FAS-antisense 1 lncRNA and production of soluble versus membrane Fas in B-cell lymphoma

Impaired Fas-mediated apoptosis is associated with poor clinical outcomes and cancer chemoresistance. Soluble Fas receptor (sFas), produced by skipping of exon 6, inhibits apoptosis by sequestering Fas ligand. Serum sFas is associated with poor prognosis of non-Hodgkin's lymphomas. We found that the alternative splicing of Fas in lymphomas is tightly regulated by a long-noncoding RNA corresponding to an antisense transcript of Fas (FAS-AS1). Levels of FAS-AS1 correlate inversely with production of sFas, and FAS-AS1 binding to the RBM5 inhibits RBM5-mediated exon 6 skipping. EZH2, often mutated or overexpressed in lymphomas, hyper-methylates the FAS-AS1 promoter and represses the FAS-AS1 expression. EZH2-mediated repression of FAS-AS1 promoter can be released by DZNeP (3-Deazaneplanocin A) or overcome by ectopic expression of FAS-AS1, both of which increase levels of FAS-AS1 and correspondingly decrease expression of sFas. Treatment with Bruton's tyrosine kinase inhibitor or EZH2 knockdown decreases the levels of EZH2, RBM5 and sFas, thereby enhancing Fas-mediated apoptosis. This is the first report showing functional regulation of Fas repression by its antisense RNA. Our results reveal new therapeutic targets in lymphomas and provide a rationale for the use of EZH2 inhibitors or ibrutinib in combination with chemotherapeutic agents that recruit Fas for effective cell killing.

EPOCH-F: A salvage regimen for multiple myeloma prior to reduced intensity allogenic hematopoietic stem cell transplantation

8592

Background: Variation in baseline host immune status contributes to inconsistent donor engraftment and may impede maximal graft-versus-myeloma effects after reduced intensity allogenic hematopoietic stem cell transplantation (RIHSCT) for advanced multiple myeloma (MM). As no specific salvage regimen has been designed for MM patients being considered for RIHSCT, we evaluated EPOCH-F a novel salvage regimen designed to provide disease control and immune depletion. Methods: EPOCH-F is an infusional chemotherapeutic regimen consisting of etoposide, vincristine and adriamycin, with prednisone, cyclophosphamide and fludarabine given in 21 day cycles prior to RIHSCT. Targeting a CD4+ T cell count, 22 pts were treated <5 cycles of EPOCH-F. Pts proceeded to RIHSCT after adequate lymphodepletion or if there was disease progression during EPOCH-F, regardless of CD4 count. Results: Median age was 53 years (range 36–65); median time from initial therapy to transplant was 12 months (range 2–168). Median number of prior therapies was 2 (range 1–8), 63% had chemotherapy sensitive disease and 68% had received a novel agent. Pts received a median of 3 cycles (range 1–5), with manageable toxicities, mostly hematologic. Grade IV Neutropenia was seen in 77% of the administered cycles with only 6 episodes of neutropenic fever. Median lymphocyte count decreased from 1423/μL (range 335–2788) to 519/μL (range 102–1420); CD4 count decreased from 320/μL (range 130–1366) to 115/μL (30–309). In 21 evaluable pts, the ≥PR rate to EPOCH-F was 22% with 13% CR/nCR. 68% had SD and only 1 pt progressed. 20 pts underwent RIHSCT from HLA matched sibling. Median Day 100 chimerism was 100% (range 60–100, mean 95). 70% of patients achieved ≥VGPR and CR/nCR was seen in 40%. Acute GVHD (grade II-IV) was seen in 47% and chronic GVHD (grade III-IV) was seen in 52% of the pts. TRM at 100 days was 5% and 30% at 60 months. Median overall survival of patients after RIHSCT was 46.1 months. Conclusions: EPOCH-F is an active regimen which provides pre-transplantation lympho-depletion, disease control and allows consistent engraftment in multiple myeloma patients undergoing RIHSCT.

No significant financial relationships to disclose.

A phase II study of a novel oral isotype-selective histone deacetylase (HDAC) inhibitor in patients with relapsed or refractory Hodgkin lymphoma

8000

Background: MGCD0103 is a non-hydroxamate, isotype-selective, inhibitor of human HDACs. Abnormal regulation of HDAC activity is associated with malignant disease in humans, and small molecule HDAC inhibitors are a novel drug class with anticancer potential. Their proposed anti-Hodgkin activity is through regulation of aberrant gene expression at the transcriptional level by inhibiting proliferation, inducing apoptosis, and/or initiating differentiation in cancer cells. Methods: A phase II trial of MGCD0103 (110 mg 3x/week in 4- week cycles) is ongoing in patients (pts) with relapsed/refractory Hodgkin Lymphoma (RRHL). The primary endpoint is a composite of objective response and stable disease. Results: As of Dec 15th, 2006, 18 pts out of a planned 12–35 have been enrolled; median age 28 (range: 21–62). All pts were previously treated with autologous and/or allogeneic stem cell transplant. The median number of cycles received to date is 2 (range: 1–4). Seven pts have completed =8 weeks (2 cycles) of therapy and are evaluable for response analysis; 5 of these had tumor reduction ranging between 21% and 70% by CT, which is associated with a significant reduction in FDG-PET activity in 4 pts. Of the 18 pts, 5 have had dose reductions/discontinuations due to: mucositis (n=1); fatigue/nausea/diarrhea (n=1); nausea/vomiting (n=1); fatigue (n=1) and pancreatitis/hypotension (n=1). Significant HDAC inhibition (>20% of total activity), was seen in PBMCs from 7/9 pts with samples. Treatment is ongoing in 14 pts; including those with tumor reduction. Criteria have been met to expand to the second stage of the study (>1 response demonstrated in the first 12 patients). Conclusions: Preliminary results suggest that single-agent MGCD0103 demonstrates significant anti-tumor activity in RRHL and is well tolerated at a Phase II dose of 110mg in this ongoing trial.

No significant financial relationships to disclose.

A phase I/II study of lenalidomide (Len) in combination with rituximab (R) in relapsed/refractory mantle cell lymphoma (MCL) with early evidence of efficacy

8030

Background: MCL remains a therapeutic challenge. R targets CD20 antigen on MCL cells while Len may target the microenvironment of MCL cells and enhance the ADCC activity of R. To test this hypothesis, we initiated a single-center; open label, phase I/II study. We now report the completed phase I. Methods: Eligible patients (pts) had 1–4 lines of prior therapy including prior thalidomide or R, regardless of resistance. Each cycle of treatment consisted of Len given orally daily on days 1–21 of a 28-day cycle and R 375 mg/m2 by IV infusion weekly for 4 weeks. A standard 3+3 dose escalation was used to determine MTD with Len doses at 10 mg, 15 mg, 20 mg, and 25 mg. DLT was defined as grade (G) 3 or 4 non-hematologic or G4 hematologic toxicity during the first cycle. Results: The phase I portion completed enrollment with 15 pts (4 at 10 mg, 3 at 15 mg, 6 at 20 mg and 2 at 25 mg). Thirteen pts were evaluable. Median age was 73 (62–84); median prior lines of therapy were 3 (1–4); median cycles received to date were 2 (1–7). Two DLT's occurred at 25 mg. One pt had G3 hypercalcemia. The other had G4 neutropenic fever and died of sepsis (G5) during the first cycle. Three additional pts were therefore enrolled at 20 mg. Common non-hematologic toxic events included pruritis (21 G1–2), hypercalcemia (9 G1–2, 1 G3), fatigue (9 G1–2), constipation (8 G1), diarrhea (6 G1–2), fever (6 G1–2), myalgias (4 G1–2, 1 G3) and elevated LDH (4 G1–2, 1 G3). Hematologic events included neutropenia (20 G1–2, 4 G3), thrombocytopenia (6 G1–2, 2 G3) and anemia (6 G1). There were no responses at 10 mg or 15 mg. At 20 mg after 2 cycles, 5 out of 6 pts achieved responses including 1 CR, 1 PR, 3 minor responses (MRs) and only 1 pt progressed. The 1 pt with PR went on to achieve a CR after 6 cycles. The 3 pts with MRs had tumor reductions by 43%, 40% and 38% respectively. These 3 patients with MRs continue to receive Len and might later achieve PR or CR. Conclusions: The MTD for Len with R in relapsed/refractory MCL was 20 mg, orally daily on days 1–21 of a 28-day cycle. Responses observed at 20 mg are promising with a favorable toxicity profile and are being evaluated further in an ongoing phase II study.

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