Vincelette, Nicole D.

Abstract Background: Cytarabine and an anthracycline, the mainstay of AML therapy, affords a five-year survival below 30%. Accordingly, there is a continuing need for improved AML therapies. CPX-351 encapsulates within liposomes a fixed 5:1 molar ratio of cytarabine and daunorubicin that is synergistic (in vitro) and markedly improved in anti-leukemic activity (in vivo). Promising evidence of improved remission and survival rates with CPX-351 compared to standard of care treatments has also been observed clinically and a pivotal Phase 3 trial is currently ongoing. Because Chk1 inhibition has been shown to enhance the actions of both cytarabine and anthracyclines, there has been interest in assessing the effect of CPX-351 when combined with Chk1 inhibitors. Here we describe the evaluation of CPX-351 alone and in combination with the Chk1 inhibitors MK-8776 and LY2603618 in AML cell lines and in clinical AML samples ex vivo. Methods: Effects of CPX-351 on Chk1 phosphorylation and cell cycle distribution in the human AML lines U937 and HL-60 were analyzed by immunoblotting and flow cytometry. Effects of Chk1 inhibitors on CPX-351-induced apoptosis were assessed by flow cytometry after propidium iodide staining (DNA cleavage), Hoechst staining (nuclear fragmentation) and colony formation in soft agar (long-term survival). Effects CPX-351 ± MK-8776 on clinical AML samples were assayed using clonogenic assays. Results: Treatment of U937 cells with CPX-351 resulted in phosphorylation of Chk1 on Ser317 and Ser296 (sites of ATR-mediated phosphorylation and autophosphorylation, respectively) as well as S phase slowing consistent with Chk1 activation. Co-treatment of AML cell lines with Chk1 inhibitors + CPX-351 resulted in increased apoptotic morphological changes and DNA fragmentation as well as diminished clonogenic survival compared to CPX-351 alone. The CPX-351/MK-8776 combination displayed enhanced antiproliferative effects against some clinical AML isolates ex vivo compared to CPX-351 alone, with additional assays ongoing. Conclusions: Collectively, these results show that Chk1 inhibition enhances the cytotoxicity of CPX-351 in AML cell lines and some clinical AML samples, offering the possibility that CPX-351 may be well suited for combining with such molecularly targeted agents. Citation Format: Nicole D. Vincelette, Larry M. Karnitz, Judith E. Karp, Douglas B. Smith, Allan D. Hess, Lawrence D. Mayer, Scott H. Kaufmann. CPX-351 (cytarabine:daunorubicin liposome for injection) anti-leukemia activity is potentiated by Chk1 inhibition. [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 3479. doi:10.1158/1538-7445.AM2015-3479

Metastatic cutaneous melanoma has poor prognosis with 2-year survival rate of 10–20%. Melanoma cells express various antigens including gp100, melanoma antigen recognized by T cells 1 (MART-1), and tyrosinase, which can induce immune-mediated anticancer response via T cell activation. Cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) is an immune check point molecule that negatively regulates T cell activation and proliferation. Accordingly, recent phase III clinical trials demonstrated significant survival benefit with ipilimumab, a human monoclonal antibody (IgG1) that blocks the interaction of CTLA-4 with its ligands. Since the efficacy of ipilimumab depends on T cell activation, it is associated with substantial risk of immune mediated adverse reactions such as colitis, hepatitis, thyroiditis, and hypophysitis. We report the first case of late onset pericarditis and cardiac tamponade associated with ipilimumab treatment in patient with metastatic cutaneous melanoma.

We describe a case of a 73-year-old man who presented with right-sided abdominal pain associated with palpable mass. Initial laboratory examination was normal except lactate dehydrogenase level. Subsequent CT image showed situs inversus and splenic mass with multiple lymph nodes enlargement. Biopsy taken from the splenic mass demonstrated mantle cell lymphoma. Staging CT examination was performed with intravenous contrast, and patient developed altered mental status, respiratory failure and acute kidney injury requiring intensive care unit care. Laboratory examination revealed hyperuricaemia, hyperphosphataemia, hyperkalaemia and hypocalcaemia, which are consistent with spontaneous tumour lysis syndrome. The patient was successfully treated with rasburicase and haemodialysis, and completed the first course of chemotherapy without further complications.