Citations

Abstract Background: PI3K/Akt activation is downstream of the B cell receptor (BCR) signaling cascade and is critical to mediate the interactions between CLL B-cell and bone marrow stroma which support leukemic survival. MK-2206 is a potent oral allosteric Akt inhibitor and we have demonstrated in vitro synergism with bendamustine (B) to induce CLL apoptosis. MK-2206 selectively abolishes BCR-stimulated cytokines CCL3, CCL4, CCL2, and IL-2Ra and significantly inhibits the BCR signaling pathway (Ding, BJH, 2013). We sought to assess the safety, maximal tolerated dose (MTD) and efficacy of MK-2206 in combination with B-rituximab (BR) in relapsed and refractory CLL/SLL patients in a phase I/II trial (NCCTG N1087 Alliance). Methods: Previously treated symptomatic CLL/SLL patients with up to 3 prior lines of therapy and ECOG performance status of 0-2 were eligible. Patients with 17p deletion or prior treatment with B were excluded. A standard phase I design was used to determine the MTD of MK-2206 in combination with BR (B 70mg/m2 for 2 days per cycle; R cycle 1: 375 mg/m2, cycle 2-6: 500 mg/m2). Phase II employed the MTD to evaluate safety and efficacy of the combination. Response was evaluated 2 months after the last cycle of therapy per IWCLL 2008 criteria. Results: 13 patients with a median age of 68 years (range 44-75) and 1.2 prior lines of therapy were treated. CLL FISH showed: del(11q) in 4 (31%), trisomy 12 in 2 (15%), del(13q) in 3 (23%), del(6q) (8%), del(17cen) (8%) and normal results in 2 (15%). IGHV was unmutated in 10 (91%) and mutated in 1 patient (9%) and was missing in 2 cases. ZAP-70 was positive in 8 (73%) and negative in 3 patients (27%). CD38 was positive in 8 (62%) and negative in 5 patients (38%). 70% of patients had received prior chemoimmunotherapy. At 90 mg of MK-2206, 1/6 patients experienced a DLT of grade 3 febrile neutropenia and hemolysis. 2/6 patients on the 135 mg dose experienced a DLT. One patient had grade 3 febrile neutropenia and one patient had a grade 3 acneiform rash. MTD was determined to be MK-2206 90 mg. The most common grade 3/4 adverse events were neutropenia (46%) including febrile neutropenia (23%), diarrhea (15%) and thrombocytopenia (15%). The most common all-grade toxicities were neutropenia (69%), thrombocytopenia (62%), anemia (54%), nausea (54%), diarrhea (39%), rash (38%), and hyperglycemia (31%). 10 patients were treated at 90 mg and 3 patients were treated at the 135 mg dose. The ORR was 92% (n=12). Responses were: 3 CR (23%), 2 CR with incomplete marrow recovery (CRi) (15%), 1 clinical CR (CCR) (8%) without marrow confirmation, 1 nodular partial remission (nPR) (8%), 5 PR (38%), and 1 progressive disease (8%). Median follow-up was 20 months (6-31 months). Median PFS in the CR/CRi group was not reached (NR) with 100% of patients progression free versus 12 months (95% CI 2 months-NR) if CR/CRi was not achieved (p=0.027). Median overall survival was NR in either the CR/CRi or non-CR/CRi groups but 2 deaths occurred in the latter group (p=0.44). One patient developed Richter transformation and died at 15 months and a second patient who had achieved PR died from autoimmune hemolytic anemia and fungal infection at 27 months. Two out of five patients who achieved CR or CRi had bone marrow MRD negative status at the final response evaluation. Conclusions: The Akt inhibitor MK-2206 administered at 90 mg once weekly in combination with BR is tolerated in patients with relapsed or refractory CLL and compares favorably to BR alone (59% ORR and 9% CR, Fischer, JCO, 2011). An ORR of 92% was observed with a 38% of patients achieving CR or CRi. The trial was terminated prematurely due to withdrawal of sponsor support, however further testing of Akt inhibition is needed given the promising results. Citation Format: Jeremy T. Larsen, Tait D. Shanafelt, Jose F. Leis, Betsy R. LaPlant, Timothy G. Call, Clive S. Zent, Curtis A. Hanson, Charles Erlichman, Thomas M. Habermann, Craig B. Reeder, Deborah A. Bowen, Michael Conte, Justin C. Boysen, Charla R. Secreto, Connie E. Lesnick, Renee C. Tschumper, Diane F. Jelinek, Neil E. Kay, Wei Ding. The Akt inhibitor MK-2206 in combination with rituximab and bendamustine demonstrates efficacy in relapsed/refractory chronic lymphocytic leukemia: Updated results from the NCCTG N1087 Alliance study. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr B02.

Abstract FoxM1, a member of the Forkhead transfection factors, has been found to be overexpressed in many human cancers including ovarian cancer. Although FoxM1 is known to be downregulated by p53, the molecular mechanisms are not well characterized. In this study, we used the MDM2 inhibitor Nutlin-3 as a tool to modulate p53 expression and investigated the mechanism by which p53 regulates FoxM1 expression in ovarian cancer cells. We observed that Nutlin-3 upregulated p53 protein and downregulated FoxM1 mRNA and protein levels in ovarian cancer cell lines with wild type TP53, but not in cell lines with mutant TP53. This effect was at least partially blocked by cycloheximide or actinomycin D, indicating a transcription- and translation-dependent mechanism. Pulse-chase studies revealed that downregulation of FoxM1 by Nutlin-3 is due to enhanced FoxM1 mRNA decay. Knockdown of p53 using shRNAs abrogated the suppression of FoxM1 expression by Nutlin-3, indicating a p53-dependent mechanism. Furthermore, silencing of FoxM1 by shRNAs in ovarian cancer cells with or without wild-type TP53 led to a significant decrease in cell proliferation. The FoxM1 inhibitor, thiostrepton, induces cytotoxicity in ovarian cancer cell lines and enhances sensitivity to cisplatin in these cells. Thiostrepton downregulates FoxM1 expression in several ovarian cancer cell lines and enhances sensitivity to carboplatin in vivo. Finally, FoxM1 expression is elevated in nearly all (47/48) ovarian tumors. In summary, the present study provides novel evidence that p53 downregulates FoxM1 in ovarian cancer cells at least in part by destabilizing FoxM1 mRNA and that FoxM1 may be targeted for therapeutic benefits in ovarian cancer. Citation Format: Xuan Zhang, Lihua Cheng, Kay Minn, Magdalena Waggoner, Nikhil K. Parelkar, Iman Jokar, George A. Vielhauer, Rashna Madan, Andrew K. Godwin, Viji Shridhar,, Jeremy Chien. Targeting p53-FoxM1 axis in ovarian cancer [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-THER-1409.

Abstract Introduction: Relapsed and refractory multiple myeloma (MM) remains a significant clinical challenge and drugs with new mechanisms of action to overcome resistance are needed. Constitutive activation of the PI3K/Akt/mTOR pathway in MM promotes tumorigenesis through propagation of the cell cycle, protein synthesis, and inhibition of apoptosis. Anti-MM effects of rapalogs are limited due to feedback activation of the PI3K/Akt signaling pathway. Agents capable of targeting PI3K and mTORC1 or both mTORC1/C2 are able to partially overcome such resistance mechanisms. However, the mTORC2 mediated increase in pAkt (Ser473) after PI3K/mTORC1 inhibition and the activation of PI3K after mTORC1/C2 inhibition could still contribute to resistance to such agents. We sought to investigate the effects of SPR965 (synthesized and provided by Sphaera Pharma, Singapore under an MTA), an orally bioavailable novel small molecule with inhibition of class 1 PI3 kinase and mTORC1/C2 kinases on MM cell lines and patient cells. Results: SPR965 induced cytotoxicity and inhibited proliferation in all MM cell lines examined with IC50 values between 25-500nM. To understand if SPR965 induced apoptotic cell death, annexin/PI staining followed by flow cytometric assays were performed, which showed a clear increase in cells undergoing apoptosis. Western blots showed increase in caspase-3, -9, and PARP cleavage confirming apoptotic induction by SPR965. Importantly, SPR965 caused potent increase in apoptosis in cytogenetically distinct MM patient cells. Next, we examined the mechanism of action of SPR965. SPR965 caused potent mTORC1 inhibition evidenced by decreased p4E-BP1, p-p70S6K, and pS6 at doses as low as 25nM. SPR965 was able to inhibit PI3K activity as shown by decreased pPDK1 and pBTK at slightly higher concentrations of 75nM. Phosphorylation of Akt S473, a TORC2 substrate, increased at initial low concentrations of SPR965, but was attenuated at concentrations of 100 nM and above, demonstrating dose-dependent inhibition of mTORC2. Such effects were also observed when we performed western blots on MM patient derived primary plasma cells. Increased levels of p27 (KIP1) were observed suggestive of G1 growth arrest, which was confirmed on cell cycle analysis. Since SPR965 caused an increase in pAkt (both T308 and S473) at doses up to 75nM, we examined if SPR965 was able to synergize with an Akt inhibitor MK2206 at doses lower than 75nM. Our results showed potent synergy suggesting that the pAkt up regulation contributes to partial resistance, which is inhibited by SPR965 at doses of 100nM and higher, doses that are still clinically achievable. Conclusion: Our findings demonstrate SPR965 induces apoptosis of MM cells through the inhibition of PI3K and mTORC1/C2 activity. Further studies are underway to better characterize the mechanism of action of SPR965, all of which will be informative for the drug to be used as a single agent or in combination with other agents in relapsed MM. Citation Format: Jeremy T. Larsen, Vijay Ramakrishnan, Jessica Haug, Teresa Kimlinger, Somdutta Sen, Dinesh Mahajan, Sundeep Dugar, S. Vincent Rajkumar, Shaji K. Kumar. Preclinical activity of dual PI3K/mTOR inhibitor SPR965 in multiple myeloma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2653. doi:10.1158/1538-7445.AM2015-2653

Introduction Treatment of symptomatic spinal metastases through surgical decompression and reconstruction is known to improve quality of life in patients with cancer. However, most studies have been performed on patients with mixed tumor histopathology. We systematically review the literature for prognostic factors specific to the surgical treatment of prostate metastases to the spine to determine the indications and outcomes of the surgical treatment. Material and Methods A systemic review of the literature was conducted to answer the following questions: Q1. Describe the survival and functional outcomes of surgery or vertebral augmentation for prostate metastases to the spine; Q2. Determine whether overall tumor burden, Gleason score, preoperative functional markers, and favorable hormonal naivety for operative intervention; Q3. Establish whether clinical outcomes vary with the evolution of operative techniques. Expert consensus was obtained using a modified Delphi process. Results A total of 16 studies met the preset inclusion criteria. These studies were all retrospective series with a level of evidence of IV. Included studies consistently showed a large effect of hormone naivety on overall survival. In addition, studies consistently demonstrated an improvement in motor function and the ability to maintain/regain ambulation following surgery resulting in moderate strength of recommendation. All other parameters were of insufficient or low strength. Conclusion There is scant literature on the surgical treatment of prostate metastases to the spine, which represents an opportunity for future research. On the basis of the existing evidence, it appears that the surgical treatment of prostate metastases to the spine has consistently favorable results. While no consistent preoperative indicators favor nonoperative treatment, hormone naivety and high Karnofsky Performance Scores have positive effects on survival and clinical outcomes.