Investigation of the Fatty Acid Profile of the M. rhomboideus Derived from Bos indicus Cattle

ObjectivesResearch has shown the m. Rhomboideus (Rho) from purebred Bos indicus (BI) to be unique in its proximate chemical composition, indicated by increased lipid deposition. Thus, potential for the depostion of mono- (MUFA) and poly- unsaturated (PUFA) fatty acids exists. The objective of this study was to assess the fatty acid composition of the intramuscular (IMF) and subcutaneous (SQF) depots in the Rho from BI crossed cattle.Materials and MethodsThree replications of 4 USDA Choice (Ch) and 4 USDA Select (Se) Rho muscles were selected from the right half of split carcasses (N = 24). Selection parameters were > 7.62-cm hump height, > 7.62-cm width, > 25.4-cm length, weight range: 2–4-kg. Muscles were removed from carcasses and vacuum packaged. After a 14-d aging period, Rho muscles were fabricated, 2.54-cm serially cut steaks (anterior to posterior), trimmed to 0.254-mm fat thickness. Steaks were assigned identification tags and designated for analysis. Rho steaks were used for proximate composition (n = 2), trained sensory analysis (n = 2), Warner-Bratzler shear force (WBS, n = 1), collagen content (n = 1), and fatty acid composition of IMF and SQF (n = 1). Steaks for trained sensory analysis were also used for color measurements and cook yield. Data were analyzed using a 2-sample t test. Sensory data were analyzed using a linear fit model with order as a random effect. All data analyzed using JMP v14.0.0. A predetermined significance level of P < 0.05 was used.ResultsTotal MUFA, PUFA and saturated fatty acid (SFA) percentages of IMF were not significant (P > 0.05) between Ch Rho muscles (43, 7.2, 47.1%, 0.89, respectively) and Se Rho muscles (43.0, 6.3, 50.7%, 0.86, respectively). Mean averages across both quality grades for total MUFA, PUFA, SFA, and MUFA:SFA (42.2, 6.8, 48.9%, 0.87, respectively) in Rho IMF were similar to reported FAC averages of Bos taurus (BT) longissimus dorsi IMF (47.8, 4.4, 47.8%, 1.0, respectively).Total MUFA percentage (49.1 vs. 45.4%) and MUFA:SFA ratio (1.1 vs. 0.9) were significantly higher (P < 0.001) in Ch SQF compared to Se SQF. However, total PUFA percentage (4.3 vs. 3.7%) and SFA (50.3 vs. 47.0%) were significantly higher (P < 0.02) in Se SQF compared to Ch SQF. Mean averages across both quality grade for total MUFA, PUFA, SFA, and MUFA:SFA (47.4, 4, 48.6%, 0.99, respectively) in SQF were similar to reported fatty acid averages of BT brisket SQF (56.8, 3, and 35.9%; 1.47, respectively).Protein content (19.4 vs. 18.6%) was higher (P < 0.02) for Ch than Se Rho muscles. L* value (50.2 vs. 47.9) was larger (P < 0.05) for Se. Ch Rho muscles contained greater amounts (P < 0.001) of total, insoluble, and soluble collagen (21.8, 21.5, 0.3 mg/g, respectively) compared to Se Rho muscles (13.8, 13.7, 0.1 mg/g, respectively). Ch Rho muscles were more tender (P < 0.001) as determined by WBS values (2.6 vs. 3.1 kg). Trained sensory analysis, pH, fat, moisture, a* and b* color values between quality grades were not different (P > 0.05).ConclusionDifferences were not seen for fatty acid composition between Ch and Se Rho IMF fat. However, higher percentages of total PUFA were found in both Ch and Se Rho IMF compared to reported longissimus dorsi IMF. Additionally, Ch Rho SQF contained higher percentages of total MUFA. However, Se Rho SQF contained higher percentages of total PUFA and SFA. Higher percentages of SFA were found in both Ch and Se SQF compared to reported brisket SQF SFA values.

The Optimization of the Concentrations of Sodium Lactate (Nal), Sodium Erythorbate (Nae), and Sodium Bicarbonate (Nab) Applied to Beef Trimmings for Ground Beef Production

ObjectivesThe objective of the study was to identify optimal concentrations of NaL, NaE and NaB applied to beef trimmings to assess their impact on quality of ground beef patties.Materials and MethodsBeef trimmings (∼50kg) were fabricated from beef forequarters (N = 5) 14 d postmortem, combined and aerobically stored (5°C) for an additional 6 d to simulate the collection, storage, transportation and receipt of a combo of beef trimmings. A 23 central composite response surface design (RSM) was used to generate 15 treatment combinations containing NaL (0.1–1.5 M), NaE (0.1–0.6 M), and NaB (0.1–1.5 M) with water used as a control. After aerobic storage, the beef trimmings (∼20% fat) were coarse ground (12 mm) and the treatment/control solution applied to the coarse ground trimmings (∼454 g) at 2% (w/w). The trimmings were reground (3 mm) and 120 g of treated sample was placed into a Petri dish and overwrapped with oxygen permeable film (OTR: 21,700 cc/m2/24h at 25°C) to form patties. The patties (2 per treatment/control) were stored under simulated retail conditions: 5°C, cool white fluorescent light (200–300 lux) and analyzed at Day 0, 3, 6, and 9 of storage to assess the effectiveness of each treatment in preventing further quality deterioration. Objective color (L*, a*, b*), 2-thiobarbituric acid (TBA) determinations, GC–MS for off-odor assessment and aerobic plate counts (APC) were conducted. The least squares means of results were generated by one-way ANOVA and Tukey HSD to identify significant differences (P < 0.05) between treatment and control patties. For RSM and multivariate RSM analyses, the data was used to generate total quadratic polynomial linear regression models and contour plots to determine the optimum ingredient concentrations for the solution.ResultsThe a* values of treated indicated a redder surface color from Day 0 to Day 9 (P < 0.05). No difference was observed for treated and control patties for TBA and hexanal counts on Day 0. The TBA values for all treatments reduced lipid oxidation compared to the control on Day 3, 6, and 9 (0.47– 0.58 vs. 0.71, 0.51– 0.58 vs. 0.74 and 0.45– 0.62 vs. 0.74, respectively; P < 0.05). No differences were observed for treated and control patties for APC from Day 0 to Day 6, except on Day 9 (8.10 vs. 8.21 Log10 CFU/g; P < 0.05). Based on these results, a* and TBA values were used to conduct RSM analyses for Day 3 and 6. Day 9 was excluded due to a significant lack of fit. The predicted value of hexanal was 0 for all treatments. The prediction of TBA values found optimum ingredient concentrations on Day 6: NaL (0.74 M), NaE (0.35 M) and NaB (1.00 M) (R2 = 0.77, respectively; P < 0.05). The prediction of a* values on Day 3 and 6 did not identify optimum ingredient concentrations for any treatment solution (R = 0.94 and 0.78, respectively; P < 0.05). Multivariate RSM was conducted to overlap the contour plots of a* and TBA values at Day 3 and 6 to better approximate the optimal ingredient concentrations for a* values. The proximal optimum concentration ranges of solutions based on the analysis were 0.3- 0.5 M NaL, 0.35 M NaE and 1M NaB with predicted a* values > 11 and TBA values < 0.52.ConclusionResults of this study suggest that a combination of NaB, NaE, and NaL can be applied to improve color stability, reduce lipid oxidation, and control off-odor of ground beef patties.

Phase I study of the checkpoint kinase 1 inhibitor GDC-0575 in combination with gemcitabine in patients with refractory solid tumors

BACKGROUND

Checkpoint kinase 1 (Chk1) inhibition following chemotherapy-elicited DNA damage overrides cell cycle arrest and induces mitotic catastrophe and cell death. GDC-0575 is a highly-selective oral small-molecule Chk1 inhibitor that results in tumor shrinkage and growth delay in xenograft models. We evaluated the safety, tolerability, and pharmacokinetic properties of GDC-0575 alone and in combination with gemcitabine. Antitumor activity and Chk1 pathway modulation were assessed.

PATIENTS AND METHODS

In this phase I open-label study, in the dose escalation stage, patients were enrolled in a GDC-0575 monotherapy Arm (1) or GDC-0575 combination with gemcitabine Arm (2) to determine the maximum tolerated dose. Patients in arm 2 received either i.v. gemcitabine 1000 mg/m2 (arm 2a) or 500 mg/m2 (arm 2b), followed by GDC-0575 (45 or 80 mg, respectively, as RP2D). Stage II enrolled disease-specific cohorts.

RESULTS

Of 102 patients treated, 70% were female, the median age was 59 years (range 27-85), and 47% were Eastern Cooperative Oncology Group PS 0. The most common tumor type was breast (37%). The most frequent adverse events (all grades) related to GDC-0575 and/or gemcitabine were neutropenia (68%), anemia (48%), nausea (43%), fatigue (42%), and thrombocytopenia (35%). Maximum concentrations of GDC-0575 were achieved within 2 hours of dosing, and half-life was ∼23 hours. No pharmacokinetic drug-drug interaction was observed between GDC-0575 and gemcitabine. Among patients treated with GDC-0575 and gemcitabine, there were four confirmed partial responses, three occurring in patients with tumors harboring TP53 mutation. Pharmacodynamic data were consistent with GDC-0575 inhibition of gemcitabine-induced expression of pCDK1/2.

CONCLUSION

GDC-0575 can be safely administered as a monotherapy and in combination with gemcitabine; however, overall tolerability with gemcitabine was modest. Hematological toxicities were frequent but manageable. Preliminary antitumor activity was observed but limited to a small number of patients with a variety of refractory solid tumors treated with GDC-0575 and gemcitabine.

CLINICAL TRIAL NUMBER

NCT01564251.

Abstract OT3-03-01: Open-label, single-arm study evaluating the antitumor activity and safety of niraparib as neoadjuvant treatment in patients with localized, HER2-negative, BRCA-mutant breast cancer

Background: Neoadjuvant chemotherapy is administered to patients with operable breast cancer to downstage the tumor to allow for less extensive surgery and to provide prognostic information about drug efficacy and risk of disease recurrence. Patients who achieve a pathological complete response (pCR) following neoadjuvant treatment have a more favorable outcome than patients with residual invasive disease. Single-agent poly(ADP-ribose) polymerase (PARP) inhibitors have clinical efficacy in BRCA-mutated breast cancer. Niraparib, a potent and selective PARP1/2 inhibitor, is approved for maintenance treatment of patients with recurrent ovarian cancer and has demonstrated strong antitumor activity in in vivo studies with BRCA1-mutant breast cancer. The objective of this study is to evaluate the antitumor activity of single-agent niraparib in the neoadjuvant treatment of patients with localized, human epidermal growth factor receptor 2 (HER2)-negative, BRCAmut breast cancer.

Trial Design: This is an open-label, single-arm pilot study with a target enrollment of 20 evaluable patients. Eligible patients are those ≥18 years old with histologically-confirmed HER2-negative localized breast cancer and either a BRCA1 or BRCA2 mutation (germline or somatic) and no prior anti-cancer therapies for the current malignancy. Patients will receive 200 mg of oral niraparib once daily for 2 months, after which they may either proceed directly to surgery or receive chemotherapy at the discretion of the physician. The primary endpoint is tumor response rate based on the change in tumor volume as measured by breast MRI after 2 months of treatment with niraparib; a response is defined as ≥30% reduction of tumor volume from baseline. Secondary endpoints include pCR rate, tumor response rate based on the change in tumor volume as measured by breast ultrasound, and safety and tolerability. Data will be summarized in a descriptive nature by frequency distributions (number and percentage of patients) for categorical variables and by the mean, median, and standard deviation for continuous variables. Tumor response rate will be tabulated together with its 95% binomial exact confidence interval.

Funding: TESARO, Inc., Waltham, MA, USA sponsored the study.

Citation Format: Han H, Hamilton E, Irie H, Isakoff S, Jelovac D, Liem A, Liu MC, Milillo A, Nangia J, Page D, Reeves J, Santa-Maria C, Duncan M, Graham JR, Chen J, Dezube BJ, Spring L. Open-label, single-arm study evaluating the antitumor activity and safety of niraparib as neoadjuvant treatment in patients with localized, HER2-negative, BRCA-mutant breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT3-03-01.

Abstract PD1-11: nextMONARCH 1: Phase 2 study of abemaciclib plus tamoxifen or abemaciclib alone in HR+, HER2- advanced breast cancer

Background

Abemaciclib is a selective CDK4 & 6 inhibitor approved on a continuous dosing schedule for HR+, HER2- advanced breast cancer (ABC) as monotherapy (MONARCH 1) and in combination with endocrine therapy (ET). A previous Phase 1b (NCT01394016) cohort of HR+ ABC patients (pts) demonstrated efficacy of abemaciclib monotherapy (150mg and 200mg Q12H starting dose); given the small sample size and nonrandomized design the impact of the starting dose was unclear. nextMONARCH 1 (NCT02747004) evaluated abemaciclib in 2 monotherapy arms, in a randomized setting. Abemaciclib has been associated with dose-dependent early onset diarrhea that is well managed with antidiarrheal therapy. nextMONARCH 1 also explored the 200mg Q12H abemaciclib dose in combination with prophylactic loperamide to reduce incidence/severity of diarrhea and dose adjustments. A third arm evaluated abemaciclib + tamoxifen as a strategy to overcome endocrine resistance.

Methods

nextMONARCH 1 is a multicenter, randomized, open-label, Phase 2 study of abemaciclib or abemaciclib + tamoxifen in women with HR+, HER2- ABC who have progressed on or after prior ET and previously received chemotherapy. Pts were stratified by presence of liver metastases and prior use of tamoxifen in the advanced setting. Randomization was 1:1:1 to abemaciclib 150mg Q12H + daily tamoxifen 20mg (Arm A) or abemaciclib 150mg Q12H (Arm B); or abemaciclib 200mg Q12H + prophylactic loperamide (Arm C). Key eligibilities were ≥2 chemotherapy regimens (1-2 administered in metastatic setting), measurable disease and no prior treatment with CDK4 & 6 inhibitors. Primary objective was progression free survival (PFS). Key secondary objectives included objective response rate (ORR), dclinical benefit rate (CBR), and safety. PFS analysis tested superiority of Arm A to C at ∼110 events across the 2 arms assuming a hazard ratio (HR) of 0.667 to achieve ∼80% power. Arm B would be considered non-inferior to Arm C if the observed PFS HR is &lt;1.2.

Results

234 pts were randomized to Arms A (n=78), B (n=79) and C (n=77). 166 PFS events have been observed (A: 57; B: 54; C: 55). Median PFS was 9.1 months in Arm A, 6.5 in Arm B and 7.4 in Arm C (A vs C: HR=.815, 95% CI, .556-1.193, p=.293; B vs C: HR=1.045, 95% CI, .711-1.535 p=.811). Investigator-assessed ORR was 34.6%, 24.1% and 32.5% (confirmed ORR: 25.6%, 19.0%, 28.6%) and CBR was 61.5%, 49.4% and 51.9% in Arms A, B and C, respectively. Prophylactic loperamide reduced the incidence and severity of diarrhea (C: 62.3%, Gr 3: 7.8%) compared to MONARCH 1 (90.2%, Gr 3: 19.7%, Dickler et al. 2017) resulting in similar rates of diarrhea with 150mg abemaciclib without prophylaxis (A: 53.8%, Gr 3: 1.3%; B: 67.1%, Gr 3: 3.8%). The adverse event profile across arms was generally consistent with other breast studies of abemaciclib.

Conclusions

nextMONARCH 1 confirmed single-agent activity of abemaciclib in heavily pretreated pts with HR+, HER2- ABC. Efficacy of abemaciclib monotherapy at 150mg was similar to 200mg. Combining tamoxifen with abemaciclib did not demonstrate a statistically significant improvement in PFS compared to abemaciclib monotherapy. Addition of prophylactic loperamide to abemaciclib 200mg resulted in diarrhea similar to 150mg without prophylaxis.

Citation Format: Hamilton E, Cortes J, Dieras V, Ozyilkan O, Chen S-C, Petrakova K, Manikhas A, Jerusalem G, Hegg R, Lu Y, Bear MM, Johnston EL, Martin M. nextMONARCH 1: Phase 2 study of abemaciclib plus tamoxifen or abemaciclib alone in HR+, HER2- advanced breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD1-11.

Abstract OT2-07-08: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Paplomata E, Borges V, Loi S, Abramson V, Hamilton E, Hurvitz S, Lin N, Walker L, Murthy RK. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-07-08.

Abstract P6-18-31: PROCLAIM-CX-072: Monotherapy for advanced triple negative breast cancer with skin metastases in a phase 1-2 trial of the PD-L1 probody therapeutic CX-072

Background: Probody™ therapeutics are novel, fully recombinant antibody prodrugs designed to remain relatively inactive in healthy tissue and to be specifically activated by proteases in the tumor microenvironment. In this way, Probody therapeutics may broaden the therapeutic window for effective but potentially toxic anticancer agents. CX-072 is a Probody therapeutic directed against programmed death-ligand 1 (PD-L1) for the treatment of cancer patients. In a first-in-human, open-label, multicenter, dose-escalation, 3+3 design, phase 1-2 study, PROCLAIM-CX-072 (PRObody CLinical Assessment In Man) (NCT03013491), 22 patients were enrolled in the phase 1 dose escalation portion. Twenty patients were evaluable per RECIST v1.1. Three patients had confirmed partial response (15%), including a 39-year-old woman with stage IV triple negative breast cancer (TNBC) treated with 10 mg/kg CX-072 monotherapy whose disease had progressed on one previous line of chemotherapy for metastatic disease. Metastatic sites included extensive nodal disease and skin/chest wall lesions. The tumor was negative for PD-L1 expression, was microsatellite stable, and had a low tumor mutational burden (4 mutations/megabase). Positive results from the phase 1 study suggest that additional exploration of treatment with CX-072 monotherapy in the TNBC patient population is warranted.

Dose expansion trial design: The phase 2 dose expansion part of the PROCLAIM-CX-072 study will include enrollment of TNBC patients with skin metastases. Key inclusion criteria for patients in the TNBC cohort are as follows: naive to immunotherapy (PD-1/PD-L1 and CTLA-4 inhibitors), approved immune checkpoint inhibitor agents not available, histologically confirmed triple negative (estrogen receptor–, progesterone receptor–, and human epidermal growth factor receptor-2–negative cancer per ASCO-CAP guidelines), previously treated with 1 to 3 systemic chemotherapy regimens, and locally advanced and recurrent skin or subcutaneous metastases not suitable for surgical resection or radiotherapy. Patients will receive doses of 10 mg/kg CX-072 intravenously every 2 weeks. Efficacy will be evaluated using RECIST v1.1 and immune-related RECIST criteria. Safety and tolerability will be assessed based on the incidence and severity of adverse events (categorized by NCI CTCAE criteria, v4.03) and relationship to study drug. Other analyses will include pharmacokinetics, incidence of anti-drug antibodies against CX-072, exploratory analysis for immune response, and CX-072 activation in the tumor.

PROBODY is a trademark of CytomX Therapeutics, Inc.

Citation Format: Adams S, Hamilton E, Ott PA, Cho D, Kalinsky K, LoRusso P, Will M, Huels V, Benson B, Murias C, Arkenau H-T. PROCLAIM-CX-072: Monotherapy for advanced triple negative breast cancer with skin metastases in a phase 1-2 trial of the PD-L1 probody therapeutic CX-072 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-18-31.

Enhanced Detection of Single Viruses On-Chip via Hydrodynamic Focusing

Planar optofluidics provide a powerful tool for facilitating chip-scale light-matter interactions. Silicon-based liquid core waveguides have been shown to offer single molecule sensitivity for efficient detection of bioparticles. Recently, a PDMS based planar optofluidic platform was introduced that opens the way to rapid development and prototyping of unique structures, taking advantage of the positive attributes of silicon dioxide-based optofluidics and PDMS based microfluidics. Here, hydrodynamic focusing is integrated into a PDMS based optofluidic chip to enhance the detection of single H1N1 viruses on-chip. Chip-plane focusing is provided by a system of microfluidic channels to force the particles towards a region of high optical collection efficiency. Focusing is demonstrated and enhanced detection is quantified using fluorescent polystyrene beads where the coefficient of variation is found to decrease by a factor of 4 with the addition of hydrodynamic focusing. The mean signal amplitude of fluorescently tagged single H1N1 viruses is found to increase with the addition of focusing by a factor of 1.64.

Antireflective light-blocking layers using a liquid top matte coating

Methods exist for the creation of antireflective thin film layers; however, many of these methods depend on the use of high temperatures, harsh chemical etches, or are made with difficult pattern materials, rendering them unusable for many applications. In addition, most methods of light blocking are specifically designed to increase light coupling and absorption in the substrate, making them incompatible with some appli-cations that also require blocking transmission of light. A method of forming a simple, patternable light-blocking layer that drastically reduces both transmission and reflection of light without dependence on processes that could damage underlying structures using a light scattering matte coating over a partially antireflective thin film light-blocking layer is presented.

Abstract P5-21-06: Alpelisib plus letrozole in estrogen receptor-Positive (ER+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (aBC): Safety and preliminary efficacy analysis from a phase 1b trial

Background

Endocrine therapy is the standard first-line treatment for postmenopausal patients (pts) with ER+, HER2– aBC. However, resistance eventually develops, often through dysregulation of PI3K/AKT/mTOR pathway, specifically mutations in PIK3CA, the gene encoding the p110α subunit of PI3K. The oral, selective PI3K inhibitor alpelisib and letrozole synergistically inhibits tumor growth in preclinical models of ER+ breast cancer. Alpelisib plus letrozole in pts with ER+ aBC is being investigated in arm 2 of a multi-arm, phase 1b study (NCT01872260).

Methods

Postmenopausal women with ER+, HER2− aBC received alpelisib (300 mg QD; continuous, 28 days cycle) plus letrozole (2.5 mg QD; continuous). Primary endpoints were to confirm MTD/RP2D of alpelisib plus letrozole in the escalation phase and to further characterize safety and tolerability in the expansion phase. Secondary and exploratory endpoints included efficacy, pharmacokinetics, and biomarkers.

Results

As of August 19, 2016, 56 pts had received alpelisib plus letrozole: 19 pts were enrolled in the escalation phase (designated here as previously treated group), of which, 95% of pts were previously treated for aBC and 37 pts were enrolled in the expansion phase (designated here as first-line group), of which, 81% of pts were treatment-naïve for aBC. 16 previously treated pts and 11 first-line pts (48% of all pts) have discontinued treatment. Most common reasons for treatment discontinuation in the full population were disease progression (23.2%) and adverse events (AEs) (8.9%). Median duration of exposure of combination (alpelisib plus letrozole) was 23 weeks and 12.7 weeks in previously treated and first-line groups, respectively. Most frequently reported any grade treatment-related AEs (≥20% incidence) in all pts were hyperglycemia (48.2%), diarrhea (48.2%), nausea (33.9%), and decreased appetite (28.6%). Most common, grade 3 or 4 AEs (≥3% incidence) suspected to be treatment-related in all pts included hyperglycemia (17.9%), rash (5.4%), and diarrhea (3.6%). Median progression-free survival was 5.7 months in the previously treated group and was not reached in the first-line group. A summary of best overall response, overall response rate and clinical benefit rate in evaluable pts is shown in the table.

 Alpelisib+Letrozole (Previously Treated group) [N=19]Alpelisib+Letrozole (First-line group) [N=27]All subjects (N=46)Best overall response, n (%)Confirmed CR000Confirmed PR04 (14.8)4 (8.7)NCRNPD6 (31.6)9 (33.3)15 (32.6)SD8 (42.1)9 (33.3)17 (37.0)PD2 (10.5)1 (3.7)3 (6.5)Unknown3 (15.8)3 (11.1)6 (13.0)ORR (CR+PR), % (95% CI)0 (0.0-17.6)14.8 (4.2-33.7)8.7 (2.4-20.8)CBR [CR+PR+(SD/NCRNPD)], % (95% CI)36.8 (16.3-61.6)70.8 (48.9-87.4)55.8 (39.90-70.9)CBR; clinical benefit rate; CI, confidence interval; CR, complete response; NCRNPD; Non-CR/Non-PD; ORR; overall response rate; PD; progressive disease; SD, stable disease.

Conclusions

Based on these preliminary data, the combination of alpelisib plus letrozole had manageable safety profile in pts with ER+, HER2– aBC and demonstrated encouraging clinical activity, particularly in the first-line patient population.

Citation Format: Juric D, Gonçalves A, Hamilton E, Boni V, Mayer IA, Turri S, Wang Y, Vogl FD, Sellami D, Campone M. Alpelisib plus letrozole in estrogen receptor-Positive (ER+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (aBC): Safety and preliminary efficacy analysis from a phase 1b trial [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 P5-21-06.

Abstract P5-20-06: Phase 1 dose escalation with ZW25, a HER2-targeted bispecific antibody, in patients (pts) with HER2-high breast cancer (BC)

Background: ZW25, a novel IgG1-like bispecific antibody, targets the same domains of HER2 as trastuzumab (T) and pertuzumab (P). In preclinical studies, ZW25 demonstrated increased tumor cell binding density and internalization relative to T and activity in T-resistant cell lines as well as models of HER2-low to high cancers. Initial dose escalation data demonstrated that once-weekly ZW25 was well tolerated at all doses evaluated and associated with single-agent anti-tumor activity in pts with heavily pre-treated (tx) HER2-expressing cancers.

Methods: 3+3 dose escalation of ZW25 given weekly (QW; 5, 10 or 15 mg/kg) or biweekly (Q2W; 20 mg/kg) in 4-week cycles. Eligibility included HER2 IHC 1, 2 or 3+ or FISH+ BC, progression after T, P and T-DM1, and measurable or non-measureable disease per RECIST 1.1. Active brain metastases were excluded. Baseline brain MRI was performed in QW cohorts only if pts had prior history (hx) of CNS mets, and in all Q2W pts regardless of hx. Assessments included AEs, LVEF, immunogenicity, PK and tumor response every 2 cycles.

Results: 8 pts with HER2-high BC were tx with ZW25 QW at 5 (n=2), 10 (n=2) or 15 mg/kg (n=4); 20 mg/kg Q2W is enrolling. 5/8 pts were HR+; 7 had measurable disease, 6 visceral disease, and 3 stable CNS disease. Median years since initial dx was 6 (range 5-16). Prior tx included T and T-DM1 (n=8); P (n= 6), and lapatinib (n=5). Median number of prior HER2-targeted regimens for metastatic disease was 6 (range 3-7) and non-hormonal HER2 regimens was 5 (range 3-7).

ZW25 was well tolerated with no DLTs or decreases in cardiac function. Most common related AEs (all Gr 1 or 2) were diarrhea (n=4), infusion reaction (IR) (n=4) and vomiting (n=3). All IRs occurred only with 1st dose. There were no treatment-related SAEs. Related Gr 3 AEs (hypophosphatemia, fatigue and arthralgia) were reported in 1 pt (10 mg/kg).

At data cut-off, pts had received 2-10 cycles of treatment, with 3 pts active. Best overall response was 2 PR (10 mg/kg), 3 SD (1 at 5 mg/kg, 2 at 15 mg/kg), and 3 PD (1 at 5 mg/kg, 2 at 15 mg/kg) for a disease control rate of 63%. Decreases in target lesions were seen in 6/7 patients with at least one tumor re-staging. One pt with SD (5 mg/kg; active on study) had an 8% decrease after C2, and 29% decrease after C8. One PR pt with prior hx of brain mets had a 33% decrease after C2 and 44% decrease after C4, although was found to have new leptomeningeal disease (LMD) at that time. Two additional pts with systemic SD (15 mg/kg; no prior hx of CNS mets) were also considered to have PD due to symptomatic brain mets. One of these pts remains on study after receiving stereotactic radiotherapy.

Conclusions: ZW25 was associated with single-agent anti-tumor activity and systemic disease control in HER2-high BC pts after a median of 6 prior HER2-targeted regimens for metastatic disease. Systemic disease control was maintained despite PD due to brain mets or LMD. The presence of CNS disease in an unscreened population is consistent with the biology of late-stage HER2-high BC. The activity and tolerability of ZW25 support further evaluation as a single agent and in combination including with CNS-directed therapies in early and late lines of treatment for HER2-expressing BC.

Citation Format: Hamilton E, Meric-Bernstam F, Infante J, Murthy R, Patnaik A, Piha-Paul SA, Tolcher A, Hausman D, Royer N, Beeram M. Phase 1 dose escalation with ZW25, a HER2-targeted bispecific antibody, in patients (pts) with HER2-high breast cancer (BC) [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 P5-20-06.