Jacobsen, Eric D.

Abstract Introduction: Targeted therapy yields deep and durable response in histiocytic neoplasms.However, relapse rate following interruption is high at 75-77%, with a median time to relapse 6-9 months in previous studies. Outcomes after discontinuation in those who have already achieved a durable response are not well understood and are the focus of this study. Methods: We performed a multicenter retrospective study, including 4 US centers, including patients with histiocytic disorders treated with BRAF inhibitor (BRAFi), MEK inhibitor (MEKi), or combination BRAF/MEKi, and whose therapy was interrupted after ≥12 months of therapy following a best response of partial (PR) or complete response (CR). Progression-free survival (PFS) and overall survival (OS) were analyzed with Kaplan-Meier method. Cox regression was performed to identify clinical and molecular factors that are associated with PFS. Results: 26 patients were included (median age 55 [range 12-72]; male 53.8%; Caucasian 69.2%). Most predominant histology was Erdheim-Chester Disease (ECD) (n=15, 57.5%), followed by mixed histiocytosis (n=5, 19.2%). Rosai-Dorfman Disease (RDD) (n=4, 15.4%), and Langerhans Cell Histiocytosis (LCH) (n=2, 7.7%). All had BRAF V600E analysis and 10 (38.5%) were positive. 19 patients underwent additional molecular testing; alternative mutations identified included MAP2K1/2 (n=6, 23.1%), NRAS (n=1, 3.8%), RAF1 (n=1, 3.8%), ASXL1 (n=1, 3.8%), and SRSF2 (n=1, 3.8%). Targeted therapy was given as frontline therapy (n=8, 30.8%) or in the relapsed refractory setting (n=18, 69.2%) with median 1 prior line of therapy (range 0-7). Targeted therapies include BRAFi (n=5, 19.2%; 2 dabrafenib, 3 vemurafenib), MEKi (n=17, 65.4%; 14 cobimetinib, 3 trametinib), and BRAF/MEKi (n=4, 15.4%; 3 dabrafenib/trametinib, 1 vemurafenib/cobimetinib). PR and CR occurred in 8 (30.8%) and 18 (69.2%) patients, respectively. The median duration of treatment was 32 months (range 13-60) (12-24 months: 9 [34.6%]; 24-36 months: 7 [26.9%]; >36 months: 10 [38.5%]). Median time from initiation of targeted therapy to best response was 6 months (<6 months: 14 [53.8%]; 6-12 months: 5 [19.2%]; >12 months: 7 [26.9%]). Median duration from best response to drug discontinuation was 19 months (12-24 months: 14 [53.8%]; 24-36 months: 7 [26.9%]; >36 months: 5[19.2%]). Reasons for drug discontinuation include toxicity (n=8, 30.8%), patient preference (n=13, 50.0%), cost prohibition (n=1, 3.8%), and other critical medical conditions (n= 4,15.4%). Eleven patients (42.3%) experienced disease progression after discontinuation of targeted therapy, 5 patients progressed within 6 months. Systemic and CNS progression were captured by PET/CT and MRI brain, respectively. At median follow-up of 33.0 months (95%CI 24.3-47.1), median PFS, defined by time from targeted therapy discontinuation to progression or death, was 29 months (95% confidence interval [CI] not estimable). Median OS was not reached. In Cox regression model, BRAF V600E mutation (hazard ratio [HR] 4.16, 95% CI 1.10-15.70, p 0.036) and CNS involvement (HR 4.64, 95% CI 1.21-17.67, p 0.025) were associated with inferior PFS. MEKi containing regimen trended toward improved PFS (HR 0.35, 95%CI 0.10-1.21, p 0.097). There was no difference in PFS when assessing demographics, histology, prior therapies, best response to targeted therapy, treatment duration, or time from best response to discontinuation. Of the 11 patients with progression, 9 were re-challenged with targeted therapy (7 switched class), 2 did not receive next line therapy (1 transitioned to hospice and passed from progression, 1 has pending evaluation for next line therapy). Of 6 with response assessments, all recaptured response (1 CR, 5 PR), and none had progressed by data cutoff. Conclusions: In patients with histiocytic neoplasm and prior durable response to targeted therapy, ~40% experienced disease progression after treatment discontinuation. BRAF V600E mutation and CNS disease are associated with inferior PFS, suggesting these subgroups may not be appropriate for limited duration of treatment. Novel approaches are needed in these high-risk patients.

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of lymphoproliferative disorders arising from mature T cells, accounting for about 10% of non-Hodgkin lymphomas. PTCL-not otherwise specified is the most common subtype, followed by angioimmunoblastic T-cell lymphoma, anaplastic large cell lymphoma, anaplastic lymphoma kinase–positive, anaplastic large cell lymphoma, anaplastic lymphoma kinase–negative, and enteropathy-associated T-cell lymphoma. This discussion section focuses on the diagnosis and treatment of PTCLs as outlined in the NCCN Guidelines for T-Cell Lymphomas.

Histiocytic neoplasms are rare hematologic disorders accounting for less than 1% of cancers of the soft tissue and lymph nodes. Clinical presentation and prognosis of these disorders can be highly variable, leading to challenges for diagnosis and optimal management of these patients. Treatment often consists of systemic therapy, and recent studies support use of targeted therapies for patients with these disorders. Observation (“watch and wait”) may be sufficient for select patients with mild disease. These NCCN Guidelines for Histiocytic Neoplasms include recommendations for diagnosis and treatment of adults with the most common histiocytic disorders: Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease.

Hepatosplenic T-cell lymphoma (HSTCL) is a rare subtype of T-cell lymphoma associated with an aggressive clinical course and a worse prognosis. HSTCL develops in the setting of chronic immune suppression or immune dysregulation in up to 20% of cases and is most often characterized by spleen, liver, and bone marrow involvement. Diagnosis and management of HSTCL pose significant challenges given the rarity of the disease along with the absence of lymphadenopathy and poor outcome with conventional chemotherapy regimens. These Guidelines Insights focus on the diagnosis and treatment of HSTCL as outlined in the NCCN Guidelines for T-Cell Lymphomas.

Mycosis fungoides (MF) is the most common subtype of cutaneous T-cell lymphoma (CTCL), and Sézary syndrome (SS) is a rare erythrodermic and leukemic subtype of CTCL characterized by significant blood involvement. Although early-stage disease can be effectively treated predominantly with skin-directed therapies, systemic therapy is often necessary for the treatment of advanced-stage disease. Systemic therapy options have evolved in recent years with the approval of novel agents such as romidepsin, brentuximab vedotin, and mogamulizumab. These NCCN Guidelines Insights discuss the diagnosis and management of MF and SS (with a focus on systemic therapy).

Abstract INTRODUCTION: Previous studies have demonstrated the clinical activity of the mTOR inhibitor RAD001 in low- grade lymphomas. Our preclinical studies demonstrated activity of mTOR inhibitors in Waldenstrom Macroglobulinemia (WM) cell lines and patient samples. This phase II study aimed to determine safety and activity of the oral mTOR inhibitor RAD001 (Novartis Pharmaceutical, MA) in patients with relapsed or refractory WM. METHODS: Patients who had at least one previous therapy for WM, and who had symptomatic relapsed or refractory disease were eligible. NCI CTCAE v3.0 was used for toxicity assessment. All patients received daily RAD001 at 10 mg. A cycle was considered 28 days. Patients were allowed to stay on therapy until progression of disease or excessive toxicity. This study was conducted in a collaborative effort between Dana Farber Cancer Institute (DFCI) and Mayo Clinic College of Medicine. Here, we report the data on the patients accrued at DFCI. RESULTS: 19 pts (15 men and 4 women) have been treated to date. All patients had symptomatic disease and required therapy. The median number of lines of prior treatment was 3 (range 1 – 5) including included rituximab, nucleoside analogues (fludarabine or 2-CDA), combination chemotherapy (e.g. CHOP, CVP), chloramucil, and bortezomib. The median IgM at baseline was 3330 mg/dL (range 1010– 7410). The median follow on RAD001 was 8 months (range 3 – 22 months). Eighteen pts are currently evaluable for response. Best responses to RAD001 after 2 cycles using IgM monoclonal protein were as follows: partial remission in 8 (44%), minimal response in 5 (28%). Progressive disease occurred in 4 (22%) and stable disease occurred in 1 (6%). The overall response rate (PR+MR) was 72%. The median duration of response has not been reached (3–22+ months). Patients tolerated therapy well without significant toxicities. Grade 3 and 4 toxicities included grade 4 thrombocytopenia in 1 patient, grade 3 pneumonia in 1 patient, grade 3 hyperglycemia in 1 patient and grade 3 mucositis in 1 patient. Other adverse events of grade 2 or lower included nail cracking, mucositis, diarrhea, and fatigue. Attributable toxicities otherwise proved manageable with appropriate supportive care, and RAD001 was generally well tolerated. One patient enrolled on the study withdrew consent and changed to hospice care within 3 weeks of therapy, and passed away due to disease progression. CONCLUSIONS: The use of the oral RAD001 single agent RAD001 in patients with relapsed or refractory WM was welltolerated and demonstrated significant activity achieving an overall response rate in 72% of patients. Future studies of combination of this agent with rituximab and bortezomib are currently being planned.

Abstract Erdheim-Chester disease (ECD) is a rare histiocytosis that was recently recognized as a neoplastic disorder owing to the discovery of recurrent activating MAPK (RAS-RAF-MEK-ERK) pathway mutations. Typical findings of ECD include central diabetes insipidus, restrictive pericarditis, perinephric fibrosis, and sclerotic bone lesions. The histopathologic diagnosis of ECD is often challenging due to nonspecific inflammatory and fibrotic findings on histopathologic review of tissue specimens. Additionally, the association of ECD with unusual tissue tropism and an insidious onset often results in diagnostic errors and delays. Most patients with ECD require treatment, except for a minority of patients with minimally symptomatic single-organ disease. The first ECD consensus guidelines were published in 2014 on behalf of the physicians and researchers within the Erdheim-Chester Disease Global Alliance. With the recent molecular discoveries and the approval of the first targeted therapy (vemurafenib) for BRAF-V600–mutant ECD, there is a need for updated clinical practice guidelines to optimize the diagnosis and treatment of this disease. This document presents consensus recommendations that resulted from the International Medical Symposia on ECD in 2017 and 2019. Herein, we include the guidelines for the clinical, laboratory, histologic, and radiographic evaluation of ECD patients along with treatment recommendations based on our clinical experience and review of literature in the molecular era.

Background Tipifarnib is a potent and selective inhibitor of the enzyme farnesyltransferase (FT). FT catalyzes post-translational attachment of farnesyl groups required for localization of signaling molecules to the inner cell membrane. CXCL12 is a ligand for CXCR4 that is essential for T cell homing to lymphoid organs and the bone marrow, and for the maintenance of immune cell progenitors. We have previously shown that FT inhibition by tipifarnib downregulates CXCL12 secretion. Herein we report preliminary efficacy, safety and biomarker data from a Phase 2 study of tipifarnib in angioimmunoblastic T-cell lymphoma (AITL) and CXCL12+ peripheral T-cell lymphoma (PTCL) patients (pts). Methods This Phase 2 study (NCT02464228) is a multi-institutional, single-arm, open-label trial initially designed as a two-stage (11+7 pts) design to determine the efficacy, safety and biomarkers of tipifarnib in pts with relapsed/refractory (R/R) PTCL age >/=18 years and a performance status of 0-2. Based on initial findings, the study was amended to include a cohort of AITL (n=12) and PTCL (n=12) pts with the CXCL12 rs2839695 A/A genotype (wt CXCL12 3'UTR cohort). Pts received tipifarnib 300 mg administered orally twice daily on days 1-21 of 28-day treatment cycles until progression of disease (PD) or unacceptable toxicity. The primary endpoint of the study is overall response rate (ORR). Tumor Whole Exon Sequencing (WES) was generated by NGS and gene expression data generated by RNA Seq. Ancillary studies also investigated the prognostic value of CXCL12 expression in pts who received standard of care treatment. Results As of 24 May 2019, 50 PTCL pts (23 AITL, 25 PTCL-NOS, 1 ALK- ALCL, 1 gamma-delta TCL) have been treated with tipifarnib, 19 pts in stages 1 and 2, and 31 pts in the ongoing AITL histology and wt CXCL12 3'UTR cohorts. Median number of prior treatment regimens was 3; 19 pts had a prior stem cell transplant. All pts (n=48 with available safety data) had at least one treatment-emergent adverse event (TEAE); 42 (88%) had at least 1 study drug-related TEAE and 13 (27%) at least 1 drug related SAE. The most frequently observed drug-related TEAEs of Grade >3 occurring in 10% or more of pts were blood and lymphatic system disorders, including neutropenia (40%), thrombocytopenia (33%), leukopenia (25%), anemia and febrile neutropenia (19% each). There have been 14 deaths on study; one related to study drug (lung infection). Of 18 evaluable pts enrolled in Stages 1 and 2 of the trial, 3 partial responses (PR), 2 of them in pts with AITL histology, and 5 best responses of stable disease (SD) were observed. In the AITL cohort (11 evaluable of 16 pts enrolled), a 45% ORR and 73% clinical benefit rate (CBR; 3 CR, 2 PR and 3 SD) was observed. In the wt CXCL12 3'UTR cohort (n=12 evaluable pts), a 42% ORR was observed (3 CR, 2 PR), with 2 of the 3 CRs observed in patients of AITL histology (n=4). A total of 23 AITL subjects were enrolled in the overall study of whom 16 had WES data. A strong association with the activity of tipifarnib was observed in 8 of the 16 (50%) carrying KIR3DL2 gene variants C336R/Q386E: 50% CR rate, 75% ORR, 100% clinical benefit rate. These tumors expressed also very low levels of CXCL5, a ligand for CXCR2, that may mediate resistance to tipifarnib. High Allele Frequency of KIR3DL2 variants predicted CR to tipifarnib treatment (ROC AUC=0.94, p<0.0001) and AITL patients carrying KIR3DL2 gene variants experienced a better outcome with tipifarnib treatment than with prior SOC treatment. While AITL tumors expressed high levels of CXCL12 and responded to tipifarnib, a trend for poor prognosis (22 vs 40 months median OS from diagnosis, HR=1.8, p=0.09) was observed in a series of 50 PTCL subjects treated with SOC therapy. Fifty percent of AITL and 35% of non-AITL samples overexpressed CXCL12. Conclusion The AITL and wt CXCL12 3'UTR cohorts met pre-specified statistical hypotheses supporting proof-of-concept for tipifarnib in PTCL. AITL histology, KIR3DL2 and CXCL12 genotype provided robust tools for the selection/stratification of PTCL subjects treated with tipifarnib. Extended enrollment of AITL patients continues and an update on enrollment and outcomes will be provided at the time of the presentation. Disclosures Sokol: EUSA: Consultancy. Foss:Mallinckrodt: Consultancy; Eisai: Consultancy; Spectrum: Other: fees for non-CME/CE services ; Acrotech: Consultancy; Seattle Genetics: Consultancy, Other: fees for non-CME/CE services ; miRagen: Consultancy. Kim:Donga: Research Funding; Celltrion: Research Funding; J&J: Research Funding; Roche: Research Funding; Kyowa-Kirin: Research Funding; Novartis: Research Funding; Mundipharma: Research Funding. Jacobsen:Kura Oncology: Research Funding. Advani:Kyowa Kirin Pharmaceutical Developments, Inc.: Consultancy; Kura: Research Funding; Roche/Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Research Funding; Pharmacyclics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Research Funding; Agensys: Research Funding; Stanford University: Employment, Equity Ownership; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merck: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Celmed: Consultancy, Membership on an entity's Board of Directors or advisory committees; Forty-Seven: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cell Medica, Ltd: Consultancy; Gilead Sciences, Inc./Kite Pharma, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Infinity Pharma: Research Funding; Millennium: Research Funding. Roncero:Kura Oncology: Research Funding. Terol:Janssen: Consultancy, Research Funding; Roche: Consultancy; Gilead: Research Funding; Astra Zeneca: Consultancy; Abbvie: Consultancy. Domingo-Domenech:Bristol-Myers Squibb: Other: Travel expenses; Roche: Other: Travel expenses; Seattle Genetics: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses. Piris:Millenium/Takeda: Membership on an entity's Board of Directors or advisory committees, Other: Lecture Fees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jansen: Membership on an entity's Board of Directors or advisory committees, Other: Lecture Fees; Nanostring: Membership on an entity's Board of Directors or advisory committees; Kyowa Kirin: Membership on an entity's Board of Directors or advisory committees; Kura: Research Funding. Rodriguez:Kura Oncology: Research Funding. Bolognese:Kura Oncology: Consultancy. Kessler:Kura Oncology: Employment. Mishra:Kura Oncology: Employment. Curry:Kura Oncology: Employment. Kurman:Kura Oncology: Employment. Scholz:Kura Oncology: Employment, Equity Ownership, Patents & Royalties. Gualberto:Kura Oncology: Employment, Equity Ownership, Patents & Royalties.

Abstract INTRODUCTION: mTOR inhibitors have been associated with responses in Mantle cell lymphoma and other lymphomas (J Clin Oncol23; 5347, 2005). Phase I and II trials with the oral everolimus (RAD001, Novartis Pharmaceuticals) have demonstrated a favorable side effect profile. This phase II study tested everolimus in patients with relapsed/refractory Waldenstrom Macroglobulinemia (WM). METHODS: Patients who had at least one previous therapy for WM and who had relapsed or refractory disease were eligible. Other eligibility criteria included symptomatic disease, > 2 weeks from last therapeutic agent used, >10% involvement with lymphoplasmacytic cells in the bone marrow, IgM paraprotein > 2x upper limit of normal, absolute neutrophil count >1000/mm3 and platelet count >75,000/mm3, serum creatinine of < 2 x upper limit of normal. NCI CTCAE v3.0 was used for toxicity assessment. Response was assessed by criteria established at the second consensus panel for WM. All patients received 10mg RAD001 daily for 28 days per cycle for 6 cycles; response was assessed after 2 cycles. RESULTS: 10pts (8 men and 2 women, median age is 62 years, range 52–71) have been treated to date. The median number of lines of prior treatment was 3 (range 1 – 5). The median IgM at baseline was 3970 mg/dL (range 3120– 7410); median M-spike at baseline was 2.07 gm/dL (range 1.41 – 4.02); and median hemoglobin was 11.3 g/dL (9.4–13.3). The median follow up was 4 months (range 1 – 7 months). Prior therapy included rituximab, nucleoside analogues (fludarabine and 2-CDA), combination chemotherapy (e.g CHOP, CVP), chlorambucil. and bortezomib. Seven patients are currently evaluable for response. The best response to single agent RAD001 after 2 cycles is presented in Table 1. Median duration of response has not been reached. Patients tolerated RAD001 well without significant toxicities. The main toxicities observed were apthous ulcers in 4 patients. One patient required dose reduction due to mucositis. One patient stopped therapy within the first month of treatment and went on to hospice care before succumbing to his disease after one month. Attributable toxicities otherwise proved manageable with appropriate supportive care and RAD001 was generally well tolerated, with no peripheral neuropathy. CONCLUSIONS: Oral RAD001 as monotherapy has been well tolerated and demonstrates exciting activity achieving PR + MR in 57%, and/or stabilization of disease in 43% of evaluable patients with relapsed WM. Accrual of a total of 30 patients is rapidly ongoing. Updated data will be presented at the meeting. Table 1 Response N=7; ORR (CR+PR+MR)= 57% Median time to best response (months) Partial Response 1 (14%) 5 Minimal Response 3 (43%) 4 (3–6) Stable Disease (SD) 3 (43%) NA Progressive Disease 0