Overall survival and risk of second malignancies with cancer chemotherapy and G-CSF support.

Background: The use of supportive granulocyte colony-stimulating factor (G-CSF) to reduce the risk of neutropenic complications in high-risk cancer patients is consistently recommended by several clinical practice guidelines. However, in a previous meta-analysis, G-CSF prophylaxis was associated with an increased risk of secondary malignancies while reducing long-term mortality. We present here an updated systematic review and meta-analysis. Materials and methods: A systematic literature search was carried out to identify randomized controlled trials of cancer patients receiving conventional-dose chemotherapy, assigned to primary G-CSF support or a control group without initial G-CSF, with at least 2 years of follow-up. Studies were categorized into one of the four groups, based on the chemotherapy regimen and study design. An updated meta-analysis was carried out; relative risk (RR) and 95% confidence intervals (CIs) for all-cause mortality and secondary malignancies were calculated. Results: Of 2604 articles screened, 14 eligible studies were identified and combined with studies identified in the previous systematic literature searches. The updated meta-analysis included a total of 68 studies presenting 71 separate comparisons. Survival was significantly improved in patients receiving primary G-CSF support, compared with patients without primary G-CSF support (mortality RR=0.92; 95% CI 0.90-0.95; ARD=-3.3%; 95% CI -4.2--2.4; P < 0.0001). The largest improvement in survival was observed with dose-dense chemotherapy regimens with G-CSF support, compared with controls receiving no G-CSF support (mortality RR=0.86; 95% CI 0.80-0.92; P < 0.0001). Patients who received primary G-CSF support experienced a significantly higher risk of secondary malignancies, compared with controls (RR=1.85; 95% CI 1.19-2.88; ARD=0.47; 95% CI 0.21-0.73; P < 0.01). Conclusions: Our findings demonstrate that overall survival is improved in patients receiving intensified chemotherapy with primary G-CSF support, compared with those receiving standard chemotherapy. Primary G-CSF support was also associated with a higher risk of developing secondary malignancies, including secondary acute myeloid leukemia and myelodysplastic syndrome.

Clinical equivalence with G-CSF biosimilars: methodologic approach in a (neo)adjuvant setting in non-metastatic breast cancer.

Biosimilars are biological medicines that have been shown to be similar to a reference biological medicine that has already been approved for use. Development of biosimilars is based on a "totality of evidence" approach that involves a series of steps by which biosimilars must demonstrate similarity to a reference product in all aspects of the drug and eliminate any remaining uncertainties. Clinical studies are then considered confirmatory and are performed to show that there are no clinically meaningful differences compared with the reference product in a sensitive patient population. The recombinant human granulocyte colony-stimulating factor (G-CSF) biosimilar EP2006/Zarxio® (filgrastim-sdnz) became the first FDA-approved biosimilar in 2015. This review evaluates how clinical equivalence can be demonstrated with G-CSF biosimilars through the identification of "sensitive" study populations and endpoints. Patients with non-metastatic breast cancer treated in the (neo)adjuvant setting represent a potentially homogenous population, making this a suitable sensitive indication for assessing filgrastim and pegfilgrastim biosimilars compared with reference products. This review includes clinical trials of G-CSF biosimilars in breast cancer, focusing on key aspects of the trials that were necessary to accurately demonstrate clinical equivalence and enable extrapolation to relevant indications, based on guidelines and biostatistical principles.

Safety and efficacy of alternating treatment with EP2006, a filgrastim biosimilar, and reference filgrastim: a phase III, randomised, double-blind clinical study in the prevention of severe neutropenia in patients with breast cancer receiving myelosuppressive chemotherapy.

Background: In 2015, the biosimilar filgrastim EP2006 became the first biosimilar approved by the US Food and Drug Administration for commercial use in the United States, marketed as Zarxio® (Sandoz). This phase III randomised, double-blind registration study in patients with breast cancer receiving (neo)adjuvant myelosuppressive chemotherapy (TAC; docetaxel + doxorubicin + cyclophosphamide) compares reference filgrastim, Neupogen® (Amgen), with two groups receiving alternating treatment with reference and biosimilar every other cycle. Patients and methods: A total of 218 patients receiving 5 µg/kg/day filgrastim over six chemotherapy cycles were randomised 1: 1: 1: 1 into four arms. Two arms received only one product, biosimilar or reference (unswitched), and two arms (switched) received alternating treatments every other cycle (biosimilar then reference or vice versa over six cycles). Since the switch occurred from cycle 2 onwards, this analysis compared pooled switched groups to the unswitched reference group for efficacy during cycles 2-6. Safety was also assessed. Non-inferiority in febrile neutropenia (FN) rates between groups for cycles 2-6 was shown if 95% were within a pre-defined margin of - 15%. Results: A total of 109 patients switched treatment, and 52 patients received reference in all cycles. Baseline characteristics were similar between groups. The incidence of FN was 0% (reference) versus 3.4% (n = 3, switched) across cycles 2-6, with a difference of - 3.4% (95% confidence interval: -9.65% to 4.96%), showing non-inferiority. Infections occurred in 9.3% (switched) versus 9.9% (reference). Hospitalisation due to FN was low (one patient in cycle 6; switched). Adverse events related to filgrastim were reported in 42.1% (switched) versus 39.2% (reference) (all cycles). Musculoskeletal/connective tissue disorders related to filgrastim occurred in 35.5% (switched) versus 39.2% (reference) (all cycles), including bone pain (30.8% versus 33.3%). No neutralising antibodies were detected. Conclusions: There were no clinically meaningful results regarding efficacy, safety or immunogenicity when switching from reference to biosimilar filgrastim/EP2006, or vice versa.

Pooled analysis of two randomized, double-blind trials comparing proposed biosimilar LA-EP2006 with reference pegfilgrastim in breast cancer.

BACKGROUND: Following the functional and physicochemical characterization of a proposed biosimilar, comparative clinical studies help to confirm biosimilarity by demonstrating similar safety and efficacy to the reference product in a sensitive patient population. PATIENTS AND METHODS: LA-EP2006 is a proposed biosimilar that has been developed for pegfilgrastim, a long-acting form of granulocyte colony-stimulating factor for the prevention of neutropenia. The current analysis reports data pooled from two independent, multinational, prospective, randomized, controlled, double-blind phase III studies of similar design comparing the safety and efficacy of reference pegfilgrastim with LA-EP2006 in patients with breast cancer receiving myelotoxic (neo)adjuvant TAC (docetaxel, doxorubicin, and cyclophosphamide) chemotherapy and requiring granulocyte colony-stimulating factor. RESULTS: A total of 624 patients were randomized in the PROTECT-1 and PROTECT-2 studies (NCT01735175; NCT01516736) (LA-EP2006: n = 314; reference: n = 310). Baseline characteristics of patients were well balanced across treatment groups. The primary end point, mean duration of severe neutropenia in the first chemotherapy cycle was similar in both the LA-EP2006 and reference groups (1.05 ± 1.055 days versus 1.01 ± 0.958 days), with a treatment difference of - 0.04 days [95% confidence interval (CI): -0.19 to 0.11] that met the equivalence criteria (the 95% CI were within the defined margin of ±1 day). Secondary end points, such as the nadir of absolute neutrophil count and the incidence of febrile neutropenia, were also similar between LA-EP2006 and reference pegfilgrastim. The safety and tolerability profile of LA-EP2006 was similar to that observed with reference pegfilgrastim, and there were no reports of neutralizing antibodies. CONCLUSIONS: This pooled analysis confirms, as a part of totality of evidence approach, that the proposed biosimilar pegfilgrastim LA-EP2006 has a comparable efficacy and safety profile to reference pegfilgrastim in patients with breast cancer receiving TAC chemotherapy. CLINICAL TRIAL NUMBERS: NCT01735175 and NCT01516736.

Predictive modeling of the outcomes of chemotherapy-induced (febrile) neutropenia prophylaxis with biosimilar filgrastim (MONITOR-GCSF study).

BACKGROUND: Risk models of chemotherapy-induced (CIN) and febrile neutropenia (FN) have to date focused on determinants measured at the start of chemotherapy. We extended this static approach with a dynamic approach of CIN/FN risk modeling at the start of each cycle. DESIGN: We applied predictive modeling using multivariate logistic regression to identify determinants of CIN/FN episodes and related hospitalizations and chemotherapy disturbances (CIN/FN consequences) in analyses at the patient ('ever' during the whole period of chemotherapy) and cycle-level (during a given chemotherapy cycle). Statistical dependence of cycle data being 'nested' under patients was managed using generalized estimation equations. Predictive performance of each model was evaluated using bootstrapped c concordance statistics. RESULTS: Static patient-level risk models of 'ever' experiencing CIN/FN adverse events and consequences during a planned chemotherapy regimen included predictors related to history, risk factors, and prophylaxis initiation and intensity. Dynamic cycle-level risk models of experiencing CIN/FN adverse events and consequences in an upcoming cycle included predictors related to history, risk factors, and prophylaxis initiation and intensity; as well as prophylaxis duration, CIN/FN in prior cycle, and treatment center characteristics. CONCLUSIONS: These 'real-world evidence' models provide clinicians with the ability to anticipate CIN/FN adverse events and their consequences at the start of a chemotherapy line (static models); and, innovatively, to assess risk of CIN/FN adverse events and their consequences at the start of each cycle (dynamic models). This enables individualized patient treatment and is consistent with the EORTC recommendation to re-appraise CIN/FN risk at the start of each cycle. Prophylaxis intensity (under-, correctly-, or over-prophylacted relative to current EORTC guidelines) is a major determinant. Under-prophylaxis is clinically unsafe. Over-prophylaxis of patients administered chemotherapy with intermediate or low myelotoxicity levels may be beneficial, both in patients with and without risk factors, and must be validated in future studies.