Treatment Outcomes of Stereotactic Ablative Body Radiotherapy on Extra-cranial Oligometastatic and Oligoprogressive Breast Cancer: Mature Results from a Single Institution Experience

AIMS

Evidence shows stereotactic ablative body radiotherapy (SABR) is used as a non-invasive ablative therapy in the treatment of multisite oligometastatic (OM) and oligoprogressive (OP) diseases originating from metastatic breast cancer. This study aims to report the treatment outcomes and to investigate what factors that are prognostic in terms of local control, progression-free survival (PFS) and overall survival (OS) in patients receiving SABR for extracranial OM and OP diseases originating from metastatic breast cancer.

MATERIALS AND METHODS

A retrospective review on treatment records of patients with OM and OP from metastatic breast cancer who underwent SABR at a single was carried out. SABR was performed with daily image-guided radiotherapy (IGRT) using a dedicated robotic SABR machine. Local control, PFS and OS were calculated using Kaplan-Meier statistics and the post-treatment toxicity data was scored following the CTCAE v4.0 protocol. Univariate and multivariate Cox regression tests were used in the subgroup analysis of prognostic factors on PFS and OS including patients' age, types of follow-up imaging (staging CT only vs whole-body MR/PET), metastases status (OM vs OP), primary breast cancer tumour grade, hormone receptors (ER/PR/HER2) status, change of systemic treatments at SABR, number of metastases, SABR treatment sites and doses.

RESULTS

56 metastatic breast cancer patients (38 patients with OM and 18 patients with OP) were involved in this retrospective review. The median follow-up was 35.6 months (range 4.0-132.9 months). The estimated local control at 1 , 2 and 5 years were 90.9%, 88.7% and 88.7%, respectively. The estimated median PFS was 19.2 months (95%CI 10.3-28.1 months); the PFS at 1, 2 and 5 years were 63.3%, 44.4% and 33.2%. The estimated OS at 1, 2 and 5 years were 98.0%, 91.9% and 74.3%, respectively with the estimated median OS of 105.1 months (95%CI 51.5-158.7 months). The vast majority of patients tolerated the treatment well with the commonest acute side effects as grade 1 fatigue. There were no statistically significant factors found in OS regression analysis. The types of follow-up imaging, metastases status, oestrogen receptor status, and number of metastases for SABR were statistically significant factors (p < 0.05) in the multivariate Cox regression analysis on PFS.

CONCLUSION

There are limited studies published on the efficacy and post-treatment toxicities of metastatic breast cancer OM and OP SABR with adequate length of follow-up. This study confirmed that SABR was a safe, non-invasive treatment option for patients with extracranial OM and OP diseases originated from primary breast cancer in terms of the acceptable post-treatment toxicities.

Cell- and Serum-Derived Proteins Act as DAMPs to Activate RAW 264.7 Macrophage-like Cells on Silicone Implants

Protein adsorption after biomaterial implantation is the first stage of the foreign body response (FBR). However, the source(s) of the adsorbed proteins that lead to damaged associated molecular patterns (DAMPs) and induce inflammation have not been fully elucidated. This study examined the effects of different protein sources, cell-derived (from a NIH/3T3 fibroblast cell lysate) and serum-derived (from fetal bovine serum), which were compared to implant-derived proteins (after a 30 min subcutaneous implantation in mice) on activation of RAW 264.7 cells cultured in minimal (serum-free) medium. Both cell-derived and serum-derived protein sources when preadsorbed to either tissue culture polystyrene or medical-grade silicone induced RAW 264.7 cell activation. The combination led to an even higher expression of pro-inflammatory cytokine genes and proteins. Implant-derived proteins on silicone explants induced a rapid inflammatory response that then subsided more quickly and to a greater extent than the studies with in vitro cell-derived or serum-derived protein sources. Proteomic analysis of the implant-derived proteins identified proteins that included cell-derived and serum-derived, but also other proteinaceous sources (e.g., extracellular matrix), suggesting that the latter or nonproteinaceous sources may help to temper the inflammatory response in vivo. These findings indicate that both serum-derived and cell-derived proteins adsorbed to implants can act as DAMPs to drive inflammation in the FBR, but other protein sources may play an important role in controlling inflammation.

Characterization of Radiographic and Molecular Changes in Mouse Brain after FLASH Irradiation

PURPOSE/OBJECTIVE(S)

Despite refinements in treatment platforms such as incorporation of high-resolution imaging and real time motion tracking, the amount of radiation dose delivered safely to a particular tissue type is limited by both tissue intrinsic and extrinsic factors. FLASH radiotherapy (RT), delivery of relatively high radiation dose at dose rates several orders of magnitude higher than that of conventional (CONV) dose-rates, may change that paradigm due to normal tissue sparing characteristics of FLASH RT. Our Radiation Oncology Physics division developed a novel FLASH kV x-ray cabinet system for preclinical laboratory research. Here we utilize this technology to establish optimal radiation parameters for FLASH effect in brain tissue of a murine model. A range of total radiation dose and dose rates that are considered to be within the window for FLASH effect are being investigated. We have identified several measurable and clinically meaningful toxicity outcomes, including radiation necrosis and blood brain barrier integrity, to assess FLASH effects in brain tissue.

MATERIALS/METHODS

A high-capacity rotating anode x-ray tube was implemented for FLASH irradiation, operating at 150 kVp with 0.025 mm Cu added filtration. A custom 3D printed immobilization tool was designed to reproducibly position animals for stereotactic irradiation of the brain. Dose and dose rate measurements were performed with calibrated radiographic film in kV solid water. Conventional dose rate irradiations were delivered using a standard laboratory irradiator (SARRP) operating at the same kVp and filtration. The depth-dose gradients in solid water were compared between the irradiators. Healthy 8-week-old C57BL6J mice were then irradiated with graded doses of FLASH and CONV x-rays (10- 60 Gy) using a single 1-cm wide AP field. Dose was prescribed to the center of the brain, at a depth of 3.25 mm. RT-induced necrosis is being monitored by serial biweekly MR imaging using a 7-T preclinical MRI machine. Histopathological changes will be assessed through H&E staining of harvested brain at 3-months post-irradiation (n = 5 per arm). FITC-Dextran infusion will be performed prior to necropsy to assess blood-brain barrier integrity.

RESULTS

Animal setup for stereotactic FLASH brain irradiation was reproducible to within 0.5mm. Measured dose rates were 75.6 Gy/s for FLASH and 3.8 Gy/min for conventional irradiations. At 5-mm depth in solid water, the PDDs agreed to within 4% between SARRP and FLASH Irradiator. Biweekly T1 post and T2 weighted image acquisition is currently underway. Histology and FITC-Dextran data will be presented when available.

CONCLUSION

We have successfully designed a high-precision platform to study x-ray FLASH effects in mice brain model. Evaluation of dose window for brain FLASH effect and molecular mechanisms of this phenomenon is an important step in the potential translation of FLASH RT for brain irradiation.

Preclinical Intraoperative FLASH Radiotherapy

PURPOSE/OBJECTIVE(S)

Intraoperative radiation therapy (IORT) is a method of delivering high radiation doses to an internal target with low dose to adjacent organs. Most organs at risk can often be moved out of the radiation field, so dose is usually limited by in-field vascular and/or nerve structures. It is known that ultra-high (FLASH) dose rate (>40 Gy/s) radiation reduces normal tissue toxicity compared to conventional, while preserving tumor control. We hypothesize that FLASH radiation can increase the dose tolerance of vascular and nerve structures, thus permitting for dose escalation in IORT. Here, we present a novel platform using orthovoltage x-rays to study FLASH effects in preclinical IORT. The experimental setup and dosimetry of the system have been established for FLASH irradiation of the abdominal aorta in rats to investigate dose tolerance.

MATERIALS/METHODS

A 150 kVp rotating anode x-ray source with a 75-kW generator was used to deliver FLASH and conventional irradiation. A 3D printed immobilization platform was designed to reproducibly place a surgically exposed rat abdominal aorta at 55mm SSD. A 3-mm thick lead collimator with a 10mm x 10mm aperture was placed into a flange adapter, which docks into the immobilization platform. Phantom and in vivo dosimetry were performed using both calibrated radiographic film and thermoluminescent dosimeters (TLD). Anesthetized 2-month-old Wistar rats underwent laparotomy to expose the abdomen for irradiation. A 10x12x1 mm3 tungsten plate was placed under the aorta to reduce spinal cord dose. Animals were then docked into the irradiator using the immobilization platform. Radiation dose in the range of 20 - 50 Gy were delivered to the abdominal aorta at FLASH and conventional dose-rates. Following treatment, animals undergo MR angiography every two months for 6 months, at which a histological evaluation of aorta wall will be performed.

RESULTS

The FLASH dose rate measured at the aorta wall in a rat carcass was 49.7 ± 1.2 Gy/s distal to the collimator. Dose measurements between the films and TLDs showed an agreement within ±3%. Positional uncertainty mainly depends on the visual localization of the aorta on the collimator window, which is verified before irradiation. Vertical uncertainty is less than 1 mm, which is important given the rapid dose fall off of the system. Eight animals went successfully through the procedure, are healthy and currently being follow up with MR angiography. More animals are being treated for meaningful statistical results. MR angiography and IORT are performed on different days to avoid longer times under anesthesia, which initially resulted on mortality. Results of the MR angiography and histological analysis will be presented.

CONCLUSION

The proposed platform has been successfully utilized for precision setup for FLASH IORT in a preclinical laboratory setting. Evaluation of FLASH effects in IORT setup will be an important step in the potential translation of FLASH IORT, where only one high-dose fraction can be delivered.

Multiscale Mechanical Characterization and Computational Modeling of Fibrin Gels

Fibrin is a naturally occurring protein network that forms a temporary structure to enable remodeling during wound healing. It is also a common tissue engineering scaffold because the structural properties can be controlled. However, to fully characterize the wound healing process and improve the design of regenerative scaffolds, understanding fibrin mechanics at multiple scales is necessary. Here, we present a strategy to quantify both the macroscale (1 - 10 mm) stress-strain response and the deformation of the mesoscale (10 - 1000 μm) network structure during unidirectional tensile tests. The experimental data were then used to inform a computational model to accurately capture the mechanical response of fibrin gels. Simultaneous mechanical testing and confocal microscopy imaging of fluorophore-conjugated fibrin gels revealed up to an 88% decrease in volume coupled with increase in volume fraction in deformed gels, and non-affine fiber alignment in the direction of deformation. Combination of the computational model with finite element analysis enabled us to predict the strain fields that were observed experimentally within heterogenous fibrin gels with spatial variations in material properties. These strategies can be expanded to characterize and predict the macroscale mechanics and mesoscale network organization of other heterogeneous biological tissues and matrices. STATEMENT OF SIGNIFICANCE: : Fibrin is a naturally-occurring scaffold that supports cellular growth and assembly of de novo tissue and has tunable material properties. Characterization of meso- and macro-scale mechanics of fibrin gel networks can advance understanding of the wound healing process and impact future tissue engineering approaches. Using structural and mechanical characteristics of fibrin gels, a theoretical and computational model that can predict multiscale fibrin network mechanics was developed. These data and model can be used to design gels with tunable properties.

A service evaluation of joint working across sectors to promote self-administration of subcutaneous systemic anti-cancer therapy in breast cancer patients

Introduction

Trastuzumab(T) is a humanized monoclonal antibody used in the treatment of HER2-positive breast cancer and is available as a subcutaneous(sc) formulation thereby allowing short and convenient administration. A lack of trained nurses to administer T at home and/or train patients at home to self-administer, together with challenges in maintaining cold-chain delivery have impeded uptake of home administration.1,2 In order to support patients’ ability to self-administer T at home, we have implemented an educational programme that includes nurse-led training, education material, support apps and follow-up telephone clinics. Home delivery of pre-filled syringes was enabled in collaboration with commercial providers for aseptics and logistic.

Aim

The aim of this service evaluation was to evaluate the utility of this programme from the patients’ perspective and to assess patient satisfaction and impact on quality of life (QOL).

Methods

A previously validated Self-Injection Assessment Questionnaire (SIAQ)3 was modified to assess patient satisfaction, perceptions and impact of the programme. Patients who had agreed to enrol on the ‘self-administration’ scheme, were asked to complete the questionnaire at baseline, at the third training session and at the second self-administered dose. Approval from a Research Ethics Committee is not required for this service evaluation.

Results

All 14 patients offered the questionnaire responded to all questions. The median age was 58 years old (age range 43-76), 11 patients were Caucasian, 2 were Asian and one was African/Caribbean. The average distance from their home address to hospital was 10.1 miles (range 4-19). Following completion of the one-to-one nurse training there was an improvement in patient confidence to self-administer sc. T. No differences in ‘feeling in control of their treatment’ or ‘satisfaction of attending hospital appointments’ were noted. Of the 11 patients who reached the self-administration stage, 10 reported that they felt ‘very confident’ and 8 reported that it was ‘very easy’ to give themselves the injection. All patients rated themselves ‘very satisfied’ with self-administration and reported that the nurse training programme helped them to be more confident. 10 patients reported that the App and written information was useful as well as the pre- and post- administration telephone clinics. All patients reported that the self-administration programme had a positive impact on their QOL by reducing the number of hospital visits. In the first 4 months of self-administration each patient reduced their hospital attendance by an average of 8 appointments (median=8) equating to 10 hours of time that would have been spent at hospital.

Discussion/Conclusion

The subcutaneous T self-administration programme was well received by patients. The nurse training sessions and supportive materials enabled patients to feel more confident about self-administration with no reported incidents or adverse events. This led to fewer hospital visits and improved QOL. This programme was critically dependent on the services of a commercial compounder and homecare provider, emphasizing the importance of joint working between the NHS and commercial sector. Evaluation of this programme will continue and will include other agents, including Phesgo® (sc trastuzumab and pertuzumab) which have more patients and will improve the reliability of the results.

References

1. Tjalma, W., Huizing, M., Papadimitriou, K. The smooth and bumpy road of trastuzumab administration: from intravenous (IV) in a hospital to subcutaneous (SC) at home. Facts Views Vis Obgyn, 2017;9(1):51-55.

2. Grady, PA, Gough, LL. Self-management: a comprehensive approach to management of chronic conditions. American Journal of Public Health 2014; 104(8):e25-31. doi:10.2105/AJPH.2014.302041

3. Keininger D, Coteur G. Assessment of self-injection experience in patients with rheumatoid arthritis: psychometric validation of the Self-Injection Assessment Questionnaire (SIAQ). Health Qual Life Outcomes. 2011;9:2. doi:10.1186/1477-7525-9-2

Final results from the PERUSE study of first-line pertuzumab plus trastuzumab plus a taxane for HER2-positive locally recurrent or metastatic breast cancer, with a multivariable approach to guide prognostication

BACKGROUND

The phase III CLinical Evaluation Of Pertuzumab And TRAstuzumab (CLEOPATRA) trial established the combination of pertuzumab, trastuzumab and docetaxel as standard first-line therapy for human epidermal growth factor receptor 2 (HER2)-positive locally recurrent/metastatic breast cancer (LR/mBC). The multicentre single-arm PERtUzumab global SafEty (PERUSE) study assessed the safety and efficacy of pertuzumab and trastuzumab combined with investigator-selected taxane in this setting.

PATIENTS AND METHODS

Eligible patients with inoperable HER2-positive LR/mBC and no prior systemic therapy for LR/mBC (except endocrine therapy) received docetaxel, paclitaxel or nab-paclitaxel with trastuzumab and pertuzumab until disease progression or unacceptable toxicity. The primary endpoint was safety. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). Prespecified subgroup analyses included subgroups according to taxane, hormone receptor (HR) status and prior trastuzumab. Exploratory univariable analyses identified potential prognostic factors; those that remained significant in multivariable analysis were used to analyse PFS and OS in subgroups with all, some or none of these factors.

RESULTS

Of 1436 treated patients, 588 (41%) initially received paclitaxel and 918 (64%) had HR-positive disease. The most common grade ≥3 adverse events were neutropenia (10%, mainly with docetaxel) and diarrhoea (8%). At the final analysis (median follow-up: 5.7 years), median PFS was 20.7 [95% confidence interval (CI) 18.9-23.1] months overall and was similar irrespective of HR status or taxane. Median OS was 65.3 (95% CI 60.9-70.9) months overall. OS was similar regardless of taxane backbone but was more favourable in patients with HR-positive than HR-negative LR/mBC. In exploratory analyses, trastuzumab-pretreated patients with visceral disease had the shortest median PFS (13.1 months) and OS (46.3 months).

CONCLUSIONS

Mature results from PERUSE show a safety and efficacy profile consistent with results from CLEOPATRA and median OS exceeding 5 years. Results suggest that paclitaxel is a valid alternative to docetaxel as backbone chemotherapy. Exploratory analyses suggest risk factors that could guide future trial design.

Primary results from IMpassion131, a double-blind, placebo-controlled, randomised phase III trial of first-line paclitaxel with or without atezolizumab for unresectable locally advanced/metastatic triple-negative breast cancer

BACKGROUND

In the phase III IMpassion130 trial, combining atezolizumab with first-line nanoparticle albumin-bound-paclitaxel for advanced triple-negative breast cancer (aTNBC) showed a statistically significant progression-free survival (PFS) benefit in the intention-to-treat (ITT) and programmed death-ligand 1 (PD-L1)-positive populations, and a clinically meaningful overall survival (OS) effect in PD-L1-positive aTNBC. The phase III KEYNOTE-355 trial adding pembrolizumab to chemotherapy for aTNBC showed similar PFS effects. IMpassion131 evaluated first-line atezolizumab-paclitaxel in aTNBC.

PATIENTS AND METHODS

Eligible patients [no prior systemic therapy or ≥12 months since (neo)adjuvant chemotherapy] were randomised 2:1 to atezolizumab 840 mg or placebo (days 1, 15), both with paclitaxel 90 mg/m² (days 1, 8, 15), every 28 days until disease progression or unacceptable toxicity. Stratification factors were tumour PD-L1 status, prior taxane, liver metastases and geographical region. The primary endpoint was investigator-assessed PFS, tested hierarchically first in the PD-L1-positive [immune cell expression ≥1%, VENTANA PD-L1 (SP142) assay] population, and then in the ITT population. OS was a secondary endpoint.

RESULTS

Of 651 randomised patients, 45% had PD-L1-positive aTNBC. At the primary PFS analysis, adding atezolizumab to paclitaxel did not improve investigator-assessed PFS in the PD-L1-positive population [hazard ratio (HR) 0.82, 95% confidence interval (CI) 0.60-1.12; P = 0.20; median PFS 6.0 months with atezolizumab-paclitaxel versus 5.7 months with placebo-paclitaxel]. In the PD-L1-positive population, atezolizumab-paclitaxel was associated with more favourable unconfirmed best overall response rate (63% versus 55% with placebo-paclitaxel) and median duration of response (7.2 versus 5.5 months, respectively). Final OS results showed no difference between arms (HR 1.11, 95% CI 0.76-1.64; median 22.1 months with atezolizumab-paclitaxel versus 28.3 months with placebo-paclitaxel in the PD-L1-positive population). Results in the ITT population were consistent with the PD-L1-positive population. The safety profile was consistent with known effects of each study drug.

CONCLUSION

Combining atezolizumab with paclitaxel did not improve PFS or OS versus paclitaxel alone. CLINICALTRIALS.GOV: NCT03125902.

An Adjusted Ideal Body Weight Index Formula With Fresh Frozen Plasma (FFP) Rescue Decreases Fluid Creep During Burn Resuscitation

Severe burn injury requires significant volume resuscitation, but over-resuscitation can be deadly. Accurate resuscitation of obese patients is challenging due to the decreased vascularity of adipose tissue. This study compares an adjusted ideal body weight index formula with fresh frozen plasma rescue to historical controls resuscitated with Parkland-based resuscitation. A retrospective review was conducted of adult patients admitted to our regional burn center with ≥ 20% total body surface area (TBSA) burns from 2010 to 2017 who survived more than 48 hours. Historical controls were resuscitated with Parkland-based resuscitation with occasional albumin. The adjusted ideal body weight (AIBW) patients were resuscitated with 2-4 mL/kg/%TBSA using an adjusted ideal body weight with fresh frozen plasma (FFP) rescue. Outcomes were compared with nonparametric statistics. A total of 161 patients met inclusion criteria: 40 patients received AIBW resuscitation and 121 patients were included as controls. The AIBW group received less fluid (3.30 vs. 4.15 mL/kg/%TBSA, p<0.001). A significant reduction in acute kidney injury requiring dialysis in the AIBW group was appreciated (5% vs. 19%, p=0.03) with improved mortality in AIBW patients as well (5% vs. 20%, p=0.03). Using an adjusted ideal body weight with FFP rescue to resuscitate patients with severe burn injury leads to a significant reduction in fluid administration without increase in acute kidney injury requiring dialysis and with improved mortality.

Role of Metal Ion-Linked Multilayer Thickness and Substrate Porosity in Surface Loading, Diffusion, and Solar Energy Conversion

Metal ion-linked multilayers offer an easily prepared and modular architecture for controlling energy and electron transfer events on nanoparticle, metal oxide films. However, unlike with planar electrodes, the mesoporous nature of the films inherently limits both the thickness of the multilayer and subsequent diffusion through the pores. Here, we systematically investigated the role of TiO₂ nanoparticle film porosity and metal ion-linked multilayer thickness in surface loading, through-pore diffusion, and overall device performance. The TiO₂ porosity was controlled by varying TiO₂ sintering times. Molecular multilayer thickness was controlled through assembling Zn^II-linked bridging molecules (B = p-terphenyl diphosphonic acid) between the metal oxide and the Ru(bpy)₂((4,4'-PO₃H₂)₂bpy)]Cl₂ dye (RuP), thus producing TiO₂-(B_n)-RuP films. Using attenuated total reflectance infrared absorption and UV-vis spectroscopy, we observed that at least two molecular layers (i.e., TiO₂-B₂ or TiO₂-B₁-RuP) could be formed on all films but subsequent loading was dependent on the porosity of the TiO₂. Rough estimates indicate that in a film with 34 nm average pore diameter, the maximum multilayer film thickness is on the order of 4.6-6 nm, which decreases with decreasing pore size. These films were then incorporated as the photoanodes in dye-sensitized solar cells with cobalt(II/III)tris(4,4'-di-tert-butyl-2,2'-bipyridine) as a redox mediator. In agreement with the surface-loading studies, electrochemical impedance spectroscopy measurements indicate that mediator diffusion is significantly hindered in films with thicker multilayers and less porous TiO₂. Collectively, these results show that care must be taken to balance multilayer thickness, substrate porosity, and size of the mediator in designing and maximizing the performance of new multilayer energy and electron management architectures.

Radiocarbon Production Events and their Potential Relationship with the Schwabe Cycle

Extreme cosmic radiation events occurred in the years 774/5 and 993/4 CE, as revealed by anomalies in the concentration of radiocarbon in known-age tree-rings. Most hypotheses point towards intense solar storms as the cause for these events, although little direct experimental support for this claim has thus far come to light. In this study, we perform very high-precision accelerator mass spectrometry (AMS) measurements on dendrochronological tree-rings spanning the years of the events of interest, as well as the Carrington Event of 1859 CE, which is recognized as an extreme solar storm even though it did not generate an anomalous radiocarbon signature. Our data, comprising 169 new and previously published measurements, appear to delineate the modulation of radiocarbon production due to the Schwabe (11-year) solar cycle. Moreover, they suggest that all three events occurred around the maximum of the solar cycle, adding experimental support for a common solar origin.

Preliminary safety and efficacy of first-line pertuzumab combined with trastuzumab and taxane therapy for HER2-positive locally recurrent or metastatic breast cancer (PERUSE)

BACKGROUND

Pertuzumab combined with trastuzumab and docetaxel is the standard first-line therapy for HER2-positive metastatic breast cancer, based on results from the phase III CLEOPATRA trial. PERUSE was designed to assess the safety and efficacy of investigator-selected taxane with pertuzumab and trastuzumab in this setting.

PATIENTS AND METHODS

In the ongoing multicentre single-arm phase IIIb PERUSE study, patients with inoperable HER2-positive advanced breast cancer (locally recurrent/metastatic) (LR/MBC) and no prior systemic therapy for LR/MBC (except endocrine therapy) received docetaxel, paclitaxel or nab-paclitaxel with trastuzumab [8 mg/kg loading dose, then 6 mg/kg every 3 weeks (q3w)] and pertuzumab (840 mg loading dose, then 420 mg q3w) until disease progression or unacceptable toxicity. The primary end point was safety. Secondary end points included overall response rate (ORR) and progression-free survival (PFS).

RESULTS

Overall, 1436 patients received at least one treatment dose (initially docetaxel in 775 patients, paclitaxel in 589, nab-paclitaxel in 65; 7 discontinued before starting taxane). Median age was 54 years; 29% had received prior trastuzumab. Median treatment duration was 16 months for pertuzumab and trastuzumab and 4 months for taxane. Compared with docetaxel-containing therapy, paclitaxel-containing therapy was associated with more neuropathy (all-grade peripheral neuropathy 31% versus 16%) but less febrile neutropenia (1% versus 11%) and mucositis (14% versus 25%). At this preliminary analysis (52 months' median follow-up), median PFS was 20.6 [95% confidence interval (CI) 18.9-22.7] months overall (19.6, 23.0 and 18.1 months with docetaxel, paclitaxel and nab-paclitaxel, respectively). ORR was 80% (95% CI 78%-82%) overall (docetaxel 79%, paclitaxel 83%, nab-paclitaxel 77%).

CONCLUSIONS

Preliminary findings from PERUSE suggest that the safety and efficacy of first-line pertuzumab, trastuzumab and taxane for HER2-positive LR/MBC are consistent with results from CLEOPATRA. Paclitaxel appears to be a valid alternative taxane backbone to docetaxel, offering similar PFS and ORR with a predictable safety profile.

CLINICALTRIALS.GOV

NCT01572038.

Abstract OT1-01-01: IMpassion131: A phase III study comparing 1L atezolizumab with paclitaxel vs placebo with paclitaxel in treatment-naive patients with inoperable locally advanced or metastatic triple negative breast cancer (TNBC)

Background: Chemotherapy (including paclitaxel) remains the predominant treatment for metastatic TNBC but clinical outcomes remain poor. Therefore, new therapeutic approaches are needed. Atezolizumab blocks the binding of PD-L1 to its receptors PD-1 and B7.1, thus restoring tumor-specific T cell immunity. TNBC is a rational target for atezolizumab therapy due to high PD-L1 expression on tumor-infiltrating immune cells (IC) and elevated T cell tumor infiltration. Furthermore, combining chemotherapy with atezolizumab is hypothesized to enhance anti-tumor immune response via neoantigen release. Atezolizumab alone and in combination with nab-paclitaxel has demonstrated promising clinical benefit in metastatic TNBC and was well tolerated, with no exacerbation of chemotherapy-associated adverse events. Atezolizumab in combination with nab-paclitaxel is being further investigated as 1L TNBC treatment in IMpassion130. IMpassion131 is a global, multi-center, randomized, double-blind, placebo-controlled study comparing the efficacy and safety of 1L atezolizumab + paclitaxel vs placebo + paclitaxel in patients with untreated, inoperable, locally advanced or metastatic TNBC. (NCT03125902)

Methods: Eligibility criteria include patients with inoperable, locally advanced or metastatic TNBC, histologically confirmed; de novo or recurrent disease after early breast cancer treated with chemotherapy ≥ 12 months prior; eligible for taxane monotherapy; no prior chemotherapy or targeted systemic therapy for inoperable locally advanced or metastatic disease; ECOG PS 0-1 and measurable disease by RECIST v1.1. Exclusion criteria include known symptomatic CNS disease, prior immunotherapy and a history of autoimmune disease. Approximately 495 patients will be randomized 2:1 to receive atezolizumab (840 mg) or placebo (q2w; days 1 and 15 of 28-day cycle) plus paclitaxel (90 mg/m2; days 1, 8, 15 of 28-day cycle) until disease progression. Stratification factors are PD-L1 expression on tumor-infiltrating IC (IC0 &lt; 1% vs IC1/2/3 ≥ 1% with VENTANA SP142 IHC assay), prior taxane therapy, presence of liver metastases and geographical region. The primary endpoint is progression-free survival (PFS) measured by RECIST v1.1. Key secondary endpoints include overall survival (OS), 12- and 18-month OS rates, 12-month PFS rate, objective response rate, duration of response, and safety. Tumor biopsies will be collected at baseline, on treatment and at disease progression to assess for biomarkers of treatment response and immune escape.

Citation Format: Miles D, André F, Gligorov J, Verma S, Xu B, Cameron D, Barrios CH, Schneeweiss A, Easton V, Ghazi Y, O'Shaughnessy J. IMpassion131: A phase III study comparing 1L atezolizumab with paclitaxel vs placebo with paclitaxel in treatment-naive patients with inoperable locally advanced or metastatic triple negative breast cancer (TNBC) [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 OT1-01-01.

Effect of docetaxel duration on clinical outcomes: exploratory analysis of CLEOPATRA, a phase III randomized controlled trial

Background

Combination pertuzumab, trastuzumab, and docetaxel (D) is considered standard first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. This post hoc, exploratory analysis of CLEOPATRA study data evaluated the clinical effects of D treatment duration within this regimen. The clinical benefits of pertuzumab and trastuzumab by different durations of D treatment were also evaluated.

Patients and methods

Patients with HER2-positive metastatic breast cancer received trastuzumab and D plus pertuzumab or placebo. Clinical outcomes were analyzed by the number of D cycles that patients received (<6D, 6D, or >6D). Progression-free survival (PFS) and overall survival (OS) for each treatment arm within each D cycle group were estimated using the Kaplan-Meier approach. Time-dependent, multivariate Cox regression was applied to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for HER2-targeted therapy and D cycle groups.

Results

Overall, 804 patients received <6D (n = 119), 6D (n = 210), or >6D (n = 475) cycles. After adjusting for pertuzumab benefits versus placebo (PFS HR = 0.61, 95% CI 0.51-0.74, P < 0.0001; OS HR = 0.60, 95% CI, 0.49-0.74, P < 0.0001), >6D versus 6D cycles was not associated with statistically significant improvements in PFS (HR = 0.80, 95% CI 0.63-1.01, P = 0.0640) or OS (HR = 0.88, 95% CI 0.69-1.12, P = 0.3073). Consistent improvements in PFS and OS were observed with pertuzumab versus placebo, irrespective of D duration. The HRs for PFS were 0.395, 0.615, and 0.633 for <6D, 6D, and >6D cycles, respectively (P < 0.05 for all D cycle groups). Corresponding HRs for OS were 0.577, 0.700, and 0.612, respectively (P < 0.05 for <6D and >6D).

Conclusions

After accounting for pertuzumab benefits, more than six cycles of D treatment was not associated with significant improvements in either PFS or OS compared with six cycles. The addition of pertuzumab to trastuzumab improved clinical outcomes versus trastuzumab plus placebo, regardless of D treatment duration.

ClinicalTrials.gov identifier

NCT00567190.

Abstract OT2-01-02: COLET: A multistage, phase 2 study evaluating the safety and efficacy of a doublet regimen of cobimetinib (C) in combination with paclitaxel (P) or triplet regimens of C in combination with atezolizumab (atezo) plus either P or nab-paclitaxel (nab-P) in metastatic triple-negative breast cancer (TNBC)

Preclinical data suggest that upregulation of the MAPK pathway confers resistance to taxane chemotherapy. Mutations and gene amplifications in the MAPK pathway are present in many TNBC tumors and may contribute to taxane resistance. Preliminary data from an initial safety run-in stage of the COLET study (ClinicalTrials.gov ID, NCT02322814; EudraCT number, 2014-002230-32) suggest improvement of clinical outcomes when MEK inhibition is combined with taxane chemotherapy. Additionally, in preclinical models, MEK inhibition was shown to enhance anti–PD-L1 activity. The monoclonal antibody PD-L1 inhibitor atezo has shown promising activity in combination with nab-P in metastatic TNBC. Accordingly, the COLET protocol was amended to include the evaluation of triplet regimens combining atezo with MEK inhibition and taxane chemotherapy[SL1] . COLET is evaluating the safety and efficacy of various combinations of C as first-line treatment for metastatic or locally advanced TNBC. Key eligibility criteria include measurable disease per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1) and left ventricular ejection fraction &gt; institutional lower limit of normal or &gt;50%. Neoadjuvant or adjuvant therapy is allowed if completed &gt;6 months prior to study entry. COLET has 3 cohorts: I, II, and III. Cohort I has 2 stages: an initial safety run-in stage (n∼12) followed by an expansion stage (n∼90) of 1:1 randomization to C + P or placebo (PBO) + P. Patients received P 80 mg/m2 on days 1, 8, and 15 and C/PBO 60 mg/day on days 3-23 of each 28-day cycle. In the expansion stage of Cohort I, randomization is stratified by prior neoadjuvant/adjuvant taxane therapy and disease-free interval from last chemotherapy dose. Cohorts II and III will evaluate the safety and efficacy of adding atezo to C + P or nab-P, respectively. Each cohort has a safety run-in stage (n∼15) and an expansion stage (additional n∼15); each will receive atezo 840 mg on days 1 and 15 and C 60 mg/day on days 3-23 of every 28-day cycle. Cohort II will receive P 80 mg/m2 and Cohort III will receive intravenous nab-P 100 mg/m2 on days 1, 8, and 15. Patients will receive treatment until disease progression or toxicity. The primary efficacy end point is investigator-assessed progression-free survival (PFS) for the expansion stage (Cohort I), and the primary PFS analysis will be performed when 60 PFS events occur across the 2 arms. This provides 77% power to detect a hazard ratio of 0.5 at a two-sided significance level of 0.05. For Cohorts II and III, the primary efficacy end point is overall response rate per RECIST v1.1; secondary end points include duration of response, PFS, and overall survival. Recruitment into the safety run-in stage of Cohort I is complete. Accrual into the randomization stage of Cohort I and the initial safety run-in stage of Cohorts II and III are ongoing. Patients from sites across North America, Europe, and the Asia-Pacific region will be enrolled.

Citation Format: Miles D, Kim S-B, McNally V, Simmons B, Wongchenko M, Xu N, Brufsky A. COLET: A multistage, phase 2 study evaluating the safety and efficacy of a doublet regimen of cobimetinib (C) in combination with paclitaxel (P) or triplet regimens of C in combination with atezolizumab (atezo) plus either P or nab-paclitaxel (nab-P) in metastatic triple-negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-02.

Abstract P4-21-04: Preliminary safety and efficacy of first-line pertuzumab combined with trastuzumab and taxane therapy for HER2-positive locally recurrent/metastatic breast cancer (PERUSE)

Background: First-line (1L) docetaxel+trastuzumab+pertuzumab (THP) for HER2-positive metastatic breast cancer (MBC) significantly improved progression-free survival (PFS) and overall survival in the phase III CLEOPATRA trial, and led to the approval of this regimen. PERUSE (NCT01572038) was designed to assess the safety and efficacy of investigator's choice of taxane+HP for 1L locally recurrent (LR)/MBC, and allows exploration of safety and efficacy in a larger population.

Methods:

PERUSE is a multicenter, single-arm phase IIIb study. Patients (pts) with Eastern Cooperative Oncology Group performance status ≤2 and no prior systemic therapy for LR/MBC (except endocrine therapy) receive T, paclitaxel (PAC), or nab-PAC plus H (8 mg/kg→6 mg/kg every 3 weeks [q3w]) and P (840 mg→420 mg q3w) until disease progression (PD) or unacceptable toxicity. The primary endpoint is safety. Secondary endpoints include best overall response (BOR) and PFS.

Results:

The safety/ITT population includes 1436 pts at data cutoff (1 Apr 2016). Median follow-up was 17.2 mo (range, &lt;1–41.4). The median pt age was 54 years (range 23–87), 64% had hormone receptor-positive disease, 27% received adjuvant H, and 75% had visceral disease. Pts received T, PAC, nab-PAC, H, and P for a median of 3.8 mo (range &lt;1–24.2; n=791), 4.2 mo (&lt;1–36.6; n=618), 3.9 mo (&lt;1–17.3; n=73), 16.0 mo (&lt;1–45.9; n=1435), and 16.1 mo (&lt;1–45.9; n=1436), respectively.

Most pts discontinued taxanes for 'other' reasons (25%), adverse events (AEs; 16%), PD, or investigator decision (15% each); H, for PD or AEs (46% and 7%); and P, for PD or AEs (46% and 8%).

Grade ≥3 treatment-emergent AEs (TEAEs) of interest are shown in table 1. Serious TEAEs were reported in 282 (36%) pts on T, 185 (31%) on PAC, and 21 (32%) on nab-PAC. Preliminary efficacy by taxane is shown in table 2.

Table 1Pts, n (%)TPACNab-PAC n=775n=589n=65Neutropenia110 (14)31 (5)1 (2)Diarrhea62 (8)50 (8)4 (6)Febrile neutropenia81 (10)7 (1)0Fatigue21 (3)10 (2)1 (2)Asthenia16 (2)10 (2)0Peripheral neuropathy10 (1)15 (3)0Anemia11 (1)12 (2)2 (3)Left ventricular dysfunction1 (&lt;1)9 (2)1 (2)

Table 2 TPACNab-PACBOR, based on pts with measureable disease at baseline, n (%)n=659n=482n=53Complete72 (11)80 (17)4 (8)Partial442 (67)319 (66)38 (72)Stable disease112 (17)62 (13)8 (15)PD18 (3)12 (2)2 (4)Missing15 (2)9 (2)1 (2)PFS, ITT populationn=775n=589n=65Pts with events, n (%)439 (57)324 (55)40 (62)Median, mo (95% confidence interval)19.6 (17.4–22.6)24.8 (20.7–27.0)18.1 (11.9–34.2)25th–75th percentile, mo9.4–not reached (NR)10.2–NR7.9–NR

Conclusion:

The preliminary findings of this large, single-arm study suggest that safety and efficacy of 1L taxane+HP for HER2-positive LR/MBC are in keeping with the results of the phase III CLEOPATRA study. There was less febrile neutropenia with PAC/nab-PAC+HP compared with THP, and preliminary PFS was similar to that seen in the CLEOPATRA study for all taxane+HP combinations.

Citation Format: Bachelot T, Puglisi F, Ciruelos E, Peretz-Yablonski T, Schneeweiss A, Easton V, Lindegger N, Restuccia E, Miles D. Preliminary safety and efficacy of first-line pertuzumab combined with trastuzumab and taxane therapy for HER2-positive locally recurrent/metastatic breast cancer (PERUSE) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-04.

Abstract P4-21-36: Splenic enlargement and bone marrow hyperplasia in patients receiving trastuzumab-emtansine for metastatic breast cancer

Introduction

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate used for treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. An association between T-DM1 and splenic enlargement was noted anecdotally on sequential whole-body MRI (WB-MRI) examinations. A retrospective analysis of WB-MRI examinations of patients on T-DM1 was undertaken to investigate the hypothesis that an increase in splenic volume is due to either a generalised hyperplasia of the bone marrow and reticulo-endothelial system and/or an increase in portal venous pressure.

Methods

12 patients underwent 29 serial WB-MRIs before and during T-DM1 therapy. Splenic volume, portal vein diameter, bone marrow muscle-normalised signal intensity (nSI), water diffusivity (apparent diffusion coefficient, ADC) and fat fraction were measured. Changes in splenic volume were analysed, and correlations between the measured variables were obtained.

Results

An increase in splenic volume was observed in 92% of patients. Mean splenic volume increased from 144cm3 (95%CI 110-177cm3) to 209cm3 (95%CI 161-257cm3) on T-DM1 therapy (p=0.006). Increase in splenic volume correlated with treatment duration (r2=0.71). Increase in normal bone marrow signal was seen (nSI 3.5 to 4.8, p=0.12), along with a decrease in fat fraction (64.3% to 57.3%, p=0.12), and reduced ADC (655µm2/s to 543µm2/s, p=0.11). No consistent changes to portal vein diameter were seen.

Discussion

An increase in splenic volume was consistently observed in patients on T-DM1 therapy. This was unrelated to portal vein changes but correlated with bone marrow hyperplasia. Caution should be applied when assessing metastatic disease in bone to avoid incorrectly attributing T-DM1-related changes in normal bone marrow to disease progression.

Citation Format: Kosmin M, Makris A, Jawad N, Miles D, Padhani AR. Splenic enlargement and bone marrow hyperplasia in patients receiving trastuzumab-emtansine for metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-21-36.

Abstract P4-22-22: Cobimetinib (C) combined with paclitaxel (P) as a first-line treatment in patients (pts) with advanced triple-negative breast cancer (COLET study): Updated clinical and biomarker results

Resistance to standard taxane-based chemotherapy is common in triple-negative breast cancer (TNBC). Mutations and gene amplifications in the MAPK pathway that upregulate MAPK signaling are present in many TNBC tumors. Upregulation of the MAPK signaling pathway can result in degradation of the pro-apoptotic protein BIM and upregulation of anti-apoptotic proteins, including BCL-2, BCL-XL, and MCL-1, thus promoting cell survival and desensitizing tumor cells to the pro-apoptotic effects of taxane chemotherapy. Updated data on clinical safety and efficacy are presented along with biomarker data evaluating the effects of treatment on induction of apoptosis.The COLET study (ClinicalTrials.gov ID, NCT02322814; EudraCT number, 2014-002230-32) consisted of a safety run-in (n∼12) followed by a blinded 1:1 randomized expansion stage (n∼90) to C + P or placebo (PBO) + P. The safety stage is complete and the randomized stage is enrolling pts. Two additional cohorts investigating the effect of adding atezolizumab will be recruiting and are out of scope of this submission. Pts in cohort I were treated with P 80 mg/m2 on days 1, 8, and 15 and C/PBO 60 mg/day on days 3–23 of each 28-day cycle until disease progression or unacceptable toxicity. Gene expression and apoptotic index were measured by RNA-Seq and TUNEL staining, respectively, to assess the biologic activity of C + P.Sixteen women (median age, 55.5 years) were enrolled in the safety run-in stage. At data snapshot (April 22, 2016), all 16 pts had received ≥1 dose of study treatment. Median time on treatment was 116 days (range, 7-336) for C and 84 days (range, 0-351) for P. Fifteen (94%) pts had ≥1 adverse event (AE); 5 (31%) pts had grade 1/2 AEs and 10 (63%) pts had grade 3 AEs (Table). No pts experienced grade 4–5 AEs. Among the 16 safety run-in patients, responses to date include partial response (PR; n = 8 [50.0%]), stable disease (SD, n = 4 [25.0%]), and progressive disease (n = 2 [12.5%]), as well as 2 pts with no post-baseline tumor assessment. Six pts maintained a PR at ∼20 weeks and three maintained a PR at ≥40 weeks. To date, matched pre- and on-treatment biopsies were evaluable for 2 pts, 1 with a PR and 1 with SD. In the patient who attained a PR, increased expression of pro-apoptosis genes, including BIM, was observed; but this was not seen in the patient experiencing SD. The PR patient also had an increase in apoptotic index. Updated biomarker data will be reported.This is the first study to evaluate C + P in TNBC. The safety profile of C + P is consistent with that of known safety profiles. Efficacy and safety will be further evaluated in the ongoing randomized stage.

Most common (any grade ≥20%) AEsTreatment-emergent AEs, n (%)C + P (safety run-in stage), N = 16 All gradesGrade 3Diarrhea10 (63)1 (6)Rash8 (50)0Nausea7 (44)0Alopecia5 (31)0Blood CPK level increase5 (31)1 (6)Stomatitis4 (25)2 (13)Asthenia4 (25)1 (6)Constipation4 (25)0Dyspnea4 (25)0Edema peripheral4 (25)0Pyrexia4 (25)0Vomiting4 (25)0AEs, adverse events; C, cobimetinib; CPK, creatinine phosphokinase; P, paclitaxel.

Citation Format: Brufsky A, Kim S-B, Velu T, García-Saenz JA, Tan-Chiu E, Sohn JH, Dirix L, Borms MV, Liu M-C, Moezi MM, Kozloff MF, Sparano JA, Xu N, Wongchenko M, Simmons B, McNally V, Miles D. Cobimetinib (C) combined with paclitaxel (P) as a first-line treatment in patients (pts) with advanced triple-negative breast cancer (COLET study): Updated clinical and biomarker results [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-22-22.

Use of maintenance endocrine therapy after chemotherapy in metastatic breast cancer

BACKGROUND

For women with oestrogen receptor+ metastatic breast cancer (MBC), the options for systemic treatment include endocrine therapy (ET) and chemotherapy. For women whose disease is also HER2+, anti-HER2 therapies are also routinely used either with chemotherapy or less commonly with ET. Where chemotherapy is used as initial therapy, treatment is often discontinued due to cumulative toxicity in the absence of disease progression. In this setting, there is the option of introducing ET with the aim of prolonging response and delaying relapse.

METHODS

Literature review revealed four trials addressing the question of whether there is a benefit from introducing ET following chemotherapy for MBC. We also sought evidence for alternative approaches, including concurrent chemotherapy and ET and continuing chemotherapy until disease progression.

RESULTS

The evidence for the use of ET after chemotherapy in MBC is limited, and the trials done were small. Furthermore, they were performed at a time when both the chemotherapy regimens and ET were different from those used currently. Despite these limitations, there is probably a modest improvement in time to progression for the sequential use of ET after chemotherapy but with no overall survival benefit. An alternative approach, particularly considering agents with relatively low toxicity, such as orally bioavailable fluoropyrimidines, is to continue chemotherapy until disease progression.

CONCLUSION

Where chemotherapy for MBC is discontinued due to toxicity, in the absence of progression, the use of ET, with its relatively low toxicity, is a reasonable approach with the aim of delaying relapse.

Abstract P5-08-18: Biomarker (BM) results from MERiDiAN, a double-blind placebo (PLA)-controlled randomized phase 3 trial of 1st-line paclitaxel (PAC) with or without bevacizumab (BEV) for HER2-negative metastatic breast cancer (mBC)

Background: In the MERiDiAN trial, progression-free survival (PFS) was significantly improved with the addition of BEV to 1st-line PAC for mBC in both the ITT population and the subgroup with high baseline plasma (p) vascular endothelial growth factor (VEGF)-A, meeting both co-primary objectives. However, a predictive effect of pVEGF-A was not seen (PFS pVEGF-A-by-treatment interaction p=0.46; secondary endpoint). We report exploratory analyses of additional candidate BMs.

Methods: Patients (pts) with HER2-negative mBC previously untreated with chemotherapy for mBC were randomized to receive PAC (90 mg/m2, days 1, 8 & 15 q4w) combined with either PLA or BEV 10 mg/kg q2w until disease progression or unacceptable toxicity. Plasma, blood and archival tumor sampling was mandatory. The BM-evaluable population (BEP) comprised all ITT pts with a baseline sample for ≥1 BM. Prespecified exploratory BM analyses included: tumor (t) CD31 (marker of microvascular density) and tVEGF-A (molecular target of BEV) by immunohistochemistry; tPAM50 gene expression; and pVEGF receptor (R)-2 by ELISA. For CD31, tVEGF-A and pVEGFR-2 analyses, the BEP was dichotomized using the median of each BM as the cutoff between low and high subgroups. BEV effect on PFS was assessed within these subgroups (unstratified analyses). Similar subgroup analyses were done for each tPAM50 molecular subtype. No adjustment was made for multiplicity of testing as the analyses were exploratory.

Results: The BEP included 467 (97%) of the 481 randomized pts. There was no correlation between CD31, tVEGF-A and pVEGFR-2. Correlations between BMs and PFS are shown below. The hazard ratio (HR) point estimate for BEV effect was lower in luminal B (0.59) than luminal A (0.96) or other smaller tPAM50 subgroups, but 95% CIs overlapped. pVEGFR-2 showed borderline significance for predictive potential using the median (10.2 ng/mL) as the cutoff. In further exploratory analyses using the 1st quartile (Q1; 8.7 ng/mL) as the cutoff, the PFS HR was 1.19 (95% CI 0.75–1.89) in the low (≤Q1) subgroup vs 0.60 (95% CI 0.46–0.79) in the high (&gt;Q1) subgroup (interaction p=0.01).

BMSubgroupNo. of events/ptsMedian PFS, mosPFS HR (95% Wald CI)Interaction p-value  PAC–PLAPAC–BEVPAC–PLAPAC–BEV  tPAM50 (N=421)Luminal A65/10367/10610.911.20.96 (0.68-1.35)Not applicable Luminal B46/6332/569.011.00.59 (0.38-0.93)  HER2 enriched8/119/105.58.30.88 (0.33-2.32)  Basal like29/3727/355.68.50.67 (0.39-1.14) tCD31 (N=410)Low69/9969/1067.610.80.71 (0.51-0.99)0.40 High78/11164/949.211.00.87 (0.62-1.22) tVEGF-A (N=434)Low78/10777/1107.411.00.68 (0.49-0.93)0.23 High76/11165/1069.210.90.89 (0.64-1.24) pVEGFR-2 (N=436)Low70/10773/1119.210.60.90 (0.64-1.25)0.06 High83/10968/1097.912.20.58 (0.42-0.81) 

Conclusions: Of the 4 candidate BMs explored here, potential predictive value was suggested only for pVEGFR-2. Correlations between pVEGFR-2 levels and outcome have been observed in previous retrospective analyses of breast cancer trials. However, similar levels in healthy donors and breast cancer pts, as well as the narrow dynamic range, may limit the utility of pVEGFR-2 as a potential predictive BM for BEV efficacy.

Citation Format: Das Thakur M, Bais C, Estay I, Vaidyanathan R, O'Shaughnessy J, Cameron D, Hubeaux S, Quah C, Miles D. Biomarker (BM) results from MERiDiAN, a double-blind placebo (PLA)-controlled randomized phase 3 trial of 1st-line paclitaxel (PAC) with or without bevacizumab (BEV) for HER2-negative metastatic breast cancer (mBC). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-18.

Abstract P4-14-27: Effect of docetaxel duration on clinical outcomes: Results from the phase III trial CLEOPATRA

Introduction:

In the CLEOPATRA study, pertuzumab (P) plus trastuzumab (T) and docetaxel (D) significantly improved median progression-free survival (PFS) and overall survival (OS) compared with placebo (Pla) plus T and D in pts with HER2-positive metastatic breast cancer. Study treatment was given every 3 weeks until disease progression (PD) or unacceptable toxicity. D starting dose was 75 mg/m2 and could be escalated or reduced per protocol. A minimum of 6 cycles of D was recommended. If D was discontinued, patients could continue P+T or Pla+T. To evaluate the potential association between D duration and clinical outcomes, we conducted post hoc exploratory analyses of the CLEOPATRA study.

Methods:

As of 11 Feb 2014 data cutoff, the safety population analyzed included 804 pts (396 Pla+T+D; 408 P+T+D) who received at least one dose of any study medication. Exposure and clinical outcomes of study treatment groups are presented by dichotomized subgroup of pts who received &lt;6 cycles of D and those who received more than 6 cycles. Median PFS and OS were estimated using Kaplan-Meier methods. Cox regression analyses were used to estimate hazard ratios (HRs).

Results:

The median number of D cycles received was 8 for both arms. Forty-one % of pts received &lt;6 (14% &lt;6; 27% exactly 6) and 59% received &gt;6 cycles.

Docetaxel Duration and Clinical Outcomes D &lt;6 cycles (n=329, 41%)D &gt;6 cycles (n=475, 59%) Pla+T+D (n=159)aP+T+D (n=170)aPla+T+D (n=237)P+T+D (n=238)Treatment Exposure#D Cycle, median (range)6 (1,6)6 (1,6)10 (7,42)10 (7,52)# Study Treatment Cycle, median (range)7 (1,78)14 (1,90)19 (7,92)28 (7,96)Duration of Study Treatment in month, median (range)6 (1,54)10 (1,63)14 (5,67)19 (5,68)Clinical OutcomesPFS in month, median (range)8.2 (6.2,9.0)12.5 (10.5,20.7)14.5 (12.6,17.2)22.8 (17.7,N/A)95% CIHR=0.59 (0.44,0.79)HR=0.65 (0.50,0.84)OS in month, median (range)29.8 (22.2,39.2)48.9 (36.8,N/A)46.7 (39.4,53.0)N/A (56.4,N/A)95% CIHR=0.67 (0.45,0.90)HR=0.62 (0.47,0.81)N/A=not available aTwo pts in each group had missing D cycle

Treatment Discontinuation Summary D &lt;6 cyclesD &gt;6 cycles Pla+T+D (n=159)P+T+D (n=170)Pla+T+D (n=237)P+T+D (n=238)D discontinuation before stopping anti-HER2 agents (n,%)90 (57)118 (69)180 (76)196 (82)Reason (n,%)    AE/intercurrent illness34 (38)27 (23)60 (33)72 (37)Patient reasonb3 (3)5 (4)5 (3)8 (4)Standard practice36 (40)59 (50)65 (36)41 (21)Adequate therapy12 (13)22 (19)36 (20)59 (30)Other1 (1)1 (1)9 (5)11 (6)Missing4 (4)4 (3)5 (3)5 (3)Discontinuation of all study treatment (T+D+Pla or P), n159170237238Reason (n,%)    AE/intercurrent illness15 (9)22 (13)25 (11)32 (13)Death10 (6)5 (3)4 (2)2 (1)Disease progression111 (70)110 (65)182 (77)154 (65)Patient reasonb17 (11)16 (9)12 (5)14 (6)Other6 (4)16 (9)12 (5)35 (15)Missing0 (0)1 (1)2 (1)1 (1)bIncluded failure to return, refused treatment, withdrawal, protocol violation

Conclusions:

Consistent with the overall study results, addition of P to T+D showed significant improvement in clinical outcomes regardless of whether &lt;6 or &gt;6 cycles of D were received. In the poster, three subgroup (&lt;6, 6 and &gt;6 D cycles) analyses and time-dependent Cox regression analysis to capture the dynamic variations in D exposure will be presented.

Citation Format: Miles D, Fung A, Yoo B, Knott A, Heeson S, Portera C, Swain S. Effect of docetaxel duration on clinical outcomes: Results from the phase III trial CLEOPATRA. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-27.

Abstract OT1-03-18: COLET: A multistage, phase 2 study evaluating the safety and efficacy of cobimetinib in combination with paclitaxel as first-line treatment for patients with metastatic triple-negative breast cancer

Background: Cobimetinib (cobi) is a potent, highly selective inhibitor of MEK that has shown benefit when administered in combination with the BRAF inhibitor vemurafenib in BRAFV600-mutated metastatic melanoma. Preclinical data suggest that up-regulation of the MAPK pathway is a potential resistance mechanism against taxane chemotherapy. Clinically, the combination of MEK inhibition and taxane chemotherapy in non–small cell lung cancer patients (pts) has improved response rate (RR) and progression-free survival (PFS). Because most triple-negative breast cancer (TNBC) pts develop resistance to taxane chemotherapy and because genetic alterations (including mutations and gene amplifications) in the MAPK pathway are present in many TNBC tumors, the combination of taxane chemotherapy and MEK inhibition could be an effective treatment option.

Study design: COLET (WO29497) is a multistage study designed to evaluate the safety of and to estimate the efficacy of cobi  paclitaxel in pts with metastatic or locally advanced TNBC who have not previously received systemic therapy for metastatic disease. The study will be conducted in 2 stages: an initial safety run-in stage of approximately 12 pts, followed by a randomized stage in which approximately 100 pts will be randomly assigned in a 1:1 ratio to receive either cobi + paclitaxel or placebo + paclitaxel. Pts will receive paclitaxel 80 mg/m2 on Days 1, 8, and 15 of each 28-day cycle and cobi/placebo 60 mg/day on Days 3-23 of each 28-day cycle until progression of disease or toxicity occurs.

Key eligibility criteria:

• Metastatic or locally advanced (not amenable to curative resection) TNBC

• No prior systemic therapy for metastatic or unresectable locally advanced TNBC

• Neoadjuvant or adjuvant chemotherapy or radiation therapy is allowed if completed &gt;6 months before the start of study treatment

• Measureable disease using Response Evaluation Criteria In Solid Tumors, version 1.1 (RECIST v1.1)

• History of or active untreated or unstable brain metastases or requiring corticosteroids for brain metastases precludes eligibility

• Left ventricular ejection fraction (LVEF) greater than the institutional lower limit of normal or above 50%

Specific aims of the safety run-in stage: Determine the safety and tolerability of cobi when administered in combination with paclitaxel.

Specific aims of the randomized stage: Investigator-assessed PFS (primary end point); safety; pharmacokinetics; the effect of intrinsic subtypes and genetic alterations in PFS; mechanisms of resistance; and health-related quality of life.

Accrual: Approximately 112 pts from sites across Europe, North America, and the Asia-Pacific region.

Statistical methods: In the randomized stage, pts will be followed up until a total of 60 PFS events occur across the 2 arms. This provides 77% power to detect a hazard ratio of 0.5 at a two-sided significance level of 0.05.

Contact information: Registered with ClinicalTrials.gov, identifier NCT02322814. For more information, please contact Roche/Genentech trials, 888-662-6728 (US only) or reference study ID WO29479 at www.roche.com/about_roche/roche_worldwide.htm.

Citation Format: Kim S-B, Miles D, Rhee J, Yan Y, Hsu J, Brufsky A. COLET: A multistage, phase 2 study evaluating the safety and efficacy of cobimetinib in combination with paclitaxel as first-line treatment for patients with metastatic triple-negative breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT1-03-18.

Abstract P4-14-01: Trastuzumab emtansine improves overall survival versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer: Final results from the phase 3 EMILIA study

Introduction

T-DM1 is indicated for the treatment of advanced HER2-positive MBC in patients who previously received trastuzumab and a taxane (separately or in combination) based on data from the phase 3 EMILIA study (BO21977/TDM4370g; NCT00829166). In the primary PFS and second interim OS analyses, respectively, T-DM1 significantly improved PFS (median 9.6 vs 6.4 months; HR=0.65; 95% CI, 0.55–0.77; p&lt;0.0001) and OS (median 30.9 vs 25.1 months; HR=0.68; 95% CI, 0.55–0.85; p&lt;0.0006) compared with capecitabine (X) plus lapatinib (L). T-DM1 treatment was associated with fewer grade ≥3 AEs (41% vs 57%) vs XL. Here we present the final OS analysis from EMILIA.

Methods

EMILIA was a randomized, open-label study of patients with centrally confirmed HER2-positive (IHC3+ and/or FISH amplification ratio ≥2.0), unresectable, locally advanced or MBC, previously treated with trastuzumab and a taxane. Patients were randomized 1:1 to T-DM1 (3.6 mg/kg IV every 3 weeks) or X (1000 mg/m2 PO twice daily, days 1–14 every 3 weeks) plus L (1250 mg PO daily). The final OS analysis was to be conducted following 632 events, and these results are descriptive only. Since the OS efficacy boundary (HR&lt;0.71, p=0.0025) was crossed in the second interim analysis, a protocol amendment allowed crossover from XL to T-DM1.

Results

From Feb 2009 to Oct 2011, 991 patients were randomized to T-DM1 (n=495) or XL (n=496). Patient disposition by the data cutoff (31 Dec 2014) is shown in Table 1. OS was longer with T-DM1 vs XL (median OS 29.9 vs 25.9 months; HR=0.75; 95% CI, 0.64–0.88; p=0.0003). In a sensitivity analysis, which censored crossover patients at the time of switching from XL to T-DM1, the HR was 0.69 (95% CI, 0.59–0.82; p&lt;0.0001). The overall safety profile was similar to previous analyses (Table 2). More grade ≥3 thrombocytopenia occurred with T-DM1 vs XL (14.3% vs 0.4%). Cardiac dysfunction occurred in 2.7% of T-DM1 patients vs 3.5% of XL patients.

Table 1. Patient disposition. T-DM1 (n=495)XL (n=496)Median treatment duration, months7.6X: 5.3  L: 5.5Median duration of follow-up, months47.841.9Discontinued study, n (%)364 (74)404 (82)Crossover, n (%)  Per protocolaNot applicable136 (27)Non-protocol therapybX: 252 (54)X: 53 (11) L: 224 (48)L: 74 (15)aMedian duration of follow-up among per-protocol crossover patients was 24.1 months.bBy investigator choice after study treatment discontinuation; X or L could be given in combination with each other or other agents after progression.

Table 2. Safety summary in patients who received ≥1 dose of study treatment.n (%)T-DM1 (n=490)XL (n=488)Grade ≥3 AEs233 (47.6)291 (59.6)Serious AEs91 (18.6)99 (20.3)AEs leading to dose reduction91 (18.6)X: 205 (42.0)  L: 98 (20.1)

Conclusions

This final analysis of EMILIA shows an OS benefit of T-DM1 compared with XL. While median drug exposure was longer with T-DM1 than XL, T-DM1 was associated with fewer grade ≥3 AEs and AEs leading to dose reduction compared with XL. These final OS results confirm that T-DM1 treatment improved survival, even in the presence of treatment crossover, and reaffirm T-DM1 as the standard of care in patients with previously treated HER2-positive MBC.

Citation Format: Diéras V, Miles D, Verma S, Pegram M, Welslau M, Baselga J, Krop I, Blackwell K, Kang B, Xu J, Green M, Gianni L. Trastuzumab emtansine improves overall survival versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer: Final results from the phase 3 EMILIA study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-01.

Trastuzumab emtansine (T-DM1) versus lapatinib plus capecitabine in patients with HER2-positive metastatic breast cancer and central nervous system metastases: a retrospective, exploratory analysis in EMILIA

BACKGROUND

We characterized the incidence of central nervous system (CNS) metastases after treatment with trastuzumab emtansine (T-DM1) versus capecitabine-lapatinib (XL), and treatment efficacy among patients with pre-existing CNS metastases in the phase III EMILIA study.

PATIENTS AND METHODS

In EMILIA, patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer previously treated with trastuzumab and a taxane were randomized to T-DM1 or XL until disease progression. Patients with treated, asymptomatic CNS metastases at baseline and patients developing postbaseline CNS metastases were identified retrospectively by independent review; exploratory analyses were carried out.

RESULTS

Among 991 randomized patients (T-DM1 = 495; XL = 496), 95 (T-DM1 = 45; XL = 50) had CNS metastases at baseline. CNS progression occurred in 9 of 450 (2.0%) and 3 of 446 (0.7%) patients without CNS metastases at baseline in the T-DM1 and XL arms, respectively, and in 10 of 45 (22.2%) and 8 of 50 (16.0%) patients with CNS metastases at baseline. Among patients with CNS metastases at baseline, a significant improvement in overall survival (OS) was observed in the T-DM1 arm compared with the XL arm [hazard ratio (HR) = 0.38; P = 0.008; median, 26.8 versus 12.9 months]. Progression-free survival by independent review was similar in the two treatment arms (HR = 1.00; P = 1.000; median, 5.9 versus 5.7 months). Multivariate analyses demonstrated similar results. Grade ≥3 adverse events were reported in 48.8% and 63.3% of patients with CNS metastases at baseline administered T-DM1 and XL, respectively; no new safety signals were observed.

CONCLUSION

In this retrospective, exploratory analysis, the rate of CNS progression in patients with HER2-positive advanced breast cancer was similar for T-DM1 and for XL, and higher overall in patients with CNS metastases at baseline compared with those without CNS metastases at baseline. In patients with treated, asymptomatic CNS metastases at baseline, T-DM1 was associated with significantly improved OS compared with XL.