Abdulraheem Yacoub

Phase 1/2 study of cyclin-dependent kinase (CDK)4/6 inhibitor palbociclib (PD-0332991) with bortezomib and dexamethasone in relapsed/refractory multiple myeloma

This phase 1/2 study was the first to evaluate the safety and efficacy of the cyclin-dependent kinase (CDK) 4/6–specific inhibitor palbociclib (PD-0332991) in sequential combination with bortezomib and dexamethasone in relapsed/refractory multiple myeloma. The recommended phase 2 dose was palbociclib 100 mg orally once daily on days 1–12 of a 21-day cycle with bortezomib 1.0 mg/m2 (intravenous) and dexamethasone 20 mg (orally 30 min pre-bortezomib dosing) on days 8 and 11 (early G1 arrest) and days 15 and 18 (cell cycle resumed). Dose-limiting toxicities were primarily cytopenias; most other treatment-related adverse events were grade ≤ 3. At a bortezomib dose lower than that in other combination therapy studies, antitumor activity was observed (phase 1). In phase 2, objective responses were achieved in 5 (20%) patients; 11 (44%) achieved stable disease. Biomarker and pharmacodynamic assessments demonstrated that palbociclib inhibited CDK4/6 and the cell cycle initially in most patients.

The efficacy and safety of continued hydroxycarbamide therapy versus switching to ruxolitinib in patients with polycythaemia vera: a randomized, double-blind, double-dummy, symptom study (RELIEF)

The randomized, double‐blind, double‐dummy, phase 3b RELIEF trial evaluated polycythaemia vera (PV)‐related symptoms in patients who were well controlled with a stable dose of hydroxycarbamide (also termed hydroxyurea) but reported PV‐related symptoms. Patients were randomized 1:1 to ruxolitinib 10 mg BID (n = 54) or hydroxycarbamide (prerandomization dose/schedule; n = 56); crossover to ruxolitinib was permitted after Week 16. The primary endpoint, ≥50% improvement from baseline in myeloproliferative neoplasm ‐symptom assessment form total symptom score cytokine symptom cluster (TSS‐C; sum of tiredness, itching, muscle aches, night sweats, and sweats while awake) at Week 16, was achieved by 43·4% vs. 29·6% of ruxolitinib‐ and hydroxycarbamide‐treated patients, respectively (odds ratio, 1·82; 95% confidence interval, 0·82–4·04; P = 0·139). The primary endpoint was achieved by 34% of a subgroup who maintained their hydroxycarbamide dose from baseline to Weeks 13–16. In a post hoc analysis, the primary endpoint was achieved by more patients with stable screening‐to‐baseline TSS‐C scores (ratio ≤ 2) receiving ruxolitinib than hydroxycarbamide (47·4% vs. 25·0%; P = 0·0346). Ruxolitinib treatment after unblinding was associated with continued symptom score improvements. Adverse events were primarily grades 1/2 with no unexpected safety signals. Ruxolitinib was associated with a nonsignificant trend towards improved PV‐related symptoms versus hydroxycarbamide, although an unexpectedly large proportion of patients who maintained their hydroxycarbamide dose reported symptom improvement.

Targeting HSF1 disrupts HSP90 chaperone function in chronic lymphocytic leukemia

CLL is a disease characterized by chromosomal deletions, acquired copy number changes and aneuploidy. Recent studies have shown that overexpression of Heat Shock Factor (HSF) 1 in aneuploid tumor cells can overcome deficiencies in heat shock protein (HSP) 90-mediated protein folding and restore protein homeostasis. Interestingly, several independent studies have demonstrated that HSF1 expression and activity also affects the chaperoning of HSP90 kinase clients, although the mechanism underlying this observation is unclear. Here, we determined how HSF1 regulates HSP90 function using CLL as a model system. We report that HSF1 is overexpressed in CLL and treatment with triptolide (a small molecule inhibitor of HSF1) induces apoptosis in cultured and primary CLL B-cells. We demonstrate that knockdown of HSF1 or its inhibition with triptolide results in the reduced association of HSP90 with its kinase co-chaperone cell division cycle 37 (CDC37), leading to the partial depletion of HSP90 client kinases, Brutons Tyrosine Kinase (BTK), c-RAF and cyclin-dependent kinase 4 (CDK4). Treatment with triptolide or HSF1 knockdown disrupts the cytosolic complex between HSF1, p97, HSP90 and the HSP90 deacetylase- Histone deacetylase 6 (HDAC6). Consequently, HSF1 inhibition results in HSP90 acetylation and abrogation of its chaperone function. Finally, tail vein injection of Mec-1 cells into Rag2−/−IL2Rγc−/− mice followed by treatment with minnelide (a pro-drug of triptolide), reduced leukemia, increased survival and attenuated HSP90-dependent survival signaling in vivo. In conclusion, our study provides a strong rationale to target HSF1 and test the activity of minnelide against human CLL.

Correlation between markers of bone metabolism and vitamin D levels in patients with monoclonal gammopathy of undetermined significance (MGUS)

Multiple myeloma (MM) lies along a spectrum of plasma cell disorders and represents the incurable malignant phase of disease. MM is felt to be uniformly preceded by an asymptomatic clonal disease called monoclonal gammopathy of undetermined significance (MGUS) that carries a lifelong risk of disease progression. While we are currently unable to predict which patients with MGUS will develop MM, the Mayo group has devised a risk stratification system to help in predicting patients with a higher risk of disease progression. Smoldering multiple myeloma (SMM) is distinguished from MGUS by a higher burden of plasma cells and an increased risk of progression to MM. There is currently no treatment for MGUS or SMM, and no treatment has been proven to reduce the risk of disease progression, though SMM remains an area of active research. Alterations in bone metabolism, mediated in part through upregulation of receptor activator of nuclear factor κβ (RANKL) and the decoy receptor osteoprotegrin (OPG), via effects on osteoblasts and osteoclastogenesis are common to both MM and MGUS and may play a role in disease progression. While patients with MGUS and SMM are generally felt to be asymptomatic, these patients do have an increased risk of bone fracture, linked to decreased bone strength and altered bone architecture. Vitamin D is a key regulator of bone metabolism associated with progressive disease in several malignancies, including MM. Dysregulation of RANKL and OPG correlates with disease activity and decreased survival, and has also been linked to altered bone metabolism in MGUS. Based on the abnormal bone metabolism observed in patients with MGUS and the central role for vitamin D in bone metabolism, we hypothesized that abnormal bone metabolism would correlate with disease risk in MGUS and that vitamin D supplementation would improve bone metabolism and markers of disease. We investigated this hypothesis by correlating the vitamin D level with the risk category of MGUS and markers of bone metabolism, RANKL and OPG. We further evaluated the impact of vitamin D supplementation on RANKL and OPG levels, as well as markers of disease activity, including serum protein electrophoresis (SPEP) and free light chains (FLCs). In this open-label trial, 50 patients with MGUS or SMM per the International Myeloma Working Group criteria who were older than 18 years of age were recruited to this study from a plasma cell dyscrasia clinic between June 2012 and November 2014. Patients with a history of osteoporosis, or other bone diseases, bisphosphonate usage within 1 year or glucocorticoid use within 3 months, pregnant patients, patients on bile acid sequestrants, anticonvulsive, or antiretroviral therapy, and patients with a history of malignancy other than in situ cancers within 5 years were excluded. Patients were stratified into two groups based on risk of disease progression, those with 0 or 1 risk factor for progression (low risk or intermediate-1 risk) vs. those with 2 or 3 risk factors (intermediate-2 or high risk), or SMM. Per the Mayo risk stratification system, possible risk factors include a non-IgG isotype, an IgG paraprotein level >1.5 g/dL, and an abnormal FLC ratio. Ethical approval for

Ibrutinib as Treatment for Patients With Relapsed/Refractory Follicular Lymphoma: Results From the Open-Label, Multicenter, Phase II DAWN Study

Purpose The Brutons tyrosine kinase inhibitor ibrutinib has demonstrated clinical activity in B-cell malignancies. The DAWN study assessed the efficacy and safety of single-agent ibrutinib in chemoimmunotherapy relapsed/refractory follicular lymphoma (FL) patients. Methods DAWN was an open-label, single-arm, phase II study of ibrutinib in patients with FL with two or more prior lines of therapy. Patients received ibrutinib 560 mg daily until progressive disease/unacceptable toxicity. The primary objective was independent review committee-assessed overall response rate (ORR; complete response plus partial response). Exploratory analyses of T-cell subsets in peripheral blood (baseline/cycle 3) and cytokines/chemokines (baseline/cycle 2) were performed for available samples. Results Between March 2013 and May 2016, 110 patients with a median of three prior lines of therapy were enrolled. At median follow-up of 27.7 months, ORR was 20.9% (95% CI, 13.7% to 29.7%, which did not meet the 18% lower-bound threshold for the primary end point). Twelve patients achieved a complete response (11%; 95% CI, 5.8% to 18.3%). Median duration of response was 19.4 months (range, 1 to ≥ 33 months), with a median progression-free survival of 4.6 months and a 30-month overall survival of 61% (95% CI, 0.51% to 0.70%). Lymphoma symptoms resolved in 67%. Seven of 32 patients who experienced initial radiologic progression responded upon continuing therapy (pseudoprogression). The most common adverse events were diarrhea, fatigue, cough, and muscle spasms; 48.2% of patients reported serious adverse events. In patients who experienced a response, regulatory T cells were downregulated at C3D1 ( P = .02), and Th1-promoting (antitumor) cytokines interferon-γ and interleukin-12 increased ( P ≤ .035). Conclusion With an ORR of 20.9%, ibrutinib failed to meet its primary efficacy end point in chemoimmunotherapy in patients with relapsed/refractory FL, although responses were durable and associated with a reduction in regulatory T cells and increases in proinflammatory cytokines.

Ruxolitinib Therapy Followed by Reduced-Intensity Conditioning for Hematopoietic Cell Transplantation for Myelofibrosis: Myeloproliferative Disorders Research Consortium 114 Study

We evaluated the feasibility of ruxolitinib therapy followed by a reduced-intensity conditioning (RIC) regimen for patients with myelofibrosis (MF) undergoing transplantation in a 2-stage Simon phase II trial. The aims were to decrease the incidence of graft failure (GF) and nonrelapse mortality (NRM) compared with data from the previous Myeloproliferative Disorders Research Consortium 101 Study. The plan was to enroll 11 patients each in related donor (RD) and unrelated donor (URD) arms, with trial termination if ≥3 failures (GF or death by day +100 post-transplant) occurred in the RD arm or ≥6 failures occurred in the URD. A total of 21 patients were enrolled, including 7 in the RD arm and 14 in the URD arm. The RD arm did not meet the predetermined criteria for proceeding to stage II. Although the URD arm met the criteria for stage II, the study was terminated owing to poor accrual and a significant number of failures. In all 19 transplant recipients, ruxolitinib was tapered successfully without significant side effects, and 9 patients (47%) had a significant decrease in symptom burden. The cumulative incidences of GF, NRM, acute graft-versus-host disease (GVHD), and chronic GVHD at 24 months were 16%, 28%, 64%, and 76%, respectively. On an intention-to-treat basis, the 2-year overall survival was 61% for the RD arm and 70% for the URD arm. Ruxolitinib can be integrated as pretransplantation treatment for patients with MF, and a tapering strategy before transplantation is safe, allowing patients to commence conditioning therapy with a reduced symptom burden. However, GF and NRM remain significant.

Biomarker analysis of patients with follicular lymphoma treated with ibrutinib in the phase 2 DAWN study

215 BIOMARKER ANALYSIS OF PATIENTS WITH FOLLICULAR LYMPHOMA TREATED WITH IBRUTINIB IN THE PHASE 2 DAWN STUDY N. Fowler* | A.K. Gopal | S.J. Schuster | J. Trotman | G. Hess | J. Hou | A. Yacoub | M. Lill | P. Martin | U. Vitolo | A. Spencer | J. Radford | W. Jurczak | J. Morton | D. Osmanov | D. Caballero | S. Deshpande | J. Vermeulen | R. Damle | M. Schaffer | S. Balasubramanian | B. Cheson | G. Salles Department of Lymphoma/Myeloma, The University of Texas MD Anderson Cancer Center, Houston, USA; Seattle Cancer Care Alliance, The University of Washington/Fred Hutchison Cancer Research Center, Seattle, USA; Lymphoma Program, Abramson Cancer Center of the University of Pennsylvania, Philadelphia, USA; Concord Hospital, University of Sydney, Haematology Department, Sydney, Australia; Department of Hematology/Oncology, Johannes Gutenberg University, Mainz, Germany; Division of Hematology/Oncology, University of Pittsburgh Medical Center and University of Pittsburgh Cancer Institute, Pittsburgh, USA; Hematologic Malignancies and Cellular Therapeutics, University of Kansas Medical Center, Kansas City, USA; Stem Cell and Bone Marrow Transplant Program, Cedars‐Sinai Medical Center, Los Angeles, USA; Weill Cornell Medical College, Cornell University, New York, USA; Hematology, Azienda Ospedaliero Universitaria Città della Salute e della Scienza di Torino, Turin, Italy; Central Clinical School, Alfred Hospital‐Monash University, Melbourne, Australia; University of Manchester and the Christie NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK; Department of Hematology, Jagiellonian University, Krakow, Poland; Clinical Haemato‐ Oncology, Haematology and Oncology Clinics of Australia, Milton, Australia; Blokhin Cancer Research Center, Russian Academy of Medical Sciences, Moscow, Russian Federation; 16 Instituto Biosanitario de Salamanca, Hospital Clínico Universitario, Salamanca, Spain; Research & Development, Janssen, Raritan, USA; Research & Development, Janssen, Leiden, The Netherlands; Lombardi Comprehensive Cancer Center, Georgetown University Hospital, Washington, District of Columbia, USA; Haematology Department, Hospices Civils de Lyon‐ Université de Lyon, Lyon, France

Abstract 1058: Synergistic activity of p97 inhibitors with histone deacetylase 6 inhibitors in mantle cell lymphoma

p97, or valosin-containing protein (VCP), is an ATPase whose function is essential to restore protein homeostasis in cells. Working in concert with the ubiquitin proteasome system, p97 promotes the retrotranslocation of misfolded proteins from the endoplasmic reticulum and/or their degradation. Consequently, p97 inhibition has emerged as a novel therapeutic target in cancer cells, especially those that depend on high protein turnover and/or ER function. p97 is also present in a complex with many protein complexes including the HSP90, histone deacetylase (HDAC) 6 and heat shock factor 1 (HSF1)-also called the repressive complex. p97 participates in the disaggregation of the repressive complex to regulate HSP90 and HSF1 function under stressed conditions. Accumulation of misfolded polyubiquitylated proteins in the cytosol or on damaged organelles promotes the binding of p97 to polyubiquitylated proteins in an HDAC6-dependent manner and promotes their turnover by autophagic degradation. Given that perturbation of protein homeostasis and ER function induces apoptosis as well as autophagy in B cell malignancies such as multiple myeloma and mantle cell lymphoma (MCL), we hypothesized that inhibition of p97 function in combination with HDAC6 inhibitors would induce proteotoxic stress and/or apoptotic cell death in MCL cells. In this study, we report that the p97 inhibitors DBeQ, ML240 and NMS-873 induce a dose-dependent loss of cell viability in cultured and primary MCL cells. Treatment of MCL cells with ML240 induces the accumulation of polyubiquitylated proteins and induces markers of ER stress such as glucose regulated protein 78 (GRP78) and phosphorylated eukaryotic initiation factor 2 (eIF2) α as well as the autophagic markers LC3-B and p62 (protein whose accumulation is suggestive of reduced autophagic clearance of misfolded proteins). Co-treatment with ML240 and the HDAC6 inhibitor ACY-1215 induces more accumulation of polyubiquitylated proteins and markers of enhanced ER stress as well as autophagy, than either agent alone. Mechanistically we determined that co-treatment with ML240 and ACY-1215 inhibits the binding of p97 to polyubiquitylated proteins and HDAC6, resulting in the reduced clearance of cytotoxic protein aggregates in the cells. Co-treatment with ML240 and ACY-1215 also induces the accumulation of cytosolic polyubiquitylated proteins and their co-localization with LC-3B puncta as demonstrated by immunofluorescent microscopy. These observations are suggestive of enhanced initiation of autophagy but not its completion. Consequently, treatment of MCL cells with ML240 and ACY-1215 resulted in enhanced proteotoxic stress and synergistic apoptotic cell death in MCL cells. Collectively our studies create a strong rationale to test efficacy of the combination of p97 inhibitors in combination with HDAC6 inhibitors in MCL. Citation Format: Rekha M. Rao, Pratikkumar H. Vekaria, Trisha Home, Anusha Vallurupalli, Abdulraheem Yacoub, Frank Schoenen, Joseph McGuirk. Synergistic activity of p97 inhibitors with histone deacetylase 6 inhibitors in mantle cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1058. doi:10.1158/1538-7445.AM2017-1058