buparlisib and Skin-Neoplasms

Cutaneous T-cell lymphoma is a form of non-Hodgkin lymphoma that manifests initially in the skin and disseminates systemically as the disease progresses. Mycosis fungoides and Sézary syndrome are the most common subtypes of cutaneous T-cell lymphoma. Advanced mycosis fungoides and Sézary syndrome are life threatening with few treatment options. We searched for new agents by high-throughput screening of selected targeted compounds and identified high-value targets, including phosphatidylinositol 3-kinase (PI3K) and cyclin-dependent kinases. To validate these hits from the screen, we developed patient-derived xenograft mouse models that recapitulated the cardinal features of mycosis fungoides and Sézary syndrome and maintained histologic and molecular characteristics of their clinical counterparts. Importantly, we established a blood-based biomarker assay using tumor cell-free DNA to measure systemic tumor burden longitudinally in living mice during drug therapy. A PI3K inhibitor, BKM120, was tested in our patient-derived xenograft model leading to disease attenuation and prolonged survival. Isoform-specific small interfering RNA knockdowns and isoform-selective PI3K inhibitors identified PI3K-δ as required for tumor proliferation. Additional studies showed a synergistic combination of PI3K-α/δ inhibitors with histone deacetylase inhibitors. The strong preclinical efficacy of this potent combination against multiple patient-derived xenograft models makes it an excellent candidate for further clinical development.

Topics: Aminopyridines; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Circulating Tumor DNA; Class I Phosphatidylinositol 3-Kinases; Drug Synergism; Female; Gene Knockdown Techniques; High-Throughput Screening Assays; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Lymphoma, T-Cell, Cutaneous; Mice; Morpholines; Protein Kinase Inhibitors; Skin; Skin Neoplasms; Tumor Burden; Xenograft Model Antitumor Assays

Malignant melanoma is the most aggressive type of skin cancer and is closely associated with the development of brain metastases. Despite aggressive treatment, the prognosis has traditionally been poor, necessitating improved therapies. In melanoma, the mitogen activated protein kinase and the phosphoinositide 3-kinase signaling pathways are commonly altered, and therapeutically inhibiting one of the pathways often upregulates the other, leading to resistance. Thus, combined treatment targeting both pathways is a promising strategy to overcome this. Here, we studied the in vitro and in vivo effects of the PI3K inhibitor buparlisib and the MEK1/2 inhibitor trametinib, used either as targeted monotherapies or in combination, on patient-derived melanoma brain metastasis cell lines. Scratch wound and trans-well assays were carried out to assess the migratory capacity of the cells upon drug treatment, whereas flow cytometry, apoptosis array and Western blots were used to study apoptosis. Finally, an in vivo treatment experiment was carried out on NOD/SCID mice. We show that combined therapy was more effective than monotherapy. Combined treatment also more effectively increased apoptosis, and inhibited tumor growth in vivo. This suggests a clinical potential of combined treatment to overcome ceased treatment activity which is often seen after monotherapies, and strongly encourages the evaluation of the treatment strategy on melanoma patients with brain metastases.

Topics: Aminopyridines; Animals; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Cell Line, Tumor; Melanoma; Mice, Inbred NOD; Mice, SCID; Mitogen-Activated Protein Kinases; Morpholines; Phosphatidylinositol 3-Kinases; Protein Kinase Inhibitors; Pyridones; Pyrimidinones; Signal Transduction; Skin Neoplasms; Treatment Outcome; Tumor Burden; Xenograft Model Antitumor Assays

Topics: Aged; Aged, 80 and over; Aminopyridines; Antineoplastic Combined Chemotherapy Protocols; Biphenyl Compounds; Carcinoma, Basal Cell; Cohort Studies; Disease-Free Survival; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Humans; Male; Maximum Tolerated Dose; Middle Aged; Morpholines; Neoplasm Invasiveness; Neoplasm Staging; Prognosis; Prospective Studies; Pyridines; Skin Neoplasms; Survival Analysis; Treatment Outcome

The PTEN hamartoma tumor syndrome (PHTS) is a complex disorder caused by germline inactivating mutations of the tumor suppressor gene PTEN. Loss of PTEN function leads to unimpeded phosphatidylinositol-3'-kinase (PI3K) activity and PI3K-driven cell division. Individuals with PHTS develop benign hamartomas in various tissues and have an increased risk of developing malignant diseases. Notably, no effective therapy currently exists for this disorder. Using both genetic mouse models and pharmacological approaches, we recently demonstrated that PI3K p110α and p110β isoforms play spatially distinct but concerted roles in the skin that are required for the development and maintenance of PHTS. We also show that treatment with a pan-PI3K inhibitor prevents the development of skin PHTS and reverses advanced-stage skin hamartomas in vivo. Here, we report that genetic ablation of only 3 out of 4 p110 alleles is sufficient to block the development of skin hamartomas resulting from the complete loss of Pten in mice. Similar to our findings in skin, we now also show that mammary gland neoplastic lesions can be prevented or reversed upon PI3K inhibition in our PHTS mouse model. Our data suggest a possible route to chemoprevention using reduced doses of PI3K inhibitors for PTEN-deficient carrier patients.

Topics: Alleles; Aminopyridines; Animals; Breast Neoplasms; Class Ia Phosphatidylinositol 3-Kinase; Disease Models, Animal; Female; Gene Dosage; Genotype; Hamartoma Syndrome, Multiple; Mice; Morpholines; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Skin Neoplasms