Successful management of in-transit cutaneous squamous cell carcinoma with anti-PD-1 immunotherapy.

This report describes the case of a 70-year-old man with metastatic squamous cell carcinoma (SCC) of the right lower leg. Soon after definitive surgical management of the primary and nodal metastases with curative intent, he relapsed, developing aggressive in-transit metastatic disease and recurrent nodal disease. The patient was treated with systemic immunotherapy alone, which not only prompted the progressive nodal metastases to regress, but also resulted in a complete response of the in-transit disease. This situation is previously undescribed in the medical literature.

Tislelizumab Versus Docetaxel in Patients With Previously Treated Advanced NSCLC (RATIONALE-303): A Phase 3, Open-Label, Randomized Controlled Trial.

INTRODUCTION: The phase 3 RATIONALE-303 trial (NCT03358875) investigated the efficacy and safety of tislelizumab versus docetaxel in pretreated patients with advanced NSCLC. Here, we report the efficacy and safety results and describe the exploratory biomarker analyses. METHODS: A total of 805 patients aged more than or equal to 18 years with locally advanced or metastatic squamous or nonsquamous NSCLC were randomized 2:1 to intravenous tislelizumab 200 mg or docetaxel 75 mg/m2 every 3 weeks. Co-primary end points were overall survival (OS) in the intent-to-treat (ITT) and programmed death-ligand 1 (PD-L1) tumor cell expression greater than or equal to 25% populations. The exploratory biomarker analyses included PD-L1 expression, tumor mutation burden, and gene expression profile. RESULTS: At the prespecified interim analysis (August 10, 2020), the co-primary end point of OS in the ITT population was met, with a statistically significant and clinically meaningful improvement in OS with tislelizumab versus docetaxel (median 17.2 versus 11.9 mo, respectively; hazard ratio [HR] = 0.64, p < 0.0001). At the final analysis (July 15, 2021), the other co-primary end point of OS in the PD-L1 tumor cell greater than or equal to 25% population was further met (median 19.3 versus 11.5 mo, respectively; HR = 0.53, p < 0.0001), and OS continued to improve in the ITT population (median 16.9 versus 11.9 mo, respectively, HR = 0.66). Exploratory biomarker analyses revealed the potential association of NOTCH1-4 mutations with improved tislelizumab efficacy for both OS and progression-free survival, whereas tissue tumor mutation burden correlated with progression-free survival benefit, but not OS benefit. No new safety signals were identified. CONCLUSIONS: Tislelizumab was found to have a significantly improved and long-term clinical benefit in OS versus docetaxel in pretreated patients with advanced NSCLC, regardless of PD-L1 expression.

Loss of STING expression is prognostic in non-small cell lung cancer.

BACKGROUND: Stimulator of interferon (IFN) genes (STING) is a protein that promotes type I IFN production essential for T-cell activation. In this study, we aim to characterize STING expression comprehensively using The Cancer Genome Atlas (TCGA) database, cell lines, and patient tumor samples stained with immunohistochemistry. METHODS: Two cohorts were evaluated comprising 721 non-small cell lung cancer (NSCLC) patients and 55 NSCLC cell lines for STING and cyclic GMP-AMP synthase (cGAS) expression using immunohistochemistry. Moreover, an independent cohort of n = 499 patients from the TCGA database was analyzed. Methylation was evaluated on STING and cGAS in five STING-negative NSCLC cell lines. RESULTS: STING RNA expression positively correlates with T cell function and development genes, negatively correlates with cell proliferation and associated with increased survival (5-year-overall survival [OS] 47.3% vs. 38.8%, p = 0.033). STING protein expression is significantly higher in adenocarcinoma (AC) and is lost with increasing stages of AC. STING-positivity is significantly higher in mutant EGFR and KRAS tumors. STING-positive NSCLC patients identified with immunohistochemistry (H-score > 50) have increased survival (median OS: 58 vs. 35 months, p = 0.02). Treatment of STING-negative cell lines with a demethylating agent restores STING expression. CONCLUSIONS: STING is ubiquitously expressed in NSCLC and associated with T cell function genes, AC histology, EGFR, and KRAS mutations and improved overall survival.

PIVOT-12: a phase III study of adjuvant bempegaldesleukin plus nivolumab in resected stage III/IV melanoma at high risk for recurrence.

Bempegaldesleukin (BEMPEG: NKTR-214) is an immunostimulatory IL-2 cytokine prodrug engineered to deliver a controlled, sustained and preferential IL-2 pathway signal. Nivolumab (NIVO), a PD-1 inhibitor, has been shown to prolong survival in patients with advanced melanoma and recurrence-free survival in the adjuvant setting. PIVOT-02 showed that BEMPEG plus NIVO was well-tolerated and demonstrated clinical activity as first-line therapy in metastatic melanoma. PIVOT-12 is a randomized, phase III, global, multicenter, open-label study comparing adjuvant therapy with BEMPEG plus NIVO versus NIVO alone in adult and adolescent patients with completely resected cutaneous stage III/IV melanoma at high risk of recurrence. The primary objective is to compare the efficacy, as measured by recurrence-free survival, of BEMPEG plus NIVO versus NIVO.

Following surgery, patients with advanced melanoma may require further treatment to reduce the likelihood of disease recurrence. Nivolumab (NIVO), a checkpoint inhibitor, reduces the risk of melanoma recurrence by enhancing the ability of the immune system to fight disease. Despite the availability of NIVO and other therapies, many patients with melanoma still experience disease recurrence after surgery. This article presents information on a clinical trial named PIVOT-12, which aims to assess the effectiveness of a new investigational drug called bempegaldesleukin that modifies the immune system and is given with NIVO to patients with stage III/IV melanoma following surgery. The main end point being measured is recurrence-free survival, which measures the time between a patient starting the study and the date of disease recurrence. Clinical Trial Registration: NCT04410445 (ClinicalTrials.gov).

A case of hyperprolactinaemia in a patient with metastatic melanoma.

Ectopic prolactin production from a malignancy is infrequently reported. We report here a 60-year-old gentleman who presented with hyperprolactinaemia (9100 mIU/L) causing expressible galactorrhoea, decreased libido and fatigue thought to be due to ectopic prolactin secretion from a metastatic melanoma. Upon initiation of pembrolizumab, the patient's symptoms resolved and he became normoprolactinaemic. This corresponded with a partial response on radiological imaging. Although the core biopsy of the metastatic melanoma did not exhibit immunostaining for prolactin, we believe that only a subset of the tumour cells possesses prolactin-secreting capacity. This case illustrates the need to consider ectopic prolactin production for a solid malignant tumour as a rare cause of hyperprolactinaemia in patients with a normal pituitary MRI, in the absence of other causes.

Cardiac Troponin I and T in Checkpoint Inhibitor-associated Myositis and Myocarditis.

Checkpoint inhibitor-associated myocarditis (ir-myocarditis) and myositis (ir-myositis) may occur concurrently among patients on checkpoint inhibitor immunotherapy. While cardiac-specific troponin I (cTnI) and troponin T (cTnT) are regarded to have similar sensitivities and specificities in conditions such as acute coronary syndrome, the cardiac specificity of cTnT has been challenged following observation that patients with neuromuscular diseases, including myositis, may have elevated cTnT without apparent clinical evidence of myocardial injury. Consequently, in the context of concurrent ir-myositis, cTnI may be a more appropriate biomarker for diagnosing and monitoring ir-myocarditis. To illustrate this point, we report a case of a patient with severe ir-myositis while on adjuvant programmed cell death protein 1 inhibitor immunotherapy for stage III melanoma, with accompanying elevation in cTnT.

Preliminary study highlights the potential of immune checkpoint inhibitors in sarcomatoid mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is well known as an aggressive disease with poor survival. This has sparked trials of alternate immune-based therapies in MPM. While up to a quarter of MPM patients respond to immune checkpoint inhibitors (ICIs), predicting response remains challenging and PD-L1 expression alone has been deemed insufficient. Additionally, patients with sarcomatoid MPM are often excluded from trials utilizing ICIs due to their rapid progression. Here, we analyze the association of T lymphocytes with response to ICI-based immunotherapy to uncover predictive immune markers across subtypes. METHODS: Retrospective analysis of immunotherapy treated mesothelioma patient cohorts from two sites were pooled. Patient characteristics, including age, sex, subtype and previous treatment were captured. Multiplex immunohistochemistry was used to assess proportions of CD4, CD8, CD45RO and FOXP3 positive infiltrates in MPM and their association with progression free (PFS) and overall (OS) survival post immunotherapy. RESULTS: Samples derived from 22 patients were analyzed; 13 (59%) had epithelioid MPM, 6 (27%) sarcomatoid and 3 (14%) biphasic. The overall ICI response rate was 40%, with a median PFS (mPFS) and OS (mOS) of 3.8 and 11.17 months, respectively. Of the subtypes, sarcomatoid patients displayed the greatest median PFS and OS (>28 months) post ICI compared to the epithelioid subtype (3 and 11 months respectively), which correlated with higher proportions of infiltrating CD8+, CD45RO+ and CD8+CD45RO+ cells. Patients who received ICIs as first-line therapy had greater PFS than those who received it as second or third line post-chemotherapy. CONCLUSIONS: High proportions of T lymphocytes and CD45RO+ cells were associated with prolonged mPFS and mOS in sarcomatoid patients treated with ICI immunotherapy. These data support the expansion of trials utilizing single and combination ICIs as first-line therapy in sarcomatoid MPM and warrants further studies testing the impact or detriment of chemotherapy pre-ICI.

NTRK and ALK rearrangements in malignant pleural mesothelioma, pulmonary neuroendocrine tumours and non-small cell lung cancer.

OBJECTIVES: Gene rearrangements involving NTRK1, NTRK2, NTRK3, ROS1 and ALK have been identified in many types of cancer, including non-small cell lung cancer (NSCLC). Data in malignant pleural mesothelioma (MPM), lung neuroendocrine tumors (NETs) and small-cell lung cancer (SCLC) are lacking. Given the activity of NTRK, ROS-1 and ALK inhibitors in tumors harboring gene fusions, we sought to explore such rearrangements in these less common tumors in addition to NSCLC. METHODS: Archival tumor tissue from patients with MPM, lung NETs, SCLC and NSCLC were used to create tissue microarrays. Immunohistochemistry (IHC) was performed using a cocktail of antibodies against TRK, ROS1 and ALK. IHC positive samples underwent RNA sequencing using the ArcherDX FusionPlex CTL diagnostic assay. Clinical data were obtained through retrospective chart review. RESULTS: We performed IHC on 1116 samples: 335 MPMs, 522 NSCLCs, 105 SCLCs and 154 lung NETs. There were 23 IHC positive cases (2.1%) including eight MPMs (2.4%), eight NETs (5.2%), five SCLC (4.8%) and two NSCLC (0.4%). The following fusions were detected: one MPM with an NTRK ex10-TPM3 ex8, another MPM with an ALK ex20-EML4ex13, one lung intermediate-grade NET (atypical carcinoid) with an ALK ex20-EML4 ex6/intron6, and two NSCLCs with an ALK ex20-EML4 ex6/intron6 rearrangement. None of the patients received targeted treatment. CONCLUSIONS: To our knowledge, we report for the first time NTRK and ALK rearrangements in a small subset of MPM. An ALK rearrangement was also detected in lung intermediate-grade NET (or atypical carcinoid). Our data suggest that IHC could be a useful screening test in such patients to ensure that all therapeutic strategies including targeted therapy are utilized.

Osimertinib in NSCLC: Real-World Data From New Zealand.

INTRODUCTION: EGFR tyrosine kinase inhibitors (TKIs) are more effective than chemotherapy in patients with EGFR-mutant NSCLC. Disease progression on EGFR TKI therapy occurs most often owing to acquired resistance from the gain of an EGFR T790M mutation. Osimertinib, a third-generation EGFR TKI, significantly improves outcomes in patients with EGFR T790M mutation-positive NSCLC compared with platinum-pemetrexed chemotherapy. We retrospectively reviewed clinical outcomes for patients receiving osimertinib through a compassionate access program in New Zealand. METHODS: Patients with a biopsy-proven or plasma-circulating tumor-DNA-proven EGFR T790M mutation received osimertinib. Data on patient and tumor characteristics, treatments, and outcomes were collected retrospectively. Survival outcomes were calculated from the time of osimertinib commencement. RESULTS: A total of 39 patients were enrolled, and data from 37 patients were analyzed. EGFR T790M status was found from plasma samples in six of 37 (16%) patients. A total of 27 of 37 patients (73%) used osimertinib as a second-line treatment. At the time of data analysis, median follow-up was 18.8 months (range 1.5-29). Overall response rate was 70% (95% confidence interval [CI]: 53-84) (26 of 37). Progression-free survival (PFS) at 12 months was 62% (95% CI: 44.8-77.5), and median PFS was 14.6 months (95% CI: 12.4-16.8). Median overall survival was not reached. Osimertinib was well tolerated, with grade 1 gastrointestinal and skin toxicity as the most common adverse effects. Three patients required dose adjustments or cessation owing to toxicity. CONCLUSION: Osimertinib is an effective treatment for New Zealanders with EGFR T790M mutated NSCLC who have progressed after first or subsequent lines of therapy.

Standard dose osimertinib for erlotinib refractory T790M-negative EGFR-mutant non-small cell lung cancer with leptomeningeal disease.

BACKGROUND: Leptomeningeal spread in non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations who experience disease progression on TKIs portends a poor prognosis. Mutation profiling of tumour DNA in cerebrospinal fluid (CSF) samples can be used to determine the presence of the EGFR T790M resistance mutation, indicating that osimertinib, a CNS-penetrating 3rd generation TKI may be efficacious. METHODS: Eight patients on EGFR TKIs who progressed with cytology-proven leptomeningeal disease at our institution were studied. EGFR mutations were profiled in CSF using droplet digital PCR (ddPCR) and compared to matched plasma samples. Clinical characteristics and survival outcomes on subsequent therapies tailored to ddPCR analysis were reported. RESULTS: None of the four patients who developed leptomeningeal disease while receiving 1st generation EGFR TKIs developed the EGFR T790M mutation in CSF. One patient who did not have extra-cranial disease and was EGFR T790M-negative in both plasma and CSF was nevertheless treated with standard-dose osimertinib, and achieved a rapid and durable response lasting 9 months to date. Three patients developed leptomeningeal disease on osimertinib, with one patient developing the EGFR C797S mutation in a cis-allelic conformation with the EGFR T790M mutation in plasma. CONCLUSIONS: Standard-dose osimertinib resulted in a clinically meaningful response in a patient with EGFR T790M-negative 1st generation EGFR TKI refractory leptomeningeal disease. Next generation sequencing and ddPCR has a role at identifying the C797S mutation and its allelic conformation with the T790M mutation with clinical implications.

Mesenchyme to epithelial transition protein expression, gene copy number and clinical outcome in a large non-small cell lung cancer surgical cohort.

BACKGROUND: In non-small cell lung cancer (NSCLC), mesenchyme to epithelial transition (MET) protein abundance increases with disease stage and is implicated in resistance to tyrosine kinase inhibitors. To better clarify the impact of MET overexpression on tumor behavior, we investigated a large cohort of patients who underwent curative surgical resection to determine whether MET gene amplification or protein abundance was prognostic. METHODS: Tissue microarrays (TMAs) were constructed using triplicate 1 mm cores of FFPE primary NSCLC specimens. TMAs underwent immunohistochemical (IHC) staining with the SP44 clone (Ventana) and cores were considered positive if >50% of tumor exhibited 2+ staining. The highest of triplicate values was used. MET gene amplification was detected using either SISH using Ventana's MET DNP probe or FISH using the D7S486/CEP 7 Abbott Probe. DNA was subjected to mutational profiling using Sequenom's LungCarta panel. RESULTS: Data from two institutions comprising 763 patients (516; 68%) male were generated, including 360 stage I, 226 stage II, 160 stage III and 18 resected stage IV. High MET protein expression was detected in 25% (193/763), and was significantly more common in adenocarcinomas than squamous cell carcinoma (P<0.01). MET gene copy number (GCN) correlated with high MET protein expression by IHC (P=0.01). Increased MET protein expression was associated with EGFR and KRAS mutations (P<0.01 for both). Once polysomy was excluded, true MET gene amplification was detected in only 8/763 (1%) of samples. In multivariate analysis, neither MET protein abundance nor GCN were correlated to overall patient survival. CONCLUSIONS: MET expression by IHC and GCN amplification was not prognostic in this large Caucasian surgical series. MET's primary role remains as a therapeutic target.

The immune checkpoint, HVEM may contribute to immune escape in non-small cell lung cancer lacking PD-L1 expression.

BACKGROUND: Herpes Virus Entry Mediator (HVEM) is an important immune checkpoint in cancer recognition. HVEM expressed on tumor cell membranes activates immune cell signaling pathways leading to either inhibition of activity (B- and T-lymphocyte attenuator, BTLA) or activation of immune activity (LIGHT). The aim of this study is to investigate the prevalence of HVEM expression and its association with PDL1 expression in NSCLC. METHODS: A TMA of 527 resected NSCLC samples and 56 NSCLC cell lines were evaluated for HVEM and PD-L1 expression. The IHC assay for HVEM was optimized on the Dako Link48 autostainer using a polyclonal antibody from R&D Systems(AF356). PD-L1 IHC was performed on the Dako Link48 autostainer using the PD-L1 28-8 pharmDx kit. Scoring HVEM employed the H-score system while for PD-L1 the tumor proportion score (TPS) was used. RESULTS: HVEM expression in the NSCLC resected samples and cell lines revealed a positive H-score more than 1 was 18.6% (77/415) and 48.2% (27/56) respectively. HVEM expression was significantly higher in patients with lymph node N2 metastasis (25.5% vs 7.9% vs 17.5%, p = 0.046) when comparing with N1 or no lymph node metastasis, and was marginally significantly higher in patients with stage III/IV disease (24.5% vs 16.4%, p = 0.059). Subgroup analysis showed that HVEM (median 45 vs 36 months, p = 0.706) and PD-L1 expression (median 45 vs 48 months, p = 0.178) status was not predictive of overall survival. HVEM was found to have a significant negative correlation with PD-L1 expression (r=-0.274, p < 0.001) in patients with NSCLC and also a weak negative correlation in NSCLC cell lines (r=-0.162, p = 0.352). CONCLUSION: HVEM was found to be overexpressed in NSCLC patients of N2 lymph node metastasis or later stage and has a negative co-relationship with PD-L1 expression. HVEM was not prognostic for NSCLC patients.

Pembrolizumab as Palliative Immunotherapy in Malignant Pleural Mesothelioma.

INTRODUCTION: There is no approved second-line treatment for malignant pleural mesothelioma (MPM). On the basis of promising early results, pembrolizumab was used off-label in Switzerland and Australia. We investigated outcomes in association with clinicopathological features and expression of programmed death ligand 1 (PD-L1). METHODS: Registry data in Australia and Switzerland were pooled. Patient characteristics, including age, sex, histological subtype, and previous treatments were captured. Outcomes were assessed locally. PD-L1 expression was categorized as negative (<5%), intermediate (5%-49%), and high (≥50%). RESULTS: A total of 93 patients (48 from Switzerland and 45 from Australia) were treated; 68 patients (73%) had epithelioid MPM, and 67 (72%) had an Eastern Cooperative Oncology Group performance status of 0 or 1. Pembrolizumab was the second-line treatment in 48 of 93 patients (52%). PD-L1 expression results were available for 66 patients (71%). Most (68%) were negative, 18% were intermediate, and 14% were high for PD-L1 expression. In the full cohort, the overall response rate (ORR) was 18%, the median progression-free survival (mPFS) was 3.1 months, and the median overall survival was 7.2 months. In patients with an Eastern Cooperative Oncology Group performance status of 0 or 1 and only one previous systemic treatment (n = 35), the ORR was 37%, the mPFS was 3.7 months, and the median overall survival was 10.2 months. The nonepitheloid histological subtype showed an improved ORR (24% versus 16% [p = 0.54) and mPFS (5.6 versus 2.8 months [p = 0.02]). Compared with intermediate and negative PD-L1 expression, high PD-L1 expression was associated with an improved ORR (44% versus 42% versus 11% [p = 0.01]) and mPFS (6.2 versus 3.9 versus 2.7 months [p = 0.04]). Toxicity was as expected. CONCLUSION: These real-world data demonstrate similar response rates but inferior survival compared with those in early-phase trials. High PD-L1 expression and nonepitheloid histological subtype were associated with greater activity. Anti-PD-L1 immunotherapy is a reasonable second-line therapy in patients with MPM.

Standard of care in immunotherapy trials: Challenges and considerations.

The success of immunotherapeutics over the past decade has fundamentally altered the therapeutic landscape in melanoma and non-small cell lung (NSCLC) cancer care. Multiple clinical trials have confirmed significant improvements in survival with a variety of immunotherapeutic strategies. The careful and appropriate selection of standard of care (SOC) therapies is key to the successful design and interpretation of these trials. To date immunotherapeutic trials have used best supportive care, matched placebo, chemotherapy, targeted therapy or, more recently, established immunotherapeutics in melanoma clinical trials as SOCs. Each of these SOC choices has a fundamental impact on the selection and validity of response assessment criteria and clinical endpoints. As yet there is no established approach, thus new data must be interpreted with an understanding of the limitations of the current paradigm. Additionally, the pace of development has mandated the use of novel clinical trial designs, answering multiple therapeutic questions simultaneously and designed to expedite regulatory approval. This review addresses the most important challenges in the selection of SOC in immunotherapeutic trials and the current and future challenges in trial design.

Digital PCR of Genomic Rearrangements for Monitoring Circulating Tumour DNA.

Identifying circulating tumour DNA (ctDNA) for monitoring of cancer therapy is dependent on the development of readily designed, sensitive cancer-specific DNA markers. Genomic rearrangements that are present in the vast majority of cancers provide such markers.Tumour DNA isolated from two fresh-frozen lung tumours underwent whole genome sequencing. Genomic rearrangements were detected using a new computational algorithm, GRIDSS. Four genomic rearrangements from each tumour were chosen for further study using rearrangement-specific primers. Six of the eight rearrangements tested were identified as tumour-specific, the remaining two were present in the germline. ctDNA was quantified using digital PCR for the tumour genomic rearrangements in patient blood. Interestingly, one of the patients had no detectable ctDNA either prior to or post surgery although the rearrangements were readily detectable in the tumour DNA.This study demonstrates the feasibility of using digital PCR based on genomic rearrangements for the monitoring of minimal residual disease. In addition, whole genome sequencing provided further information enabling therapeutic choices including the identification of a cryptic EGFR exon 19 deletion in one patient and the identification of a high somatic mutation load in the other patient. This approach can be used as a model for all cancers with rearranged genomes.

Combination approaches in NSCLC involving immune checkpoint inhibitors.

Immune checkpoint inhibition has been proven to be highly efficacious in NSCLC and associated with durable responses in a limited number of patients. Chemotherapy and targeted therapies, which have also expanded rapidly in this field lead to high response rates and improved survival although inevitably resistance occurs and hence treatment failure. There is increasing evidence showing that chemotherapy and targeted therapy interplay with the immune system including exerting effects on tumor cells and the host immune cells. Naturally combining both of these treatment modalities to induce cytotoxic effects on tumor cells to release tumor antigens and priming of the immune system should in turn lead to enhanced anticancer activity. This review will explore some of the preclinical rationale and clinical trial data we have to date on combining various systemic therapies with immunotherapies.

Update on Mucin-1 immunotherapy in cancer: a clinical perspective.

INTRODUCTION: Mucin 1 (MUC1) is particularly well suited as a cancer immunotherapy target due to the elevated protein expression and aberrant forms associated with malignancy. A variety of therapeutic strategies have been explored, including antibodies intended to induce cancer cell destruction, and vaccinations with peptides, tumor extracts, and gene expression systems. AREAS COVERED: MUC1 immunotherapeutic strategies have included vaccination with peptide sequences, glycan molecules, viruses, and dendritic cells, monoclonal antibodies and monoclonal antibody conjugates. Here we review the relevant clinical trials in each field of immunotherapy with particular focus on large and recently published trials. EXPERT OPINION: Long clinical experience in the trial setting has reduced concerns of immunotherapy associated toxicities and inappropriate immune responses, with the main limitation (common to many experimental approaches) being a lack of clinical efficacy. However, there have been sufficient treatment-associated responses to justify continued pursuit of MUC1 targeted immunotherapies. The focus now should be on application to the relevant cancers under appropriate circumstances and combination with the emerging non-specific immunotherapy approaches such as the PD-1 pathway inhibitors.

Cost-effectiveness analysis of docetaxel versus weekly paclitaxel in adjuvant treatment of regional breast cancer in New Zealand.

BACKGROUND: There have been recent important changes to adjuvant regimens and costs of taxanes for the treatment of early breast cancer, requiring a re-evaluation of comparative cost effectiveness. In particular, weekly paclitaxel is now commonly used but has not been subjected to cost-effectiveness analysis. AIM: Our aim was to estimate the cost effectiveness of adjuvant docetaxel and weekly paclitaxel versus each other, and compared with standard 3-weekly paclitaxel, in women aged ≥25 years diagnosed with regional breast cancer in New Zealand. METHODS: A macrosimulation Markov model was used, with a lifetime horizon and health system perspective. The model compared 3-weekly docetaxel and weekly paclitaxel versus standard 3-weekly paclitaxel (E1199 regimen) in the hospital setting. Data on overall survival and toxicities (febrile neutropenia and peripheral neuropathy) were derived from relevant published clinical trials. Epidemiological and cost data were derived from New Zealand datasets. Health outcomes were measured with health-adjusted life-years (HALYs), similar to quality-adjusted life-years (QALYs). Costs included intervention and health system costs in year 2011 values, with 3% per annum discounting on costs and HALYs. RESULTS: The mean HALY gain per patient compared with standard 3-weekly paclitaxel was 0.51 with weekly paclitaxel and 0.21 with docetaxel, while incremental costs were $NZ 12,284 and $NZ 4,021, respectively. The incremental cost-effectiveness ratio (ICER) of docetaxel versus 3-weekly paclitaxel was $NZ 19,400 (purchasing power parity [PPP]-adjusted $US 13,100) per HALY gained, and the ICER of weekly paclitaxel versus docetaxel was $NZ 27,100 ($US 18,300) per HALY gained. In terms of net monetary benefit, weekly paclitaxel was the optimal strategy for willingness-to-pay (WTP) thresholds >$NZ 27,000 per HALY gained. However, the model was highly sensitive to uncertainty around survival differences, while toxicity-related morbidity had little impact. Thus, if it was assumed that weekly paclitaxel and docetaxel had the same efficacy, docetaxel would be favoured over weekly paclitaxel. CONCLUSION: Both weekly paclitaxel and docetaxel are likely to be cost effective compared with standard 3-weekly paclitaxel. Weekly paclitaxel was the optimal choice for WTP thresholds greater than $NZ27,000 per HALY gained (PPP-adjusted $US 18,000). However, uncertainty remains around relative survival benefits, and weekly paclitaxel becomes cost ineffective versus docetaxel if it is assumed that the two regimens have equal effectiveness. Reduced uncertainty about the relative survival benefits may improve decision making for funding.