The authors present the first case report of a patient with lymphoma who developed disseminated cryptococcal osteomyelitis and meningitis while being treated with the PEP-C (prednisone, etoposide, procarbazine and cyclophosphamide) chemotherapy regimen. During investigation of fever and new bony lesions, fungal culture from a rib biopsy revealed that the patient had cryptococcal osteomyelitis. Further evaluation demonstrated concurrent cryptococcal meningitis. The patient’s disseminated cryptococcal infections completely resolved after a full course of antifungal treatment. Cryptococcal osteomyelitis is itself an extremely rare diagnosis, and the unique presentation with concurrent cryptococcal meningitis in our patient with lymphoma was likely due to his PEP-C treatment. It is well recognised that prolonged intensive chemotherapeutic regimens place patients at risk for atypical infections; yet physicians should recognise that even chronic low-dose therapies can put patients at risk for fungal infections. Physicians should consider fungal infections as part of the infectious investigation of a lymphopaenic patient on PEP-C.
Deregulation of c-Myc plays a central role in the tumorigenesis of many human cancers. Yet, the development of drugs regulating c-Myc activity has been challenging. To facilitate the identification of c-Myc inhibitors, we developed a molecular imaging sensor based high throughput-screening (HTS) system. This system uses a cell-based assay to detect c-Myc activation in a HTS format, which is established from a pure clone of a stable breast cancer cell line that constitutively expresses a c-Myc activation sensor. Optimization of the assay performance in the HTS format resulted in uniform and robust signals at the baseline. Using this system, we performed a quantitative HTS against approximately 5,000 existing bioactive compounds from five different libraries. Thirty-nine potential hits were identified, including currently known c-Myc inhibitors. There are a few among the top potent hits that are not known for anti-c-Myc activity. One of these hits is nitazoxanide (NTZ), a thiazolide for treating human protozoal infections. Validation of NTZ in different cancer cell lines revealed a high potency for c-Myc inhibition with IC50 ranging between 10 - 500nM. Oral administration of NTZ in breast cancer xenograft mouse models significantly suppressed tumor growth by inhibition of c-Myc and induction of apoptosis. These findings suggest a potential of NTZ to be repurposed as a new anti-tumor agent for inhibition of c-Myc associated neoplasia. Our work also demonstrated the unique advantage of molecular imaging in accelerating discovery of drugs for c-Myc targeted cancer therapy.
c-Myc activation sensor; molecular imaging; high throughput screening; c-Myc inhibitors; nitazoxanide
Rigosertib (ON01910.Na), is a targeted therapeutic that inhibits multiple kinases, including PI3K and Plk1. Rigosertib has been found to induce the proliferative arrest and apoptosis of myeloblasts but not of other normal hematopoietic cells. Rigosertib has significant clinical activity as a therapy for patients with high-risk myelodysplastic syndrome (MDS) who are otherwise refractory to DNA methyltransferase (DNMT) inhibitors. Moreover, rigosertib has potential clinical activity in a multitude of solid tumors.
The objective of this review is to evaluate the mechanism of activity, efficacy and dosing of rigosertib. Furthermore, we discuss the challenge in the clinical development of rigosertib, to identify the specific patients that are most likely to benefit from this therapeutic agent. A PubMed search was performed using the following key words: rigosertib and ON01910.Na.
We describe the application of a novel nanoscale proteomic assay, the nanoimmunoassay (NIA), a tractable approach for measuring the activity and predicting the efficacy of rigosertib, in real-time, using limited human clinical specimens. Our strategy suggests a possible paradigm where proteomic analysis during the pre-clinical and clinical development of a therapy can be used to uncover biomarkers for the analysis and prediction of efficacy in human patients.
Nanoimmunoassay; myelodysplastic syndromes; polo-like kinase; phosphatidylinositol 3-kinase; Rigosertib; ON 01910.Na; DNA methyl transferase inhibitors
The targeted inactivation of a single oncogene can induce dramatic tumor regression, suggesting that cancers are “oncogene addicted.” Tumor regression following oncogene inactivation has been thought to be a consequence of restoration of normal physiological programs that induce proliferative arrest, apoptosis, differentiation, and cellular senescence. However, recent observations illustrate that oncogene addiction is highly dependent upon the host immune cells. In particular, CD4+ helper T cells were shown to be essential to the mechanism by which MYC or BCR-ABL inactivation elicits “oncogene withdrawal.” Hence, immune mediators contribute in multiple ways to the pathogenesis, prevention, and treatment of cancer, including mechanisms of tumor initiation, progression, and surveillance, but also oncogene inactivation-mediated tumor regression. Data from both the bench and the bedside illustrates that the inactivation of a driver oncogene can induce activation of the immune system that appears to be essential for sustained tumor regression.
Oncogene addiction; MYC; Tumor microenvironment; Tumor immunology
Current methods of protein detection are insensitive to detecting subtle changes in oncoprotein activation that underlie critical cancer signaling processes. The requirement for large numbers of cells precludes serial tumor sampling for assessing a response to therapeutics. Therefore, we have developed a nano-fluidic proteomic immunoassay (NIA) to quantify total and low abundance protein isoforms in 4 nanoliters of lysate. Our method could quantify levels of MYC and BCL2 proteins in Burkitt’s versus follicular lymphoma; identify changes in activation of ERK1/2, MEK1, STAT3/5, JNK and caspase 3 in imatinib-treated chronic myelogeneous leukemia (CML) cells; measure a novel change in phosphorylation of an ERK2 isomer in CML patients who responded to imatinib; and detect a decrease in STAT3/5 phosphorylation in lymphoma patients treated with atorvastatin. Therefore, we have described a novel and highly sensitive method for interrogating oncoprotein expression and phosphorylation in clinical specimens for the development of new therapeutics for cancer.
The phosphatidylinositol 3-kinase pathway (PI3K) is known to play an active role in many malignancies. The role of PI3K inhibition in the treatment of lymphomas has not been fully delineated. We sought to identify a role for therapeutic PI3K inhibition across a range of B cell lymphomas.
We selected three small molecule inhibitors to test in a panel of 60 cell lines that comprised diverse lymphoma types. We tested the selective PI3K inhibitor BKM120 and the dual PI3K/MTOR inhibitors BEZ235 and BGT226 in these cell lines. We applied gene expression profiling to better understand the molecular mechanisms associated with responsiveness to these drugs.
We found that higher expression of the PAK1 gene was significantly associated with resistance to all three PI3K inhibitors. Through RNA-interference mediated knock-down of the PAK1 gene, we demonstrated a dramatic increase in the sensitivity to PI3K inhibition. We further tested a small molecule inhibitor of PAK1 and found significant synergy between PI3K inhibition and PAK1 inhibition.
Thus we demonstrate that PI3K inhibition is broadly effective in lymphomas and PAK1 is a key modulator of resistance to PI3K inhibition.
Leukemias and lymphomas; kinase and phosphatase inhibitors; diffuse large B cell lymphoma; DLBCL; Hodgkin lymphoma; Burkitt lymphoma; primary mediastinal B cell lymphoma; phosphatidylinositol 3-kinase pathway; PI3 Kinase; PI3K; PAK1; drug resistance
We present the first case report of a lymphoma patient who developed disseminated cryptococcal osteomyelitis and meningitis while being treated with the PEP-C (prednisone, etoposide, procarbazine and cyclophosphamide) chemotherapy regimen. During work-up of fever and new bony lesions, fungal culture from a rib biopsy revealed that the patient had cryptococcal osteomyelitis. Further evaluation demonstrated concurrent cryptococcal meningitis. The patient’s disseminated cryptococcal infections completely resolved after a full course of antifungal treatment. Cryptococcal osteomyelitis is itself an extremely rare diagnosis, and the unique presentation with concurrent cryptococcal meningitis in our patient with lymphoma was likely due to his PEP-C treatment. It is well recognized that prolonged intensive chemotherapeutic regimens place patients at risk for atypical infections; yet physicians should recognize that even chronic low-dose therapies can put patients at risk for fungal infections. Physicians should consider fungal infections as part of the infectious work up of a lymphopenic patient on PEP-C.
In a Phase I/II clinical trial, 13 higher risk red blood cell-dependent myelodysplastic syndrome (MDS) patients unresponsive to hypomethylating therapy were treated with the multikinase inhibitor ON01910.Na. Responses occurred in all morphologic, prognostic risk and cytogenetic subgroups, including four patients with marrow complete responses among eight with stable disease, associated with good drug tolerance. In a subset of patients, a novel nanoscale immunoassay showed substantially decreased AKT2 phosphorylation in CD34+ marrow cells from patients responding to therapy but not those who progressed on therapy. These data demonstrate encouraging efficacy and drug tolerance with ON01910.Na treatment of higher risk MDS patients.
MDS; Treatment; ON01910.Na; rigosertib; nanoimmunoassay; AKT signaling pathway
Bryostatin 1 is a naturally occurring complex macrolide with potent anti-neoplastic activity. However, its extremely low natural occurrence has impeded clinical advancement. We developed a strategy directed at the design of simplified and synthetically more accessible bryostatin analogs. Our lead analog, “picolog”, can be step-economically produced. Picolog, compared to bryostatin, exhibited superior growth inhibition of MYC-induced lymphoma in vitro. A key mechanism of picolog's (and bryostatin's) activity is activation of PKC. A novel nano-immunoassay (NIA) revealed that picolog treatment increased phospho-MEK2 in the PKC pathway. Moreover, the inhibition of PKC abrogated picolog's activity. Finally, picolog was highly potent at 100 micrograms/kg and well tolerated at doses ranging from 100 micrograms/kg to 1 milligram/kg in vivo for the treatment of our aggressive model of MYC-induced lymphoma. We provide the first in vivo validation that the bryostatin analog, picolog, is a potential therapeutic agent for the treatment of cancer and other diseases.
bryostatin; picolog; lymphoma; PKC
Current treatments for high-grade lymphoma often have curative potential, but unfortunately many cases relapse and develop therapeutic resistance. Thus, there remains a need for novel therapeutics that can target the residual cancer cells whose phenotypes are distinct from the bulk tumor and that are capable of reforming tumors from very few cells. Oncolytic viruses offer an approach to destroy tumors by multiple mechanisms, but they can not effectively reach residual disease or micrometastases, especially within the lymphatic system. To address these limitations, we have generated immune cells infected with oncolytic viruses as a therapeutic strategy that can combine effective cellular delivery with synergistic tumor killing. In this study, we tested this approach against minimal disease states of lymphomas characterized by the persistence of cancer cells which display stem cell-like properties and resistance to conventional therapies. We found that the immune cells were capable of trafficking to and targeting residual cancer cells. The combination biotherapy used prevented relapse by creating a long-term, disease-free state, with acquired immunity to the tumor functioning as an essential mediator of this effect. Immune components necessary for this acquired immunity were identified. We further demonstrated that the dual-biotherapy could be applied before or after conventional therapy. Our approach offers a potentially powerful new way to clear residual cancer cells, showing how restoring immune surveillance is critical for maintenance of a disease-free state.
oncolytic vaccinia; lymphoma; CIK cells; Immune cell therapy
Oncogene addiction is thought to occur cell autonomously. Immune effectors are implicated in the induction and restraint of tumorigenesis, but their role in oncogene inactivation mediated tumor regression is unclear. Here, we show that an intact immune system, specifically CD4+ T-cells, is required for the induction of cellular senescence, shut down of angiogenesis and chemokine expression resulting in sustained tumor regression upon inactivation of the MYC or BCR-ABL oncogenes in mouse models of T-cell acute lymphoblastic lymphoma and pro-B-cell leukemia, respectively. Moreover, immune effectors knocked out for thrombospondins failed to induce sustained tumor regression. Hence, CD4+ T-cells are required for the remodeling of the tumor microenvironment through the expression of chemokines, such as thrombospondins, in order to elicit oncogene addiction.
cancer; drug delivery; nanotubes; pi interactions; nano-biotechnology
MicroRNA (miRNA) dysregulation frequently occurs in cancer. Analysis of whole blood miRNA in tumor models has not been widely reported, but could potentially lead to novel assays for early detection and monitoring of cancer. To determine whether miRNAs associated with malignancy could be detected in the peripheral blood, we used real-time reverse transcriptase-PCR to determine miRNA profiles in whole blood obtained from transgenic mice with c-MYC-induced lymphoma, hepatocellular carcinoma and osteosarcoma. The PCR-based assays used in our studies require only 10 nanograms of total RNA, allowing serial mini-profiles (20 – 30 miRNAs) to be carried out on individual animals over time. Blood miRNAs were measured from mice at different stages of MYC-induced lymphomagenesis and regression. Unsupervised hierarchical clustering of the data identified specific miRNA expression profiles that correlated with tumor type and stage. The miRNAs found to be altered in the blood of mice with tumors frequently reverted to normal levels upon tumor regression. Our results suggest that specific changes in blood miRNA can be detected during tumorigenesis and tumor regression.
Conditional transgenic models have established that tumors require sustained oncogene activation for tumor maintenance, exhibiting the phenomenon known as “oncogene-addiction.” However, most cancers are caused by multiple genetic events making it difficult to determine which oncogenes or combination of oncogenes will be the most effective targets for their treatment.
To examine how the MYC and K-rasG12D oncogenes cooperate for the initiation and maintenance of tumorigenesis, we generated double conditional transgenic tumor models of lung adenocarcinoma and lymphoma. The ability of MYC and K-rasG12D to cooperate for tumorigenesis and the ability of the inactivation of these oncogenes to result in tumor regression depended upon the specific tissue context. MYC-, K-rasG12D- or MYC/K-rasG12D-induced lymphomas exhibited sustained regression upon the inactivation of either or both oncogenes. However, in marked contrast, MYC-induced lung tumors failed to regress completely upon oncogene inactivation; whereas K-rasG12D-induced lung tumors regressed completely. Importantly, the combined inactivation of both MYC and K-rasG12D resulted more frequently in complete lung tumor regression. To account for the different roles of MYC and K-rasG12D in maintenance of lung tumors, we found that the down-stream mediators of K-rasG12D signaling, Stat3 and Stat5, are dephosphorylated following conditional K-rasG12D but not MYC inactivation. In contrast, Stat3 becomes dephosphorylated in lymphoma cells upon inactivation of MYC and/or K-rasG12D. Interestingly, MYC-induced lung tumors that failed to regress upon MYC inactivation were found to have persistent Stat3 and Stat5 phosphorylation.
Taken together, our findings point to the importance of the K-Ras and associated down-stream Stat effector pathways in the initiation and maintenance of lymphomas and lung tumors. We suggest that combined targeting of oncogenic pathways is more likely to be effective in the treatment of lung cancers and lymphomas.