First-in-human study of JNJ-67571244, a CD33 × CD3 bispecific antibody, in relapsed/refractory acute myeloid leukemia and myelodysplastic syndrome.

Relapsed/refractory (r/r) acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) outcomes remain poor. A targeted cluster of differentiation (CD)33 × CD3 bispecific antibody, JNJ-67571244, was assessed to identify the maximum tolerated dose (MTD), recommended phase II dose (RP2D), safety and tolerability, and preliminary clinical activity in patients with r/rAML or r/rMDS. This first-in-human, open-label, phase I, dose-escalation/dose-expansion study included patients with r/rAML or r/rMDS who were ineligible for or had exhausted standard therapeutic options. JNJ-67571244 was administered intravenously or subcutaneously using step-up dosing until ≥1 discontinuation condition was met. Outcomes included safety/tolerability, preliminary clinical activity, and systemic pharmacokinetics and pharmacodynamics. The study was terminated after evaluating 10 dose-escalation cohorts (n = 68) and before starting dose-expansion. Overall, 11 (16.2%) patients experienced ≥1 dose-limiting toxicity; all experienced ≥1 treatment-emergent adverse event (TEAE; treatment related: 60 [88.2%]); and 64 (94.1%) experienced ≥1 TEAE of Grade ≥3 toxicity (treatment related: 28 [41.2%]). Although some patients had temporary disease burden reductions, no responses were seen. JNJ-67571244 administration increased multiple cytokines, which coincided with incidence of cytokine release syndrome, infusion-related reactions, and elevated liver function tests. A prolonged step-up strategy was tested to improve tolerability, though this approach did not prevent hepatotoxicity. T-cell activation following treatment suggested target engagement but did not correlate with clinical activity. Safely reaching the projected exposure level for JNJ-67571244 efficacy was not achieved, thus MTD and RP2D were not determined.

The anti-interleukin-6 antibody siltuximab down-regulates genes implicated in tumorigenesis in prostate cancer patients from a phase I study.

BACKGROUND: Interleukin-6 (IL-6) is associated with prostate cancer morbidity. In several experimental models, IL-6 has been reported to have anti-apoptotic and pro-angiogenic effects. Siltuximab (CNTO 328) is a monoclonal anti-IL-6 antibody which has been successfully applied in several models representing prostate cancer. This study was designed to assess preliminary safety of siltuximab in patients with early prostate cancer. PATIENTS AND METHODS: Twenty patients scheduled to undergo radical prostatectomy received either no drug or siltuximab (6 mg/kg, five patients per group with administration once, two times, and three times prior to surgery). Blood samples were collected for pharmacokinetic and pharmacodynamic analyses. Expression of elements of IL-6 signaling pathways was analyzed in tumor tissue by immunohistochemistry. Gene analysis in tumor specimens was performed with the DASL array. RESULTS: No adverse events related to siltuximab were observed. Patients treated with siltuximab presented with higher levels of proliferation and apoptosis markers. Following a single dose, serum concentrations of siltuximab declined in a biexponential manner. This study revealed a decrease in phosphorylation of Stat3 and p44/p42 mitogen-activated protein kinases. In addition, gene expression analyses indicate down-regulation of genes immediately downstream of the IL-6 signaling pathway and key enzymes of the androgen signaling pathway. CONCLUSIONS: Preliminary safety of siltuximab is favorable. Future studies in which siltuximab could be combined with androgen-deprivation therapy and experimental therapies in advanced prostate cancer are justified.

Drug-inducible, dendritic cell-based genetic immunization.

Determining the mechanism of Ag loading of Langerhans cells (LC) for genetic immunization (GI) is complicated by the inability to distinguish between the response generated by direct transfection of LC from that due to exogenous uptake. To unravel this mechanism, we examined the impact of gene gun treatment on LC with respect to their activation and migration from skin, transgene expression, and ability to initiate humoral and cellular immune responses upon transfer to naive mice. To assess responses generated by direct LC transfection, an RU486-inducible expression system was used as a GI vector. In vitro skin organ cultures were developed from gene gun immunized mouse ear specimens to obtain LC. Gene gun treatment markedly augmented (3-fold) LC migration from ear skin, and these LC expressed the transgene at RNA and protein levels. Transfer of 2 x 10(5) migratory cells resulted in identical cellular responses to, but 10-fold lower humoral responses than, standard GI. Using an RU486-inducible system, we were able to measure responses generated by directly transfected LC. Our results indicate that direct transfection is a predominant pathway for LC Ag loading. The ability to regulate transgene expression with inducible DC-based vaccines demonstrates a new level of immunological control.