Selinexor in Combination with R-CHOP for Frontline Treatment of Non-Hodgkin Lymphoma: Results of a Phase I Study

PURPOSE

The nuclear exporter protein exportin-1 (XPO1) is overexpressed in non-Hodgkin lymphoma (NHL) and correlates with poor prognosis. We evaluated enhancing R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) activity in NHL by targeted inhibition of XPO1 using the selective inhibitor of nuclear export (SINE) compounds.

PATIENTS AND METHODS

We evaluated the antitumor activity of SINE compounds in combination with CHO chemotherapy in vitro and in vivo. Newly diagnosed NHL patients in a phase I dose-escalation study received R-CHOP for 6 cycles with weekly selinexor (60, 80, and 100 mg), then selinexor maintenance therapy for one year. RT-PCR, Western blotting, and RNA sequencing were performed on patient blood samples.

RESULTS

SINE compounds synergized with CHO in vitro in NHL cell lines and in vivo in our murine xenograft model. In our phase I study, selinexor was dosed at 60 mg (n = 6) and 80 mg (n = 6). The most common adverse events (AE) among 12 patients were fatigue (67%) and nausea (100%). Grade 3-4 AEs were infrequent. Ten evaluable patients had an overall response rate of 100% and complete remission rate of 90% with sustained remissions (median follow-up: 476 days). Maximally tolerated dose was not reached; however, the recommended phase II dose was 60 mg selinexor weekly after evaluating tolerability and discontinuation rates for each dose cohort. Analysis of patient blood samples revealed downregulation of XPO1 and several prosurvival markers.

CONCLUSIONS

SINE compounds enhance the activity of CHO in vitro and in vivo. Selinexor in combination with R-CHOP was generally well tolerated and showed encouraging efficacy in NHL (NCT03147885).

Abstract 3438: Selective inhibitors of Mcl-1 with potent activity against multiple myeloma patient cells and animal xenografts

To date most of the studies targeting apoptotic machinery have focused on inhibiting Bcl2 and BclXL proteins that have shown limited clinical utility. This could be in part due to the over-expression of Myeloid Leukemia-1 (Mcl-1) that carries similar anti-apoptotic functions. Our recent evaluations of Multiple Myeloma (MM) patient derived samples have shown consistent over-expression of Mcl-1 suggesting that it is an attractive therapeutic target. We have discovered a novel druggable site in Mcl-1 protein. Using structure based drug design we have developed small molecule inhibitors (SMIs) of Mcl-1 that bind with high affinity to the BH-3 hydrophobic groove of the protein thereby displacing different pro-apoptotic partners such as Bax, Bak, Bok and Bid with activity against MM cells (IC50 5 μM) and anti-tumor activity in animal xenografts. The lead SMI (UMI-77) inhibits growth and induces apoptosis in MM cells. Molecular analysis of MM cells reveals activation of pro-apoptotic factors post UMI-77 treatment. Co-immunoprecipitation studies show that UMI-77 disrupts the Mcl-1-Bax and Mcl-1-Bak interactions. The drug synergizes with standard proteasome inhibitor Velcade (5 nM) and Carfilosimib (1 nM). In patient derived MM cells (n=45), UMI-77 inhibits growth and induces apoptosis that is concurrent with induction of Bax, Bak and enhancement in cleaved fractions of caspases 3 and 9. At similar concentrations UMI-77 does not affect normal peripheral lymphocytes. UMI-77 is well tolerated by animals at MTD (60 mg/kg i.v.). In a mice lymphoma model, oral administration of UMI-77 significantly reduced tumor growth and histological examination of tumors revealed suppression of Mcl-1 protein expression along with enhancement of pro-apoptotic markers. Our novel Mcl-1 inhibitors provide a new therapeutic option for cancers for MM that overexpress Mcl-1 that have failed standard therapies.

Citation Format: Asfar S. Azmi, Zaneta Nikolovka-Coleska, Muneer Abidi, Kelley Marsack, Ashiq Masood, Hiroshi Yano, Silvana Pregja, Jeffrey Zonder, Ramzi M. Mohammad. Selective inhibitors of Mcl-1 with potent activity against multiple myeloma patient cells and animal xenografts. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3438. doi:10.1158/1538-7445.AM2013-3438