Model-informed approach for risk management of bleeding toxicities for bintrafusp alfa, a bifunctional fusion protein targeting TGF-β and PD-L1

Bintrafusp Alfa for Recurrent or Metastatic Cervical Cancer After Platinum Failure: A Nonrandomized Controlled Trial

Importance

Cervical cancer is a common and lethal cancer worldwide. Bintrafusp alfa is a first-in-class bifunctional fusion protein composed of the extracellular domain of the human transforming growth factor β receptor II (or transforming growth factor β trap) fused via a flexible linker to the C-terminus of each heavy chain of an immunoglobulin G1 antibody blocking programmed cell death 1 ligand 1.

Objective

To evaluate the safety and response rates of bintrafusp alfa in patients with recurrent or metastatic cervical cancer.

Design, Setting, and Participants

This phase 2 nonrandomized controlled trial evaluated bintrafusp alfa monotherapy in patients with recurrent or metastatic cervical cancer with disease progression during or after platinum-based chemotherapy. Data were collected from March 2020 to February 2022.

Intervention

Patients received bintrafusp alfa, 1200 mg, intravenously once every 2 weeks.

Main Outcomes and Measures

The primary end point was confirmed objective response rate per Response Evaluation Criteria in Solid Tumors version 1.1 by an independent review committee.

Results

At data cutoff, 146 of 203 screened patients received 1 or more doses of bintrafusp alfa; of these, the median (range) age was 53 (24-79) years. The study met its primary end point of a 95% CI above the objective response rate benchmark of 15%, with a confirmed objective response rate of 21.9% (95% CI, 15.5-29.5) per the independent review committee. Of these patients, 19 (59.4%) had a durable response of 6 months or more. At data cutoff, responses were ongoing in 13 of 32 responders (40.6%). The most common treatment-related adverse events were anemia (25 [17.1%]), rash (21 [14.4%]), hypothyroidism (15 [10.3%]), and pruritus (15 [10.3%]). Any-cause adverse events of special interest included anemia (82[56.2%]), bleeding events (81 [55.5%]), and immune-related adverse events (49 [33.6%]).

Conclusions and Relevance

This phase 2 nonrandomized controlled trial of bintrafusp alfa met its primary end point, which may support the potential of a bispecific therapy targeting transforming growth factor β and programmed cell death 1 ligand 1 in patients with recurrent or metastatic cervical cancer.

Trial Registration

ClinicalTrials.gov Identifier: NCT04246489.

Transforming growth factor-β receptors: versatile mechanisms of ligand activation

Transforming growth factor-β (TGF-β) signaling is initiated by activation of transmembrane TGF-β receptors (TGFBR), which deploys Smad2/3 transcription factors to control cellular responses. Failure or dysregulation in the TGF-β signaling pathways leads to pathological conditions. TGF-β signaling is regulated at different levels along the pathways and begins with the liberation of TGF-β ligand from its latent form. The mechanisms of TGFBR activation display selectivity to cell types, agonists, and TGF-β isoforms, enabling precise control of TGF-β signals. In addition, the cell surface compartments used to release active TGF-β are surprisingly vibrant, using thrombospondins, integrins, matrix metalloproteinases and reactive oxygen species. The scope of TGFBR activation is further unfolded with the discovery of TGFBR activation initiated by other signaling pathways. The unique combination of mechanisms works in series to trigger TGFBR activation, which can be explored as therapeutic targets. This comprehensive review provides valuable insights into the diverse mechanisms underpinning TGFBR activation, shedding light on potential avenues for therapeutic exploration.

Safety, pharmacokinetics, pharmacodynamics, and antitumor activity of SAR439459, a TGFβ inhibitor, as monotherapy and in combination with cemiplimab in patients with advanced solid tumors: Findings from a phase 1/1b study

SAR439459 (SAR'459), a "second-generation" human anti-transforming growth factor beta (TGFβ) monoclonal antibody, enhances the activity of immune checkpoint inhibitors. In this phase I/Ib study, we evaluated the safety, pharmacokinetics (PK), pharmacodynamics, and antitumor activity of SAR'459 ± cemiplimab (intravenous) in patients with advanced solid tumors. Increasing doses of SAR'459 were administered every 2 or 3 weeks (Q2W, Q3W) alone (Part 1A) or with 3 mg/kg cemiplimab Q2W or 350 mg Q3W (Part 1B). In Part 2A (dose expansion), melanoma patients were randomly (1:1) administered 22.5 or 7.5 mg/kg SAR'459. In Part 2B (dose expansion), 22.5 mg/kg SAR'459 and 350 mg cemiplimab Q3W were administered. The primary end points were maximum tolerated dose (MTD) or maximum administered dose (MAD; Part 1), preliminary antitumor activity (Part 2B), and optimal monotherapy dose (Part 2A). Twenty-eight and 24 patients were treated in Parts 1A and 1B, respectively; MTD was not reached, MAD was 15 (Q2W) and 22.5 mg/kg (Q3W) alone and in combination, respectively. Fourteen and 95 patients, including 14 hepatocellular carcinoma (HCC) patients, were treated in Parts 2A and 2B, respectively. The population PK model yielded satisfactory goodness-of-fit plots and adequately described the observed data by a two-compartment PK model with linear elimination. Objective responses were not observed in Parts 1 and 2A. In Part 2B, objective response rate was 8.4% and 7.1% across tumor types and the HCC cohort, respectively. The most frequent treatment-emergent adverse effects were hemorrhagic events (43.5%), keratoacanthoma (6.8%), and skin neoplasms (6.2%). Fatal bleeding occurred in 21.4% HCC patients despite the implementation of mitigation measures. SAR'459 monotherapy and combination with cemiplimab appeared relatively safe and tolerable in limited number of patients in dose escalation. However, the study was discontinued due to the unclear efficacy of SAR'459 and bleeding risk, particularly in HCC patients.

First-in-human study of GFH018, a small molecule inhibitor of transforming growth factor-β receptor I inhibitor, in patients with advanced solid tumors

BACKGROUND

Transforming growth factor-β (TGF-β) is a cytokine with multiple functions, including cell growth regulation, extracellular matrix production, angiogenesis homeostasis adjustment and et al. TGF-β pathway activation promotes tumor metastasis/progression and mediates epithelial-mesenchymal transmission suppressing immunosurveillance in advanced tumors. GFH018, a small molecule inhibitor blocking TGF-β signal transduction, inhibits the progression and/or metastasis of advanced cancers. This first-in-human study evaluated the safety, tolerability, pharmacokinetics (PK), and efficacy of GFH018 monotherapy in patients with advanced solid tumors.

METHODS

This phase I, open-label, multicenter study used a modified 3+3 dose escalation and expansion design. Adult patients with advanced solid tumors failing the standard of care were enrolled. Starting at 5 mg, eight dose levels up to 85 mg were evaluated. Patients received GFH018 BID (14d-on/14d-off) starting on the 4th day after a single dose on cycle 1, day 1. Subsequent cycles were defined as 28 days. The study also explored the safety of 85 mg BID 7d-on/7d-off. Adverse events were graded using NCI criteria for adverse events (NCI-CTCAE v5.0). PK was analyzed using a noncompartmental method. Efficacy was evaluated using RECIST 1.1. Blood samples were collected for biomarker analysis.

RESULTS

Fifty patients were enrolled and received at least one dose of GFH018. No dose-limiting toxicity occurred, and the maximum tolerated dose was not reached. Forty-three patients (86.0%) had at least one treatment-related adverse event (TRAE), and three patients (6.0%) had ≥ G3 TRAEs. The most common TRAEs (any grade/grade ≥3) were AST increased (18%/0%), proteinuria (14%/2%), anemia (14%/2%), and ALT increased (12%/0%). No significant cardiotoxicity or bleeding was observed. GFH018 PK was linear and dose-independent, with a mean half-life of 2.25-8.60 h from 5 - 85 mg. Nine patients (18.0%) achieved stable disease, and one patient with thymic carcinoma achieved tumor shrinkage, with the maximum target lesion decreased by 18.4%. Serum TGF-β1 levels were not associated with clinical responses. The comprehensive recommended dose for Phase II was defined as 85 mg BID 14d-on/14d-off.

CONCLUSIONS

GFH018 monotherapy presented a favorable safety profile without cardiac toxicity or bleeding. Modest efficacy warrants further studies, including combination strategies.

TRIAL REGISTRATION

ClinicalTrial. gov ( https://www.

CLINICALTRIALS

gov/ ), NCT05051241. Registered on 2021-09-02.

Phase I Trial of First-line Bintrafusp Alfa in Patients with Locally Advanced or Persistent/Recurrent/Metastatic Cervical Cancer

PURPOSE

Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of TGFβ receptor II (a TGFβ "trap") fused to a human IgG1 mAb blocking programmed death-ligand 1 (PD-L1), was evaluated as treatment in patients with locally advanced or persistent, recurrent, or metastatic (P/R/M) cervical cancer.

PATIENTS AND METHODS

In this multicenter, open-label, phase Ib trial (NCT04551950), patients with P/R/M cervical cancer received bintrafusp alfa 2,400 mg once every 3 weeks plus cisplatin or carboplatin plus paclitaxel with (Cohort 1A; n = 8) or without (Cohort 1B; n = 9) bevacizumab; patients with locally advanced cervical cancer received bintrafusp alfa 2,400 mg every 3 weeks plus cisplatin plus radiation, followed by bintrafusp alfa monotherapy maintenance (Cohort 2; n = 8). The primary endpoint was safety; secondary endpoints included efficacy (including objective response rate) and pharmacokinetics.

RESULTS

At the data cutoff of April 27, 2022, patients in Cohorts 1A, 1B, and 2 had received bintrafusp alfa for a median duration of 37.9, 31.1, and 16.7 weeks, respectively. Two dose-limiting toxicities (grade 4 amylase elevation and grade 3 menorrhagia) unrelated to bintrafusp alfa were observed in Cohort 1B and none in other cohorts. Most treatment-emergent adverse events of special interest were grades 1-2 in severity, most commonly anemia (62.5%-77.8%) and bleeding events (62.5%-77.8%). Objective response rate was 75.0% [95% confidence interval (CI), 34.9-96.8], 44.4% (95% CI, 13.7-78.8), and 62.5% (95% CI, 24.5-91.5) in Cohorts 1A, 1B, and 2, respectively.

CONCLUSIONS

Bintrafusp alfa had manageable safety and demonstrated clinical activity, further supporting the investigation of TGFβ/PD-L1 inhibition in human papillomavirus-associated cancers, including cervical cancer.

Tumor growth inhibition modeling in patients with second line biliary tract cancer and first line non-small cell lung cancer based on bintrafusp alfa trials

This analysis aimed to quantify tumor dynamics in patients receiving either bintrafusp alfa (BA) or pembrolizumab, by population pharmacokinetic (PK)-pharmacodynamic modeling, and investigate clinical and molecular covariates describing the variability in tumor dynamics by pharmacometric and machine-learning (ML) approaches. Data originated from two clinical trials in patients with biliary tract cancer (BTC; NCT03833661) receiving BA and non-small cell lung cancer (NSCLC; NCT03631706) receiving BA or pembrolizumab. Individual drug exposure was estimated from previously developed population PK models. Population tumor dynamics models were developed for each drug-indication combination, and covariate evaluations performed using nonlinear mixed-effects modeling (NLME) and ML (elastic net and random forest models) approaches. The three tumor dynamics' model structures all included linear tumor growth components and exponential tumor shrinkage. The final BTC model included the effect of drug exposure (area under the curve) and several covariates (demographics, disease-related, and genetic mutations). Drug exposure was not significant in either of the NSCLC models, which included two, disease-related, covariates in the BA arm, and none in the pembrolizumab arm. The covariates identified by univariable NLME and ML highly overlapped in BTC but showed less agreement in NSCLC analyses. Hyperprogression could be identified by higher tumor growth and lower tumor kill rates and could not be related to BA exposure. Tumor size over time was quantitatively characterized in two tumor types and under two treatments. Factors potentially related to tumor dynamics were assessed using NLME and ML approaches; however, their net impact on tumor size was considered as not clinically relevant.

Bintrafusp Alfa Versus Pembrolizumab in Patients With Treatment-Naive, Programmed Death-Ligand 1-High Advanced NSCLC: A Randomized, Open-Label, Phase 3 Trial

INTRODUCTION

Bintrafusp alfa, a first-in-class bifunctional fusion protein composed of the extracellular domain of TGF-βRII (a TGF-β "trap") fused to a human immunoglobulin G1 monoclonal antibody blocking programmed death-ligand 1 (PD-L1), has exhibited clinical activity in a phase 1 expansion cohort of patients with PD-L1-high advanced NSCLC.

METHODS

This adaptive phase 3 trial (NCT03631706) compared the efficacy and safety of bintrafusp alfa versus pembrolizumab as first-line treatment in patients with PD-L1-high advanced NSCLC. Primary end points were progression-free survival according to Response Evaluation Criteria in Solid Tumors version 1.1 per independent review committee and overall survival.

RESULTS

Patients (N = 304) were randomized one-to-one to receive either bintrafusp alfa or pembrolizumab (n = 152 each). The median follow-up was 14.3 months (95% confidence interval [CI]: 13.1-16.0 mo) for bintrafusp alfa and 14.5 months (95% CI: 13.1-15.9 mo) for pembrolizumab. Progression-free survival by independent review committee was not significantly different between bintrafusp alfa and pembrolizumab arms (median = 7.0 mo [95% CI: 4.2 mo-not reached (NR)] versus 11.1 mo [95% CI: 8.1 mo-NR]; hazard ratio = 1.232 [95% CI: 0.885-1.714]). The median overall survival was 21.1 months (95% CI: 21.1 mo-NR) for bintrafusp alfa and 22.1 months (95% CI: 20.4 mo-NR) for pembrolizumab (hazard ratio = 1.201 [95% CI: 0.796-1.811]). Treatment-related adverse events were higher with bintrafusp alfa versus pembrolizumab; grade 3-4 treatment-related adverse events occurred in 42.4% versus 13.2% of patients, respectively. The study was discontinued at an interim analysis as it was unlikely to meet the primary end point.

CONCLUSIONS

First-line treatment with bintrafusp alfa did not exhibit superior efficacy compared with pembrolizumab in patients with PD-L1-high, advanced NSCLC.

A multistate modeling and simulation framework to learn dose-response of oncology drugs: Application to bintrafusp alfa in non-small cell lung cancer

The dose/exposure-efficacy analyses are often conducted separately for oncology end points like best overall response, progression-free survival (PFS) and overall survival (OS). Multistate models offer to bridge these dose-end point relationships by describing transitions and transition times from enrollment to response, progression, and death, and evaluating transition-specific dose effects. This study aims to apply the multistate pharmacometric modeling and simulation framework in a dose optimization setting of bintrafusp alfa, a fusion protein targeting TGF-β and PD-L1. A multistate model with six states (stable disease [SD], response, progression, unknown, dropout, and death) was developed to describe the totality of endpoints data (time to response, PFS, and OS) of 80 patients with non-small cell lung cancer receiving 500 or 1200 mg of bintrafusp alfa. Besides dose, evaluated predictor of transitions include time, demographics, premedication, disease factors, individual clearance derived from a pharmacokinetic model, and tumor dynamic metrics observed or derived from tumor size model. We found that probabilities of progression and death upon progression decreased over time since enrollment. Patients with metastasis at baseline had a higher probability to progress than patients without metastasis had. Despite dose failed to be statistically significant for any individual transition, the combined effect quantified through a model with dose-specific transition estimates was still informative. Simulations predicted a 69.2% probability of at least 1 month longer, and, 55.6% probability of at least 2-months longer median OS from the 1200 mg compared to the 500 mg dose, supporting the selection of 1200 mg for future studies.