MVX-ONCO-1 in advanced refractory cancers: Safety, feasibility, and preliminary efficacy results from all HNSCC patients treated in two ongoing clinical trials

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Background: MVX-ONCO-1 is an active, personalized cancer immunotherapy combining irradiated autologous tumor cells and encapsulated, genetically engineered allogeneic cells producing GM-CSF. The immunostimulant cytokine is released locally in a sustained manner over one week at the immunization site. All cancer types are potential candidates and more than 40 patients have been treated in two clinical trials. Here we report the data on all HNSCC patients treated, as of 31st January 2021. Methods: Eleven (11) patients with locally advanced/metastatic HNSCC relapsing after at least one line of systemic therapy were enrolled in 2 open-label, single-arm clinical trials (NCT02193503 and NCT02999646) evaluating the safety, feasibility and efficacy of MVX-ONCO-1. All patients were treated with at least 5 administrations of MVX-ONCO-1 over 8 weeks (W1,2,3,4,6,8). Each administration consists of the subcutaneous implantation in healthy skin of 2 capsules containing each 8x105 cells, producing > 20ng/24h of GM-CSF, and an injection of 4x106 irradiated autologous tumor cells between the 2 capsules. Results: Eleven (11) patients are evaluable for safety and feasibility. Ten patients (91%) with at least 6 months, respectively 9 patients (82%) with 12 months follow-up are evaluable for efficacy analysis. Eight patients (80%) failed both Cisplatin based chemotherapy and anti-PD1 therapies prior to enrolment. The most common treatment-related adverse event (AE) was local hematoma at implantation site in 3 patients (27%). None experienced > grade 2 treatment-related AE. Overall Survival is 70% (7/10pts) at 6 months, and 56% (5/9pts) at 12 months. Eight patients (80%) presented some degree of disease control with 4SDs, 2PRs and 2CRs. Both CRs are longstanding, with both patients not any longer on anticancer therapy for 24 and 6 months respectively. While 1 PR was observed on MVX-ONCO-1, 1PR and 1CR were observed on subsequent Nivolumab therapy (both CPS0), and 1 CR was observed after carboplatin-cetuximab. Two patients had progressive disease as best overall response. Conclusions: Treatment with MVX-ONCO-1 is feasible, safe and well tolerated. Preliminary efficacy data shows an encouraging rate of tumor control including prolonged CR in patients subsequently treated with nivolumab or chemotherapy. Efficacy of the concurrent use of anti-PD-1 and MVX-ONCO will be assessed in a planned clinical trial. Clinical trial information: NCT02999646.

[The Onco-hematology clinical research unit at the Geneva University Hospital: example of a fruitful public-private partners]

A better understanding of the molecular deregulation leading to carcinogenesis allows the development of numerous novel targeted therapeutic candidates. Clinical research in oncology is a critical step to evaluate in a thorough manner the safety and efficacy of these innovative compounds. During the last four years the fruitful partnership between the Geneva University Hospitals and the Dr. Henri Dubois-Ferriere Dinu Lipatti Foundation lead to a dedicated clinical research unit for cancer patients with a staff of ten people. Since 2010, more than 300 patients were enrolled in more than 70 distinct clinical trials evaluating novel therapies for both solid tumors and hematologic malignancies. Interestingly, classical cytostatic drugs now represent only a small fraction of the new anti-cancer therapies in the pipeline.

The paraoxonase-1 pathway is not a major bioactivation pathway of clopidogrel in vitro

BACKGROUND AND PURPOSE

Clopidogrel is a prodrug bioactivated by cytochrome P450s (CYPs). More recently, paraoxonase-1 (PON1) has been proposed as a major contributor to clopidogrel metabolism. The purpose of this study was to assess the relative contribution of CYPs and PON1 to clopidogrel metabolism in vitro.

EXPERIMENTAL APPROACH

Clopidogrel metabolism was studied in human serum, recombinant PON1 enzyme (rePON1), pooled human liver microsomes (HLMs), HLMs with the CYP2C19*1/*1 genotype and HLMs with the CYP2C19*2/*2 genotype. Inhibition studies were also performed using specific CYP inhibitors and antibodies. Clopidogrel and its metabolites were measured using LC/MS/MS method.

KEY RESULTS

PON1 activity was highest in the human serum and there was no difference in PON1 activity between any of the HLM groups. The production of clopidogrel's active metabolite (clopidogrel-AM) from 2-oxo-clopidogrel in pooled HLMs was approximately 500 times that in serum. When 2-oxo-clopidogrel was incubated with rePON1, clopidogrel-AM was not detected. Clopidogrel-AM production from 2-oxo-clopidogrel was lower in CYP2C19*2/*2 HLMs compared with CYP2C19*1/*1 HLMs, while PON1 activity in HLMs with both genotypes was similar. Moreover, incubation with inhibitors of CYP3A, CYP2B6 and CYP2C19 significantly reduced clopidogrel bioactivation while a PON1 inhibitor, EDTA, had only a weak inhibitory effect.

CONCLUSION AND IMPLICATIONS

This in vitro study shows that the contribution of PON1 to clopidogrel metabolism is limited at clinically relevant concentrations. Moreover, CYP2C19, CYP2B6 and CYP3A play important roles in the bioactivation of clopidogrel.

Pharmacokinetic interaction between prasugrel and ritonavir in healthy volunteers

The new anti-aggregating agent prasugrel is bioactivated by cytochromes P450 (CYP) 3A and 2B6. Ritonavir is a potent CYP3A inhibitor and was shown in vitro as a CYP2B6 inhibitor. The aim of this open-label cross-over study was to assess the effect of ritonavir on prasugrel active metabolite (prasugrel AM) pharmacokinetics in healthy volunteers. Ten healthy male volunteers received 10 mg prasugrel. After at least a week washout, they received 100 mg ritonavir, followed by 10 mg prasugrel 2 hr later. We used dried blood spot sampling method to monitor prasugrel AM pharmacokinetics (C_max, t_1/2, t_max, AUC_{0–6 hr}) at 0, 0.25, 0.5, 1, 1.5, 2, 4 and 6 hr after prasugrel administration. A ‘cocktail’ approach was used to measure CYP2B6, 2C9, 2C19 and 3A activities. In the presence of ritonavir, prasugrel AM C_max and AUC were decreased by 45% (mean ratio: 0.55, CI 90%: 0.40–0.7, p = 0.007) and 38% (mean ratio: 0.62, CI 90%: 0.54–0.7, p = 0.005), respectively, while t_1/2 and t_max were not affected. Midazolam metabolic ratio (MR) dramatically decreased in presence of ritonavir (6.7 ± 2.6 versus 0.13 ± 0.07) reflecting an almost complete inhibition of CYP3A4, whereas omeprazole, flurbiprofen and bupropion MR were not affected. These data demonstrate that ritonavir is able to block prasugrel CYP3A4 bioactivation. This CYP-mediated drug–drug interaction might lead to a significant reduction of prasugrel efficacy in HIV-infected patients with acute coronary syndrome.

Ritonavir inhibits the two main prasugrel bioactivation pathways in vitro: a potential drug-drug interaction in HIV patients

Prasugrel is an antiplatelet prodrug used in patients with acute coronary syndrome. Prasugrel is mainly bioactivated by cytochromes P450 3A4/5 and CYP2B6. HIV patients are at risk of cardiovascular disease, and the protease inhibitor ritonavir is a potent inhibitor of these 2 CYPs. The aim of this in vitro study was to determine the impact of ritonavir in prasugrel metabolism. Human liver microsomes (HLMs) and recombinant microsomes were used to identify the enzymes responsible for the bioactivation of prasugrel. Prasugrel concentrations of 5 to 200 μM were used for Km determination. Inhibition by ritonavir was characterized using HLMs at concentrations of 0.1 to 30 μM. Prasugrel active metabolite determination was performed with a validated liquid chromatography-mass spectrometry method. Using recombinant microsomes, prasugrel biotransformation was mainly performed by CYP2B6, CYP2D6, CYP2C19, CYP3A4, and CYP3A5. With specific inhibitors of CYP3A, CYP2B6, CYP2D6, CYP2C9, and CYP2C19, active metabolite production was decreased by 38% ± 15% with 4-(4-chlorobenzyl)pyridine (CYP2B6 inhibitor) and by 45 ± 16% with ketoconazole (CYP3A inhibitor). The Km value for prasugrel metabolism in HLMs was determined to be 92.5 μM. Ritonavir at 0.1 to 30 μM was shown to be a potent dose-dependent inhibitor of prasugrel. In this in-vitro study, we found a potent inhibition of prasugrel bioactivation by ritonavir compared to the specific inhibitors of CYP3A and CYP2B6 due to the simultaneous inhibition of CYP2B6 and CYP3A by ritonavir. This finding suggests a potential significant drug-drug interaction between these two drugs.