Phase 3 Study of Subcutaneous Versus Intravenous Ravulizumab in Eculizumab-Experienced Adult Patients with PNH: Primary Analysis and 1-Year Follow-Up.

INTRODUCTION: This study compared the pharmacokinetics (PK) of the ravulizumab on-body delivery system for subcutaneous (SUBQ) administration with intravenous (IV) ravulizumab in eculizumab-experienced patients with paroxysmal nocturnal hemoglobinuria (PNH). METHODS: Patients with PNH received SUBQ ravulizumab (n = 90) or IV ravulizumab (n = 46) during the 10-week randomized treatment period; all patients then received SUBQ ravulizumab during an extension period (< 172 weeks; data cutoff 1 year). Primary endpoint was day 71 serum ravulizumab trough concentration (Ctrough). Secondary endpoints were ravulizumab Ctrough and free C5 over time. Efficacy endpoints included change in lactate dehydrogenase (LDH), breakthrough hemolysis (BTH), transfusion avoidance, stabilized hemoglobin, and Treatment Administration Satisfaction Questionnaire (TASQ) score. Safety, including adverse events (AEs) and adverse device effects (ADEs), was assessed until data cutoff. RESULTS: SUBQ ravulizumab demonstrated PK non-inferiority with IV ravulizumab (day 71 SUBQ/IV geometric least-squares means ratio 1.257 [90% confidence interval 1.160-1.361; p < 0.0001]). Through 1 year of SUBQ administration, ravulizumab Ctrough values were > 175 µg/mL (PK threshold) and free C5 < 0.5 µg/mL (PD threshold). Efficacy endpoints remained stable: mean (standard deviation, SD) LDH percentage change was 0.9% (20.5%); BTH events, 5/128 patients (3.9%); 83.6% achieved transfusion avoidance; 79.7% achieved stabilized hemoglobin. Total TASQ score showed improved satisfaction with SUBQ ravulizumab compared with IV eculizumab (mean [SD] change at SUBQ day 351, - 69.3 [80.1]). The most common AEs during SUBQ treatment (excluding ADEs) were headache (14.1%), COVID-19 (14.1%), and pyrexia (10.9%); the most common ADE unrelated to a device product issue was injection site reaction (4.7%). Although many patients had ≥ 1 device issue-related ADE, full SUBQ dose administration was achieved in 99.9% of attempts. CONCLUSIONS: SUBQ ravulizumab provides an additional treatment choice for patients with PNH. Patients may switch to SUBQ ravulizumab from IV eculizumab or ravulizumab without loss of efficacy. TRIAL REGISTRATION: NCT03748823.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder characterized by the destruction of red blood cells (hemolysis) within blood vessels. In addition to hemolysis, patients with PNH are susceptible to life-threatening blood clots (thromboses). Eculizumab and ravulizumab are types of treatments for PNH, called C5 inhibitors. In the blood, these treatments bind to C5 protein and prevent the destruction of red blood cells, reducing the symptoms and complications of PNH. Both treatments are approved for use via intravenous (through the vein) administration. Ravulizumab is also approved in the USA for use via subcutaneous (under the skin) administration. This study compared subcutaneous ravulizumab with intravenous ravulizumab in patients with PNH who had previously been treated with eculizumab. During the initial treatment period of 71 days, 90 patients received subcutaneous ravulizumab and 46 received intravenous ravulizumab. Following this period, all patients received subcutaneous ravulizumab. At day 71, the amount of ravulizumab in the blood of patients taking subcutaneous ravulizumab was no less than in patients taking intravenous ravulizumab and was maintained over 1 year of treatment. Efficacy measures (how well it works) remained stable in patients taking subcutaneous ravulizumab for 1 year and side effects were comparable with those of intravenous ravulizumab. Patients reported more satisfaction with subcutaneous ravulizumab than intravenous eculizumab, as assessed by the Treatment Administration Satisfaction Questionnaire. This study showed that patients with PNH can switch from intravenous eculizumab or ravulizumab to subcutaneous ravulizumab without loss of efficacy. Subcutaneous ravulizumab provides an additional treatment choice for patients with PNH.

Low Rate of Clinically Evident Extravascular Hemolysis in Patients with Paroxysmal Nocturnal Hemoglobinuria Treated with a Complement C5 Inhibitor: Results from a Large, Multicenter, US Real-World Study.

Purpose: Most patients with paroxysmal nocturnal hemoglobinuria (PNH) treated with a complement protein 5 (C5) inhibitor achieve full control of terminal complement activity and intravascular hemolysis. The minority remains anemic and transfusion dependent despite this control. Etiology for ongoing anemia is multifactorial and includes bone marrow failure, breakthrough hemolysis, extravascular hemolysis (EVH) and nutritional deficiencies. Patients and Methods: To evaluate the potential etiologies of hemoglobin levels <10 g/dL despite receiving C5 inhibitor therapy, we performed a retrospective US chart review of adult patients with PNH and treated for at least 12 months with eculizumab (n=53), ravulizumab (n=32), or eculizumab followed by ravulizumab (n=15). Clinically evident EVH was defined as at least one transfusion, reticulocyte count ≥120×109/L and hemoglobin level ≤9.5 g/dL. Safety data were not collected. Mean treatment duration was 26.5±17.2 months. Results: Treatment with C5 inhibitors significantly improved hemoglobin, lactate dehydrogenase, and number of transfusions versus baseline. Among the patients with hemoglobin <10 g/dL during the last 6 months of treatment (n=38), one patient (eculizumab) had clinically evident EVH, and 10 patients had active concomitant bone marrow failure. Bone marrow failure was a major contributor to hemoglobin <10 g/dL and transfusion dependence; clinically evident EVH was uncommon. Conclusion: A range of hematologic causes need to be considered when evaluating anemia in the presence of treatment with a C5 inhibitor.

Composite endpoint to evaluate complement inhibition therapy in patients with paroxysmal nocturnal hemoglobinuria.

This study developed and explored a novel composite endpoint to assess the overall impact that treatment can have on patients living with paroxysmal nocturnal hemoglobinuria (PNH). Candidate composite endpoint variables were selected by a group of experts and included: lactate dehydrogenase levels as a measure of intravascular hemolysis; complete terminal complement inhibition; absence of major adverse vascular events, including thrombosis; absence of any adverse events leading to death or discontinuation of study treatment; transfusion avoidance; and improvements in fatigue-related quality of life as determined by the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue score. From these variables, a novel composite endpoint was constructed and explored using data collected in the ravulizumab PNH Study 301 (NCT02946463). Thresholds were defined and reported for each candidate variable. Five of the six candidate variables were included in the final composite endpoint; the FACIT-Fatigue score was excluded. Composite endpoint criterion was defined as patients meeting all five selected individual component thresholds. All patients in the ravulizumab arm achieved complete terminal complement inhibition and a reduction in lactate dehydrogenase levels; 51.2% and 41.3% of patients in the ravulizumab arm and eculizumab arm, respectively, achieved all composite endpoint component thresholds (treatment difference: 9.4%; 95% confidence interval: -3.0, 21.5). The composite endpoint provided a single and simultaneous measurement of overall benefit for patients receiving treatment for PNH. Use of the composite endpoint in future PNH research is recommended to determine clinical benefit, and its use in health technology assessments should be evaluated.

Cost burden of breakthrough hemolysis in patients with paroxysmal nocturnal hemoglobinuria receiving ravulizumab versus eculizumab.

Objectives: Although complement inhibition is highly effective, patients with paroxysmal nocturnal hemoglobinuria (PNH) may experience intravascular breakthrough hemolysis (BTH). Underlying causes may include elevated free C5, pregnancy, or non-pregnancy complement-activating conditions (e.g. infections). This study compared BTH-related resource utilization and costs in PNH patients treated with eculizumab versus ravulizumab. Methods: A cost model was developed using data from a targeted literature review and a survey of experienced clinicians. Costs associated with BTH episodes were calculated by cause and weighted by the proportion attributed to each cause and the cost of treating each episode. The model captured direct medical costs in 2018 US dollars. Annual BTH-related healthcare resource utilization was also calculated. Results: BTH episodes in the literature were commonly associated with elevated lactate dehydrogenase and aspartate aminotransferase, hemoglobinuria, transfusion needs, and/or recurrence of PNH symptoms. The majority of BTH management costs in eculizumab-treated patients related to changing from the approved dosing regimen following an episode of BTH, rather than acute management. No ongoing dosing changes were expected for ravulizumab-treated patients following episodes of BTH, substantially reducing its ongoing management costs. Resource utilization was greater for eculizumab-treated patients than ravulizumab-treated patients due to higher incidence of BTH, and risk of elevated free C5-related BTH. Total incremental cost was substantially lower for ravulizumab- vs eculizumab-treated patients ($407 vs $9379); results were consistent when pregnant women were not included ($386 vs $3472). Conclusion: Overall resource use and costs for BTH are estimated to be lower for PNH patients receiving ravulizumab compared with eculizumab.

The mammalian-membrane two-hybrid assay (MaMTH) for probing membrane-protein interactions in human cells.

Cell signaling, one of key processes in both normal cellular function and disease, is coordinated by numerous interactions between membrane proteins that change in response to stimuli. We present a split ubiquitin-based method for detection of integral membrane protein-protein interactions (PPIs) in human cells, termed mammalian-membrane two-hybrid assay (MaMTH). We show that this technology detects stimulus (hormone or agonist)-dependent and phosphorylation-dependent PPIs. MaMTH can detect changes in PPIs conferred by mutations such as those in oncogenic ErbB receptor variants or by treatment with drugs such as the tyrosine kinase inhibitor erlotinib. Using MaMTH as a screening assay, we identified CRKII as an interactor of oncogenic EGFR(L858R) and showed that CRKII promotes persistent activation of aberrant signaling in non-small cell lung cancer cells. MaMTH is a powerful tool for investigating the dynamic interactomes of human integral membrane proteins.

c-MET as a potential therapeutic target and biomarker in cancer.

The receptor tyrosine kinase c-MET and its ligand, hepatocyte growth factor (HGF), regulate multiple cellular processes that stimulate cell proliferation, invasion and angiogenesis. This review provides an overview of the evidence to support c-MET or the HGF/c-MET signaling pathway as relevant targets for personalized cancer treatment based on high frequencies of c-MET and/or HGF overexpression, activation, amplification in non-small cell lung carcinoma (NSCLC), gastric, ovarian, pancreatic, thyroid, breast, head and neck, colon and kidney carcinomas. Additionally, the current knowledge of small molecule inhibitors (tivantinib [ARQ 197]), c-MET/HGF antibodies (rilotumumab and MetMAb) and mechanisms of resistance to c-MET-targeted therapies are discussed.

MET and KRAS gene amplification mediates acquired resistance to MET tyrosine kinase inhibitors.

The establishment of the role of MET in human cancer has led to the development of small-molecule inhibitors, many of which are currently in clinical trials. Thus far, nothing is known about their therapeutic efficacy and the possible emergence of resistance to treatment, a problem that has been often observed with other receptor tyrosine kinase (RTK) inhibitors. To predict mechanisms of acquired resistance, we generated resistant cells by treating MET-addicted cells with increasing concentrations of the MET small-molecule inhibitors PHA-665752 or JNJ38877605. Resistant cells displayed MET gene amplification, leading to increased expression and constitutive phosphorylation of MET, followed by subsequent amplification and overexpression of wild-type (wt) KRAS. Cells harboring KRAS amplification progressively lost their MET dependence and acquired KRAS dependence. Our results suggest that MET and KRAS amplification is a general mechanism of resistance to specific MET inhibitors given that similar results were observed with two small inhibitors and in different cell lines of different histotypes. To our knowledge, this is the first report showing that overexpression of wt KRAS can overcome the inhibitory effect of a RTK inhibitor. In view of the fact that cellular models of resistance to inhibitors targeting other tyrosine kinases have predicted and corroborated clinical findings, our results provide insights into strategies for preventing and/or overcoming drug resistance.

Activation of HER family members in gastric carcinoma cells mediates resistance to MET inhibition.

BACKGROUND: Gastric cancer is the second leading cause of cancer mortality in the world. The receptor tyrosine kinase MET is constitutively activated in many gastric cancers and its expression is strictly required for survival of some gastric cancer cells. Thus, MET is considered a good candidate for targeted therapeutic intervention in this type of tumor, and MET inhibitors recently entered clinical trials. One of the major problems of therapies targeting tyrosine kinases is that many tumors are not responsive to treatment or eventually develop resistance to the drugs. Perspective studies are thus mandatory to identify the molecular mechanisms that could cause resistance to these therapies. RESULTS: Our in vitro and in vivo results demonstrate that, in MET-addicted gastric cancer cells, the activation of HER (Human Epidermal Receptor) family members induces resistance to MET silencing or inhibition by PHA-665752 (a selective kinase inhibitor). We provide molecular evidences highlighting the role of EGFR, HER3, and downstream signaling pathways common to MET and HER family in resistance to MET inhibitors. Moreover, we show that an in vitro generated gastric cancer cell line resistant to MET-inhibition displays overexpression of HER family members, whose activation contributes to maintenance of resistance. CONCLUSIONS: Our findings predict that gastric cancer tumors bearing constitutive activation of HER family members are poorly responsive to MET inhibition, even if this receptor is constitutively active. Moreover, the appearance of these alterations might also be responsible for the onset of resistance in initially responsive tumors.

Molecular mechanisms of acquired resistance to tyrosine kinase targeted therapy.

In recent years, tyrosine kinases (TKs) have been recognized as central players and regulators of cancer cell proliferation, apoptosis, and angiogenesis, and are therefore considered suitable potential targets for anti-cancer therapies. Several strategies for targeting TKs have been developed, the most successful being monoclonal antibodies and small molecule tyrosine kinase inhibitors. However, increasing evidence of acquired resistance to these drugs has been documented, and extensive preclinical studies are ongoing to try to understand the molecular mechanisms by which cancer cells are able to bypass their inhibitory activity.This review intends to present the most recently identified molecular mechanisms that mediate acquired resistance to tyrosine kinase inhibitors, identified through the use of in vitro models or the analysis of patient samples. The knowledge obtained from these studies will help to design better therapies that prevent and overcome resistance to treatment in cancer patients.