Pharmacology: Mechanism of Action: CTLA-4 is a negative regulator of T-cell activity. Tremelimumab is a monoclonal antibody that binds to CTLA-4 and blocks the interaction with its ligands CD80 and CD86, releasing CTLA-4-mediated inhibition of T-cell activation. In synergistic mouse tumor models, blocking CTLA-4 activity resulted in decreased tumor growth and increased proliferation of T cells in tumors.
Immunogenicity: The observed incidence of anti-drug antibodies (ADA) is highly dependent on the sensitivity and specificity of the assay. Differences in assay methods preclude meaningful comparisons of the incidence of ADA in the studies described as follows with the incidence of ADA in other studies, including those of tremelimumab.
In the HIMALAYA study, of the 182 patients who were treated with a single dose of tremelimumab in combination with durvalumab once in every 4 weeks therapy and evaluable for the presence of ADAs against tremelimumab at predose week 0 and week 4, 11% (20/182) of patients tested positive for anti-tremelimumab antibodies. Among the 20 patients who tested positive for ADAs 40% (8/20) tested positive for neutralizing antibodies against tremelimumab. There was no identified clinically significant effect of anti-tremelimumab antibodies on the pharmacokinetics or safety of tremelimumab; however, the effect of ADAs and neutralizing antibodies on the effectiveness of tremelimumab is unknown.
In the POSEIDON study, of the 278 ADA-evaluable patients who were treated with IMJUDO 75 mg for up to five doses in combination with durvalumab 1,500 mg and platinum-based chemotherapy every 3 weeks and evaluated for presence of ADAs against tremelimumab at pre-dose week 0, week 3, and week 12, 14% (38/278) of patients tested positive for anti-tremelimumab antibodies. Among the 38 patients who tested positive for ADAs, 82% (31/38) tested positive for neutralizing antibodies against tremelimumab. There was no identified clinically significant effect of anti-tremelimumab antibodies on pharmacokinetics or safety of tremelimumab, however, the effect of ADAs on effectiveness of tremelimumab is unknown.
Pharmacodynamics: The exposure-response relationship and time course of pharmacodynamic response for the safety and effectiveness of tremelimumab have not been fully characterized.
Clinical Studies: Hepatocellular Carcinoma (HCC): Unresectable HCC - HIMALAYA: The efficacy of IMJUDO in combination with durvalumab was evaluated in the HIMALAYA study (NCT03298451), a randomized (1:1:1), open-label, multicenter study in patients with confirmed uHCC who had not received prior systemic treatment for HCC. Patients were randomized to one of two investigational arms (IMJUDO plus durvalumab or durvalumab) or sorafenib. Study treatment consisted of IMJUDO as a one-time single intravenous infusion of 300 mg in combination with durvalumab 1,500 mg on the same day, followed by durvalumab every 4 weeks; durvalumab 1,500 mg every 4 weeks; or sorafenib 400 mg given orally twice daily, until disease progression or unacceptable toxicity. The efficacy assessment of IMJUDO is based on patients randomized to the IMJUDO plus durvalumab arm versus the sorafenib arm. Randomization was stratified by macrovascular invasion (MVI) (yes or no), etiology of liver disease (hepatitis B virus vs. hepatitis C virus vs. others) and ECOG performance status (0 vs. 1).
The study enrolled patients with BCLC Stage C or B (not eligible for locoregional therapy). The study excluded patients with 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. Esophagogastroduodenoscopy was not mandated prior to enrollment but adequate endoscopic therapy, according to institutional standards, was required for patients with a history of esophageal variceal bleeding or those assessed as high risk for esophageal variceal bleeding by the treating physician.
Study treatment was permitted beyond disease progression if the patient was clinically stable and was deriving clinical benefit as determined by the investigator.
The major efficacy outcome measure was overall survival (OS) between the IMJUDO plus durvalumab arm versus the sorafenib arm. Additional efficacy outcomes were investigator-assessed progression-free survival (PFS), objective response rate (ORR) and duration of response (DoR) according to RECIST v1.1. Tumor assessments were conducted every 8 weeks for the first 12 months and then every 12 weeks thereafter.
The baseline demographics of the IMJUDO plus durvalumab and sorafenib arms were as follows: male (85%), age < 65 years (50%), median age of 65 years (range: 18 to 88 years), White (46%), Asian (49%), Black or African American (2%), Native Hawaiian or other Pacific Islander (0.1%), race Unknown (2%), Hispanic or Latino (5%), Not Hispanic or Latino (94%), ethnicity Unknown (1%), ECOG PS 0 (62%); Child-Pugh Class score A (99%), macrovascular invasion (26%), extrahepatic spread (53%), viral etiology hepatitis B (31%), hepatitis C (27%), uninfected (42%).
Efficacy results are presented in Table 1 and Figure 1. (See Table 1 and Figure 1.)
Click on icon to see table/diagram/image
Click on icon to see table/diagram/image
Metastatic NSCLC: Metastatic NSCLC - POSEIDON: The efficacy of IMJUDO in combination with durvalumab and platinum-based chemotherapy in previously untreated metastatic NSCLC patients with no sensitizing epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) genomic tumor aberrations was investigated in POSEIDON, a randomized, multicenter, active-controlled, open-label trial (NCT03164616). Eligible patients had Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 and must have had no prior chemotherapy or any other systemic therapy for metastatic NSCLC. Choice of platinum-based chemotherapy was at the Investigator's discretion, taking into consideration the calculated creatinine clearance. Patients with active and/or untreated brain metastases; a history of active primary immunodeficiency; autoimmune disorders including 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 were ineligible.
Randomization was stratified by tumor cells (TC) PD-L1 expression (TC ≥ 50% vs. TC < 50%), disease stage (Stage IVA vs. Stage IVB), and histology (non-squamous vs. squamous).
Patients were randomized 1:1:1 to receive IMJUDO in combination with durvalumab and platinum-based chemotherapy according to the regimens listed as follows, durvalumab and platinum-based chemotherapy (an unapproved regimen for metastatic NSCLC), or platinum-based chemotherapy. The evaluation of efficacy for metastatic NSCLC relied on comparison between: [1] IMJUDO 75 mg (or 1 mg/kg for patients < 30 kg) with durvalumab 1,500 mg and platinum-based chemotherapy every 3 weeks for 4 cycles, followed by durvalumab 1,500 mg every 4 weeks as a single agent. A fifth dose of IMJUDO 75 mg (or 1 mg/kg for patients < 30 kg) was given at Week 16 in combination with durvalumab dose 6.
[2] Platinum-based chemotherapy every 3 weeks as monotherapy for 4 cycles. Patients could receive an additional 2 cycles (a total of 6 cycles post-randomization), as clinically indicated, at Investigator's discretion.
Patients received IMJUDO and durvalumab in combination with one of the following platinum-based chemotherapy regimens: [1] Non-squamous NSCLC: Pemetrexed 500 mg/m
2 with carboplatin AUC 5-6 or cisplatin 75 mg/m
2 every 3 weeks for 4 cycles.
[2] Squamous NSCLC: Gemcitabine 1,000 or 1,250 mg/m
2 on Days 1 and 8 with cisplatin 75 mg/m
2 or carboplatin AUC 5-6 on Day 1 every 3 weeks for 4 cycles.
[3] Non-squamous and Squamous NSCLC: Nab-paclitaxel 100 mg/m
2 on Days 1, 8, and 15 with carboplatin AUC 5-6 on Day 1 every 3 weeks for 4 cycles.
IMJUDO was given up to a maximum of 5 doses. Durvalumab and histology-based pemetrexed continued every 4 weeks until disease progression or unacceptable toxicity. Administration of durvalumab monotherapy was permitted beyond disease progression if the patient was clinically stable and deriving clinical benefit as determined by the Investigator. Patients with disease progression during durvalumab monotherapy were given the option to be retreated with 4 additional cycles of IMJUDO in combination with durvalumab. Tumor assessments were performed at Week 6, Week 12, and then every 8 weeks thereafter.
The major efficacy outcome measures were progression free survival (PFS) and overall survival (OS) of IMJUDO and durvalumab in combination with platinum-based chemotherapy compared to platinum-based chemotherapy alone. Additional efficacy outcome measures were overall 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.
A total of 675 patients were randomized to receive either IMJUDO with durvalumab and platinum-based chemotherapy (n=338) or platinum-based chemotherapy (n=337). The median age was 63 years (range: 27 to 87), 46% of patients age ≥ 65 years, 77% male, 57% White, 34% Asian, 0.3% Native Hawaiian or Other Pacific Islander, 3% American Indian or Alaska Native, 2% Black or African American, 4% Other Race, 79% former or current smoker, 34% ECOG PS 0, and 66% ECOG PS 1. Thirty-six percent had squamous histology, 63% non-squamous histology, 29% PD-L1 expression TC ≥ 50%, 71% PD-L1 expression TC < 50%.
Efficacy results are summarized in Table 2 and Figure 2. (See Table 2 and Figure 2.)
Click on icon to see table/diagram/image
Click on icon to see table/diagram/image
Pharmacokinetics: The pharmacokinetics of tremelimumab was studied in patients with other solid tumors following administration of doses 1 mg/kg, 3 mg/kg, and 10 mg/kg (1- to 10-times the approved recommended dosage) administered once every 4 weeks for 4 doses. The pharmacokinetics of tremelimumab as a single dose of 300 mg were evaluated in patients with HCC.
The AUC of tremelimumab increased proportionally from 1 mg/kg to 10 mg/kg every 4 weeks (1 to 10-times the approved recommended dosage) and steady state was achieved at approximately 12 weeks.
Distribution: The geometric mean (% coefficient of variation [CV%]) of tremelimumab for central (V1) and peripheral (V2) volume of distribution was 3.45 (24%) and 2.66 (34%) L, respectively.
Elimination: The geometric mean (CV%) terminal half-life of tremelimumab was 16.9 days (19%) after a single dose and 18.2 days (19%) during steady state. The geometric mean (CV%) clearance of tremelimumab was 0.286 L/day (32%) after a single dose and 0.263 L/day (32%) during steady state.
Specific Populations: There were no clinically significant differences in the pharmacokinetics of tremelimumab based on body weight (34 to 149 kg), age (18 to 87 years), sex, race (White, Black, Asian, Native Hawaiian, Pacific Islander, or American Indian), serum albumin levels (0.3 to 396 g/L), lactate dehydrogenase levels (12 to 5570 U/L), soluble PD-L1 (67 to 349 pg/mL), tumor type (NSCLC, HCC), organ dysfunction including mild to moderate renal impairment (CLcr 30 to 89 mL/min), and mild to moderate hepatic impairment (bilirubin < 3 x ULN and any AST).
The effect of severe renal impairment (CLcr 15 to 29 mL/min) or severe hepatic impairment (bilirubin > 3 x ULN and any AST) on the pharmacokinetics of tremelimumab is unknown.
Toxicology: Nonclinical Toxicology: Carcinogenesis, Mutagenesis, Impairment of Fertility: The carcinogenic and genotoxic potential of tremelimumab have not been evaluated.
Animal fertility studies have not been conducted with tremelimumab.