enriched in specific subtypes reflected preferential dysregulation of additional pathways, such as induction of TGF-β signaling in BRAF melanomas and inactivation of the SWI/SNF complex in (N)RAS melanomas, and select co-mutation patterns coordinated selective response to immune checkpoint blockade. We also defined the mutational landscape of Triple Wild-Type melanomas and identified enrichment of DNA repair defect signatures in this subtype, which were associated with transcriptional downregulation of key DNA repair genes and may revive previously discarded or currently unconsidered therapeutic modalities for genomically stratified melanoma patient subsets. Broadly, harmonized meta-analysis of melanoma whole-exomes identified distinct molecular drivers that may point to multiple opportunities for biological and therapeutic investigation.

Effect of Eribulin With or Without Pembrolizumab on Progression-Free Survival for Patients With Hormone Receptor-Positive, ERBB2-Negative Metastatic Breast Cancer: A Randomized Clinical Trial

Importance

Prior studies have shown that only a small proportion of patients with hormone receptor (HR)-positive metastatic breast cancer (MBC) experience benefit from programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitors given as monotherapy. There are data suggesting that activity may be greater with combination strategies.

Objective

To compare the efficacy of eribulin plus pembrolizumab vs eribulin alone in patients with HR-positive, ERBB2 (formerly HER2)-negative MBC.

Design, Setting, and Participants

Multicenter phase 2 randomized clinical trial of patients with HR-positive, ERBB2-negative MBC who had received 2 or more lines of hormonal therapy and 0 to 2 lines of chemotherapy.

Interventions

Patients were randomized 1:1 to eribulin, 1.4 mg/m2 intravenously, on days 1 and 8 plus pembrolizumab, 200 mg/m2 intravenously, on day 1 of a 21-day cycle or eribulin alone. At time of progression, patients in the eribulin monotherapy arm could cross over and receive pembrolizumab monotherapy.

Main Outcomes and Measures

The primary end point was progression-free survival (PFS). Secondary end points were objective response rate (ORR) and overall survival (OS). Exploratory analyses assessed the association between PFS and PD-L1 status, tumor-infiltrating lymphocytes (TILs), tumor mutational burden (TMB), and genomic alterations.

Results

Eighty-eight patients started protocol therapy; the median (range) age was 57 (30-76) years, median (range) number of prior lines of chemotherapy was 1 (0-2), and median (range) number of prior lines of hormonal therapy was 2 (0-5). Median follow-up was 10.5 (95% CI, 0.4-22.8) months. Median PFS and ORR were not different between the 2 groups (PFS, 4.1 vs 4.2 months; hazard ratio, 0.80; 95% CI, 0.50-1.26; P = .33; ORR, 27% vs 34%, respectively; P = .49). Fourteen patients started crossover treatment with pembrolizumab; 1 patient experienced stable disease. All-cause adverse events occurred in all patients (grade ≥3, 65%) including 2 treatment-related deaths in the combination group, both from immune-related colitis in the setting of sepsis, attributed to both drugs. The PD-L1 22C3 assay was performed on archival tumor samples in 65 patients: 24 (37%) had PD-L1-positive tumors. Analysis indicated that PD-L1 status, TILs, TMB, and genomic alterations were not associated with PFS.

Conclusions and Relevance

In this randomized clinical trial of patients with HR-positive, ERBB2-negative MBC, the addition of pembrolizumab to eribulin did not improve PFS, ORR, or OS compared with eribulin alone in either the intention-to-treat or PD-L1-positive populations. Further efforts to explore the benefits of adding checkpoint inhibition to chemotherapy among less heavily pretreated patients are needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT03051659.

A phase Ib study of pembrolizumab (pembro) plus trastuzumab emtansine (T-DM1) for metastatic HER2+ breast cancer (MBC)

1046

Background: Preclinical evidence suggests treatment (tx) with T-DM1 plus an anti-PD1 antibody triggers antitumor immunity. We conducted a phase 1 trial to determine the safety and explore the efficacy of T-DM1 plus pembro. Methods: Eligible patients (pts) had MBC previously treated with trastuzumab (H) and taxane (T), were T-DM1-naïve, and received >1 prior line of tx for MBC or developed recurrence within 6 months (mo) of adjuvant tx. A dose de-escalation (esc) design was used with 6 pts in the dose-finding cohort, followed by an expansion (exp) cohort at the recommended phase 2 dose (RP2D), with mandatory baseline biopsies (bx). The primary endpoint was safety and tolerability. Secondary endpoints included objective response rate (ORR), progression-free survival (PFS), and clinical benefit rate (CBR: complete response + partial response + stable disease >24 weeks). Associations between immune biomarkers and tx response were explored. Results: 20 pts started protocol tx (6 in dose de-esc cohort; 14 in exp cohort). Median follow-up was 23.5 mo. Pts had median age 54 yrs and median 1 line of prior MBC tx (range 0-2); 100% had received prior T, H, and pertuzumab. There were no dose-limiting toxicities in the dose de-esc cohort; thus full doses of T-DM1 (3.6 mg/kg q21 days) and pembro (200 mg q21 days) were the RP2D. 85% of pts experienced tx-related adverse events (AEs) > grade (gr) 1; 20% of pts experienced gr3 AEs. There were no gr>4 AEs. Gr3 AEs were fatigue; AST increase; ALT increase; pneumonia; pneumonitis; oral mucositis; and vomiting, each in 1 pt. 17 pts had baseline bx; 6 pts had repeat bx after 1 tx cycle. Efficacy results, overall and by PD-L1 Combined Positive Score (CPS; 22C3 staining) and tumor-infiltrating lymphocyte (TIL) status, are shown in the table. Tumors’ antigen presentation will be explored through HLA/dendritic cell marker staining and immune signatures by RNA sequencing. Conclusions: T-DM1 plus pembro was safe and tolerable. The regimen demonstrated clinical activity. Further exploration of immune-related predictive biomarkers is warranted. Clinical trial information: NCT03032107 . [Table: see text]

Abstract CT050: Expansion cohort of Phase I study of oral sapacitabine and oral seliciclib in patients with metastatic breast cancer and BRCA1/2 mutations

Introduction: Sapacitabine, a nucleoside analog, and seliciclib, a cyclin-dependent kinase 2/9 inhibitor, constitute a novel oral regimen aimed at augmenting DNA damage and impairing cell cycle checkpoints. The initial phase I cohort investigating this combination demonstrated a 25% response rate in BRCA carriers. Hence, we developed an expansion cohort to assess the safety and efficacy of this regimen in patients with metastatic breast cancer and BRCA1/2 mutations.

Methods: We enrolled 20 patients with HER2-negative metastatic breast cancer and germline or somatic BRCA1/2 mutations, who were treated with sapacitabine 50 mg twice daily for days 1-7 followed by seliciclib 800 mg twice daily for days 8-10 of a 21-day cycle. Baseline or archival biopsies underwent RAD51 immunohistochemistry to assess for functional homologous recombination proficiency. Available tissue was sent for whole exome and transcriptome sequencing, and pre- and post-treatment blood was submitted for cell-free DNA sequencing to assess for genomic correlates of response.

Results: Participants received a median of 2 prior lines of chemotherapy for metastatic disease. Of the 9 patients who received a prior platinum agent, 6 progressed on this therapy. In addition to chemotherapy, 7 patients received and progressed on a prior PARP inhibitor. The overall response rate for sapacitabine and seliciclib in this cohort was 10%, consisting of 2 patients with partial responses lasting 4.7 and 9.0 months, respectively. The clinical benefit rate (CR + PR + SD ≥ 6 months) was 30%, and durations of stable disease ≥ 6 months ranged from 7.4 to 11.7 months. For all patients, median PFS was 3.7 months. The most frequent grade 3/4 adverse events were neutropenia (25% of patients), transaminitis (20%), and rash (10%). No patients who progressed on prior PARP inhibitor therapy and 6 of 13 patients (46%) with no history of PARP inhibitor resistance experienced clinical benefit (p = 0.052 by Fisher’s exact test). In contrast, 1 of 6 patients (17%) who progressed on prior platinum chemotherapy and 5 of 14 patients (36%) with no history of platinum resistance experienced clinical benefit (p = 0.61 by Fisher’s exact test). Notably, the tumors of some resistant patients harbored BRCA reversion mutations. Additional genomic analyses and RAD51 immunohistochemistry will be presented.

Conclusions: The combination of sapacitabine and seliciclib was safe and led to durable clinical benefit in some patients with metastatic breast cancer and BRCA1/2 mutations. Prior progression on PARP inhibitors predicted resistance to this combination, associated in some cases with BRCA reversion mutations. Based on these results, the combination of sapacitabine and the PARP inhibitor olaparib is now being investigated in patients with PARP-naïve metastatic HER2-negative breast cancer and germline BRCA1/2 mutations.

Citation Format: Tanya Keenan, David Liu, Haitham Elmarakeby, Daniel Stover, Bose Kochupurakkal, Adam Tracy, Elaine Danielczyk, Leilani Anderson, Chelsea Andrews, Brendan Reardon, Beth Overmoyer, Eric Winer, Daniella Zheleva, Judy Chiao, David Blake, Eliezer Van Allen, Geoffrey I. Shapiro, Sara Tolaney. Expansion cohort of Phase I study of oral sapacitabine and oral seliciclib in patients with metastatic breast cancer and BRCA1/2 mutations [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 CT050.

Randomized phase II study of eribulin mesylate (E) with or without pembrolizumab (P) for hormone receptor-positive (HR+) metastatic breast cancer (MBC)

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Background: Studies of checkpoint inhibitor monotherapy show only modest activity in HR+ MBC. We report data from the first randomized study comparing E plus P versus E alone in HR+/HER2- MBC. Methods: Eligible patients (pts) had HR+/HER2- MBC, ≥2 lines of hormonal therapies and 0-2 lines of chemotherapy for MBC. Pts were randomized 1:1 to E 1.4mg/m2 intravenously (IV) on d1 and d8 with P 200 mg/m2 IV on d1 of a 21-day cycle (Arm A) or E alone (Arm B). At time of progression, pts in arm B could crossover and receive P alone. Primary endpoint was progression-free survival (PFS). Key secondary endpoints were: objective response rate (ORR) and overall survival (OS). Exploratory analyses assessed the association between PFS and PD-L1 status, tumor-infiltrating lymphocytes (TILs), neutrophil-lymphocyte ratio (NLR), tumor mutation burden (TMB), and genomic alterations by next generation sequencing on archival tissue. Results: 88 pts initiated protocol therapy; the median age was 58, median prior lines of chemotherapy 1, prior lines of hormonal therapy 2. Median follow-up was 6.3 months. Median PFS and ORR were not different between Arms A and B (PFS 4.1 vs 4.2 months p = 0.38; ORR 25% and 34% respectively (p = 0.49). 14 patients initiated crossover treatment with pembrolizumab; 1 patient experienced a PR (ORR 7%). All-cause AEs occurred in 100% of pts (G3-4, 54.6%) including 2 treatment related deaths on Arm A, both from known AEs attributed to both drugs. PD-L1 assay was performed in 65 pts: 24 (36.9%) had PD-L1 positive ( > 1% with 22C3, centrally tested) tumors. PD-L1 status, TILs, NLR, TMB, and genomic alterations were not associated with PFS (Table). Updated data, including OS and genomic results, will be presented. Conclusions: Among pts with HR+/HER2- MBC, the combination of E and P was not associated with longer PFS than E alone in the ITT or PD-L1+ population, though the PD-L1+ subgroup had very limited power to assess P benefit. Clinical trial information: NCT03051659. [Table: see text]

Abstract P2-02-18: Higher mutation burden and mutant allele fraction of circulating tumor DNA corresponds to worse progression free survival in metastatic breast cancer patients

Introduction: Genomic profiling of circulating tumor DNA (ctDNA) allows non-invasive monitoring of tumor genetic changes and molecular heterogeneity. In addition to actionable mutations, mutational landscape derived from ctDNA could provide a better representation of overall tumor burden and tumor heterogeneity, as well as potentially impact clinical outcomes. To evaluate this hypothesis, this study assessed the association of mutation burden and average mutant allele fraction (MAF) with tumor subtype, therapeutic response, and survival in patients with metastatic breast cancer.

Methods: Whole blood samples from patients with metastatic breast cancer were collected during clinic visits before start of a new therapy. Plasma-derived cell-free DNA underwent complete next-generation sequencing of 73 cancer-related genes with the Guardant360 test. Mutation burden was defined as the number of genes with mutations, and average MAF was calculated as the sum of the highest MAF for each mutated gene divided by the number of genes with mutations. Time to progression was measured from the date of new treatment initiation after circulating tumor DNA collection to the date of progression. Multivariate cox proportional hazard models assessed the association of mutation burden and average MAF with progression free survival (PFS), adjusted for age, receptor subtype (hormone receptor positive, HR+; human epidermal growth factor 2 positive, HER2+; triple negative breast cancer, TNBC), treatment subtype (chemotherapy vs. targeted therapy), and number of prior metastatic breast cancer therapies. A p value of 0.05 was considered statistically significant.

Results: The study population consisted of 158 women with metastatic breast cancer (108 HR+, 14 HER2+, 19 TNBC) with a median age of 59 years and a median of 2 prior metastatic breast cancer therapies. Median follow up time was 4.0 months, and median PFS was 15.7 months. Mutation burden was greater in triple negative compared to hormone receptor positive breast cancer (7.5 vs. 4.8, p = 0.02) but no different in patients with > 2 prior metastatic therapies vs. not (5.1 vs. 4.7, p = 0.60) and age >45 vs. not (5.0 vs. 3.9; p = 0.26). In univariate models, high mutation burden (> median of 2) and high MAF (> median of 1.4) were significantly associated with worse PFS (Table). These results were similar in effect size and significance when adjusted for age, receptor subtype, treatment subtype, and number of prior metastatic breast cancer therapies. Impact of mutation burden on response to specific therapies will be presented at the meeting.

VariableHazard Ratio95% Confidence Intervalp valueHigh mutation burden1.991.12-3.540.02High mutant allele fraction1.881.06-3.330.03

Conclusions: Higher ctDNA mutation burden and average MAF is associated with worse progression free survival and possibly reflects a more treatment refractory phenotype. Whether immunotherapy, alone or in combination, could influence the clinical outcomes in metastatic breast cancer patients with high ctDNA mutation burden is unclear and warrants additional research.

Citation Format: Keenan T, Juric D, Niemierko A, Spring L, Park H, Malvarosa G, Beeler M, Moy B, Ellisen L, Isakoff S, Bardia A. Higher mutation burden and mutant allele fraction of circulating tumor DNA corresponds to worse progression free survival in metastatic breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-02-18.

Quality of life and mood predict posttraumatic stress disorder after hematopoietic stem cell transplantation

BACKGROUND

During hospitalization for hematopoietic stem cell transplantation (HCT), patients experience a steep deterioration in quality of life (QOL) and mood. To our knowledge, the impact of this deterioration on patients' QOL and posttraumatic stress disorder (PTSD) symptoms after HCT is unknown.

METHODS

We conducted a prospective longitudinal study of patients hospitalized for HCT. They assessed QOL using the Functional Assessment of Cancer Therapy-Bone Marrow Transplantation (FACT-BMT) and depression and anxiety symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9) at the time of admission for HCT, during hospitalization, and 6 months after HCT. We also used the Hospital Anxiety and Depression Scale (HADS) to measure patients' anxiety and depression symptoms at baseline and during HCT hospitalization. The PTSD Checklist was used to assess for PTSD symptoms. Multivariable linear regression models were used to identify predictors of QOL and PTSD symptoms at 6 months.

RESULTS

We enrolled 90 of 93 consecutively eligible patients (97%) undergoing autologous and allogeneic HCT. Data at 6 months were available for 67 participants. At 6 months, 28.4% of participants met the criteria for PTSD and 43.3% had clinically significant depression. On multivariable regression analyses adjusting for significant covariates, changes in QOL and depression scores from week 2 of HCT hospitalization to baseline predicted worse QOL (changes in scores between week 2 and baseline [Δ] QOL: β, 0.94 [P<.0001] and Δ PHQ-9: β, -2.59 [P = 0.001]) and PTSD symptoms (Δ QOL: β, -0.40 [P<.0001] and Δ PHQ-9: β, 1.26 [P<.0001]) at 6 months after HCT.

CONCLUSIONS

Six months after HCT, a significant percentage of patients met the criteria for PTSD and depression. A decline in QOL and an increase in depressive symptoms during hospitalization for HCT were found to be the most important predictors of 6-month QOL impairment and PTSD symptoms. Therefore, managing symptoms of depression and QOL deterioration during HCT hospitalization may be critical to improving QOL at 6 months and reducing the risk of PTSD. Cancer 2016;122:806-812. © 2015 American Cancer Society.

Potentially avoidable hospitalizations in older patients with acute myeloid leukemia (AML)

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Background: Many older adults ( ≥ 60) with AML have a poor prognosis and spend a significant portion of their life from diagnosis until death in the hospital. We examined the reasons for hospitalizations and identified potentially avoidable hospitalizations. Methods: We conducted a retrospective analysis of 200 patients ( ≥ 60) diagnosed with AML between 1/1/2006 and 10/30/2011 at two hospitals in Boston to examine the reasons for hospitalizations during treatment. Practicing physicians used a consensus-driven medical record review process to identify primary reason for each hospitalization and categorize it as “potentially avoidable” or “not avoidable” based on a novel adaptation of the Graham’s criteria for potentially avoidable hospital admissions. We compared the rate of potentially avoidable hospitalization between older patients receiving intensive chemotherapy (n = 124) versus non-intensive chemotherapy (n = 76) using Fisher’s Exact test. Results: We evaluated 627 hospitalizations after the diagnosis of AML in 200 unique patients. The median age was 69 years [range 60-90] and the median number of hospitalizations was 4.0 [range 0-18]. 33.2% of patients underwent stem cell transplantation. The most common primary reasons for hospitalizations were: fever/infection (38.3%), planned hospitalizations for chemotherapy or transplantation (35.9%), and uncontrolled symptoms (10.5%). We identified 108/627 hospitalizations (17.2%) as potentially avoidable. Among potentially avoidable hospitalizations, 40.7% were due to premature hospital discharge, 22.2% could have been managed in the outpatient setting, 13.9% failed to have timely outpatient follow-up, and 13% were due to patients’ medication non-adherence. There were no differences in potentially avoidable hospitalizations between patients receiving intensive vs. non-intensive chemotherapy (16.9% vs. 17.8%, P = 0.83). Conclusions: Most hospitalizations in older patients with AML are unavoidable and driven by the illness course and its treatments. However, a minority of hospitalizations is potentially avoidable and should be the focus of future interventions to reduce health care utilization and the burden of AML on this population.

Quality of life and depression during hospitalization for hematopoietic stem cell transplantation to predict quality of life and post-traumatic stress disorder symptoms at 6 months post-transplant

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Background: Patients undergoinghematopoietic stem cell transplantation (HCT) experience a steep deterioration in quality of life (QOL) and mood during hospitalization for HCT. The impact of this deterioration on patients’ long-term QOL and post-traumatic stress disorder (PTSD) symptoms is unknown. Methods: We conducted a prospective longitudinal study of patients hospitalized for HCT. At baseline (day-6), day+1, day+8, and 6 months post-HCT, we assessed QOL (Functional Assessment of Cancer Therapy-Bone Marrow Transplantation [FACT-BMT]) and mood (Hospital Anxiety and Depression Scale [HADS]). We used the PTSD Checklist to assess for PTSD symptoms at 6 months. We used multivariable linear regression models to identify predictors of QOL and PTSD symptoms at 6 months post-HCT. Results: We enrolled 97% (90/93) of consecutively eligible patients undergoing autologous (n = 30), myeloablative allogeneic (n = 30), or reduced intensity allogeneic (n = 30) HCT. Overall, patients’ QOL at 6 months (mean FACT-BMT: 110, 95%CI [104-116]) recovered to baseline pre-transplant values (mean FACT-BMT: 110, 95% CI [107-115]). At 6 months, 28.4% of participants met provisional diagnostic criteria for PTSD, and 43.3% had clinically significant depression. In multivariable regression analyses adjusting for baseline QOL, mood, other covariates, change in QOL and depression scores during hospitalization for HCT predicted impaired QOL (DQOL β = 1.13, P < 0.0001, D HADS-depression β = 2.51, P = 0.001) and PTSD symptoms (DQOL β = 0.50, P < 0.0001, DHADS-depression β = 1.22, P < 0.0001) at 6 months post-HCT. Conclusions: While patients’ overall QOL at 6 months post-HCT returned to baseline values, a significant proportion met provisional diagnostic criteria for PTSD and depression. The decline in QOL and increase in depressive symptoms during hospitalization for HCT were the most important predictors of long-term QOL impairment and PTSD symptoms. Future studies should evaluate whether interventions to improve QOL and reduce psychological distress during HCT may improve long-term QOL and reduce the risk of PTSD symptoms.

Qualitative study of patients’ and family caregivers’ (FC) perceptions and information preferences about hospice

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Background: Despite the benefits of hospice for patients with advanced cancer and their FC, many patients are referred late or not at all. To assess potential patient and FC barriers to enrollment, we assessed their perceptions, knowledge, and information preferences about hospice. Methods: We conducted qualitative interviews with 16 adult patients with metastatic cancer and a prognosis ≤ 12 months and 8 of their FC. We used a semi-structured interview guide to elicit their perceptions (including perceived barriers to utilization), knowledge, and information preferences about hospice. Two raters coded interviews independently and reached acceptable inter-rater reliability (κ > 0.85). We used content analysis to identify themes. Results: We found similar themes between patients and FC interviews. Participants had mixed views about which patients need hospice with some stating it is for patients only at the end-of-life and others perceiving it as important for patients who need care their family cannot provide. Notably, most patients perceived themselves as not needing hospice in the near future. While the majority perceived the role of hospice to enhance quality of life and provide comfort, some viewed it as providing practical support, including 24-hour care. 50% of participants had positive feelings about hospice, while others were more ambivalent. All participants felt they needed more information about hospice, yet they were mixed regarding the optimal timing of this information. Many thought it would be helpful to have information about hospice through pamphlets, websites, or videos, prior to a discussion with their oncologist. Most viewed denial and hope as the main barriers to early hospice enrollment. Conclusions: Study participants had misunderstandings about which patients were appropriate for hospice and regarding the services offered. Participants expressed strong desires for more information about hospice with educational tools, although were mixed about the optimal timing for reviewing these tools. These findings suggest that patients and FC would benefit from interventions to enhance their understanding of hospice and to facilitate a discussion with their oncologists.

Comparison of the Genomic Landscape Between Primary Breast Cancer in African American Versus White Women and the Association of Racial Differences With Tumor Recurrence

PURPOSE

African American women are more likely to die as a result of breast cancer than white women. The influence of somatic genomic profiles on this racial disparity is unclear. We aimed to compare the racial distribution of tumor genomic characteristics and breast cancer recurrence.

METHODS

We assessed white and African American women with stage I to III breast cancer diagnosed from 1988 to 2013 and primary tumors submitted to The Cancer Genome Atlas from 2010 to 2014. We used Cox proportional hazards models to evaluate the association of race and genetic traits with tumor recurrence.

RESULTS

We investigated exome sequencing and gene expression data in 663 and 711 white and 105 and 159 African American women, respectively. African Americans had more TP53 mutations (42.9% v 27.6%; P = .003) and fewer PIK3CA mutations (20.0% v 33.9%; P = .008). Intratumor genetic heterogeneity was greater in African American than white tumors overall by 5.1 units (95% CI, 2.4 to 7.7) and within triple-negative tumors by 4.1 units (95% CI, 1.4 to 6.8). African Americans had more basal tumors by the 50-gene set predictor using the predication analysis of microarray method (PAM50; 39.0% v 18.6%; P < .001) and fewer PAM50 luminal A tumors (17.0% v 34.7%; P < .001). Among triple-negative subtypes, African Americans had more basal-like 1 and mesenchymal stem-like tumors. African Americans had a higher risk of tumor recurrence than whites (hazard ratio, 2.22; 95% CI, 1.05 to 4.67). Racial differences in TP53 mutation, PAM50 basal subtype, and triple-negative tumor prevalence but not intratumor genetic heterogeneity influenced the magnitude and significance of the racial disparity in tumor recurrence.

CONCLUSION

African Americans had greater intratumor genetic heterogeneity and more basal gene expression tumors, even within triple-negative breast cancer. This pattern suggests more aggressive tumor biology in African Americans than whites, which could contribute to racial disparity in breast cancer outcome.

Prognostic understanding, quality of life and mood in patients undergoing hematopoietic stem cell transplantation

Little is known about how patients undergoing hematopoietic stem cell transplantation (HCT) and their family caregivers (FC) perceive their prognosis. We examined prognostic understanding in patients undergoing HCT and their FC and its relationship with quality of life (QOL) and mood. We conducted a longitudinal study of patients (and FC) hospitalized for HCT. We used a questionnaire to measure participants' prognostic understanding and asked the oncologists to estimate patients' prognosis prior to HCT. We assessed QOL and mood weekly and evaluated the relationship between prognostic understanding, and QOL and mood using multivariable linear mixed models. We enrolled 90 patients undergoing (autologous (n=30), myeloablative (n=30) or reduced intensity allogeneic (n=30)) HCT. About 88.9% of patients and 87.1% of FC reported it is 'extremely' or 'very' important to know about prognosis. However, 77.6% of patients and 71.7% of FC reported a discordance and more optimistic prognostic perception compared to the oncologist (P<0.0001). Patients with a concordant prognostic understanding with their oncologists reported worse QOL (β=-9.4, P=0.01) and greater depression at baseline (β=1.7, P=0.02) and over time ((β=1.2, P<0.0001). Therefore, Interventions are needed to improve prognostic understanding, while providing patients with adequate psychological support.

Quality of life and mood of patients and family caregivers during hospitalization for hematopoietic stem cell transplantation

BACKGROUND

We conducted a study to investigate the impact of hospitalization for hematopoietic stem cell transplantation (HCT) on the quality of life (QOL) and mood of patients and family caregivers (FC).

METHODS

We conducted a longitudinal study of patients who were hospitalized for HCT and their FC. We assessed QOL (using the Functional Assessment of Cancer Therapy-Bone Marrow Transplantation) and mood (using the Hospital Anxiety and Depression Scale) at baseline (6 days before HCT), day +1, and day +8 of HCT. We administered the Medical Outcomes Study Health Survey Short Form-36 to examine FC QOL (Physical Component Scale and Mental Component Scale). To identify predictors of changes in QOL, we used multivariable linear mixed models.

RESULTS

We enrolled 97% of eligible patients undergoing autologous (30 patients), myeloablative (30 patients), or reduced intensity (30 patients) allogeneic HCT. Patients' QOL markedly declined (mean Functional Assessment of Cancer Therapy-Bone Marrow Transplantation score, 109.6 to 96.0; P<.0001) throughout hospitalization. The percentage of patients with depression (Hospital Anxiety and Depression Scale-Depression score of >7) more than doubled from baseline to day +8 (15.6% to 37.8%; P<.0001), whereas the percentage of patients with anxiety remained stable (22.2%; P = .8). These results remained consistent when data were stratified by HCT type. Baseline depression (β, -2.24; F, 42.2 [P<.0001]) and anxiety (β, -0.63; F, 4.4 [P =.03]) were found to independently predict worse QOL throughout hospitalization. FC QOL declined during the patient's hospitalization (physical component scale: 83.1 to 79.6 [P =.03] and mental component scale: 71.6 to 67.4 [P =.04]).

CONCLUSIONS

Patients undergoing HCT reported a steep deterioration in QOL and substantially worsening depression during hospitalization. Baseline anxiety and depression predicted worse QOL during hospitalization, underscoring the importance of assessing pre-HCT psychiatric morbidity.

Relation of hepatic steatosis to atherogenic dyslipidemia

Hepatic steatosis is closely associated with the metabolic syndrome. We assessed for an independent association between hepatic steatosis and atherogenic dyslipidemia after adjustment for obesity, physical activity, hyperglycemia, and systemic inflammation. We studied 6,333 asymptomatic subjects without clinical cardiovascular disease undergoing a health screen in Brazil from November 2008 to July 2010. Hepatic steatosis was diagnosed by ultrasound. Atherogenic dyslipidemia was defined using 2 definitions: criteria for (1) metabolic syndrome or (2) insulin resistance (triglyceride/high-density-lipoprotein cholesterol ratio of ≥2.5 in women and ≥3.5 in men). In hierarchical multivariate regression models, we evaluated for an independent association of hepatic steatosis with atherogenic dyslipidemia. Hepatic steatosis was detected in 36% of participants (average age 43.5 years, 79% men, average body mass index 26.3 kg/m(2)). Subjects with hepatic steatosis had similar levels of low-density-lipoprotein cholesterol, with significantly lower level of high-density-lipoprotein cholesterol and higher level of triglyceride compared with those without steatosis. Hepatic steatosis remained significantly independently associated with atherogenic dyslipidemia of both definitions (metabolic syndrome [odds ratio 2.47, 95% confidence interval 2.03 to 3.02] and insulin resistance [odds ratio 2.50, 95% confidence interval 2.13 to 2.91]) after multivariate adjustment. Stratified analyses showed a persistent independent association in nonobese subjects, those without metabolic syndrome, those with normal high-sensitivity C-reactive protein, nonalcohol abusers, and those with normal liver enzymes. Hepatic steatosis was significantly associated with atherogenic dyslipidemia independent of obesity, physical activity, hyperglycemia, and systemic inflammation after multivariate adjustment. In conclusion, this adds to the growing body of evidence that hepatic steatosis may play a direct metabolic role in conferring increased cardiovascular risk.

Abstract 567: Causal Assessment of Uric Acid and Risk of Myocardial Infarction, a Mendelian Randomization Study

Introduction

Prospective studies suggest that high serum uric acid (UA) levels are associated with increased risk of myocardial infarction (MI), but causality of this association remains uncertain. Mendelian randomization studies assess causality by using genetic variants as unbiased proxies for circulating biomarkers. We tested the hypothesis that genetically raised UA levels are causally related to elevated MI risk.

Methods

All reported UA associated genetic variants were assessed for pleiotropy in public genome-wide association databases and in the Pakistan Risk of Myocardial Infarction Study (PROMIS), in which we measured >25 atherosclerosis-related biomarkers in >10,000 people. Genetic variants lacking pleiotropic associations (p<0.01) were evaluated for association with MI in 7031 cases and 6360 controls in PROMIS.

Results

Among the individuals studied (mean age 54 ± 10 years; 81% male), 1316 had UA measurements with mean UA 5.71 ± 1.54 mg/dl. Of the 36 genetic variants associated with UA at genome-wide significance (p <5x10-8), 5 were independent and not associated with any factors investigated. For each variant, genetically raised UA was not associated with MI risk in a concordant direction (Table). A score-based instrumental variable analysis found no causal relationship between UA levels and MI (OR 0.91, 95% CI 0.74 - 1.12, p = 0.39). This analysis will be repeated with CARDIoGRAM data in time for presentation.

Conclusions

(1) Genetically raised UA levels were not associated with elevated MI risk, and (2) the collection of UA genetic instruments did not reject the null hypothesis of no causal relationship. We suggest that UA levels are not causally related to MI risk.

Impact of fitness versus obesity on routinely measured cardiometabolic risk in young, healthy adults

Obesity demonstrates a direct relation with cardiovascular risk and all-cause mortality, while cardiorespiratory fitness demonstrates an inverse relation. In clinical practice, several cardiometabolic (CM) risk factors are commonly measured to gauge cardiovascular risk, but the interaction between fitness and obesity with regard to CM risk has not been fully explored. In this study, 2,634 Brazilian adults referred for employer-sponsored heath exams were assessed. Obesity was defined as body mass index >30 kg/m(2) or waist circumference >102 cm in men or >88 cm in women when body mass index was 25 to 30 kg/m(2). Fitness was quantified by stage achieved on an Ellestad treadmill stress test, with those completing stage 4 considered fit. Hepatic steatosis was determined by ultrasound. CM risk factors were compared after stratifying patients into 4 groups: fit and normal weight, fit and obese, unfit and normal weight, and unfit and obese. Approximately 22% of patients were obese; 12% were unfit. Fitness and obesity were moderately correlated (ρ = 0.38 to 0.50). The sample included 6.5% unfit and normal-weight subjects and 16% fit and obese subjects. In overweight and obese patients, fitness was negatively associated with CM risk (p <0.01 for all values). In fit patients, increasing body mass index was positively associated with CM risk (p <0.01 for all values). In instances of discordance between fitness and obesity, obesity was the stronger determinant of CM risk. In conclusion, fitness and obesity are independently associated with CM risk. The effects of fitness and obesity are additive, but obesity is more strongly associated with CM risk when fitness and obesity are discordant. These findings underscore the need for weight loss in obese patients and suggest an unmeasured benefit of fitness.

Relation of uric acid to serum levels of high-sensitivity C-reactive protein, triglycerides, and high-density lipoprotein cholesterol and to hepatic steatosis

Increased uric acid (UA) is strongly linked to cardiovascular disease. However, the independent role of UA is still debated because it is associated with several cardiovascular risk factors including obesity and metabolic syndrome. This study assessed the association of UA with increased high-sensitivity C-reactive protein (hs-CRP), increased ratio of triglyceride to high-density lipoprotein cholesterol (TG/HDL), sonographically detected hepatic steatosis, and their clustering in the presence and absence of obesity and metabolic syndrome. We evaluated 3,518 employed subjects without clinical cardiovascular disease from November 2008 through July 2010. Prevalence of hs-CRP ≥3 mg/L was 19%, that of TG/HDL ≥3 was 44%, and that of hepatic steatosis was 43%. In multivariable logistic regression after adjusting for traditional cardiovascular risk factors and confounders, highest versus lowest UA quartile was associated with hs-CRP ≥3 mg/L (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.01 to 2.28, p = 0.04), TG/HDL ≥3 (OR 3.29, 95% CI 2.36 to 4.60, p <0.001), and hepatic steatosis (OR 3.10, 95% CI 2.22 to 4.32, p <0.001) independently of obesity and metabolic syndrome. Association of UA with hs-CRP ≥3 mg/L became nonsignificant in analyses stratified by obesity. Ascending UA quartiles compared to the lowest UA quartile demonstrated a graded increase in the odds of having 2 or 3 of these risk conditions and a successive decrease in the odds of having none. In conclusion, high UA levels were associated with increased TG/HDL and hepatic steatosis independently of metabolic syndrome and obesity and with increased hs-CRP independently of metabolic syndrome.

Protracted developmental trajectories of GABAA receptor alpha1 and alpha2 subunit expression in primate prefrontal cortex

BACKGROUND

In schizophrenia, working memory dysfunction is associated with altered expression of gamma-aminobutyric acid (GABA)(A) receptor alpha1 and alpha2 subunits in the dorsolateral prefrontal cortex (DLPFC). In rodents, cortical alpha subunit expression shifts from low alpha1 and high alpha2 to high alpha1 and low alpha2 during early postnatal development. Because these two alpha subunits confer different functional properties to the GABA(A) receptors containing them, we determined whether this shift in alpha1 and alpha2 subunit expression continues through adolescence in the primate DLPFC, potentially contributing to the maturation of working memory during this developmental period.

METHODS

Levels of GABA(A) receptor alpha1 and alpha2 subunit mRNAs were determined in the DLPFC of monkeys aged 1 week, 4 weeks, 3 months, 15-17 months (prepubertal), and 43-47 months (postpubertal) and in adult monkeys using in situ hybridization, followed by the quantification of alpha1 subunit protein by western blotting. We also performed whole-cell patch clamp recording of miniature inhibitory postsynaptic potentials (mIPSPs) in DLPFC slices prepared from pre- and postpubertal monkeys.

RESULTS

The mRNA and protein levels of alpha1 and alpha2 subunits progressively increased and decreased, respectively, throughout postnatal development including adolescence. Furthermore, as predicted by the different functional properties of alpha1-containing versus alpha2-containing GABA(A) receptors, the mIPSP duration was significantly shorter in postpubertal than in prepubertal animals.

CONCLUSIONS

In contrast to rodents, the developmental shift in GABA(A) receptor alpha subunit expression continues through adolescence in primate DLPFC, inducing a marked change in the kinetics of GABA neurotransmission. Disturbances in this shift might underlie impaired working memory in schizophrenia.

Nonlinear ligament viscoelasticity

Ligaments display time-dependent behavior, characteristic of a viscoelastic solid, and are nonlinear in their stress-strain response. Recent experiments (25) reveal that stress relaxation proceeds more rapidly than creep in medial collateral ligaments, a fact not explained by linear viscoelastic theory but shown by Lakes and Vanderby (17) to be consistent with nonlinear theory. This study tests the following hypothesis: nonlinear viscoelasticity of ligament requires a description more general than the separable quasilinear viscoelasticity (QLV) formulation commonly used. The experimental test for this hypothesis involves performing both creep and relaxation studies at various loads and deformations below the damage threshold. Freshly harvested, rat medial collateral ligaments (MCLs) were used as a model. Results consistently show a nonlinear behavior in which the rate of creep is dependent upon stress level and the rate of relaxation is dependent upon strain level. Furthermore, relaxation proceeds faster than creep; consistent with the experimental observations of Thornton et al. (25) The above results from rat MCLs are not consistent with a separable QLV theory. Inclusion of these nonlinearities would require a more general formulation.

A ligand-reversible dimerization system for controlling protein-protein interactions

Chemically induced dimerization provides a general way to gain control over intracellular processes. Typically, FK506-binding protein (FKBP) domains are fused to a signaling domain of interest, allowing crosslinking to be initiated by addition of a bivalent FKBP ligand. In the course of protein engineering studies on human FKBP, we discovered that a single point mutation in the ligand-binding site (Phe-36 --> Met) converts the normally monomeric protein into a ligand-reversible dimer. Two-hybrid, gel filtration, analytical ultracentrifugation, and x-ray crystallographic studies show that the mutant (F(M)) forms discrete homodimers with micromolar affinity that can be completely dissociated within minutes by addition of monomeric synthetic ligands. These unexpected properties form the basis for a "reverse dimerization" regulatory system involving F(M) fusion proteins, in which association is the ground state and addition of ligand abolishes interactions. We have used this strategy to rapidly and reversibly aggregate fusion proteins in different cellular compartments, and to provide an off switch for transcription. Reiterated F(M) domains should be generally useful as conditional aggregation domains (CADs) to control intracellular events where rapid, reversible dissolution of interactions is required. Our results also suggest that dimerization is a latent property of the FKBP fold: the crystal structure reveals a remarkably complementary interaction between the monomer binding sites, with only subtle changes in side-chain disposition accounting for the dramatic change in quaternary structure.

Regulation of protein secretion through controlled aggregation in the endoplasmic reticulum

A system for direct pharmacologic control of protein secretion was developed to allow rapid and pulsatile delivery of therapeutic proteins. A protein was engineered so that it accumulated as aggregates in the endoplasmic reticulum. Secretion was then stimulated by a synthetic small-molecule drug that induces protein disaggregation. Rapid and transient secretion of growth hormone and insulin was achieved in vitro and in vivo. A regulated pulse of insulin secretion resulted in a transient correction of serum glucose concentrations in a mouse model of hyperglycemia. This approach may make gene therapy a viable method for delivery of polypeptides that require rapid and regulated delivery.

A theory of mind perspective on cognitive, affective, and intimacy deficits in child sexual offenders

Previous work in the area of sexual offending has suggested that factors such as intimacy deficits, problems empathizing with victims, and cognitive distortions have all been associated with the genesis and maintenance of sexual abuse. While researchers have constructed theories to account for the role of these variables in sexual offending, a framework that unites their study is lacking. Recently Ward, Keenan, and Hudson have proposed that sexual offenders may suffer from a deficit in their ability to understand and attribute mental states to others. Their review of the literature on the etiology of sexual offending suggested that intimacy deficits, empathy deficits, and cognitive distortions all point to a lack of awareness of other peoples' beliefs, desires, perspectives, and needs, what is commonly referred to in the developmental literature as a theory of mind. In this paper, we expand on this argument, illustrating some of the developmental pathways by which deficits in one's theory of mind can explain the pattern of deficits exhibited by many sexual offenders.

Chronic inhalation carcinogenicity study of commercial hexane solvent in F-344 rats and B6C3F1 mice

The carcinogenic and chronic toxicity potential of commercial hexane solvent was evaluated in F-344 rats and B6C3F1 mice (50/sex/concentration/species) exposed by inhalation for 6 h/day, 5 days/week for 2 years. Target hexane vapor concentrations were 0, 900, 3000, and 9000 ppm. There were no significant differences in survivorship between control and hexane-exposed groups, and clinical observations were generally unremarkable. Small, but statistically significant decreases in body weight gain were seen in rats of both sexes in the mid- and high-exposure groups and in high-expsoure female mice. The only noteworthy histopathological finding in rats was epithelial cell hyperplasia in the nasoturbinates and larynx of exposed groups. This response was judged to be indicative of upper respiratory tract tissue irritation. No significant differences in tumor incidence between control and hexane-exposed rats were found. In mice, uterine tissue from the high-exposure females exhibited a significant decrease in the severity of cystic endometrial hyperplasia compared to controls. An increase in the combined incidence of hepatocellular adenomas and carcinomas was observed in high-exposure female mice. The incidence of liver tumors was not increased in the mid- or low-exposure female mice or in male mice exposed to hexane. An increased incidence of pituitary adenomas was observed in female, but not male mice. This finding was not believed to have been treatment-related because the incidence in the control group was unusually low, and the incidence in exposed groups was not dose-related and was within the historical control range. No other neoplastic changes judged to be treatment-related were observed in tissues from male or female mice. In conclusion, chronic exposure to commercial hexane solvent at concentrations up to 9000 ppm was not carcinogenic to F-344 rats or to male B6C3F1 mice, but did result in an increased incidence of liver tumors in female mice.

Synthesis and activity of bivalent FKBP12 ligands for the regulated dimerization of proteins

The total synthesis and in vitro activities of a series of chemical inducers of dimerization (CIDs) is described. The use of small-molecule CIDs to control the dimerization of engineered FKBP12-containing fusion proteins has been demonstrated to have broad utility in biological research as well as potential medical applications in gene and cell therapies. The facility and flexibility of preparation make this new class of wholly synthetic compounds exceptionally versatile tools for the study of intracellular signaling events mediated by protein-protein interactions or protein localization. While some congeners possess potency comparable to or better than the first generation natural product-derived CID, FK1012, structure-activity relationships are complex and underscore the need for application-specific compound optimizations.

A versatile synthetic dimerizer for the regulation of protein-protein interactions

The use of low molecular weight organic compounds to induce dimerization or oligomerization of engineered proteins has wide-ranging utility in biological research as well as in gene and cell therapies. Chemically induced dimerization can be used to activate intracellular signal transduction pathways or to control the activity of a bipartite transcription factor. Dimerizer systems based on the natural products cyclosporin, FK506, rapamycin, and coumermycin have been described. However, owing to the complexity of these compounds, adjusting their binding or pharmacological properties by chemical modification is difficult. We have investigated several families of readily prepared, totally synthetic, cell-permeable dimerizers composed of ligands for human FKBP12. These molecules have significantly reduced complexity and greater adaptability than natural product dimers. We report here the efficacies of several of these new synthetic compounds in regulating two types of protein dimerization events inside engineered cells--induction of apoptosis through dimerization of engineered Fas proteins and regulation of transcription through dimerization of transcription factor fusion proteins. One dimerizer in particular, AP1510, proved to be exceptionally potent and versatile in all experimental contexts tested.

Care of patients with type II diabetes: a study of family physicians' compliance with clinical practice guidelines

BACKGROUND

Most patients with type II diabetes mellitus receive care by family physicians. The goals of this study were to determine the level of diabetes care provided by family physicians; to assess family physicians' compliance with the Canadian Diabetes Association (CDA) guidelines; and to examine relationships between various aspects of diabetes care and glycemic control.

METHODS

A retrospective medical chart review was conducted of 118 patients with type II diabetes mellitus in 10 family practice clinics in Newfoundland. The study population consisted of 55 male and 63 female patients with a mean age of 64 (range 29 to 88) years. Using standardized forms based on the CDA guidelines, information about plasma glucose and lipid levels, presence of diabetes complications, and physician management practices were extracted from patient charts. The main outcome measure was glycosylated hemoglobin (HbA1c) levels.

RESULTS

Only 53% patients had HbA1c measurements done in the previous year; these persons had a significantly longer duration of diabetes that those who did not have their HbA1c measured. Eighty-seven percent of patients had optimal or good plasma glucose levels. Compliance with CDA guidelines by physicians was poor; physicians were doing about half the recommended checks and procedures.

CONCLUSIONS

Data from the present study seem to suggest that family physicians are doing a good job of providing care for their patients with type II diabetes. The results, however, should be interpreted with caution until further research is done to replicate our findings because of the limitations of this small retrospective study.

A humanized system for pharmacologic control of gene expression

Gene therapy was originally conceived as a medical intervention to replace or correct defective genes in patients with inherited disorders. However, it may have much broader potential as an alternative delivery platform for protein therapeutics, such as cytokines, hormones, antibodies and novel engineered proteins. One key technical barrier to the widespread implementation of this form of therapy is the need for precise control over the level of protein production. A suitable system for pharmacologic control of therapeutic gene expression would permit precise titration of gene product dosage, intermittent or pulsatile treatment, and ready termination of therapy by withdrawal of the activating drug. We set out to design such a system with the following properties: (1) low baseline expression and high induction ratio; (2) positive control by an orally bioavailable small-molecule drug; (3) reduced potential for immune recognition through the exclusive use of human proteins; and (4) modularity to allow the independent optimization of each component using the tools of protein engineering. We report here the properties of this system and demonstrate its use to control circulating levels of human growth hormone in mice implanted with engineered human cells.

Two-generation reproduction study on commercial hexane solvent

The reproductive effects of inhalation exposure to commercial hexane vapors were evaluated in Sprague-Dawley rats. Males and females were exposed to commercial hexane vapor at target concentrations of 0, 900, 3000 or 9000 ppm for 6 h a day, 5 or 7 days a week, over two generations. In addition to pre-breed exposures of 10 weeks' duration, exposures continued through mating, gestation and lactation. At both the F0 breed to produce F1 litters and the F1 breed to produce F2 litters, reproductive parameters were unaffected by commercial hexane exposure. The mating, fertility and gestational indices, as well as litter size and postnatal survival, were not significantly different between exposure groups. However, reductions in body weight and body weight gain were observed in both F1 and F2 litters exposed to 9000 ppm. Effects on body weight were not observed in offspring exposed to the two lower concentrations of commercial hexane. Histopathological examination of selected tissues revealed hyaline droplet nephropathy in adult F0 and F1 males exposed to 9000 ppm. This finding was anticipated and is not believed to be relevant for the assessment of human health effects. No other treatment-related histopathological lesions were observed. Thus, exposure of rats to commercial hexane for two generations resulted in reduced body weight gains at 9000 ppm but no adverse effects on reproduction. These findings suggest that occupational exposure to commercial hexane vapors at currently recommended threshold limit value concentrations (i.e. TLV for n-hexane is 50 ppm and TLV for other hexane isomers is 500 ppm) should not pose a reproductive hazard.