Gladstone, Douglas E.

Abstract Hairy cell leukemia (HCL) and HCL variant (HCLv) are distinct, rare, and chronic splenic B-cell lymphomas/leukemias that partially overlap in clinicopathologic presentation but differ in genetic basis, prognosis, and management. HCL is caused by the BRAF-V600E kinase–activating mutation in >95% of the patients, usually has excellent responses to chemotherapy with purine analogues, and is also amenable to BRAF inhibitor–based targeted treatments. In contrast, HCLv lacks BRAFV600E mutation, requires combined therapy with purine analogues in addition to rituximab, and generally shows less durable responses. Here, an international team of hematologists, experts on these rare diseases, was convened by the Hairy Cell Leukemia Foundation to update the previous guidelines (published in 2017) by providing a summary of current methods to diagnose and manage patients with HCL and HCLv as well as a prospective on newer targeted therapies to further improve outcomes.

Abstract Introduction: Nivolumab (nivo) is a fully human IgG4 monoclonal antibody (mAb) targeting programmed death receptor-1 (PD-1). Nivo has demonstrated clinical activity and an acceptable safety profile in a phase 1b study (NCT01592370; CheckMate 039) in patients (pts) with relapsed/refractory hematologic malignancies. In pts diagnosed with Hodgkin lymphoma (HL), after a median 86 weeks of follow-up, 7/20 responders maintained a response for >1.5 years (Ansell S et al. Blood 2015;126:583), and after a median follow-up of 67 weeks, clinical activity (investigator-assessed objective response rate) was demonstrated in follicular lymphoma (FL; 40%), diffuse large B-cell lymphoma (DLBCL; 36%), mycosis fungoides (15%), and peripheral T-cell lymphoma (PTCL; 40%) (Lesokhin AM et al. J Clin Oncol 2016;34:2698). CheckMate 039 also included a cohort of pts who had received nivo in combination with ipilimumab (ipi), a fully human mAb targeting cytotoxic T-lymphocyte antigen 4 (CTLA-4). Combination of CTLA-4 and PD-1 blockade has shown superior efficacy compared with nivo or ipi alone in preclinical studies and solid tumor malignancies (Wolchok JD et al. N Engl J Med 2013;369:122; Larkin JM et al. N Engl J Med 2015;373:22; Antonia SJ et al. Lancet Oncol 2016;17:883). The aim of this cohort study was to evaluate the safety and efficacy of combined immune checkpoint blockade (nivo+ipi) in pts with the following hematologic malignancies: HL, B-cell non-Hodgkin lymphoma (B-NHL; FL and DLBCL), T-cell NHL (T-NHL; cutaneous T-cell lymphoma [CTCL] and PTCL]), and multiple myeloma (MM). Methods: Nivo+ipi were given at 3 mg/kg IV and 1 mg/kg IV, respectively, every 3 weeks for 4 doses, followed by nivo monotherapy (3 mg/kg) every 2 weeks for up to 2 years. Pts with any of the above histologies, relapsed or refractory disease after ≥2 prior lines of therapy, and adequate organ function were included in the study. Prior systemic therapy may have included chemotherapy and autologous hematopoietic stem cell transplantation (auto-HSCT). Prior anti-PD-1 therapy and allogeneic (allo)-HSCT were not permitted. The primary endpoint was safety. Secondary endpoints included investigator-assessed objective response rate (ORR), best overall response, duration of response (DOR), and progression-free survival (PFS). Results: In total, 65 pts were treated with nivo+ipi (31 HL, 15 B-NHL, 11 T-NHL, 7 MM, and 1 with primary mediastinal B-cell lymphoma [PMBL] who was included in the overall safety cohort only). Median (range) number of prior systemic therapies was 4 (2, 10; HL), 3, (1, 16; B-NHL), 4 (1, 11; T-NHL), and 5 (2, 20; MM). Among patients with HL, only 13% (4/31) had prior auto-HSCT. 2 pts with HL and 1 with T-NHL proceeded to allo-HSCT after stopping study therapy. Across all cohorts, median follow-up was 11.4 months. 5 pts (8%) discontinued due to a drug-related adverse event (AE). The most common drug-related AEs of any grade were fatigue (17 pts [26%]), pyrexia (15 [23%]), and diarrhea (12 [18%]). 19 pts (29%) had a drug-related AE of grade ≥3. 31 pts (48%) had a serious AE. 24 pts (37%) died: HL 2 pts, B-NHL 11, T-NHL 6, MM 4, PMBL 1. Among those pts, 22 (34%) were from disease progression (HL 2 pts, B-NHL 10, T-NHL 5, MM 4, PMBL 1); no deaths were due to an AE. Clinical outcome data are presented (Table). Conclusions: These are the first reported data of combination checkpoint blockade therapy in hematologic malignancies. Overall, the combination of nivo+ipi in these heavily pretreated patients demonstrated a safety and efficacy profile similar to that previously reported for nivo monotherapy in HL, NHL, and MM. Additional follow-up may further clarify the role of ipi in this cohort of patients. In this predominantly transplant-naïve group of patients with HL, the efficacy of nivo+ipi was similar to that seen in patients with relapsed/refractory HL treated with nivo alone. Funding: Bristol-Myers Squibb (BMS). Medical writing: S Addison, Caudex, funded by BMS Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Gutierrez:Bayer Health Care Pharmaceuticals, Inc.: Other: Traveling and Lodging- Food and Beverage; E.R. Squibb & Sons, LLC (Bristol Myers Squibb): Consultancy, Other: Travel and Lodging; Incyte Corporation: Consultancy; Pfizer Inc: Consultancy; Merck Sharp & Dohme Corporation: Consultancy, Other: Travel and Lodging; Pharmacyclics LLC, An AbbVie Company: Other: Food and Beverage. Shipp:Cell Signaling: Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Bayer: Research Funding; Merck, Gilead, Takeda: Other: Scientific Advisory Board. Moskowitz:Seattle Genetics: Research Funding; Seattle Genetics, Merck: Consultancy. Borello:Bristol-Myers Squibb: Research Funding, Speakers Bureau. Popa-Mckiver:Bristol-Myers Squibb: Employment, Equity Ownership. Farsaci:Bristol-Myers Squibb: Employment. Zhu:Bristol-Myers Squibb: Employment. Armand:Sequenta Inc: Research Funding; Pfizer: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Infinity Pharmaceuticals: Consultancy; Roche: Research Funding; Merck: Consultancy, Research Funding.

Abstract Among mechanisms underlying cytotoxic drug resistance is activation of diverse DNA damage response (DDR) pathways. Poly(ADP-ribose) polymerases (PARP)-1/2 facilitate both single- and double-strand break (DSB) repair and play a key role in the base excision repair (BER) of chemotherapy-damaged DNA. The PARP inhibitor veliparib (V) potentiates the cytotoxicity of different chemotherapeutics, including temozolomide (TEM). TEM induces distinct alkylating events in neoplastic cells whose ultimate outcome depends on the interaction of BER, mismatch repair (MMR), O(6)-methylguanine-DNA methyltransferase (MGMT), and DSB repair. While clinical activity of TEM has been mainly observed in MGMT-deficient AML, V potentiated cytotoxicity of TEM in leukemia cells in vitro in the setting of MGMT overexpression or deficient MMR pathway (Mol Cancer Ther, 2009). Methods: We conducted a Phase I study to determine maximum tolerated dose (MTD) and recommended Phase II dose (RP2D) of V+TEM, using a 3+3 dose escalation. Patients (pts) ≥60 years (yrs) with newly diagnosed poor cytogenetic-risk AML/ALL who were not candidates for intensive therapy, or ≥18 yrs with relapsed/refractory AML/ALL, secondary AML (therapy-related or arising from MDS or MPN), and CMMoL-2 were eligible. Any number of prior regimens, including allogeneic transplant (alloSCT), were allowed. V was given orally day (d)1 once, then twice a day on d4-12 at one of 6 dose levels (DL) (DL1A-B 20mg; DL2-DL3-DL4-DL5-DL6: 40-80-120-150-200 mg). TEM was given orally once a day on d3-9 (DL1A 150 mg/m2/d; DL1B-DL6 200 mg/m2/d). 28-day cycles (cy) were repeated depending on response/tolerability (4-6 weeks delay allowed) with V on d1-8 and TEM d1-5. TEM was taken on empty stomach with antiemetics and V was taken irrespective of meals. Results: Forty-nine pts with median age 69 yrs (range, 22-88; 47% ≥70) were treated. Of 47 AML pts, 29 (62%) had secondary AML and 27 (57%) adverse karyotype. Median number of prior treatments for AML was 1 (range, 0-6): 18 (38%) had median 1 prior therapy (range, 1-3) for MDS; 30 (64%), 9 (18%), 34 (69%) received hypomethylating agents, alloSCT and intensive chemotherapy, respectively. Overall 42 (85%) pts were refractory to their last treatment. Pts received a median of 1 (range, 1-7) cy of therapy. Two did not complete cy 1, pt withdrawal d5 and progressive fungal pneumonia d9 with death d15 of progressive disease (PD). The MTD/RP2D was defined at V 150 mg and TEM 200 mg/m2; 2 of 4 pts treated at V 200 mg and TEM 200 mg/m2 developed dose-limiting toxicity of grade (gr) 3 oral mucositis/esophagitis. The most frequent drug-related toxicities (NCI CTC v4) were gr 1/2 nausea/vomiting (39%), fatigue (26%), oropharyngeal mucositis (26%), constipation (12%), and diarrhea (10%). Other common toxicities were infectious, including febrile neutropenia (29%), pneumonia (20%), bacteremia (18%). One (2%) pt died ≤d30 and 12 (24%) ≤d60 mainly of PD (1 pt fungal pneumonia before count recovery d31). Overall response rate was 33% (complete remission (CR), hematologic improvement (HI)/stable disease) with 8 (16%) pts achieving CR (1 CRi). Median overall survival was 5.03 months, for all responders 11.58 months, and for CR pts 19.89 months (Fig 1). Responses occurred at all DLs. Three CR pts underwent alloSCT; 2 remain in CR at ~3 yrs. Pharmacokinetics (PK): V or TEM PKs were not altered with co-administration. There was a correlation between the DLT of mucositis and V single (Cmax P=0.005; AUC P=0.009) and multiple dose exposure (Cmax P = 0.02; AUC P=0.03). Pharmacodynamics and pharmacoepigenetics: Four of 39 pts examined had MGMT methylation (3 CR; 75%) and 2 had BRCA-1 methylation (1 HI) in peripheral blood (PB) or bone marrow (BM) mononuclear cells (MC). Defective FancD2 pathway was observed in the BMMC of 19/19 pts using FancD2 ubiquitylation assays but did not correlate with response. V reduced PAR levels by >75% in PBMC of most pts and in the presence of TEM. Induction of γ-H2AX in CD34+ cells was seen upon V/V+TEM treatment. Conclusion: V plus TEM demonstrated safety and activity in this resistant and elderly leukemia population. Response rate was higher in MGMT methylated pts, but responses were also seen in pts who had no MGMT methylation, had failed multiple therapies, had secondary AML and/or adverse karyotype. Future clinical study should aim to identify pts with defective DDR pathways who are most likely to respond to this therapeutic approach. Figure 1. Figure 1. Disclosures Off Label Use: Temozolomide is not approved for AML. Beumer:Millenium: Other: Research support. Gore:Celgene: Consultancy, Honoraria, Research Funding.

Abstract Purpose: The PARP inhibitor veliparib delays DNA repair and potentiates cytotoxicity of multiple classes of chemotherapy drugs, including topoisomerase I inhibitors and platinating agents. This study evaluated veliparib incorporation into leukemia induction therapy using a previously described topotecan/carboplatin backbone. Experimental Design: Employing a 3+3 trial design, we administered escalating doses of veliparib combined with topotecan + carboplatin in relapsed or refractory acute leukemias, aggressive myeloproliferative neoplasms (MPN), and chronic myelomonocytic leukemia (CMML). Results: A total of 99 patients received veliparib 10–100 mg orally twice daily on days 1–8, 1–14, or 1–21 along with continuous infusion topotecan 1.0–1.2 mg/m2/d + carboplatin 120–150 mg/m2/d on days 3–7. The MTD was veliparib 80 mg twice daily for up to 21 days with topotecan 1.2 mg/m2/d + carboplatin 150 mg/m2/d. Mucositis was dose limiting and correlated with high veliparib concentrations. The response rate was 33% overall (33/99: 14 CR, 11 CRi, 8 PR) but was 64% (14/22) for patients with antecedent or associated aggressive MPNs or CMML. Leukemias with baseline DNA repair defects, as evidenced by impaired DNA damage–induced FANCD2 monoubiquitination, had improved survival [HR = 0.56 (95% confidence interval, 0.27–0.92)]. A single 80-mg dose of veliparib, as well as veliparib in combination with topotecan + carboplatin, induced DNA damage as manifested by histone H2AX phosphorylation in CD34+ leukemia cells, with greater phosphorylation in cells from responders. Conclusions: The veliparib/topotecan/carboplatin combination warrants further investigation, particularly in patients with aggressive MPNs, CMML, and MPN- or CMML-related acute leukemias. Clin Cancer Res; 23(4); 899–907. ©2016 AACR.

Abstract Purpose: In preclinical studies, the PARP inhibitor veliparib enhanced the antileukemic action of temozolomide through potentiation of DNA damage. Accordingly, we conducted a phase 1 study of temozolomide with escalating doses of veliparib in patients with relapsed, refractory acute myeloid leukemia (AML) or AML arising from aggressive myeloid malignancies. Experimental Design: Patients received veliparib [20–200 mg once a day on day 1 and twice daily on days 4–12 in cycle 1 (days 1–8 in cycle ≥2)] and temozolomide [150–200 mg/m2 daily on days 3–9 in cycle 1 (days 1–5 in cycle ≥2)] every 28 to 56 days. Veliparib pharmacokinetics and pharmacodynamics [ability to inhibit poly(ADP-ribose) polymer (PAR) formation and induce H2AX phosphorylation] were assessed. Pretreatment levels of MGMT and PARP1 protein, methylation of the MGMT promoter, and integrity of the Fanconi anemia pathway were also examined. Results: Forty-eight patients were treated at seven dose levels. Dose-limiting toxicities were oral mucositis and esophagitis lasting >7 days. The MTD was veliparib 150 mg twice daily with temozolomide 200 mg/m2 daily. The complete response (CR) rate was 17% (8/48 patients). Veliparib exposure as well as inhibition of PAR polymer formation increased dose proportionately. A veliparib-induced increase in H2AX phosphorylation in CD34+ cells was observed in responders. Three of 4 patients with MGMT promoter methylation achieved CR. Conclusions: Veliparib plus temozolomide is well tolerated, with activity in advanced AML. Further evaluation of this regimen and of treatment-induced phosphorylation of H2AX and MGMT methylation as potential response predictors appears warranted. Clin Cancer Res; 23(3); 697–706. ©2016 AACR.

Abstract Purpose: Incorporation of cytarabine into DNA activates checkpoint kinase 1 (Chk1), which stabilizes stalled replication forks, induces S-phase slowing, and diminishes cytarabine cytotoxicity. The selective Chk1 inhibitor SCH 900776 abrogates cytarabine-induced S-phase arrest and enhances cytarabine cytotoxicity in acute leukemia cell lines and leukemic blasts in vitro. To extend these findings to the clinical setting, we have conducted a phase I study of cytarabine and SCH 900776. Experimental Design: Twenty-four adults with relapsed and refractory acute leukemias received timed sequential, continuous infusion cytarabine 2 g/m2 over 72 hours (667 mg/m2/24 hours) beginning on day 1 and again on day 10. SCH 900776 was administered as a 15- to 30-minute infusion on days 2, 3, 11, and 12. The starting dose of SCH 900776 was 10 mg/m2/dose. Results: Dose-limiting toxicities consisting of corrected QT interval prolongation and grade 3 palmar-plantar erythrodysesthesia occurred at 140 mg flat dosing (dose level 5, equivalent to 80 mg/m2). Complete remissions occurred in 8 of 24 (33%) patients, with 7 of 8 at 40 mg/m2 or higher. SCH 900776 did not accumulate at any dose level. Marrow blasts obtained pretreatment and during therapy showed increased phosphorylation of H2Ax after SCH 900776 beginning at 40 mg/m2, consistent with unrepaired DNA damage. Conclusions: These data support a randomized phase II trial of cytarabine +/− SCH 900776 at a recommended flat dose of 100 mg (equivalent to 56 mg/m2) for adults with poor-risk leukemias. The trial (SP P05247) was registered at www.clinicaltrials.gov as NCT00907517. Clin Cancer Res; 18(24); 6723–31. ©2012 AACR.

Abstract In classical Hodgkin lymphoma, circulating clonotypic malignant cells express CD20, which potentially explains the observed activity of rituximab. This multicenter phase 2 study investigated the combination of rituximab-ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) for stage II-IV untreated classical Hodgkin lymphoma. A goal was to assess the behavior of circulating clonotypic B cells clinically. Of 49 evaluable patients, 69% had stage IIB-IV disease; 8% had CD20+ Hodgkin and Reed-Sternberg cells. Rituximab-ABVD was generally well tolerated. Delivered relative dose intensity was 94% for AVD and 79% for bleomycin. After 6 cycles, 81% of patients were in complete remission. Only 8% received radiation therapy. The actuarial 3-year event-free and overall survival rates were 83% and 98%, respectively. EBV copy number in plasma fell dramatically during cycle 1 in patients with EBV+ tumors. Persistence of detectable circulating clonotypic B cells was associated with a greater relapse frequency (P < .05). Rituximab-ABVD and clonotypic B cells warrant additional study in classical Hodgkin lymphoma. This trial was registered at www.clinicaltrials.gov as NCT00369681.