Imfinzi Mechanism of Action

Pharmacology: Pharmacodynamics: Mechanism of action: Expression of programmed cell death ligand-1 (PD-L1) protein is an adaptive immune response that helps tumours evade detection and elimination by the immune system. PD-L1 expression can be induced by inflammatory signals (e.g., IFN-gamma) and can be expressed on both tumour cells and tumour-associated immune cells in tumour microenvironment. PD-L1 blocks T-cell function and activation through interaction with PD-1 and CD80 (B7.1). By binding to its receptors, PD-L1 reduces cytotoxic T-cell activity, proliferation, and cytokine production.
Durvalumab is a fully human, high affinity, immunoglobulin G1 kappa (IgG1κ) monoclonal antibody that blocks the interaction of PD-L1 with PD-1 and CD80 (B7.1). Durvalumab does not induce antibody dependent cell-mediated cytotoxicity (ADCC). Blockade of PD-L1/PD-1 and PD-L1/CD80 interactions enhances antitumour immune responses. These antitumour responses may result in tumour elimination.
The combination of tremelimumab, a CTLA-4 inhibitor and durvalumab, a PD-L1 inhibitor functions to enhance anti-tumour T-cell activation and function at multiple stages of the immune response resulting in improved anti-tumour responses. In murine syngeneic tumour models, dual blockade of PD-L1 and CTLA-4 resulted in enhanced anti-tumour activity.
In preclinical studies, PD-L1 blockade by durvalumab led to increased T-cell activation and decreased tumour size in xenograft mouse models of human melanoma and/or pancreatic cancer cells as well as mouse syngeneic colorectal cancer.
Clinical trials: Durvalumab doses of 10 mg/kg every 2 weeks or 1500 mg every 4 weeks were evaluated in NSCLC and ES-SCLC clinical studies. Based on the modelling and simulation of exposure, exposure-safety relationships and exposure-efficacy data comparisons, there are no anticipated clinically significant differences in efficacy and safety between durvalumab doses of 10 mg/kg every 2 weeks or 1500 mg every 4 weeks.
Non-small cell lung cancer (NSCLC): Randomised, placebo-controlled phase 3 study in patients with locally advanced, unresectable NSCLC after chemoradiation (PACIFIC study): The efficacy of IMFINZI was evaluated in the PACIFIC study, a randomised, double-blind, placebo-controlled, multicentre study in 713 patients with histologically or cytologically confirmed locally advanced, unresectable NSCLC. Patients had completed at least 2 cycles of definitive platinum-based chemotherapy with radiation therapy within 1 to 42 days prior to initiation of the study and had an ECOG performance status of 0 or 1. Ninety-two percent of patients had received a total dose of 54 to 66 Gy of radiation. The study excluded patients who had progressed following chemoradiation therapy, patients with prior exposure to any anti-PD-1 or anti-PD-L1 antibody, patients with active or prior documented autoimmune disease within 2 years of initiation of the study; a history of immunodeficiency; a history of severe immune-mediated adverse reactions; medical conditions that required systemic immunosuppression (except physiological dose of systemic corticosteroids); active tuberculosis or hepatitis B or C or HIV infection or patients receiving live attenuated vaccine within 30 days before or after the start of IMFINZI. Patients were randomised 2:1 to receive 10 mg/kg IMFINZI (n=476) or 10 mg/kg placebo (n=237) via intravenous infusion every 2 weeks for up to 12 months or until unacceptable toxicity or confirmed disease progression. Randomisation was stratified by gender, age (<65 years vs. ≥65 years) and smoking status (smoker vs. non- smoker). Patients with disease control at 12 months were given the option to be re-treated upon disease progression. Tumour assessments were conducted every 8 weeks for the first 12 months and then every 12 weeks thereafter.
Patients were enrolled regardless of their tumour PD-L1 expression level. Where available, archival tumour tissue specimens taken prior to chemoradiation therapy were retrospectively tested for PD-L1 expression on tumour cells (TC) using the VENTANA PD-L1 (SP263) IHC assay. Of the 713 patients randomised, 63% of patients provided a tissue sample of sufficient quality and quantity to determine PD-L1 expression and 37% were unknown.
The demographics and baseline disease characteristics were well balanced between study arms. Baseline demographics of the overall study population were as follows: male (70%), age ≥65 years (45%), white (69%), Asian (27%), other (4%), current smoker (16%), past-smoker (75%), and never smoker (9%), WHO/ECOG PS 0 (49%), WHO/ECOG PS 1 (51%). Disease characteristics were as follows: Stage IIIA (53%), Stage IIIB (45%), histological sub-groups of squamous (46%), non-squamous (54%). Of 451 patients with PD L1 expression available, 67% were TC ≥1% [PD-L1 TC 1-24% (32%), PD L1 TC ≥25% (35%)] and 33% were TC <1%.
The two primary endpoints of the study were progression-free survival (PFS) and overall survival (OS) of IMFINZI vs. placebo. Secondary efficacy endpoints included PFS at 12 months (PFS 12) and 18 months (PFS 18) from randomisation and Time from Randomisation to Second Progression (PFS2). PFS was assessed by Blinded Independent Central Review (BICR) according to RECIST 1.1.
The study demonstrated a statistically significant improvement in PFS in the IMFINZI-treated group compared with the placebo group [hazard ratio (HR) = 0.52 (95% CI: 0.42, 0.65), p < 0.0001]. The study demonstrated a statistically significant improvement in OS in the IMFINZI-treated group compared with the placebo group [HR = 0.68 (95% CI: 0.53, 0.87), p=0.00251].
In the 5 year follow-up analysis, with a median follow-up of 34.2 months, IMFINZI continued to demonstrate improved OS and PFS compared to placebo. The OS and PFS results from the primary analysis and the follow-up analysis are summarized in Table 1. Kaplan-Meier curves for OS and PFS from the 5 year follow-up analysis are presented in Figures 1 and 2. (See Table 1 and Figures 1 and 2.)


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The improvements in PFS and OS in favour of patients receiving IMFINZI compared to those receiving placebo were consistently observed in all predefined subgroups analysed, including ethnicity, age, gender, smoking history, EGFR mutation status and histology. ALK mutation status was not analysed in this study.
Post-hoc subgroup analysis by PD-L1 expression: Additional subgroup analyses were conducted to evaluate the efficacy by tumour PD-L1 expression (≥25%, 1-24%, ≥1%, <1%) and for patients whose PD-L1 status could not be established (PD-L1 unknown). PFS and OS results from the 5 year follow-up analysis are summarised in Figures 3 and 4. Overall the safety profile of durvalumab in PD-L1 TC ≥1% subgroup was consistent with the intent to treat population, as was the PD-L1 TC <1% subgroup. (See Figures 3 and 4.)


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Patient reported outcomes: Patient-reported symptoms, function and health-related quality of life (HRQoL) were collected using the EORTC QLQ-C30 and its lung cancer module (EORTC QLQ-LC13). The LC13 and C30 were assessed at baseline and every 4 weeks for the first 8 weeks, then every 8 weeks until completion of the treatment period or discontinuation of study drug due to toxicity or disease progression. Compliance was similar between the IMFINZI and placebo treatment groups (83% vs 85.1% overall of evaluable forms completed).
At baseline, no differences in patient reported symptoms, function or HRQoL were observed between IMFINZI and placebo groups. Throughout the duration of the study to week 48, there was no clinically meaningful difference between IMFINZI and placebo groups in symptoms, functioning and HRQoL (as assessed by a difference of greater than or equal to 10 points).
NSCLC-POSEIDON Study: POSEIDON was a study designed to evaluate the efficacy of IMFINZI with or without tremelimumab in combination with platinum-based chemotherapy. POSEIDON was a randomised, open-label, multicenter study in 1013 metastatic NSCLC patients with no sensitising epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) genomic tumour aberrations. Patients with histologically or cytologically documented metastatic NSCLC were eligible for enrolment. Patients had no prior chemotherapy or any other systemic therapy for metastatic NSCLC. Prior to randomisation, patients had tumour PD-L1 status confirmed by using the Ventana PD-L1 (SP263) assay. Patients had a World Health Organization (WHO)/Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 at enrolment.
The study excluded patients with active or prior documented autoimmune disease; active and/or untreated brain metastases; a history of immunodeficiency; administration of systemic immunosuppression within 14 days before the start of IMFINZI or tremelimumab, except physiological dose of systemic corticosteroids; active tuberculosis or hepatitis B or C or HIV infection; or patients receiving live attenuated vaccine within 30 days before or after the start of IMFINZI and/or tremelimumab (see Precautions).
Randomisation was stratified by tumour cells (TC) PD-L1 expression (TC ≥50% vs. TC <50%), disease stage (Stage IVA vs. Stage IVB, per the 8th edition of American Joint Committee on Cancer), and histology (non-squamous vs. squamous).
Patients were randomised 1:1:1 to receive: Arm 1: IMFINZI 1500 mg with tremelimumab 75 mg and platinum-based chemotherapy every 3 weeks for 4 cycles followed by, IMFINZI 1500 mg every 4 weeks as monotherapy. A fifth dose of tremelimumab 75 mg was given at Week 16 alongside IMFINZI dose 6; Arm 2: IMFINZI 1500 mg and platinum-based chemotherapy every 3 weeks for 4 cycles, followed by IMFINZI 1500 mg every 4 weeks as monotherapy; Arm 3: Platinum-based chemotherapy every 3 weeks for 4 cycles. Patients could receive 2 additional cycles (a total of 6 cycles post-randomisation), as clinically indicated, at the Investigator's discretion.
In the 3 treatment arms, patients received one of the following histology-based chemotherapy regimens: Non-squamous NSCLC: Pemetrexed 500 mg/m² with carboplatin AUC 5-6 or cisplatin 75 mg/m² every 3 weeks. Unless contraindicated by the investigator, pemetrexed maintenance could be given.
Squamous NSCLC: Gemcitabine 1000 or 1250 mg/m² on Days 1 and 8 with cisplatin 75 mg/m² or carboplatin AUC 5-6 on Day 1 every 3 weeks.
Non-squamous or squamous NSCLC: Nab-paclitaxel 100 mg/m² on Days 1, 8, and 15 with carboplatin AUC 5-6 on Day 1 every 3 weeks.
Tremelimumab was given up to a maximum of 5 doses unless there was disease progression or unacceptable toxicity. IMFINZI and histology-based pemetrexed maintenance therapy (when applicable) was continued until disease progression or unacceptable toxicity.
Tumour assessments were conducted at Week 6 and Week 12 from the date of randomisation, and then every 8 weeks until confirmed objective disease progression. Survival assessments were conducted every 2 months following treatment discontinuation.
The dual primary endpoints of the study were progression-free survival (PFS) and overall survival (OS) for IMFINZI + platinum-based chemotherapy vs. platinum-based chemotherapy alone. The key secondary endpoints of the study were PFS and OS for IMFINZI + tremelimumab + platinum-based chemotherapy and platinum-based chemotherapy alone. The secondary endpoints included objective response rate (ORR) and Duration of Response (DoR). PFS, ORR, and DoR, were assessed using Blinded Independent Central Review (BICR) according to RECIST v1.1.
The demographics and baseline disease characteristics were well-balanced between study arms. Baseline demographics of the overall study population were as follows: male (76.0%), age ≥65 years (47.1%), age ≥75 years (11.3%) median age 64 years (range: 27 to 87 years), White (55.9%), Asian (34.6%), Black or African American (2.0%), Other (7.6%), non-Hispanic or Latino (84.2%), current smoker or past-smoker (78.0%), WHO/ECOG PS 0 (33.4%), WHO/ECOG PS 1 (66.5%). Disease characteristics were as follows: Stage IVA (50.0%), Stage IVB (49.6%), histological sub-groups of squamous (36.9%), non-squamous (62.9%), brain metastases (10.5%), PD-L1 expression TC ≥50% (28.8%), PD-L1 expression TC <50% (71.1%).
The study showed a statistically significant improvement in OS with IMFINZI + tremelimumab + platinum-based chemotherapy vs. platinum-based chemotherapy. IMFINZI + tremelimumab + platinum-based chemotherapy showed a statistically significant improvement in PFS vs. platinum-based chemotherapy alone. The results are summarised as follows. (See Table 2 and Figures 5 and 6.)


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Figure 7 summarises efficacy results of OS by tumour PD-L1 expression in prespecified subgroup analyses. (See Figure 7.)


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Elderly population: A total of 75 patients aged ≥75 years were enrolled in the IMFINZI in combination with tremelimumab and chemotherapy (n=35) and platinum-based chemotherapy only (n=40) arms of the POSEIDON study. An exploratory HR of 1.05 (95% CI: 0.64, 1.71) for OS was observed for the IMFINZI in combination with tremelimumab and platinum-based chemotherapy vs. platinum-based chemotherapy within this study subgroup. Due to the exploratory nature of this subgroup analysis no definitive conclusions can be drawn, but caution is suggested when considering this regimen for elderly patients.
SCLC-CASPIAN Study: CASPIAN was a study designed to evaluate the efficacy of IMFINZI with or without tremelimumab in combination with etoposide and either carboplatin or cisplatin. CASPIAN was a randomized, open-label, multicenter study in 805 treatment naïve ES-SCLC patients with WHO/ECOG Performance status of 0 or 1, suitable to receive a platinum-based chemotherapy regimen as first-line treatment for SCLC, with life expectancy ≥12 weeks, at least one target lesion by RECIST 1.1 and adequate organ and bone marrow function. Patients with asymptomatic or treated brain metastases were eligible. The study excluded patients with a history of chest radiation therapy; a history of active primary immunodeficiency; autoimmune disorders including paraneoplastic syndrome (PNS); active or prior documented autoimmune or inflammatory disorders; use of systemic immunosuppressants within 14 days before the first dose of the treatment except physiological dose of systemic corticosteroids; active tuberculosis or hepatitis B or C or HIV infection; or patients receiving live attenuated vaccine within 30 days before or after the start of IMFINZI.
Randomisation was stratified by the planned platinum-based therapy in cycle 1 (carboplatin or cisplatin).
Patients were randomised 1:1:1 to receive: Arm 1: IMFINZI 1500 mg + tremelimumab 75 mg + etoposide and either carboplatin or cisplatin; Arm 2: IMFINZI 1500 mg + etoposide and either carboplatin or cisplatin; Arm 3: Either carboplatin (AUC 5 or 6 mg/mL/min) or cisplatin (75-80 mg/m²) on Day 1 and etoposide (80-100 mg/m²) intravenously on Days 1, 2, and 3 of each 21-day cycle for between 4-6 cycles.
For patients randomised to Arm 1 and 2, etoposide and either carboplatin or cisplatin was limited to 4 cycles on an every 3 week schedule subsequent to randomisation. IMFINZI monotherapy continued until disease progression or unacceptable toxicity. Administration of IMFINZI monotherapy was permitted beyond disease progression if the patient was clinically stable and deriving clinical benefit as determined by the investigator.
Patients randomised to Arm 3, were permitted to receive a total of up to 6 cycles of etoposide and either carboplatin or cisplatin. After completion of chemotherapy, prophylactic cranial irradiation (PCI) was permitted only in Arm 3 per investigator discretion.
Tumour assessments were conducted at Week 6 and Week 12 from the date of randomisation, and then every 8 weeks until confirmed objective disease progression. Survival assessments were conducted every 2 months following treatment discontinuation.
The primary endpoints of the study were OS of IMFINZI + chemotherapy (Arm 2) vs. chemotherapy alone (Arm 3) and IMFINZI + tremelimumab + chemotherapy (Arm 1) vs. chemotherapy alone (Arm 3). The key secondary endpoint was PFS. Other secondary endpoints were Objective Response Rate (ORR), OS and PFS landmarks and Patient-Reported Outcomes (PRO). PFS and ORR were assessed using Investigator assessments according to RECIST v1.1.
The demographics and baseline disease characteristics were well balanced between the two study arms (268 patients in Arm 2 and 269 patients in Arm 3). Baseline demographics of the overall study population were as follows: male (69.6%), age ≥65 years (39.6%), median age 63 years (range: 28 to 82 years), white (83.8%), Asian (14.5%), black or African American (0.9%), other (0.6%), non-Hispanic or Latino (96.1%), current or past-smoker (93.1%), never smoker (6.9%), WHO/ECOG PS 0 (35.2%), WHO/ECOG PS 1 (64.8%), Stage IV 90.3%, 24.6% of the patients received cisplatin and 74.1% of the patients received carboplatin. In Arm 3, 56.8% of the patients received 6 cycles of etoposide + platinum and 7.8% of the patients received PCI.
At a planned interim (primary) analysis the study demonstrated a statistically significant improvement in OS with IMFINZI + etoposide + platinum (Arm 2) vs. etoposide + platinum alone (Arm 3) [HR=0.73 (95% CI: 0.591, 0.909), p=0.0047]. IMFINZI + etoposide + platinum demonstrated an improvement in PFS vs. etoposide + platinum alone [HR=0.78 (95% CI: 0.645, 0.936).
The PFS, ORR and DoR results from the planned final analysis (DCO: 27 Jan 2020) are summarized in Table 3. Kaplan-Meier curve for PFS is presented in Figure 9.
The OS results with the planned long-term OS follow-up analysis (DCO: 22 March 2021) (median follow-up: 39.3 months) are presented in Table 3. IMFINZI + etoposide + platinum (Arm 2) vs. etoposide + platinum (Arm 3) continued to demonstrate sustained improvement in OS. Kaplan-Meier curves for OS is presented in Figure 8. (See Table 3 and Figures 8 and 9.)


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Subgroup analysis: The improvements in OS in favor of patients receiving IMFINZI + chemotherapy compared to those receiving chemotherapy alone, were consistently observed across the prespecified subgroups based on demographics, geographical region, carboplatin or cisplatin use and disease characteristics.
BTC-TOPAZ-1 Study: TOPAZ-1 was a study designed to evaluate the efficacy of IMFINZI in combination with gemcitabine and cisplatin. TOPAZ-1 was a randomised, double-blind, placebo-controlled, multicentre study in 685 patients with unresectable or metastatic BTC (including intrahepatic and extrahepatic cholangiocarcinoma and gallbladder carcinoma) and ECOG Performance status of 0 or 1. Patients had not received previous therapy in the advanced/unresectable setting. Patients who developed recurrent disease > 6 months after surgery and/or completion of adjuvant therapy were included. Patients must have had an adequate organ and bone marrow function, and have had acceptable serum bilirubin levels (≤2.0 x the upper limit of normal (ULN)), and any clinically significant biliary obstruction had to be resolved before randomisation.
The study excluded patients with ampullary carcinoma, with brain metastases, active or prior documented autoimmune or inflammatory disorders, HIV infection or active infections, including tuberculosis or hepatitis C or patients with current or prior use of immunosuppressive medication within 14 days before the first dose of IMFINZI. Patients with active HBV were allowed to participate if they were on antiviral therapy.
Randomisation was stratified by disease status (initially unresectable vs. recurrent) and primary tumour location (intrahepatic cholangiocarcinoma vs. extrahepatic cholangiocarcinoma vs. gallbladder carcinoma).
Patients were randomised 1:1 to receive: Arm 1: IMFINZI 1500 mg administered on Day 1 + gemcitabine 1000 mg/m² and cisplatin 25 mg/m² (each administered on Days 1 and 8) every 3 weeks (21 days) for up to 8 cycles, followed by IMFINZI 1500 mg every 4 weeks until disease progression or unacceptable toxicity, or; Arm 2: Placebo administered on Day 1 + gemcitabine 1000 mg/m² and cisplatin 25 mg/m² (each administered on Days 1 and 8) every 3 weeks (21 days) for up to 8 cycles, followed by placebo every 4 weeks until disease progression or unacceptable toxicity.
Tumour assessments were conducted every 6 weeks for the first 24 weeks after the date of randomisation, and then every 8 weeks until confirmed objective disease progression.
The primary endpoint of the study was OS, the key secondary endpoint was PFS. Other secondary endpoints were ORR, Duration of Response (DoR) and PRO. PFS, ORR and DoR were investigator-assessed according to RECIST v1.1.
The demographics and baseline disease characteristics were well balanced between the two study arms (341 patients in Arm 1 and 344 patients in Arm 2). Baseline demographics of the overall study population were as follows: male (50.4%), age <65 years (53.3%), white (37.2%), Asian (56.4%), Black or African American (2.0%), other (4.2%), non-Hispanic or Latino (93.1%), ECOG PS 0 (49.1%), vs. PS 1 (50.9%), primary tumour location (intrahepatic bile duct 55.9%, extrahepatic bile duct 19.1% and gallbladder 25.0%), disease status [recurrent (19.1%) vs. unresectable (80.7%), metastatic (86.0%) vs. locally advanced (13.9%)]. PD-L1 expression was evaluated on tumour and immune cells using the Ventana PD-L1 (SP263) assay and the TAP (tumour area positivity) algorithm, 58.7% patients had TAP ≥1% and 30.1% TAP <1%.
OS and PFS were formally tested at a pre-planned interim analysis (data cut-off 11 Aug 2021) after a median follow-up of 9.8 months. Efficacy results are shown in Table 4 and Figure 10. The maturity for OS was 62% and the maturity for PFS was 84%. IMFINZI + chemotherapy (Arm 1) showed statistically significant improvement vs. placebo + chemotherapy (Arm 2) in OS and in PFS. (See Table 4.)


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An additional planned follow-up analysis of OS (data cut-off 25 Feb 2022) was performed 6.5 months after the interim analysis with an OS maturity of 77%. IMFINZI + chemotherapy continued to demonstrate improved OS vs. chemotherapy alone [HR=0.76, (95% CI: 0.64, 0.91)] and the medium follow-up increased to 12 months. (See Figures 10 and 11.)


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HCC-HIMALAYA Study: The efficacy of IMFINZI given in combination with a single dose of tremelimumab 300 mg was evaluated in the HIMALAYA Study, a randomised, open-label, multicentre study in patients with confirmed uHCC who did not receive prior systemic treatment for HCC. The study included patients with Barcelona Clinic Liver Cancer (BCLC) Stage C or B (not eligible for locoregional therapy) and Child-Pugh Score Class A.
The study excluded patients with brain metastases or a history of brain metastases, co-infection of viral hepatitis B and hepatitis C; active or prior documented gastrointestinal (GI) bleeding within 12 months; ascites requiring non-pharmacologic intervention within 6 months; hepatic encephalopathy within 12 months before the start of treatment; active or prior documented autoimmune or inflammatory disorders.
Patients with oesophageal varices were included except those with active or prior documented GI bleeding within 12 months prior to study entry.
Randomisation was stratified by macrovascular invasion (MVI) (yes vs. no), aetiology of liver disease (confirmed hepatitis B virus vs. confirmed hepatitis C virus vs. others) and ECOG performance status (0 vs. 1). The HIMALAYA study randomized 1171 patients 1:1:1 to receive: IMFINZI: durvalumab 1500 mg every 4 weeks; Tremelimumab 300 mg as a single dose + IMFINZI 1500 mg; followed by IMFINZI 1500 mg every 4 weeks; S: Sorafenib 400 mg twice daily.
Tumour assessments were conducted every 8 weeks for the first 12 months and then every 12 weeks thereafter. Survival assessments were conducted every month for the first 3 months following treatment discontinuation and then every 2 months.
The primary endpoint was OS. Secondary endpoints included PFS, Investigator-assessed ORR and DoR according to RECIST v1.1.
The demographics and baseline disease characteristics were well balanced between study arms. The baseline demographics of the overall study population were as follows: male (83.7%), age <65 years (50.4%) White (44.6%), Asian (50.7%), Black or African American (1.7%), Other race (2.3%), ECOG PS 0 (62.6%); Child-Pugh Class score A (99.5%), macrovascular invasion (25.2%), extrahepatic spread (53.4%), baseline AFP <400 ng/mL (63.7%), baseline AFP ≥ 400 ng/mL (34.5%), viral aetiology; hepatitis B (30.6%), hepatitis C (27.2%), uninfected (42.2%), evaluable PD-L1 data (86.3%), PD-L1 Tumour area positivity (TAP) ≥1% (38.9%), PD-L1 TAP <1% (48.3%) [Ventana PD-L1 (SP263) assay].
Results are presented in Table 5 and Figure 12. (See Table 5 and Figure 12.)


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Pharmacokinetics: The pharmacokinetics (PK) of durvalumab was assessed for IMFINZI as a single agent, in combination with chemotherapy, in combination with tremelimumab and platinum-based chemotherapy and in combination with tremelimumab.
The PK of durvalumab was studied in 2903 patients with solid tumours with doses ranging from 0.1 to 20 mg/kg administered intravenously once every two, three or four weeks as monotherapy. PK exposure increased more than dose-proportionally (non-linear PK) at doses <3 mg/kg, and dose proportionally (linear PK) at doses ≥3 mg/kg. Steady state was achieved at approximately 16 weeks. Based on population PK analysis that included 1878 patients who received durvalumab monotherapy in the dose range of ≥10 mg/kg every 2 weeks, the geometric mean steady state volume of distribution (V_ss) was 5.64 L. Durvalumab clearance (CL) decreased over time resulting in a geometric mean steady state clearance (CL_ss) of 8.16 mL/h at Day 365; the decrease in CLss was not considered clinically relevant. The terminal half-life (t_1/2), based on baseline CL, was approximately 18 days. There was no clinically meaningful difference between the PK of durvalumab as a single agent, in combination with chemotherapy, in combination with tremelimumab and platinum-based chemotherapy and in combination with tremelimumab. The primary elimination pathways of durvalumab are protein catabolism via reticuloendothelial system or target mediated disposition.
Special populations: Age (19-96 years), body weight (31-149 kg), gender, positive anti-drug antibody (ADA) status, albumin levels, LDH levels, creatinine levels, soluble PD-L1, tumour type, race or ECOG status had no clinically significant effect on the PK of durvalumab.
Renal impairment: Mild (creatinine clearance (CrCL) 60 to 89 mL/min) and moderate renal impairment (creatinine clearance (CrCL) 30 to 59 mL/min) had no clinically significant effect on the PK of durvalumab. The effect of severe renal impairment (CrCL 15 to 29 mL/min) on the PK of durvalumab is unknown; however, as IgG monoclonal antibodies are not primarily cleared via renal pathways, a change in renal function is not expected to influence durvalumab exposure.
Hepatic impairment: Mild hepatic impairment (bilirubin ≤ULN and AST >ULN or bilirubin >1.0 to 1.5 x ULN and any AST) or moderate hepatic impairment (bilirubin >1.5 to 3 x ULN and any AST) had no clinically significant effect on the PK of durvalumab. The effect of severe hepatic impairment (bilirubin >3.0 x ULN and any AST) on the pharmacokinetics of durvalumab is unknown; however, as IgG monoclonal antibodies are not primarily cleared via hepatic pathways, a change in hepatic function is not expected to influence durvalumab exposure.
Toxicology: Preclinical safety data: Genotoxicity: The genotoxic potential of durvalumab has not been evaluated. As a large protein molecule, durvalumab is not expected to interact directly with DNA or other chromosomal material.
Carcinogenicity: The carcinogenic potential of durvalumab has not been evaluated.