Chrystelle Brignone

A Phase I Pharmacokinetic and Biological Correlative Study of IMP321, a Novel MHC Class II Agonist, in Patients with Advanced Renal Cell Carcinoma

Purpose: To evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of IMP321, a recombinant soluble LAG-3Ig fusion protein which agonizes MHC class II–driven dendritic cell activation. Experimental Design: Patients with advanced renal cell carcinoma were treated with escalating doses of IMP321 s.c. Blood samples were assayed to determine plasma pharmacokinetic parameters, detect human anti-IMP321 antibody formation, and determine long-lived CD8 T cell responses. Results: Twenty-one advanced renal cell carcinoma patients received 119 injections of IMP321 at doses ranging from 0.050 to 30 mg/injection s.c. biweekly for 6 injections. No clinically significant adverse events were observed. Good systemic exposure to the product was obtained following s.c. injections of doses above 6 mg. IMP321 induced both sustained CD8 T-cell activation and an increase in the percentage of long-lived effector-memory CD8 T cells in all patients at doses above 6 mg. Tumor growth was reduced and progression-free survival was better in those patients receiving higher doses (>6 mg) of IMP321: 7 of 8 evaluable patients treated at the higher doses experienced stable disease at 3 months compared with only 3 of 11 in the lower dose group (P = 0.015). Conclusion: The absence of toxicity and the demonstration of activity at doses above 6 mg warrant further disease-directed studies of IMP321 in combined regimens (e.g., chemoimmunotherapy). (Clin Cancer Res 2009;15(19):6225–31)

First-line chemoimmunotherapy in metastatic breast carcinoma: combination of paclitaxel and IMP321 (LAG-3Ig) enhances immune responses and antitumor activity

BackgroundIMP321 is a recombinant soluble LAG-3Ig fusion protein that binds to MHC class II with high avidity and mediates APC and then antigen-experienced memory CD8+ T cell activation. We report clinical and biological results of a phase I/II in patients with metastatic breast carcinoma (MBC) receiving first-line paclitaxel weekly, 3 weeks out of 4.MethodsMBC patients were administered one dose of IMP321 s.c. every two weeks for a total of 24 weeks (12 injections). The repeated single doses were administered the day after chemotherapy at D2 and D16 of the 28-day cycles of paclitaxel (80 mg/m2 at D1, D8 and D15, for 6 cycles). Blood samples were taken 13 days after the sixth and the twelfth IMP321 injections to determine sustained APC, NK and memory CD8 T cell responses.ResultsThirty MBC patients received IMP321 in three cohorts (doses: 0.25, 1.25 and 6.25 mg). IMP321 induced both a sustained increase in the number and activation of APC (monocytes and dendritic cells) and an increase in the percentage of NK and long-lived cytotoxic effector-memory CD8 T cells. Clinical benefit was observed for 90% of patients with only 3 progressors at 6 months. Also, the objective tumor response rate of 50% compared favorably to the 25% rate reported in the historical control group.ConclusionsThe absence of toxicity and the demonstration of activity strongly support the future development of this agent for clinical use in combined first-line regimens.Trial registrationClinicalTrials.gov NCT00349934

MHC Class II Engagement by Its Ligand LAG-3 (CD223) Contributes to Melanoma Resistance to Apoptosis

Melanoma is the most aggressive skin cancer in humans that often expresses MHC class II (MHC II) molecules, which could make these tumors eliminable by the immune system. However, this MHC II expression has been associated with poor prognosis, and there is a lack of immune-mediated eradication. The lymphocyte activation gene-3 (LAG-3) is a natural ligand for MHC II that is substantially expressed on melanoma-infiltrating T cells including those endowed with potent immune-suppressive activity. Based on our previous data showing the signaling capacity of MHC II in melanoma cells, we hypothesized that LAG-3 could contribute to melanoma survival through its MHC II signaling capacity in melanoma cells. In this study, we demonstrate that both soluble LAG-3 and LAG-3–transfected cells can protect MHC II-positive melanoma cells, but not MHC II-negative cells, from FAS-mediated and drug-induced apoptosis. Interaction of LAG-3 with MHC II expressed on melanoma cells upregulates both MAPK/Erk and PI3K/Akt pathways, albeit with different kinetics. Inhibition studies using specific inhibitors of both pathways provided evidence of their involvement in the LAG-3–induced protection from apoptosis. Altogether, our data suggest that the LAG-3–MHC II interaction could be viewed as a bidirectional immune escape pathway in melanoma, with direct consequences shared by both melanoma and immune cells. In the future, compounds that efficiently hinder LAG-3–MHC II interaction might be used as an adjuvant to current therapy for MHC II-positive melanoma.

A soluble form of lymphocyte activation gene-3 (IMP321) induces activation of a large range of human effector cytotoxic cells

The principal antitumor immune response is mediated through the activation of type 1 cytotoxic (Tc1) CD8 T cells, NK cells, and monocytes/macrophages. In this study, we investigated the potency of a clinical-grade soluble form of lymphocyte activation gene-3 protein (IMP321), a physiological high-affinity MHC class II binder, at inducing in PBMCs an appropriate cytotoxic-type response in short-term ex vivo assays. We found that IMP321 binds to a minority (<10%) of MHC class II + cells in PBMCs, including all myeloid dendritic cells, and a small fraction of monocytes. Four hours after addition of IMP321 to PBMCs, these myeloid cells produce TNF-α and CCL4 as determined by intracellular staining. At 18 h, 1% of CD8+ T cells and 3.7% NK cells produce Tc1 cytokines such as IFN-γ and/or TNF-α (mean values from 60 blood donors). Similar induction was observed in metastatic cancer patient PBMCs, but the values were lower for the NK cell subset. Early APC activation by IMP321 is needed for this Tc1-type activation because pure sorted CD8+ T cells could not be activated by IMP321. Only Ag-experienced, fully differentiated granzyme+ CD8 T cells (effector and effector memory but not naive or central memory T cells) are induced by IMP321 to full Tc1 activation. In contrast to IMP321, TLR1-9 agonists induce IL-10 and are therefore unable to induce this Tc1 IFN-γ+ response. Thus, IMP321 has many properties that confirm its potential to be a new class of immunopotentiator in cancer patients.

IMP321 (sLAG-3), an immunopotentiator for T cell responses against a HBsAg antigen in healthy adults: a single blind randomised controlled phase I study

BackgroundLAG-3 (CD223) is a natural high affinity ligand for MHC class II. The soluble form (sLAG-3) induces maturation of monocyte-derived dendritic cells in vitro and is used as a potent Th1-like immune enhancer with many antigens in animal models. To extend this observation to human, a proof of concept study was conducted with a clinical-grade sLAG-3, termed IMP321, coinjected with alum-non-absorbed recombinant hepatitis B surface antigen.MethodsIn a randomised, single blind controlled phase I dose escalation study, 48 seronegative healthy volunteers aged 18–55 years were vaccinated at 0, 4 and 8 weeks by subcutaneous injection with 10 μg HBsAg mixed with saline (control) or with IMP321 at one of four doses (3, 10, 30 and 100 μg). To evaluate the efficacy of this three injections over 2 months immunization protocol, an additional control group was injected with the commercial vaccine Engerix-B®.ResultsIMP321 was very well tolerated. Indeed, a lower incidence of adverse events was reported from the HBsAg plus IMP321 groups than from the Engerix-B® group. HBsAg-specific antibody responses (anti-HBs) appeared sooner and were higher at 8 and 12 weeks in IMP321 recipients compared to HBsAg control subjects. More importantly, increased numbers of responders to HBsAg were found in IMP321 recipients compared HBsAg group, as revealed by higher post-vaccination frequencies of CD4 Th1 or CD8 Tc1 antigen specific T cells. IMP321 induced CD4 Th1 antigen-specific T cells in some of these naïve individuals after only one injection, especially in the 10 and 30 μg dose groups.ConclusionIMP321 as an adjuvant to HBsAg was well-tolerated and enhanced T cell response vaccine immunogenicity (i.e. induced both CD4 Th1 and CD8 Tc1 antigen-specific T cells). This latter property has allowed the development of IMP321 as an immunopotentiator for therapeutic vaccines.