High-throughput screening using patient-derived tumor xenografts to predict clinical trial drug response.

Profiling candidate therapeutics with limited cancer models during preclinical development hinders predictions of clinical efficacy and identifying factors that underlie heterogeneous patient responses for patient-selection strategies. We established ∼1,000 patient-derived tumor xenograft models (PDXs) with a diverse set of driver mutations. With these PDXs, we performed in vivo compound screens using a 1 × 1 × 1 experimental design (PDX clinical trial or PCT) to assess the population responses to 62 treatments across six indications. We demonstrate both the reproducibility and the clinical translatability of this approach by identifying associations between a genotype and drug response, and established mechanisms of resistance. In addition, our results suggest that PCTs may represent a more accurate approach than cell line models for assessing the clinical potential of some therapeutic modalities. We therefore propose that this experimental paradigm could potentially improve preclinical evaluation of treatment modalities and enhance our ability to predict clinical trial responses.

JAK1/2 and Pan-deacetylase inhibitor combination therapy yields improved efficacy in preclinical mouse models of JAK2V617F-driven disease.

PURPOSE: The myeloproliferative neoplasm myelofibrosis is characterized by frequent deregulation of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling, and JAK inhibitors were shown to reduce splenomegaly and ameliorate disease-related symptoms. However, the mutant clone and bone marrow fibrosis persist in the majority of patients. Using preclinical models, we explored whether JAK and pan-deacetylase inhibitor combination yielded additional benefits. EXPERIMENTAL DESIGN: The combination of the JAK1/2 inhibitor ruxolitinib and panobinostat was investigated using two different mouse models of JAK2(V617F)-driven disease. A Ba/F3 JAK2(V617F) cell-driven leukemic disease model was used to identify tolerated and efficacious doses. The drugs were then evaluated alone and in combination in a mouse model of myeloproliferative neoplasm-like disease based on transplantation of bone marrow transduced with a retrovirus expressing JAK2(V617F). Exposures were determined in blood and tissues, and phosphorylated STAT5 and acetylated histone H3 pharmacodynamic readouts were assessed in spleen and bone marrow. Histologic analysis was conducted on spleen and bone marrow, including staining of reticulin fibers in the latter organ. RESULTS: The combination of ruxolitinib and panobinostat was found to have a more profound effect on splenomegaly, as well as on bone marrow and spleen histology, compared with either agent alone, and the analysis of pharmacodynamic readouts showed that ruxolitinib and panobinostat have nonoverlapping and complementary effects. CONCLUSION: Combining JAK1/2 and pan-deacetylase inhibitors was fairly well tolerated and resulted in improved efficacy in mouse models of JAK2(V617F)-driven disease compared with the single agents. Thus, the combination of ruxolitinib and panobinostat may represent a promising novel therapeutic modality for myeloproliferative neoplasms.