ALBERT

Description: Hairy cell leukemia is a chronic B-cell disorder that follows an indolent, but progressive course. Cladribine (2-chlorodeoxyadenosine) induces complete remissions in the majority of patients after a single course. We report the long-term outcomes, including response rates and their duration; time-to-treatment failure (TTF) rates; retreatment results; toxicities; and survival rates of patients treated at Scripps Clinic (La Jolla, CA). A total of 358 patients with hairy cell leukemia were treated with cladribine at 0.087 or 0.1 mg/kg body weight per day by continuous intravenous infusion for 7 days. The expected number of second neoplasms was based on the National Cancer Institute’s Surveillance Epidemiology and End Results data. Of 349 evaluable patients, 319 (91%) achieved an initial complete response and 22 (7%) a partial response with an overall median duration of response follow-up of 52 months. Ninety patients (26%) had relapsed at a median of 29 months. The TTF rate for all 341 responders was 19% at 48 months, 16% for complete responders, and 54% for partial responders. Of 53 evaluable patients treated with second courses of cladribine at first relapse, 33 (62%) achieved complete responses and 14 (26%) partial responses. Twenty-seven patients (8%) developed second neoplasms (only 1 hematopoietic) with an observed-to-expected ratio of 1.88 (95% confidence interval, 1.24 to 2.74). The overall survival rate was 96% at 48 months. Single courses of cladribine induced long-lasting complete responses in the vast majority of patients. Relapse rates for complete responders were low. Patients who relapse can be successfully retreated with cladribine. Cladribine has high efficacy and a favorable acute and long-term toxicity profile when administered to patients with hairy cell leukemia. © 1998 by The American Society of Hematology.

Description: Cladribine treatment of hairy cell leukemia (HCL) is complicated by neutropenic fever in 42% of patients despite documented infections being relatively uncommon. We performed a study of priming filgrastim followed by cladribine and then filgrastim again to determine if filgrastim would lead to a reduction of neutropenia and febrile episodes. Thirty-five patients received filgrastim and cladribine and were compared with 105 historic controls treated with cladribine alone. Cladribine was administered at 0.1 mg/kg/d by continuous infusion for 7 days. Filgrastim was administered at 5 μg/kg/d subcutaneously on days −3, −2, and −1 and then again after the completion of cladribine until the absolute neutrophil count (ANC) was ≥2 × 109/L on 2 consecutive days (days +8, +9, etc). After filgrastim priming, the median ANC increased from 0.9 × 109/L to 2.26 × 109/L (2.5-fold increase), and after cladribine, the median nadir ANC in the filgrastim-treated group was 0.53 × 109/L compared with 0.29 × 109/L among historic controls (P = .04). The median number of days to an ANC greater than 1.0 × 109/L was 9 days in the filgrastim-treated group versus 22 days among historic controls (P 〈 10−5). The percentage of febrile patients, number of febrile days, and frequency of admissions for antibiotics were not statistically different in the two groups. Filgrastim regularly increases the ANC in patients with HCL and shortens the duration of severe neutropenia after cladribine. This phase II study, with comparison to historical controls, failed to detect any clinical advantage from the use of filgrastim and cladribine in the treatment of HCL. Accordingly, the routine adjunctive use of filgrastim with cladribine in the treatment of HCL cannot be recommended.

Description: Langerhans-cell histiocytosis (LCH) results from the accumulation of tissue histiocytes derived from the same progenitor cells as monocytes. Because cladribine is potently toxic to monocytes, we conducted a phase II trial of cladribine. Cladribine was administered to 13 LCH patients at 0.14 mg/kg per day by 2-hour intravenous infusion for 5 consecutive days, every 4 weeks for a maximum of six courses. Median age was 42 years (range, 19 to 72) and median pretreatment disease duration was 99 months (range, 6 to 252). One patient was untreated, one had received prior prednisone only, one prior radiation only, six prior radiation and chemotherapy, and four prior surgery, radiation, and chemotherapy. Seven patients had cutaneous involvement, six multifocal osseous, six pulmonary, two each with soft tissue and nodal involvement, and four had diabetes insipidus. Of 13 patients, 12 were evaluable for response and all for toxicity. After a median of three courses (range, 1 to 6), seven (58%) patients achieved complete responses (two pathologic and five clinical) and two (17%) patients achieved partial responses; overall response rate, 75%. Median response follow-up duration was 33 months (range, 1 to 65). Seven patients experienced grade 3 to 4 neutropenia. Only one patient had a documented infection, dermatomal herpes zoster. At a median follow-up of 42 months (range, 5 to 76), 12 patients remain alive and one patient has died. Thus, cladribine has major activity in adult LCH and warrants further investigation in both pediatric and adult LCH as a single agent and in combination with other drugs.

Description: Key Points HCL patients ≤40 years at diagnosis treated with cladribine obtain complete and durable responses, but ultimately relapse. There was no increased risk of second primary malignancies in young hairy cell leukemia patients followed for protracted periods.

Description: Cladribine treatment of hairy cell leukemia (HCL) is complicated by neutropenic fever in 42% of patients despite documented infections being relatively uncommon. We performed a study of priming filgrastim followed by cladribine and then filgrastim again to determine if filgrastim would lead to a reduction of neutropenia and febrile episodes. Thirty-five patients received filgrastim and cladribine and were compared with 105 historic controls treated with cladribine alone. Cladribine was administered at 0.1 mg/kg/d by continuous infusion for 7 days. Filgrastim was administered at 5 μg/kg/d subcutaneously on days −3, −2, and −1 and then again after the completion of cladribine until the absolute neutrophil count (ANC) was ≥2 × 109/L on 2 consecutive days (days +8, +9, etc). After filgrastim priming, the median ANC increased from 0.9 × 109/L to 2.26 × 109/L (2.5-fold increase), and after cladribine, the median nadir ANC in the filgrastim-treated group was 0.53 × 109/L compared with 0.29 × 109/L among historic controls (P = .04). The median number of days to an ANC greater than 1.0 × 109/L was 9 days in the filgrastim-treated group versus 22 days among historic controls (P 〈 10−5). The percentage of febrile patients, number of febrile days, and frequency of admissions for antibiotics were not statistically different in the two groups. Filgrastim regularly increases the ANC in patients with HCL and shortens the duration of severe neutropenia after cladribine. This phase II study, with comparison to historical controls, failed to detect any clinical advantage from the use of filgrastim and cladribine in the treatment of HCL. Accordingly, the routine adjunctive use of filgrastim with cladribine in the treatment of HCL cannot be recommended.

Description: Introduction: Acute myeloid leukemia (AML) remains a challenging malignancy to treat, with high mortality despite recent advances in cancer care. The mainstay of therapy is intensive chemotherapy including anthracyclines and antimetabolites, with or without allogeneic bone marrow transplant. The standard of care has not changed significantly in decades, and treatment options are limited for patients who do not respond to induction, or who relapse. Although the genetic and molecular diversity of AML is well recognized, the effective integration of targeted therapies into treatment regimens has been difficult. The current study evaluates the in vitro activity of an array of antineoplastic agents in AML, with the goal of identifying drug sensitivity patterns that may help guide therapies based on mutational and cytogenetic profiling. Methods: 51 patients with AML were enrolled in the study from September 2013 to July 2016 under an IRB approved consenting process at Scripps Health. Samples were collected at both diagnosis and relapse if available. Both bone marrow and peripheral blood were accepted, with a requirement of significant circulating blasts if peripheral blood was used. Samples were tested for common biomarkers and cytogenetic abnormalities. 2,500 cells per well were transferred onto tissue culture treated plates. Drugs with potential antileukemic activity were added to each well in concentrations of 0.1, 1.0, and 10.0 μM. The cells were incubated with the drugs for 96 hours at 37oC. Cell viability was measured and reported as a percentage of plate-specific controls incubated with dimethylsulfoxide alone. Results: Drugs were grouped by therapeutic class. In vitro responses to anthracyclines and antimetabolites were noted across all mutational subtypes of AML. BCL-2 inhibitors and the histone deacetylase inhibitor romidepsin showed significant in vitro antileukemic activity across all subtypes. Proteasome inhibitors almost universally showed robust in vitro activity, even at the lowest drug concentration. The drug pevonedistat, a selective small-molecule inhibitor of NEDD8-activating enzyme, had significant differential activity depending on mutational status. FLT3-ITD mutations conferred sensitivity to the molecule, while mutations in NPM1 appeared to confer resistance. For the 10.0 μM concentration of pevonedistat, the average cell viability was 149.8% vs 37.3% (P=0.02) for the NPM1 mutated samples vs the FLT3-ITD mutated samples respectively. Conclusion: This in vitro assay demonstrates the ability to rapidly determine sensitivity of human AML cells to a wide variety of antileukemic drugs. Limitations include the fixed concentrations used across all medications which allowed comparisons between patients, but limits comparison of drug efficacy for an individual patient. The mechanism of some medications, such as hypomethylating agents and tretinoin, may require longer duration of exposure, thus confounding interpretation of the 96-hour viability results. Despite these limitations, we were able to find interesting patterns of responses across a wide spectrum of AML types. Anticipated applications of the assay include experimentation with novel drug combinations, directing in vivo clinical studies, and informing individualized treatment decisions in AML. Disclosures No relevant conflicts of interest to declare.

Description: Hairy cell leukemia is a chronic B-cell disorder that follows an indolent, but progressive course. Cladribine (2-chlorodeoxyadenosine) induces complete remissions in the majority of patients after a single course. We report the long-term outcomes, including response rates and their duration; time-to-treatment failure (TTF) rates; retreatment results; toxicities; and survival rates of patients treated at Scripps Clinic (La Jolla, CA). A total of 358 patients with hairy cell leukemia were treated with cladribine at 0.087 or 0.1 mg/kg body weight per day by continuous intravenous infusion for 7 days. The expected number of second neoplasms was based on the National Cancer Institute’s Surveillance Epidemiology and End Results data. Of 349 evaluable patients, 319 (91%) achieved an initial complete response and 22 (7%) a partial response with an overall median duration of response follow-up of 52 months. Ninety patients (26%) had relapsed at a median of 29 months. The TTF rate for all 341 responders was 19% at 48 months, 16% for complete responders, and 54% for partial responders. Of 53 evaluable patients treated with second courses of cladribine at first relapse, 33 (62%) achieved complete responses and 14 (26%) partial responses. Twenty-seven patients (8%) developed second neoplasms (only 1 hematopoietic) with an observed-to-expected ratio of 1.88 (95% confidence interval, 1.24 to 2.74). The overall survival rate was 96% at 48 months. Single courses of cladribine induced long-lasting complete responses in the vast majority of patients. Relapse rates for complete responders were low. Patients who relapse can be successfully retreated with cladribine. Cladribine has high efficacy and a favorable acute and long-term toxicity profile when administered to patients with hairy cell leukemia. © 1998 by The American Society of Hematology.

Description: Langerhans-cell histiocytosis (LCH) results from the accumulation of tissue histiocytes derived from the same progenitor cells as monocytes. Because cladribine is potently toxic to monocytes, we conducted a phase II trial of cladribine. Cladribine was administered to 13 LCH patients at 0.14 mg/kg per day by 2-hour intravenous infusion for 5 consecutive days, every 4 weeks for a maximum of six courses. Median age was 42 years (range, 19 to 72) and median pretreatment disease duration was 99 months (range, 6 to 252). One patient was untreated, one had received prior prednisone only, one prior radiation only, six prior radiation and chemotherapy, and four prior surgery, radiation, and chemotherapy. Seven patients had cutaneous involvement, six multifocal osseous, six pulmonary, two each with soft tissue and nodal involvement, and four had diabetes insipidus. Of 13 patients, 12 were evaluable for response and all for toxicity. After a median of three courses (range, 1 to 6), seven (58%) patients achieved complete responses (two pathologic and five clinical) and two (17%) patients achieved partial responses; overall response rate, 75%. Median response follow-up duration was 33 months (range, 1 to 65). Seven patients experienced grade 3 to 4 neutropenia. Only one patient had a documented infection, dermatomal herpes zoster. At a median follow-up of 42 months (range, 5 to 76), 12 patients remain alive and one patient has died. Thus, cladribine has major activity in adult LCH and warrants further investigation in both pediatric and adult LCH as a single agent and in combination with other drugs.

Description: Cladribine induces protracted remissions in patients with hairy cell leukemia (HCL). However, many long-term responders ultimately relapse. We sought to determine whether long-term complete responders subsequent to a single 7-day course of cladribine were without minimal residual disease (MRD) and potentially cured of HCL. From the 358-person Scripps Clinic cladribine database, we identified 19 patients in continuous and complete hematologic response (median age, 75 years; median time from diagnosis, 18 years; and median time from cladribine, 16 years). Nine of 19 (47%) patient samples had no evidence of residual disease; 7 of 19 (37%) samples had MRD; and 3 of 19 (16%) had morphologic evidence of HCL in hematoxylin and eosin–stained bone marrow sections. These results indicate that HCL is potentially curable after cladribine treatment. In addition, patients with MRD and even gross morphologic disease can live many years without manifesting hematologic relapses.

Description: Acute myeloid leukemia (AML) remains an incurable blood cancer largely due to rapid emergence of resistance to conventional treatments. Thus, new therapeutic modalities are greatly needed to halt AML development. Here, using genetic and xenograft mouse models, we reveal that inhibition of the ubiquitin ligase RNF5 in human AML cell lines and in MLL-AF9-driven AML severely decreased the leukemogenic potential of those cells and prolonged survival of model leukemic mice. These findings suggest the possibility that targeting a single gene, namely RNF5, could effectively inhibit different AML subtypes. We initially focused on RNF5 as its expression is upregulated in AML patient cohorts as well as in AML-derived cell lines compared with normal hematopoietic cells. Furthermore, high RNF5 expression in AML patient specimens correlated with poor prognosis, relapse and short overall patient survival. By contrast, specimens from AML patients who responded to therapy exhibited low RNF5 levels. In vitro, RNF5 loss impaired the clonogenic potential of MLL-AF9-transduced bone marrow cells and markedly attenuated growth and survival of AML but not CML or T-ALL cell lines, in which RNF5 is also highly expressed. High-throughput screen and bioinformatics analysis identified RNF5 and ER-associated degradation (ERAD) components, as augmenting AML cell sensitivity to histone deacetylase (HDAC) inhibition. Indeed, inhibition of RNF5 sensitized AML cells to HDAC inhibitors. Correspondingly, a favorable prognosis was observed in AML patients exhibiting low expression of RNF5 and HDAC. Collectivity, our studies identify a potential new therapeutic modality based on targeting RNF5 to inhibit AML and suggest that RNF5 expression could serve as a prognostic marker and means to stratify patients for treatment with HDAC inhibitors. Disclosures Ofran: AbbVie: Membership on an entity's Board of Directors or advisory committees. Vuori:Bionano Genomics: Membership on an entity's Board of Directors or advisory committees.