A Phase 1 First-in-Human Study of FS118, a Tetravalent Bispecific Antibody Targeting LAG-3 and PD-L1 in Patients with Advanced Cancer and PD-L1 Resistance.

PURPOSE: This phase 1 study (NCT03440437) evaluated the safety, tolerability, pharmacokinetics (PK), and activity of FS118, a bispecific antibody-targeting LAG-3 and PD-L1, in patients with advanced cancer resistant to anti-PD-(L)1 therapy. PATIENTS AND METHODS: Patients with solid tumors, refractory to anti-PD-(L)1-based therapy, received intravenous FS118 weekly with an accelerated dose titration design (800 µg to 0.3 mg/kg) followed by 3+3 ascending dose expansion (1 to 20 mg/kg). Primary objectives were safety, tolerability, and PK. Additional endpoints included antitumor activity, immunogenicity, and pharmacodynamics. RESULTS: Forty-three patients with a median of three prior regimens in the locally advanced/metastatic setting, including at least one anti-PD-(L)1 regimen, received FS118 monotherapy. FS118 was well tolerated, with no serious adverse events relating to FS118 reported. No dose-limiting toxicities (DLT) were observed, and an MTD was not reached. The recommended phase 2 dose of FS118 was established as 10 mg/kg weekly. The terminal half-life was 3.9 days. Immunogenicity was transient. Pharmacodynamic activity was prolonged throughout dosing as demonstrated by sustained elevation of soluble LAG-3 and increased peripheral effector cells. The overall disease control rate (DCR) was 46.5%; this disease control was observed as stable disease, except for one late partial response. Disease control of 54.8% was observed in patients receiving 1 mg/kg or greater who had acquired resistance to PD-(L)1-targeted therapy. CONCLUSIONS: FS118 was well tolerated with no DLTs observed up to and including 20 mg/kg QW. Further studies are warranted to determine clinical benefit in patients who have become refractory to anti-PD-(L)1 therapy. See related commentary by Karapetyan and Luke, p. 835.

Evaluation of B cell maturation antigen as a target for antibody drug conjugate mediated cytotoxicity in multiple myeloma.

B-cell maturation antigen (BCMA, also termed TNFRSF17) is an attractive therapeutic target due to its restricted expression on normal and malignant plasma cells (PC). GSK2857916 (or J6M0-MMAF) is a BCMA-specific antibody conjugated to the microtubule-disrupting agent monomethyl auristatin F (MMAF) via a protease-resistant linker. To evaluate the clinical potential of this agent, tumour cells from seventy multiple myeloma (MM) patients were assessed for BCMA expression by immunohistochemistry and flow cytometry. All patients tested expressed BCMA, at varying levels, and both surface and intracellular expression were observed. BCMA expression is maintained through relapse, extramedullary spread and in residual disease post therapy. BCMA levels may also be prognostically useful as higher levels of BCMA were associated with poorer outcomes, even taking into account genetic risk. We observed rapid internalization of surface BCMA and newly expressed protein by 1 h, suggesting a mechanism for J6M0-MMAF activity even with low surface antigen. J6M0-MMAF mediated cytotoxicity of MM cells varied with dose and antigen levels, with clonogenic progenitors killed at lower doses than mature cells. In comparison, J6M0-MMAF killing of primary CD138(+) myeloma cells occurred with slower kinetics. Our observations support BCMA to be a promising therapeutic target in MM for novel therapies such as J6M0-MMAF.

A dose-escalation study of recombinant human interleukin-18 in combination with rituximab in patients with non-Hodgkin lymphoma.

Interleukin-18 (IL-18) is an immunostimulatory cytokine with antitumor activity in preclinical models. Rituximab is a CD20 monoclonal antibody with activity against human B-cell lymphomas. A phase I study of recombinant human (rh) IL-18 given with rituximab was performed in patients with CD20+ lymphoma. Cohorts of 3-4 patients were given infusions of rituximab (375 mg/m2) weekly for 4 weeks with escalating doses of rhIL-18 as a 2-hour intravenous infusion weekly for 12 consecutive weeks. Toxicities were graded using standard criteria. Blood samples were obtained for safety, pharmacokinetic, and pharmacodynamic studies. Nineteen patients with CD20+ B-cell non-Hodgkin lymphoma were given rituximab in combination with rhIL-18 at doses of 1, 3, 10, 20, 30, and 100 µg/kg. Common side effects included chills, fever, headache, and nausea. Common laboratory abnormalities included transient, asymptomatic lymphopenia, hyperglycemia, anemia, hypoalbuminemia, and bilirubin and liver enzyme elevations. No dose-limiting toxicities were observed. Biologic effects of rhIL-18 included transient lymphopenia and increased expression of activation antigens on lymphocytes. Increases in serum concentrations of IFN-γ, GM-CSF, and chemokines were observed after dosing. Objective tumor responses were seen in 5 patients, including 2 complete and 3 partial responses. rhIL-18 can be given in biologically active doses by weekly infusions in combination with rituximab to patients with lymphoma. A maximum tolerated dose of rhIL-18 plus rituximab was not determined. Further studies of rhIL-18 and CD20 monoclonal antibodies in B-cell malignancies are warranted.

Chemoimmunotherapy using pegylated liposomal Doxorubicin and interleukin-18 in recurrent ovarian cancer: a phase I dose-escalation study.

Recombinant interleukin (IL)-18 (SB-485232) is an immunostimulatory cytokine, with shown antitumor activity in combination with pegylated liposomal doxorubicin (PLD) in preclinical models. This phase I study evaluated the safety, tolerability, and biologic activity of SB-485232 administered in combination with PLD in subjects with recurrent ovarian cancer. The protocol comprised four cycles of PLD (40 mg/m(2)) on day 1 every 28 days, in combination with SB-485232 at increasing doses (1, 3, 10, 30, and 100 µg/kg) on days 2 and 9 of each cycle, to be administered over five subject cohorts, followed by discretionary PLD monotherapy. Sixteen subjects were enrolled. One subject withdrew due to PLD hypersensitivity. Most subjects (82%) were platinum-resistant or refractory, and had received a median of three or more prior chemotherapy regimens. SB-485232 up to 100 µg/kg with PLD had an acceptable safety profile. Common drug-related adverse events were grade 1 or 2 (no grade 4 or 5 adverse events). Concomitant PLD administration did not attenuate the biologic activity of IL-18, with maximal SB-485232 biologic activity already observed at 3 µg/kg. Ten of 16 enrolled subjects (63%) completed treatment, whereas five (31%) subjects progressed on treatment. A 6% partial objective response rate and a 38% stable disease rate were observed. We provide pilot data suggesting that SB-485232 at the 3 µg/kg dose level in combination with PLD is safe and biologically active. This combination warrants further study in a phase II trial.