Exploring the Prevalence of Oral Features for Early Detection of PTEN Hamartoma Tumour Syndrome.

AIMS: Patients with PTEN hamartoma tumour syndrome (PHTS) have an increased risk of developing cancer due to a pathogenic germline variant in the PTEN tumour suppressor gene. Early recognition of PHTS facilitates initiation of cancer surveillance which is highly effective in preventing the development of advanced malignancies. PHTS is rare and due to its varied phenotype, even within families, oral abnormalities may be a valuable tool in the identification of these patients at an early stage before cancer development. MATERIALS AND METHODS: Between 1997 and 2020, phenotypic characteristics were evaluated in 81 paediatric (median age: 9 years) and 86 adult (median age: 40 years) PHTS patients by one of 2 medical experts during yearly surveillance visits at a Dutch PHTS expertise centre. Oral features evaluated included gingival hypertrophy, oral papillomas, and high palate (in adults). RESULTS: Within adults, gingival hypertrophy was present in 94%, oral papillomas in 88%, and a high palate in 89%. All adult patients had at least one of these oral features, and 99% showed at least 2 oral features. Oral features were less common in paediatric patients, especially under 11 years of age. Gingival hypertrophy was observed in 44% and oral papillomas in 54% of paediatric patients. CONCLUSIONS: The presence of 2 or 3 oral features may indicate PHTS in adults or adolescents, especially if macrocephaly is present. Dental professionals are well-positioned to recognise these oral manifestations could be related to PHTS. They can initiate an overall clinical assessment of the patient by alerting the patient's medical practitioner of the findings and the possible need for genetic testing. This could significantly improve outcomes, including life expectancy, for patients and possibly for their relatives. CLINICAL RELEVANCE: Dental professionals are ideally placed to recognise oral features and initiate early assessment of PHTS which could significantly improve patient outcomes.

Family health beliefs and cascade genetic testing in Asian families with hereditary cancer risk: "Okay, now what?"

The limited literature on Asian family communication of hereditary cancer risk and cascade genetic testing for pathogenic variants (PVs) in BRCA1 and BRCA2 has reported that Asian patients have selective communication of test results and lower cascade testing rates. To better understand the factors that impact communication and cascade testing in Asian families, we conducted an in-depth qualitative study guided by the Health Belief Model. Participants with heterozygous PVs in ATM, BRCA1, BRCA2, CHEK2, or PALB2, who identified their family's origins to an Asian country, were recruited from the Stanford Cancer Genetics Research Database in October-November 2021. Utilizing a constructivist approach, we conducted sixteen semi-structured interviews around family communication and cascade genetic testing. The research team analyzed the transcript data using a reflexive thematic approach. Extensive discussions between the research team resulted in three primary themes presented in this paper: (1) the role of family health beliefs in cascade genetic testing, (2) changes in communication as a result of genetic testing, and (3) genetics providers' role in supporting family discussions on cascade genetic testing. Certain health beliefs, such as perceived susceptibility to cancer and self-efficacy to take action, were co-created by family members and these shared beliefs influenced decisions about genetic testing, family communication, and family support during the cascade genetic testing process. Participants shared strategies for how genetics providers can prepare Asian patients for more effective conversations with relatives and better address potential testing barriers by tailoring information and providing anticipatory guidance. This study represents an important contribution to the literature about cascade testing among an underrepresented group. Shared family health beliefs about genetic testing may be particularly relevant for this community and these findings can inform strategies to increase cascade genetic testing in Asian families.

Safety and anti-tumour activity of the IgE antibody MOv18 in patients with advanced solid tumours expressing folate receptor-alpha: a phase I trial.

All antibodies approved for cancer therapy are monoclonal IgGs but the biology of IgE, supported by comparative preclinical data, offers the potential for enhanced effector cell potency. Here we report a Phase I dose escalation trial (NCT02546921) with the primary objective of exploring the safety and tolerability of MOv18 IgE, a chimeric first-in-class IgE antibody, in patients with tumours expressing the relevant antigen, folate receptor-alpha. The trial incorporated skin prick and basophil activation tests (BAT) to select patients at lowest risk of allergic toxicity. Secondary objectives were exploration of anti-tumour activity, recommended Phase II dose, and pharmacokinetics. Dose escalation ranged from 70 µg-12 mg. The most common toxicity of MOv18 IgE is transient urticaria. A single patient experienced anaphylaxis, likely explained by detection of circulating basophils at baseline that could be activated by MOv18 IgE. The BAT assay was used to avoid enrolling further patients with reactive basophils. The safety profile is tolerable and maximum tolerated dose has not been reached, with evidence of anti-tumour activity observed in a patient with ovarian cancer. These results demonstrate the potential of IgE therapy for cancer.

Patient-reported function, health-related quality of life, and symptoms in APHINITY: pertuzumab plus trastuzumab and chemotherapy in HER2-positive early breast cancer.

BACKGROUND: We assessed health-related quality of life (symptoms of therapy/patient functioning/global health status), in APHINITY (pertuzumab/placebo, trastuzumab, and chemotherapy as adjuvant HER2-positive early breast cancer therapy). METHODS: Patients received 1 year/18 cycles of pertuzumab/placebo with trastuzumab and chemotherapy and completed EORTC QLQ-C30 and BR23 questionnaires until 36 months post-randomisation/disease recurrence. Changes ≥10 points from baseline were considered clinically meaningful. RESULTS: 87-97% of patients completed questionnaires. In the pertuzumab versus placebo arms, mean decrease in physical function scores (baseline → end of taxane) was -10.7 (95% CI -11.4, -10.0) versus -10.6 (-11.4, -9.9), mean decrease in global health status was -11.2 (-12.2, -10.2) versus -10.2 (-11.1, -9.2), and mean increase in diarrhoea scores (baseline → end of taxane) was +22.3 (21.0, 23.6) versus +9.2 (8.2, 10.2). Diarrhoea scores remained elevated versus baseline in the pertuzumab arm throughout HER2-targeted treatment (week 25: +13.2; end of treatment: +12.2). Role functioning was maintained in both arms. CONCLUSIONS: Improved invasive disease-free survival achieved by adding pertuzumab to trastuzumab and chemotherapy did not adversely affect the ability to conduct activities of daily living versus trastuzumab and chemotherapy alone. Patient-reported diarrhoea worsened during taxane therapy in both arms, persisting during HER2-targeted treatment in the pertuzumab arm. CLINICALTRIALS.GOV: NCT01358877.

Antitumor activity without on-target off-tumor toxicity of GD2-chimeric antigen receptor T cells in patients with neuroblastoma.

The reprogramming of a patient's immune system through genetic modification of the T cell compartment with chimeric antigen receptors (CARs) has led to durable remissions in chemotherapy-refractory B cell cancers. Targeting of solid cancers by CAR-T cells is dependent on their infiltration and expansion within the tumor microenvironment, and thus far, fewer clinical responses have been reported. Here, we report a phase 1 study (NCT02761915) in which we treated 12 children with relapsed/refractory neuroblastoma with escalating doses of second-generation GD2-directed CAR-T cells and increasing intensity of preparative lymphodepletion. Overall, no patients had objective clinical response at the evaluation point +28 days after CAR-T cell infusion using standard radiological response criteria. However, of the six patients receiving ≥108/meter2 CAR-T cells after fludarabine/cyclophosphamide conditioning, two experienced grade 2 to 3 cytokine release syndrome, and three demonstrated regression of soft tissue and bone marrow disease. This clinical activity was achieved without on-target off-tumor toxicity. Targeting neuroblastoma with GD2 CAR-T cells appears to be a valid and safe strategy but requires further modification to promote CAR-T cell longevity.

Basophils from Cancer Patients Respond to Immune Stimuli and Predict Clinical Outcome.

Basophils are involved in manifestations of hypersensitivity, however, the current understanding of their propensity for activation and their prognostic value in cancer patients remains unclear. As in healthy and atopic individuals, basophil populations were identified in blood from ovarian cancer patients (n = 53) with diverse tumor histologies and treatment histories. Ex vivo basophil activation was measured by CD63 expression using the basophil activation test (BAT). Irrespective of prior treatment, basophils could be activated by stimulation with IgE- (anti-FcεRI and anti-IgE) and non-IgE (fMLP) mediated triggers. Basophil activation was detected by ex vivo exposure to paclitaxel, but not to other anti-cancer therapies, in agreement with a clinical history of systemic hypersensitivity reactions to paclitaxel. Protein and gene expression analyses support the presence of basophils (CCR3, CD123, FcεRI) and activated basophils (CD63, CD203c, tryptase) in ovarian tumors. Greater numbers of circulating basophils, cells with greater capacity for ex vivo stimulation (n = 35), and gene signatures indicating the presence of activated basophils in tumors (n = 439) were each associated with improved survival in ovarian cancer. Circulating basophils in cancer patients respond to IgE- and non-IgE-mediated signals and could help identify hypersensitivity to therapeutic agents. Activated circulating and tumor-infiltrating basophils may be potential biomarkers in oncology.

A first-in-human phase I study to determine the maximum tolerated dose of the oral Src/ABL inhibitor AZD0424.

BACKGROUND: Src is involved in cancer invasion and metastasis. AZD0424, an oral inhibitor of Src and ABL1, has shown evidence of anti-tumour activity in pre-clinical studies. METHODS: A phase Ia, dose escalation study was performed to assess the safety of continuous oral dosing with AZD0424 in advanced solid tumours. Secondary objectives included investigation of AZD0424 pharmacokinetics, effect on Src activity using markers of bone turnover, and anti-tumour activity. RESULTS: 41 patients were treated; 34 received AZD0424 once-daily at doses ranging from 5 mg to 150 mg, and 7 received 40 mg bi-daily 41.5% of patients experienced at least one AZD0424-related adverse event that was Grade 3-5 in severity, with patients treated at doses above 60 mg per day experiencing multiple treatment-related toxicities. The most commonly observed AZD0424-related adverse events were nausea, fatigue, anorexia and alopecia. Cmax and AUC increased linearly with dose and the mean±standard deviation t1/2 was 8.4±2.8 h. Clear evidence of Src target inhibition was seen at doses ⩾20 mg per day. No responses were observed and 7 patients (17.1%) achieved stable disease lasting 6 weeks or more. CONCLUSIONS: AZD0424 displayed no evidence of efficacy as monotherapy despite a clear pharmacodynamic effect. Further evaluation of AZD0424 monotherapy in patients with solid tumours is not recommended.

Extracellular Adenosine Stimulates Vacuolar ATPase-Dependent Proton Secretion in Medullary Intercalated Cells.

Acidosis is an important complication of AKI and CKD. Renal intercalated cells (ICs) express the proton pumping vacuolar H+-ATPase (V-ATPase) and are extensively involved in acid-base homeostasis. H+ secretion in type A intercalated cells (A-ICs) is regulated by apical vesicle recycling and stimulated by cAMP. In other cell types, cAMP is increased by extracellular agonists, including adenosine, through purinergic receptors. Adenosine is a Food and Drug Administration-approved drug, but very little is known about the effect of adenosine on IC function. Therefore, we investigated the role of adenosine in the regulation of V-ATPase in ICs. Intravenous treatment of mice with adenosine or agonists of ADORA2A and ADORA2B purinergic P1 receptors induced V-ATPase apical membrane accumulation in medullary A-ICs but not in cortical A-ICs or other IC subtypes. Both receptors are located in A-IC apical membranes, and adenosine injection increased urine adenosine concentration and decreased urine pH. Cell fractionation showed that adenosine or an ADORA2A or ADORA2B agonist induced V-ATPase translocation from vesicles to the plasma membrane and increased protein kinase A (PKA)-dependent protein phosphorylation in purified medullary ICs that were isolated from mice. Either ADORA2A or ADORA2B antagonists or the PKA inhibitor mPKI blocked these effects. Finally, a fluorescence pH assay showed that adenosine activates V-ATPase in isolated medullary ICs. Our study shows that medullary A-ICs respond to luminal adenosine through ADORA2A and ADORA2B receptors in a cAMP/PKA pathway-dependent mechanism to induce V-ATPase-dependent H+ secretion.

Anti-Folate Receptor-α IgE but not IgG Recruits Macrophages to Attack Tumors via TNFα/MCP-1 Signaling.

IgE antibodies are key mediators of antiparasitic immune responses, but their potential for cancer treatment via antibody-dependent cell-mediated cytotoxicity (ADCC) has been little studied. Recently, tumor antigen-specific IgEs were reported to restrict cancer cell growth by engaging high-affinity Fc receptors on monocytes and macrophages; however, the underlying therapeutic mechanisms were undefined and in vivo proof of concept was limited. Here, an immunocompetent rat model was designed to recapitulate the human IgE-Fcε receptor system for cancer studies. We also generated rat IgE and IgG mAbs specific for the folate receptor (FRα), which is expressed widely on human ovarian tumors, along with a syngeneic rat tumor model expressing human FRα. Compared with IgG, anti-FRα IgE reduced lung metastases. This effect was associated with increased intratumoral infiltration by TNFα+ and CD80+ macrophages plus elevated TNFα and the macrophage chemoattractant MCP-1 in lung bronchoalveolar lavage fluid. Increased levels of TNFα and MCP-1 correlated with IgE-mediated tumor cytotoxicity by human monocytes and with longer patient survival in clinical specimens of ovarian cancer. Monocytes responded to IgE but not IgG exposure by upregulating TNFα, which in turn induced MCP-1 production by monocytes and tumor cells to promote a monocyte chemotactic response. Conversely, blocking TNFα receptor signaling abrogated induction of MCP-1, implicating it in the antitumor effects of IgE. Overall, these findings show how antitumor IgE reprograms monocytes and macrophages in the tumor microenvironment, encouraging the clinical use of IgE antibody technology to attack cancer beyond the present exclusive reliance on IgG. Cancer Res; 77(5); 1127-41. ©2017 AACR.

Development of downstream processing to minimize beta-glucan impurities in GMP-manufactured therapeutic antibodies.

The presence of impurities or contaminants in biological products such as monoclonal antibodies (mAb) could affect efficacy or cause adverse reactions in patients. ICH guidelines (Q6A and Q6B) are in place to regulate the level of impurities within clinical drug products. An impurity less often reported and, therefore, lacking regulatory guideline is beta-glucan. Beta-glucans are polysaccharides of d-glucose monomers linked by (1-3) beta-glycosidic bonds, and are produced by prokaryotic and eukaryotic organisms, including plants. They may enter manufacturing processes via raw materials such as cellulose-based membrane filters or sucrose. Here we report the detection of beta-glucan contamination of a monoclonal IgE antibody (MOv18), manufactured in our facility for a first-in-human, first-in-class clinical trial in patients with cancer. Since beta-glucans have potential immunostimulatory properties and can cause symptomatic infusion reactions, it was of paramount importance to identify the source of beta-glucans in our product and to reduce the levels to clinically insignificant concentrations. We identified beta-glucans in sucrose within the formulation buffer and within the housing storage buffer of the virus removal filter. We also detected low level beta-glucan contamination in two of four commercially available antibodies used in oncology. Both formulation buffers contained sucrose. We managed to reduce levels of beta-glucan in our product 10-fold, by screening all sucrose raw material, filtering the sucrose by Posidyne® membrane filtration, and by incorporating extra wash steps when preparing the virus removal filter. The beta-glucan levels now lie within a range that is unlikely to cause clinically significant immunological effects. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1494-1502, 2016.

Trends in the characteristics, dose-limiting toxicities and efficacy of phase I oncology trials: The Cancer Research UK experience.

INTRODUCTION: Phase I oncology trials have evolved over the years, and these changes could have implications for future studies and patients. METHODS: Adult trials sponsored by Cancer Research UK Centre for Drug Development between 1995 and 2013 were analysed. Forty-nine trials were divided into two groups based on the starting date for recruitment: 1995-2003 (24 trials, n = 603) and 2004-2013 (25 trials, n = 750) for comparative purposes. RESULTS: From 1995-2003 to 2004-2013, there was a shift towards studying non-cytotoxic agents that are administered orally. In later trials, patients tended to have better performance status, were older, had greater disease burden, and were more likely to have received prior treatment. In 2004-2013, wider variety of dose escalation designs were used, and studies were more likely to be multicentre, target/disease specific, conducted in first-/any-line setting and to require tumour biopsy. The overall incidence of dose-limiting toxicities (DLTs) was unchanged (10.9%; risk of death 0.4%), but DLTs such as neuropathy, stomatitis and thrombocytopaenia were less frequent in the more recent trials, while elevated liver enzymes were more frequent. Non-classical DLTs emerged in the later trials, including hypertension, hypophosphataemia, cardiac and ophthalmic toxicities. Disease control rate (DCR) increased from 27.9% (1995-2003) to 36.0% (2004-2013; P = 0.0033) due to higher rates of disease stabilisation. CONCLUSION: Changes in trial designs, therapeutic agents, patient characteristics and DLTs were observed. Although the nature of DLTs changed, the incidence was similar in the two time periods and DCR improved, suggesting that the benefit-risk balance for patients participating in early-phase trials remains acceptable.

Beta-glucan contamination of pharmaceutical products: How much should we accept?

Beta-glucans are large polysaccharides produced by a range of prokaryotic and eukaryotic organisms. They have potential immunostimulatory properties and have been used with therapeutic intent as anti-microbial and anti-tumour agents. A range of other potentially beneficial effects have been described, and oral forms of beta-glucans are widely available over-the-counter and online. Parenteral formulations are popular in parts of Asia and are the subject of ongoing trials, worldwide. Beta-glucans are also potential contaminants of pharmaceutical products, and high levels have been described in some blood products. However, little is known about the clinical effects of such contamination, considerable uncertainty exists over the level at which immunostimulation may occur, and there are no guidelines available on acceptable levels. We encountered beta-glucan contamination of one of our products, and we suspect that others may encounter similar issues since the origin of beta-glucan contamination includes commonly used filters and solutions applied in the manufacture of biotherapeutic agents. It is likely that regulators will increasingly enquire about beta-glucan levels in pharmaceutical products, especially those with an immunomodulatory mechanism of action. Here, we review the literature on beta-glucans in pharmaceutical products and propose an acceptable level for therapeutic agents for parenteral use.

Macrophages and dendritic cells in the post-testicular environment.

Macrophages (MΦ) and dendritic cells (DCs) are heterogeneous families of functionally and developmentally related immune cells that play crucial roles in tissue homeostasis and the regulation of immune responses. During the past 5 years, immunologists have generated a considerable amount of data that challenge dogmas about the ontogeny and functions of these highly versatile cells. The male excurrent duct system plays a critical role in the establishment of fertility by allowing sperm maturation, transport and storage. In addition, it is challenged by pathogens and must establish a protective and tolerogenic environment for a continuous flow of autoantigenic spermatozoa. The post-testicular environment and, in particular, the epididymis contain an intricate network of DCs and MΦ; however, the immunophysiology of this intriguing and highly specialized mucosal system is poorly understood. This review summarizes the current trends in mouse MΦ and DC biology and speculates about their roles in the steady-state epididymis. Unraveling immune cell functions in the male reproductive tract is an essential prerequisite for the design of innovative strategies aimed at controlling male fertility and treating infertility.

Neoadjuvant chemotherapy with trastuzumab followed by adjuvant trastuzumab versus neoadjuvant chemotherapy alone, in patients with HER2-positive locally advanced breast cancer (the NOAH trial): a randomised controlled superiority trial with a parallel HER2-negative cohort.

BACKGROUND: The monoclonal antibody trastuzumab has survival benefit when given with chemotherapy to patients with early, operable, and metastatic breast cancer that has HER2 (also known as ERBB2) overexpression or amplification. We aimed to assess event-free survival in patients with HER2-positive locally advanced or inflammatory breast cancer receiving neoadjuvant chemotherapy with or without 1 year of trastuzumab. METHODS: We compared 1 year of treatment with trastuzumab (given as neoadjuvant and adjuvant treatment; n=117) with no trastuzumab (118), in women with HER2-positive locally advanced or inflammatory breast cancer treated with a neoadjuvant chemotherapy regimen consisting of doxorubicin, paclitaxel, cyclophosphamide, methotrexate, and fluorouracil. Randomisation was done with a computer program and minimisation technique, taking account of geographical area, disease stage, and hormone receptor status. Investigators were informed of treatment allocation. A parallel cohort of 99 patients with HER2-negative disease was included and treated with the same chemotherapy regimen. Primary endpoint was event-free survival. Analysis was by intention to treat. This study is registered, number ISRCTN86043495. FINDINGS: Trastuzumab significantly improved event-free survival in patients with HER2-positive breast cancer (3-year event-free survival, 71% [95% CI 61-78; n=36 events] with trastuzumab, vs 56% [46-65; n=51 events] without; hazard ratio 0.59 [95% CI 0.38-0.90]; p=0.013). Trastuzumab was well tolerated and, despite concurrent administration with doxorubicin, only two patients (2%) developed symptomatic cardiac failure. Both responded to cardiac drugs. INTERPRETATION: The addition of neoadjuvant and adjuvant trastuzumab to neoadjuvant chemotherapy should be considered for women with HER2-positive locally advanced or inflammatory breast cancer to improve event-free survival, survival, and clinical and pathological tumour responses. FUNDING: F Hoffmann-La Roche.

Randomized phase II trial of first-line trastuzumab plus docetaxel and capecitabine compared with trastuzumab plus docetaxel in HER2-positive metastatic breast cancer.

PURPOSE To evaluate trastuzumab (H) and docetaxel (T) with or without capecitabine (X) as first-line combination therapy for human epidermal growth factor receptor 2 (HER2) -positive advanced breast cancer. PATIENTS AND METHODS Patients with HER2-positive locally advanced or metastatic breast cancer were randomly assigned to H (8 mg/kg loading; 6 mg/kg every 3 weeks) plus T (75 mg/m(2) in HTX arm, 100 mg/m(2) in HT arm, every 3 weeks) with or without X (950 mg/m(2) twice per day on days 1 to 14 every 3 weeks). The primary end point was overall response rate (ORR). Results In 222 patients, median follow-up was approximately 24 months. ORR was high with both regimens (70.5% with HTX; 72.7% with HT; P = .717); complete response rate was 23.2% with HTX compared with 16.4% with HT. HTX demonstrated significantly longer progression-free survival: median 17.9 months compared with 12.8 months with HT (hazard ratio, 0.72; P = .045), which translates to a gain of around 5 months. Two-year survival probability was 75% with HTX compared with 66% with HT. Febrile neutropenia (27% v 15%) and grade 3/4 neutropenia (77% v 54%) incidences were higher with HT than HTX. Treatment-related grade 3 hand-foot syndrome (17% v < 1%) and grade 3/4 diarrhea (11% v 4%) occurred more commonly with HTX than HT. One case of congestive heart failure occurred in each arm. CONCLUSION HTX is an effective and feasible first-line therapy for HER2-positive locally advanced or metastatic breast cancer, although it should be reserved for patients with good performance status who are not receiving long-term steroids.

Utility of serum HER2 extracellular domain assessment in clinical decision making: pooled analysis of four trials of trastuzumab in metastatic breast cancer.

PURPOSE: Trastuzumab is a humanized monoclonal antibody directed against human epidermal growth factor receptor 2 (HER2). Trastuzumab alone or in combination with chemotherapy has been shown to be effective in patients with HER2-positive early and metastatic breast cancer. The extracellular domain (ECD) of the HER2 protein may be shed into the serum and is detectable using an enzyme-linked immunosorbent assay. Correlations have been reported between raised baseline ECD levels and response to trastuzumab, suggesting that serum ECD levels may be useful in making treatment decisions in patients with HER2-positive breast cancer. We investigated this relationship, and also the effect of trastuzumab and chemotherapy on ECD levels, in patients with advanced breast cancer. METHODS: This study analyzed sequential ECD determinations on 322 patients treated with six different treatment regimens in four clinical trials. RESULTS: Baseline values were available in 296 patients, and of these, 205 (69%) had raised levels (> 15 ng/mL). No clear relationship was found between baseline ECD levels and tumor response. After initiating combination therapy, ECD levels declined irrespective of treatment received and tumor response. For trastuzumab monotherapy, some trend between changes in ECD levels in early cycles and best response was discernable, but the overlap was too broad to be clinically useful. Disease progression was not reliably predicted by rising ECD levels in the majority of patients. CONCLUSION: Based on our data, we cannot recommend using serum HER2 ECD levels to make trastuzumab or other treatment decisions for individual patients with advanced/metastatic breast cancer.

Phase II study of efficacy, safety, and pharmacokinetics of trastuzumab monotherapy administered on a 3-weekly schedule.

PURPOSE: This phase II study investigated the efficacy, safety, and pharmacokinetics of trastuzumab monotherapy given as first-line treatment once every 3 weeks (3-weekly) in women with human epidermal growth factor receptor 2 (HER2) -positive metastatic breast cancer (MBC). PATIENTS AND METHODS: Patients with previously untreated HER2-positive MBC received a loading dose of trastuzumab, 8 mg/kg intravenously (IV) and then 6 mg/kg IV at 3-week intervals until disease progression or patient withdrawal. RESULTS: In total, 105 patients received a median of five cycles of therapy (range, 1 to 35+). The overall response rate was 19% (23% in patients with measurable centrally confirmed immunohistochemistry [IHC] 3+ and/or fluorescence in situ hybridization [FISH] -positive disease) and clinical benefit rate (complete and partial responses plus stable disease for at least 6 months) was 33% (36% in patients with measurable centrally confirmed IHC 3+ and/or FISH-positive disease). Median time to progression was 3.4 months (range, 0.6 to 23.6 months). The most common treatment-related adverse events were rigors, pyrexia, headache, nausea, and fatigue. Median baseline left ventricular ejection fraction was 63%; this did not significantly change over the course of the study. The average exposure to trastuzumab observed in this study was similar to that in previous studies of the weekly regimen. However, as expected, mean trough trastuzumab concentrations were lower and peak levels were higher with 3-weekly trastuzumab compared with weekly treatments. CONCLUSION: Administering higher doses on a 3-weekly schedule did not compromise the efficacy and safety of trastuzumab in women with HER2-positive MBC, and average exposure was similar to that observed with weekly therapy. Three-weekly trastuzumab may represent a convenient alternative to weekly administration.