Kate J. Newberry

Targeting BTK with Ibrutinib in Relapsed or Refractory Mantle-Cell Lymphoma

BACKGROUND Brutons tyrosine kinase (BTK) is a mediator of the B-cell-receptor signaling pathway implicated in the pathogenesis of B-cell cancers. In a phase 1 study, ibrutinib, a BTK inhibitor, showed antitumor activity in several types of non-Hodgkins lymphoma, including mantle-cell lymphoma. METHODS In this phase 2 study, we investigated oral ibrutinib, at a daily dose of 560 mg, in 111 patients with relapsed or refractory mantle-cell lymphoma. Patients were enrolled into two groups: those who had previously received at least 2 cycles of bortezomib therapy and those who had received less than 2 complete cycles of bortezomib or had received no prior bortezomib therapy. The primary end point was the overall response rate. Secondary end points were duration of response, progression-free survival, overall survival, and safety. RESULTS The median age was 68 years, and 86% of patients had intermediate-risk or high-risk mantle-cell lymphoma according to clinical prognostic factors. Patients had received a median of three prior therapies. The most common treatment-related adverse events were mild or moderate diarrhea, fatigue, and nausea. Grade 3 or higher hematologic events were infrequent and included neutropenia (in 16% of patients), thrombocytopenia (in 11%), and anemia (in 10%). A response rate of 68% (75 patients) was observed, with a complete response rate of 21% and a partial response rate of 47%; prior treatment with bortezomib had no effect on the response rate. With an estimated median follow-up of 15.3 months, the estimated median response duration was 17.5 months (95% confidence interval [CI], 15.8 to not reached), the estimated median progression-free survival was 13.9 months (95% CI, 7.0 to not reached), and the median overall survival was not reached. The estimated rate of overall survival was 58% at 18 months. CONCLUSIONS Ibrutinib shows durable single-agent efficacy in relapsed or refractory mantle-cell lymphoma. (Funded by Pharmacyclics and others; ClinicalTrials.gov number, NCT01236391.)

Lenalidomide in combination with rituximab for patients with relapsed or refractory mantle-cell lymphoma: a phase 1/2 clinical trial

BACKGROUND The combination of rituximab and lenalidomide has shown promise for the treatment of mantle-cell lymphoma (MCL) in preclinical studies. We aimed to identify the maximum tolerated dose (MTD) of lenalidomide when combined with rituximab in a phase 1 trial and to assess the efficacy and safety of this combination in a phase 2 trial in patients with relapsed or refractory MCL. METHODS Patients with relapsed or refractory MCL who had received one to four previous lines of treatment were enrolled in this single-arm, open-label, phase 1/2 trial at MD Anderson Cancer Center. In phase 1, to identify the MTD of lenalidomide, four patient cohorts received escalating doses (10, 15, 20, and 25 mg) of daily oral lenalidomide on days 1-21 of each 28-day cycle. 375 mg/m(2) intravenous rituximab was also administered in four weekly doses during cycle 1 only. In phase 2, patients received rituximab plus the MTD of lenalidomide, following the same cycles as for phase 1. Treatment in both phases continued until disease progression, stem-cell transplantation, or severe toxicity. The primary efficacy endpoint was overall response (complete or partial response). The secondary efficacy endpoint was survival. We used the Kaplan-Meier method to estimate response duration, progression-free survival, and overall survival. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00294632. FINDINGS 52 patients were enrolled between Feb 10, 2006 and July 30, 2009, 14 in phase 1 and 44 (including six patients who received the MTD of lenalidomide in the phase 1 portion) in phase 2. The MTD was 20 mg lenalidomide. One patient who was treated with 25 mg lenalidomide developed a grade 4 non-neutropenic infection and died. In the phase 2 portion of the study, grade 3-4 haematological toxicities included neutropenia (29 patients), lymphopenia (16 patients), leucopenia (13 patients), and thrombocytopenia (ten patients). There were only two episodes of febrile neutropenia. Among 44 patients in phase 2, 25 (57%) had an overall response: 16 (36%) had a complete response and nine (20%) had a partial response. The median response duration was 18·9 months (95% CI 17·0 months to not reached [NR]). The median progression-free survival was 11·1 months (95% CI 8·3 to 24·9 months), and the median overall survival was 24·3 months (19·8 months to NR). Five of 14 patients who had received bortezomib treatment before enrolment achieved an overall response. INTERPRETATION Oral lenalidomide plus rituximab is well tolerated and effective for patients with relapsed or refractory MCL. FUNDING Celgene.

Oral lenalidomide with rituximab in relapsed or refractory diffuse large cell, follicular and transformed lymphoma: a phase II clinical trial

Lenalidomide–rituximab therapy is effective in grade 1–2 follicular and mantle cell lymphoma, but its efficacy in diffuse large B-cell lymphoma (DLBCL), transformed large cell lymphoma (TL) and grade 3 follicular lymphoma (FLG3) is unknown. In this phase II trial, 45 patients with relapsed or refractory DLBCL (n=32), TL (n=9) or FLG3 (n=4) who had received 1–4 prior lines of treatment were given 20 mg oral lenalidomide on days 1–21 of each 28-day cycle, and intravenous rituximab (375 mg/m2) weekly during cycle 1. Grade 3/4 hematological toxicities included neutropenia (53%), lymphopenia (40%), thrombocytopenia (33%), leukopenia (27%) and anemia (18%), with a median follow-up time of 29.1 months (range 14.7–52.0 months). Overall response (OR) rate was 33%; median response duration was 10.2 months. Median progression-free survival (PFS) and overall survival (OS) were 3.7 and 10.7 months, respectively. Nine of the 15 responding patients (three partial response (PR), six complete response (CR)) proceeded with stem cell transplantation (SCT) and were censored at the time of transplantation. When data were analyzed without censoring, median PFS remained 3.7 months and response duration increased to 30.9 months. Rituximab plus oral lenalidomide is well tolerated and effective for patients with relapsed/refractory DLBCL and TL. SCT after lenalidomide–rituximab is associated with prolonged response duration.

Correlation of mutation profile and response in patients with myelofibrosis treated with ruxolitinib

Although most patients with myelofibrosis (MF) derive benefit from ruxolitinib, some are refractory, have a suboptimal response, or quickly lose their response. To identify genes that may predict response to ruxolitinib, we performed targeted next-generation sequencing (NGS) of a panel of 28 genes recurrently mutated in hematologic malignancies in a cohort of patients with MF who were treated with ruxolitinib in a phase 1/2 study. We also tested for CALR deletions by standard polymerase chain reaction methods. Ninety-eight percent of patients had a mutation in ≥1 gene. Seventy-nine (82.1%) patients had the JAK2(V617F) mutation, 9 (9.5%) had CALR mutations (7 type 1, 2 type 2), 3 (3.1%) had MPL mutations, and 4 (4.2%) were negative for all 3. ASXL1/JAK2 and TET2/JAK2 were the most frequently comutated genes. Mutations in NRAS, KRAS, PTPN11, GATA2, TP53, and RUNX1 were found in <5% of patients. Spleen response (≥50% reduction in palpable spleen size) was inversely correlated with the number of mutations; patients with ≤2 mutations had ninefold higher odds of a spleen response than those with ≥3 mutations (odds ratio = 9.37; 95% confidence interval, 1.86-47.2). Patients with ≥3 mutations also had a shorter time to treatment discontinuation and shorter overall survival than those with fewer mutations. In multivariable analysis, only number of mutations and spleen response remained associated with time to treatment discontinuation. Patients with ≥3 mutations had the worst outcomes, suggesting that multigene profiling may be useful for therapeutic planning for MF.

Promoter Recognition by a Complex of Spx and the C-Terminal Domain of the RNA Polymerase α Subunit

Background Spx, an ArsC (arsenate reductase) family member, is a global transcriptional regulator of the microbial stress response and is highly conserved amongst Gram-positive bacteria. Bacillus subtilis Spx protein exerts positive and negative control of transcription through its interaction with the C-terminal domain of the RNA polymerase (RNAP) α subunit (αCTD). Spx activates trxA (thioredoxin) and trxB (thioredoxin reductase) in response to thiol stress, and bears an N-terminal C10XXC13 redox disulfide center that is oxidized in active Spx. Methodology/Principal Findings The structure of mutant SpxC10S showed a change in the conformation of helix α4. Amino acid substitutions R60E and K62E within and adjacent to helix α4 conferred defects in Spx-activated transcription but not Spx-dependent repression. Electrophoretic mobility-shift assays showed αCTD interaction with trxB promoter DNA, but addition of Spx generated a supershifted complex that was disrupted in the presence of reductant (DTT). Interaction of αCTD/Spx complex with promoter DNA required the cis-acting elements -45AGCA-42 and -34AGCG-31 of the trxB promoter. The SpxG52R mutant, defective in αCTD binding, did not interact with the αCTD-trxB complex. SpxR60E not only failed to complex with αCTD-trxB, but also disrupted αCTD-trxB DNA interaction. Conclusions/Significance The results show that Spx and αCTD form a complex that recognizes the promoter DNA of an Spx-controlled gene. A conformational change during oxidation of Spx to the disulfide form likely alters the structure of Spx α helix α4, which contains residues that function in transcriptional activation and αCTD/Spx-promoter interaction. The results suggest that one of these residues, R60 of the α4 region of oxidized Spx, functions in αCTD/Spx-promoter contact but not in αCTD interaction.

Structures of BmrR-Drug Complexes Reveal a Rigid Multidrug Binding Pocket and Transcription Activation through Tyrosine Expulsion

BmrR is a member of the MerR family and a multidrug binding transcription factor that up-regulates the expression of the bmr multidrug efflux transporter gene in response to myriad lipophilic cationic compounds. The structural mechanism by which BmrR binds these chemically and structurally different drugs and subsequently activates transcription is poorly understood. Here, we describe the crystal structures of BmrR bound to rhodamine 6G (R6G) or berberine (Ber) and cognate DNA. These structures reveal each drug stacks against multiple aromatic residues with their positive charges most proximal to the carboxylate group of Glu-253 and that, unlike other multidrug binding pockets, that of BmrR is rigid. Substitution of Glu-253 with either alanine (E253A) or glutamine (E253Q) results in unpredictable binding affinities for R6G, Ber, and tetraphenylphosphonium. Moreover, these drug binding studies reveal that the negative charge of Glu-253 is not important for high affinity binding to Ber and tetraphenylphosphonium but plays a more significant, but unpredictable, role in R6G binding. In vitro transcription data show that E253A and E253Q are constitutively active, and structures of the drug-free E253A-DNA and E253Q-DNA complexes support a transcription activation mechanism requiring the expulsion of Tyr-152 from the multidrug binding pocket. In sum, these data delineate the mechanism by which BmrR binds lipophilic, monovalent cationic compounds and suggest the importance of the redundant negative electrostatic nature of this rigid drug binding pocket that can be used to discriminate against molecules that are not substrates of the Bmr multidrug efflux pump.

Role of neoplastic monocyte-derived fibrocytes in primary myelofibrosis.

Estrov and collaborators examine the role of fibrocytes in primary myelofibrosis and propose a novel therapeutic approach.

Phase II evaluation of IPI-926, an oral Hedgehog inhibitor, in patients with myelofibrosis

Abstract The clinical safety and efficacy of IPI-926 was evaluated in 14 patients with myelofibrosis in a phase II study. Patients received 160 mg IPI-926 orally in continuous 28-day cycles. The median treatment duration was 5.1 months, and all patients had discontinued treatment by 7.5 months. Nine patients discontinued due to lack of response as determined by the treating physician, two after developing acute leukemia and one due to disease progression/loss of response. Twelve patients had slight reductions in spleen size (less than 50% from baseline), but symptoms did not improve consistently. One patient achieved transfusion independence lasting 5 months. Reductions in GLI1 mRNA and protein levels, JAK2V617F allele burden, degree of fibrosis or cytokine levels were observed in some patients, but were not significant when evaluated for the cohort. Low-grade gastrointestinal/liver abnormalities were the most common toxicities. The results did not support continued evaluation of IPI-926 as a monotherapy in myelofibrosis.

A Phase I/II Study of the Janus Kinase (JAK)1 and 2 Inhibitor Ruxolitinib in Patients With Relapsed or Refractory Acute Myeloid Leukemia

BACKGROUND Ruxolitinib is a potent and specific JAK1/JAK2 inhibitor recently approved for the treatment of myelofibrosis. PATIENTS AND METHODS We conducted a single-center phase I/II clinical study testing 3 dose levels (50 mg b.i.d. [n = 4], 100 mg b.i.d. [n = 5], and 200 mg b.i.d. [n = 18]). We enrolled 27 patients older than 14 years with relapsed or refractory acute myeloid leukemia (n = 26) or acute lymphoid leukemia (n = 1). RESULTS The median age was 66 (range, 25-88) years. Thirteen patients were evaluable for dose-limiting toxicities. The most common Grade 3 or 4 nonhematologic event was infection (n = 26 events; most frequently pneumonia; 15 of 26; 58%). One patient with multiple relapses after 7 lines of therapy had a CRp at a ruxolitinib dose of 200 mg b.i.d. CONCLUSION In this cohort of heavily pretreated patients with relapsed or refractory acute leukemias, ruxolitinib was overall reasonably well tolerated, with 1 patient achieving CRp.

Therapeutic benefit of decitabine, a hypomethylating agent, in patients with high-risk primary myelofibrosis and myeloproliferative neoplasm in accelerated or blastic/acute myeloid leukemia phase

Myeloproliferative neoplasm (MPN) transformed to acute myeloid leukemia (MPN-AML), MPN in accelerated phase (MPN-AP), and high-risk primary myelofibrosis (PMF) are associated with a poor response to therapy and very short survival. Several reports have suggested clinical activity of hypomethylating agents in these patients. We conducted a retrospective study of 21 patients with MPN-AML, 13 with MPN-AP and 11 with DIPSS-plus high-risk PMF treated with decitabine at our institution over the last 7 years and evaluated their clinical outcomes. Six patients (29%) with MPN-AML responded to decitabine (3 CR, 2 CRi, and 1 PR); median response duration was 7 months. The median overall survival (OS) was significantly higher in those who responded (10.5 vs 4 months). Among patients with MPN-AP, 8 patients (62%) benefited; the median response duration was 6.5 months. The median OS was 11.8 months in responders vs 4.7 months in non-responders. Among patients with DIPSS-plus high-risk PMF, 9 (82%) benefited; the median response duration was 9 months. The median OS was 32 months in responders vs 16.3 months in non-responders. Decitabine is a viable therapeutic option for patients with MPN-AML, MP-AP and high-risk PMF. Prospective clinical studies combining decitabine with other clinically active agents are needed to improve overall outcome.