First-in-Human, Multicenter Phase I Study of IPH4102, First-in-Class Humanized Anti-KIR3DL2 Monoclonal Antibody, in Relapsed/Refractory Cutaneous T-Cell Lymphomas: Preliminary Safety, Exploratory and Clinical Activity Results

KIR3DL2 is expressed in all subtypes of cutaneous T-cell lymphomas (CTCL), irrespective of clinical stage, with the highest prevalence of expression in Sézary syndrome (SS) and transformed mycosis fungoides (MF), two subgroups of patients with a high unmet need for clinically impactful therapies.

KIR3DL2 belongs to the killer immunoglobulin-like receptor (KIRs) family and is expressed on minor subpopulations of normal NK, CD8 and CD4 T cells.

IPH4102 is a first-in-class anti-KIR3DL2 monoclonal antibody (mAb). It selectively depletes KIR3DL2-expressing cells by recruiting immune effectors. Its main modes of action include antibody-dependent cell-cytotoxicity (ADCC) and -phagocytosis (ADCP). IPH4102 has shown potent efficacy in preclinical models, in particular ex vivo autologous assays using primary CTCL cells.

IPH4102 is currently being investigated in a first-in-human dose-finding phase 1 study (NCT02593045) evaluating repeated administrations of single-agent IPH4102 in relapsed/refractory CTCL patients.

The primary objective is to assess the safety and tolerability of increasing doses of IPH4102. Secondary objectives include PK, immunogenicity and signals of anti-tumor clinical activity. Exploratory biomarkers aim to characterize KIR3DL2-expressing and non-expressing cells in involved tissue/disease compartments and to monitor changes during IPH4102 treatment. Minimal residual disease (MRD) is measured in the skin, blood and/or lymph nodes. Assessment of ex vivo NK cell-mediated ADCC against autologous tumor cells is also performed pre-dose on SS patient samples.

The study has two sequential portions, a dose-escalation followed by a cohort expansion. The dose-escalation portion has a 3+3 design with accelerated titration and aims to determine the maximal tolerated dose (MTD) or recommended phase 2 dose (RP2D). In the cohort expansion portion, two CTCL subtype-specific cohorts will be studied, each to include 10 additional patients to further explore MTD or RP2D.

Eligible CTCL patients must have received at least 2 lines of anti-neoplastic systemic therapy. Centrally assessed KIR3DL2 expression on malignant cells in skin or blood is required for inclusion.

Patients receive IPH4102 administrations until progression or unacceptable toxicity. Intra-patient dose-escalation is allowed, only past the first complete clinical assessment at week 5 and provided the upper next dose-level is declared safe by the safety committee.

Enrollment into study IPH4102-101 started in November 2015 and is currently ongoing. At time of abstract submission, dose-levels #1 to #6 have been completed.

A total of 13 patients have been treated at these 6 dose-levels and are evaluable for safety and clinical activity. These patients comprise 10 SS (including 1 with evidence of large-cell transformation), 2 MF and 1 "not-otherwise-specified" CD4⁺ CTCL. Median age is 71 years (range 50 - 90). For these 13 patients, only grade 1 or 2 related adverse events (AEs) have been reported with IPH4102 treatment. No patient experienced a DLT or a related AE of grade ≥3. No IPH4102-related skin rashes or infections have been observed so far.

Results of immuno-phenotyping of patients' blood lymphocytes show consistency of local and central assessments. In addition, ex vivo functional assay results confirm that SS patients' NK cells are functional and able to kill autologous tumor cells through ADCC with IPH4102.

Our preliminary data from the phase 1 study of a novel targeted immune therapy show excellent tolerability in advanced CTCL patients. Updated results including exploratory biomarker assessment results will be presented and discussed at the meeting.