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In classical Hodgkin lymphoma (cHL), responsiveness to immune-checkpoint blockade (ICB) is associated with specific tumor microenvironment (TME) and peripheral blood features. The role of ICB in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is not established. To gain insights into its potential in NLPHL, we compared TME and peripheral blood signatures between HLs using an integrative multiomic analysis. A discovery/validation approach in 121 NLPHL and 114 cHL patients highlighted >2-fold enrichment in programmed cell death-1 (PD-1) and T-cell Ig and ITIM domain (TIGIT) gene expression for NLPHL versus cHL. Multiplex imaging showed marked increase in intra-tumoral protein expression of PD-1+ (and/or TIGIT+) CD4+ T-cells and PD-1+CD8+ T-cells in NLPHL compared to cHL. This included T-cells that rosetted with lymphocyte predominant (LP) and Hodgkin Reed-Sternberg (HRS) cells. In NLPHL, intra-tumoral PD-1+CD4+ T-cells frequently expressed TCF-1, a marker of heightened T-cell response to ICB. The peripheral blood signatures between HLs were also distinct, with higher levels of PD-1+TIGIT+ in TH1, TH2, and regulatory CD4+ T-cells in NLPHL versus cHL. Circulating PD-1+CD4+ had high levels of TCF-1. Notably, in both lymphomas, highly expanded populations of clonal TIGIT+PD-1+CD4+ and TIGIT+PD-1+CD8+ T-cells in the blood were also present in the TME, indicating that immune-checkpoint expressing T-cells circulated between intra-tumoral and blood compartments. In in vitro assays, ICB was capable of reducing rosette formation around LP and HRS cells, suggesting that disruption of rosetting may be a mechanism of action of ICB in HL. Overall, results indicate that further evaluation of ICB is warranted in NLPHL., (© 2024 The Author(s). American Journal of Hematology published by Wiley Periodicals LLC.)

Classic Hodgkin lymphoma (HL) is rare disease, with an incidence of approximately 85,000 patients globally per year and a predilection for adolescents and young adults (ages 15-39). Since the introduction of combination chemotherapy in the 1960's and radiation dating back to the early 1900's, therapeutic options and by extension, clinical outcomes have improved dramatically with 5-year overall survival (OS) approaching 90% today. [1](#ref-0001) Advances in understanding HL biology have additionally facilitated development of targeted agents and immunotherapy which have further improved short and long-term outcomes. Despite continued improvements in up-front and salvage therapy, long-term survivors of HL experience several treatment-associated late toxicities, thus, along with efforts to improve therapeutic efficacy, efforts to reduce late effects remain a high-priority in the field., (© 2023 John Wiley & Sons Ltd.)

Despite widespread vaccination rates, we are living with high transmission rates of SARS-CoV-2. Although overall hospitalisation rates are falling, the risk of serious infection remains high for patients who are immunocompromised because of haematological malignancies. In light of the ongoing pandemic and the development of multiple agents for treatment, representatives from the Haematology Society of Australia and New Zealand and infectious diseases specialists have collaborated on this consensus position statement regarding COVID-19 management in patients with haematological disorders. It is our recommendation that both patients with haematological malignancies and treating specialists be educated regarding the preventive and treatment options available and that patients continue to receive adequate vaccinations, keeping in mind the suboptimal vaccine responses that occur in haematology patients, in particular, those with B-cell malignancies and on B-cell-targeting or depleting therapy. Patients with haematological malignancies should receive treatment for COVID-19 in accordance with the severity of their symptoms, but even mild infections should prompt early treatment with antiviral agents. The issue of de-isolation following COVID-19 infection and optimal time to treatment for haematological malignancies is discussed but remains an area with evolving data. This position statement is to be used in conjunction with advice from infectious disease, respiratory and intensive care specialists, and current guidelines from the National COVID-19 Clinical Evidence Taskforce and the New Zealand Ministry of Health and Cancer Agency Te Aho o Te Kahu COVID-19 Guidelines., (© 2023 The Authors. Internal Medicine Journal published by John Wiley & Sons Australia, Ltd on behalf of Royal Australasian College of Physicians.)

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported. We analyzed long-term results of the response-adapted trial for adult patients with advanced-stage Hodgkin lymphoma. The aim was to confirm noninferiority of treatment de-escalation by omission of bleomycin from doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) for interim fluorodeoxyglucose positron emission tomography (iPET)-negative patients and assess efficacy and long-term safety for iPET-positive patients who underwent treatment intensification with escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisolone (BEACOPP/BEACOPP14). The median follow-up is 7.3 years. For all patients, the 7-year progression-free survival (PFS) and overall survival (OS) are 78.2% (95% CI, 75.6 to 80.5) and 91.6% (95% CI, 89.7 to 93.2), respectively. The 1.3% difference in 3-year PFS (95% CI, -3.0 to 4.7) between ABVD and doxorubicin, vinblastine, and dacarbazine (AVD) now falls within the predefined noninferiority margin. Among 172 patients with positive iPET, the 7-year PFS was 65.9% (95% CI, 58.1 to 72.6) and the 7-year OS was 83.2% (95% CI, 76.2 to 88.3). The cumulative incidence of second malignancies at 7 years was 5.5% (95% CI, 4.0 to 7.5) for those receiving ABVD/AVD and 2.5% (95% CI, 0.8 to 7.7) for those escalated to BEACOPP. With extended follow-up, these results confirm noninferiority of treatment de-escalation after a negative iPET. Escalation with BEACOPP for iPET-positive patients is effective and safe, with no increase in second malignancies.

High-dose intravenous methotrexate (HD-MTX) CNS prophylaxis in high-risk diffuse large B cell lymphoma (DLBCL) remains controversial. We describe real-world CNS relapse incidence following baseline cerebrospinal fluid (CSF) analysis to exclude asymptomatic leptomeningeal involvement in newly diagnosed high-risk DLBCL patients with versus without single-route HD-MTX CNS prophylaxis. Consecutively diagnosed high-risk systemic DLBCL patients without leptomeningeal involvement by CSF analysis (noCNS) were identified retrospectively. Five-year CNS relapse incidence and survival outcomes were examined, as stratified by receipt of HD-MTX prophylaxis. Secondary analysis of survival outcomes in patients with synchronous leptomeningeal involvement (CNSinv) by CSF analysis at diagnosis were compared with the noCNS group. No significant difference in 5-year CNS relapse incidence was observed following HD-MTX prophylaxis versus no prophylaxis (total n = 445) despite similar CNS-IPI risk; 6.2% versus 5.6%, adjusted HR 1.08 (95% CI 0.41-2.85), p = .88; nor in 5-year progression free survival (PFS) or overall survival (OS) risk. Of CNSinv patients, 93.3% had ≥1 extranodal site. Increased CNS relapse/progression risk (5-year risk; HR 10.7 [95% CI 5.35-21.37], p < .0001) and inferior PFS and OS were observed in CNSinv versus all noCNS patients. The CNSinv group had superior OS compared with noCNS patients who later experienced CNS relapse (HR 0.55, p = .052). HD-MTX prophylaxis does not reduce CNS relapse risk in high-risk systemic DLBCL without leptomeningeal involvement by CSF analysis at diagnosis. Asymptomatic patients with synchronous leptomeningeal involvement on baseline CSF examination are at increased risk of further CNS disease events and inferior survival compared to patients without CSF involvement., (© 2023 Wiley Periodicals LLC.)

Lymphoma in pregnancy (LIP) presents unique clinical, social and ethical challenges; however, the evidence regarding this clinical scenario is limited. We conducted a multicentre retrospective observational study reporting on the features, management, and outcomes of LIP in patients diagnosed between January 2009 and December 2020 at 16 sites in Australia and New Zealand for the first time. We included diagnoses occurring either during pregnancy or within the first 12 months following delivery. A total of 73 patients were included, 41 diagnosed antenatally (AN cohort) and 32 postnatally (PN cohort). The most common diagnoses were Hodgkin lymphoma (HL; 40 patients), diffuse large B-cell lymphoma (DLBCL; 11) and primary mediastinal B-cell lymphoma (PMBCL; six). At a median follow up of 2.37 years, the 2- and 5-year overall survival (OS) for patients with HL were 91% and 82%. For the combined DLBCL and PMBCL group, the 2-year OS was 92%. Standard curative chemotherapy regimens were successfully delivered to 64% of women in the AN cohort; however, counselling regarding future fertility and termination of pregnancy were suboptimal, and a standardised approach to staging lacking. Neonatal outcomes were generally favourable. We present a large multicentre cohort of LIP reflecting contemporary practice and identify areas in need of ongoing research., (© 2023 The Authors. British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

Comprehensive clinical characteristics of Australian patients with classical Hodgkin Lymphoma (cHL) have not previously been systematically collected and described. We report real-world data of 498 eligible patients from the first 5 years of the Lymphoma and Related Diseases Registry (LaRDR), including baseline characteristics, histologic subtype, and treatment patterns in first-line therapy. Patient demographics and distribution of histopathological subtypes of cHL are similar to reported international cohorts. Doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) was the most common therapy for both early and advanced-stage disease, and 48% of patients with the early-stage disease received radiotherapy. Treatment patterns are consistent with international guidelines. In comorbid patients ≥60 years of age with advanced-stage disease, there is greater variation in treatment. In patients with a recorded response, the objective response rate (ORR) was 96% in early-stage disease, and 88% in advanced-stage disease. Early progression-free survival data suggest Australian patients with cHL have good outcomes, similar to other international studies., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Australia and New Zealand have achieved excellent community control of COVID-19 infection. In light of the imminent COVID-19 vaccination roll out in both countries, representatives from the Haematology Society of Australia and New Zealand and infectious diseases specialists have collaborated on this consensus position statement regarding COVID-19 vaccination in patients with haematological disorders. It is our recommendation that patients with haematological malignancies, and some benign haematological disorders, should have expedited access to high-efficacy COVID-19 vaccines, given that these patients are at high risk of morbidity and mortality from COVID-19 infection. Vaccination should not replace other public health measures in these patients, given that the effectiveness of COVID-19 vaccination, specifically in patients with haematological malignancies, is not known. Given the limited available data, prospective collection of safety and efficacy data of COVID-19 vaccination in this patient group is a priority., (© 2021 Royal Australasian College of Physicians.)

All-trans retinoic acid (ATRA) and arsenic trioxide (ATO) are effective induction therapy for acute promyelocytic leukaemia (APL). However, early thrombo-haemorrhagic complications and mortality remain high. We aimed to investigate how the timing of ATRA initiation and the inclusion of ATO influence patient outcomes. Clinical records were retrospectively reviewed for all patients treated for APL in a single, tertiary centre during 2000-2017. Among 70 patients with APL, 36 (51.4%) presented with thrombo-haemorrhagic complications, and four (5.8%) died within 30 days. The median time to ATRA initiation was 11.2 (range 0-104) h from the time of admission. Patients requiring more transfusions started on ATRA sooner (P = 0.04). Patients with adverse early events did not start ATRA later (P = 0.99). Nevertheless, patients that required additional tests for diagnosis (PML immunofluorescence or molecular) started on ATRA later (28.5 versus 5.3 h; P < 0.0001), and had more thrombo-haemorrhagic complications (P = 0.04). Long-term survival was actually better in patients who started ATRA later (P = 0.03), which is likely explained by higher proportion of low risk patients in this group. Patients treated with ATO (n = 23) maintained higher fibrinogen levels and required less transfusions during induction (P < 0.05), with no disease-related deaths in this group over a median follow-up time of 37.8 months (interquartile range 44.9 months). In summary, fast ATRA initiation reduces early but not late adverse events in APL patients, and the inclusion of ATO helps further improve both early and late outcomes in APL., Competing Interests: Declaration of Competing Interest Authors declare no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: The EPOCH regimen, consisting of vincristine sulfate, doxorubicin hydrochloride, and etoposide phosphate, is typically administered by continuous infusion over four days to oncology inpatients. If the EPOCH regimen was available to be administered through portable elastomeric pumps, chemotherapy could be transitioned to an outpatient setting, reducing inpatient bed days and overall healthcare costs. However, a lack of stability data for the admixtures in the elastomeric infusion devices currently prevents the transition of the regime to an outpatient setting. The purpose of this study is to determine the physical and chemical stability of the admixture in polyisoprene elastomeric pumps under different storage conditions to support the transition of the EPOCH regime to an outpatient setting., Methods: The physico-chemical stability of three admixtures at a range of clinically relevant concentrations compounded in polyisoprene elastomeric infusors was determined when refrigerated at 2-6℃ over a 14-day period followed by 35℃ up to 7 days in the dark, and under standardized fluorescent light to simulate scenarios in clinical practice., Results: All tested admixtures were compatible and the drugs were stable in the elastomeric infusors for up to 14 days when stored at 2-6℃ followed by 7 days at 35℃ in the dark, with nominal losses of <5%. The major degradant of etoposide phosphate was its active form etoposide. There was no degradation (<1% loss) found when the admixture was exposed to a standardized fluorescent light dose of 80 klux-h (25℃) for 10 h. The temperature and light conditions the infusors were exposed to during the stability study were more severe than the conditions determine during clinical administration., Conclusion: The extended stability of the three infusional admixtures compounded in elastomeric infusion pumps demonstrated herein permits advance preparation and storage of these drugs, reducing pharmacy compounding resources. The demonstrated stability at 35℃ and under light exposure, conditions more severe than those experienced during clinical practice, support continuous infusions for up to seven days from the elastomeric infusors without a loss of potency. The proven stability of the EPOCH regimens in the tested elastomeric infusion device supports the transition of treatment to an outpatient setting which will reduce inpatient bed days and overall healthcare costs.

Current guidelines recommend that a rapid test be used to assist diagnosis of acute promyelocytic leukaemia (APL), but the choice of an assay is discretionary. PML immunofluorescence (PML IF) identifies the microparticulate pattern of the PML protein localisation, highly specific for APL. The aim of this study was to evaluate clinical utility of PML IF in a real-life setting based on a retrospective records review for all patients who had PML IF performed in our centre between 2000 and 2017. Final analysis included 151 patients, 70 of whom had APL. PML IF was reported on average 3 days faster than cytogenetics. Compared with genetic results, PML IF showed sensitivity of 96% and specificity of 100%. PML IF accurately predicted APL in four APL cases with cryptic karyotype/FISH and excluded APL in 98% cases tested based on the suspicious immunophenotype alone, 21/28 of whom had mutated NPM1. Results of PML IF influenced decision to start ATRA in 25 (36%) APL patients and led to its termination in six non-APL patients. In conclusion, PML IF is a fast and reliable test that facilitates accurate treatment decisions when APL is suspected. This performance of PML IF remains hard to match in a real-life setting., (Copyright © 2019 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.)

Background: We tested interim positron-emission tomography-computed tomography (PET-CT) as a measure of early response to chemotherapy in order to guide treatment for patients with advanced Hodgkin's lymphoma., Methods: Patients with newly diagnosed advanced classic Hodgkin's lymphoma underwent a baseline PET-CT scan, received two cycles of ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) chemotherapy, and then underwent an interim PET-CT scan. Images were centrally reviewed with the use of a 5-point scale for PET findings. Patients with negative PET findings after two cycles were randomly assigned to continue ABVD (ABVD group) or omit bleomycin (AVD group) in cycles 3 through 6. Those with positive PET findings after two cycles received BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone). Radiotherapy was not recommended for patients with negative findings on interim scans. The primary outcome was the difference in the 3-year progression-free survival rate between randomized groups, a noninferiority comparison to exclude a difference of 5 or more percentage points., Results: A total of 1214 patients were registered; 937 of the 1119 patients (83.7%) who underwent an interim PET-CT scan according to protocol had negative findings. With a median follow-up of 41 months, the 3-year progression-free survival rate and overall survival rate in the ABVD group were 85.7% (95% confidence interval [CI], 82.1 to 88.6) and 97.2% (95% CI, 95.1 to 98.4), respectively; the corresponding rates in the AVD group were 84.4% (95% CI, 80.7 to 87.5) and 97.6% (95% CI, 95.6 to 98.7). The absolute difference in the 3-year progression-free survival rate (ABVD minus AVD) was 1.6 percentage points (95% CI, -3.2 to 5.3). Respiratory adverse events were more severe in the ABVD group than in the AVD group. BEACOPP was given to the 172 patients with positive findings on the interim scan, and 74.4% had negative findings on a third PET-CT scan; the 3-year progression-free survival rate was 67.5% and the overall survival rate 87.8%. A total of 62 patients died during the trial (24 from Hodgkin's lymphoma), for a 3-year progression-free survival rate of 82.6% and an overall survival rate of 95.8%., Conclusions: Although the results fall just short of the specified noninferiority margin, the omission of bleomycin from the ABVD regimen after negative findings on interim PET resulted in a lower incidence of pulmonary toxic effects than with continued ABVD but not significantly lower efficacy. (Funded by Cancer Research UK and Others; ClinicalTrials.gov number, NCT00678327.).

International guidelines recommend that positron emission tomography-computed tomography (PET-CT) should replace CT in Hodgkin lymphoma (HL). The aims of this study were to compare PET-CT with CT for staging and measure agreement between expert and local readers, using a 5-point scale (Deauville criteria), to adapt treatment in a clinical trial: Response-Adapted Therapy in Advanced Hodgkin Lymphoma (RATHL). Patients were staged using clinical assessment, CT, and bone marrow biopsy (RATHL stage). PET-CT was performed at baseline (PET0) and after 2 chemotherapy cycles (PET2) in a response-adapted design. PET-CT was reported centrally by experts at 5 national core laboratories. Local readers optionally scored PET2 scans. The RATHL and PET-CT stages were compared. Agreement among experts and between expert and local readers was measured. RATHL and PET0 stage were concordant in 938 (80%) patients. PET-CT upstaged 159 (14%) and downstaged 74 (6%) patients. Upstaging by extranodal disease in bone marrow (92), lung (11), or multiple sites (12) on PET-CT accounted for most discrepancies. Follow-up of discrepant findings confirmed the PET characterization of lesions in the vast majority. Five patients were upstaged by marrow biopsy and 7 by contrast-enhanced CT in the bowel and/or liver or spleen. PET2 agreement among experts (140 scans) with a κ (95% confidence interval) of 0.84 (0.76-0.91) was very good and between experts and local readers (300 scans) at 0.77 (0.68-0.86) was good. These results confirm PET-CT as the modern standard for staging HL and that response assessment using Deauville criteria is robust, enabling translation of RATHL results into clinical practice., (© 2016 by The American Society of Hematology.)

There is no consensus regarding optimal follow-up mode for Hodgkin lymphoma (HL) patients that achieve complete remission following chemotherapy or combined chemo- and radiation therapy. Several studies demonstrated high sensitivity of positron emission tomography/computerized tomography (PET/CT) in detecting disease progression; however, these techniques are currently not recommended for routine follow-up. This retrospective study conducted in two Israeli (N = 291) and one New Zealand academic centres (N = 77), compared a group of HL patients, followed-up with routine imaging every 6 months during the first 2 years after achieving remission, once in the third year, with additional dedicated studies performed due to symptoms or physical findings (Group I) to a group of patients without residual masses who underwent clinically-based surveillance with dedicated imaging upon relapse suspicion (Group II). Five-year overall survival (OS) was 94% and median time to relapse was 8·6 months for both modes. Relapse rates in Groups I and II were 13% and 9%, respectively. During the first 3 years of follow-up, 47·5 and 4·7 studies were performed per detected relapse in Groups I and II, respectively. The current study demonstrated no benefit in either progression-free survival (PFS) or OS in HL patients followed by routine imaging versus clinical follow-up. The cost was 10 times higher for routine imaging., (© 2013 John Wiley & Sons Ltd.)

We used differential time to positivity between central and peripheral blood cultures to evaluate the positive predictive value (PPV) of the National Healthcare Safety Network central line-associated bloodstream infection (CLABSI) surveillance definition among hematology patients with febrile neutropenia. The PPV was 27.7%, which suggests that, when the definition is applied to this population, CLABSI rates will be substantially overestimated.

Purpose: In diffuse large B-cell lymphoma (DLBCL), prior studies suggest that concordant bone marrow involvement with DLBCL portends a poorer prognosis, whereas discordant bone marrow involvement with small B-cell lymphoma does not. We examined the significance of bone marrow involvement in patients treated in the current era of therapy including rituximab., Patients and Methods: We performed a retrospective analysis of the prognostic impact of bone marrow involvement in an unselected population of patients with newly diagnosed DLBCL treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone in British Columbia and Auckland, New Zealand, with complete clinical information and evaluable staging bone marrow biopsies., Results: In total, 795 patients were identified. Six hundred seventy (84.3%) of 795 had a negative bone marrow, 67 patients (8.4%) had concordant and 58 (7.3%) had discordant involvement. Median follow-up was 41 months (range, 1 to 115). Progression-free survival (PFS) was inferior in those with concordant (P < .001) and discordant (P = .019) involvement while overall survival (OS) was inferior in those with concordant involvement (P < .001) only. In a multivariate analysis controlling for the International Prognostic Index (IPI) score, concordant involvement remained an independent predictor of PFS (P < .001) and OS (P = .007). Discordant involvement was associated with older age, elevated lactate dehydrogenase, advanced stage, and increased number of extranodal sites and was not a negative prognostic factor independent of the IPI score., Conclusion: The negative prognostic impact of discordant involvement is adequately represented by the IPI score, while the risk with concordant involvement is greater than that encompassed by this predictor. The results emphasize the need for accurate staging assessment of bone marrow involvement in DLBCL.

The effect of age on the hematopoietic system has always been an area of clinical interest. Alterations in lymphocyte immunophenotype and function with age have been clearly demonstrated as has a decrease in neutrophil function. However, controversy continues to surround the significance of unexplained anaemia in the elderly patient and the extent to which this could be a physiological occurrence. The weight of evidence from animal and human studies would suggest that anaemia is not a physiological occurrence but may have a multifactorial pathogenesis. Are older patients therefore, appropriate candidates for high dose therapy, including autologous stem cell transplantation? The loss of telomeric DNA from hematopoietic progenitor cells with aging implies that stem cell collections from an older patient may have compromised replicative capacity with a reduced response to hematopoietic growth factors. Recent studies, however, show that age is not an obstacle for the collection of a stem cell product, which is capable of restoring normal hematopoietic function. A study of autologous stem cell transplantation has shown comparable neutrophil and platelet recovery times between younger and older patients., (Copyright 2004 Taylor and Francis Ltd)

Chronic lymphocytic leukemia (CLL) cells express the CD20 antigen, and monoclonal antibodies against CD20 have resulted in remissions. We hypothezised that the anti-CD20 antibody rituximab (Rituxan) may be useful in reducing the number of contaminating CLL cells in stem cell collections for use in autologous transplantation. A pilot study in 5 patients was designed using rituximab 375 mg/m(2) as an in vivo purging step following cyclophosphamide 4 gm/m(2) and granulocyte colony-stimulating factor/granulocyte-macrophage colony-stimulating factor (G-CSF/GM-CSF) mobilization therapy for patients with advanced-stage CLL undergoing autologous stem cell transplantation. Eligible patients had 0-30% marrow involvement prior to mobilization. A single pre-rituximab leukapheresis product was obtained after the white blood cells (WBC) reached 800/mm(3) to serve as a control but was not reinfused. Rituximab was administered the following day and subsequent leukaphereses were commenced 48 h later to reach a total of >2 x 10(6) CD34(+) cells/kg. Dual-color flow cytometry CD5/CD19 and consensus PCR using primers to the joining region and FR3 of the variable region of the immunoglobulin heavy chain (IgH) were used to evaluate the degree of contaminating CLL cells in the leukapheresis product and to monitor disease status post transplant. All 5 patients were informative for the consensus PCR assay. Four of 5 patients mobilized >2 x 10(6) CD34(+) cells/kg and proceeded to cyclophosphamide 120 mg/kg and total body irradiation (6 x 200 cGy) with stem cell rescue. All leukaphereses products were positive by PCR for the IgH rearrangement and 4/5 contained CD5/CD19 dual-positive cells. Comparing the pre- and post-rituximab leukapheresis products, a reduction in the percentage of CD5(+)/CD19(+) cells was seen in 4/5 patients. All patients engrafted at a median of 13.5 days to ANC > 500/mm(3) and 11 days to platelets >20,000/mm(3). No regimen-related mortality was seen. Although 2 patients tested positive on PCR for the IgH rearrangement early after transplant, all patients had absence of the IgH gene rearrangement at 1 year and no CD5/CD19 dual-positive cells were could be detected in the bone marrow. This includes 1 heavily pretreated patient who received stem cells containing up to 30% CD5(+)/CD19(+) cells. We conclude that purging with Rituximab 48 h prior to stem cell collection was able to reduce significantly (but not eliminate) the percentage of CLL cells in the leukaphereses. However, despite the infusion of CD5(+)/CD19(+) cells in the stem cell coions, patients were able to obtain durable complete molecular remissions, implying that the PCR-positive cells in the leukaphereses may not have long-term clonogenic potential. The results also support the recommendation to test if rituximab should be part of a maintenance regimen after transplant to prevent disease recurrence in high-risk patients.

Malignant cells in the stem cell product have been shown to contribute to disease recurrence in patients who relapse after autologous transplantation. Immunologic methods of purging tumor cells from stem cell products focus on either removal of specific target cells or positive selection of HPC. mAb are the key component of many purging strategies and are employed both in vitro and in vivo. Cytotoxic cellular therapies are an emerging method of tumor cell eradication.

Leukaemic transformation of essential thrombocythaemia is a rare event and is usually associated with previous treatment with either alkylating agents or radioactive phosphorous. We describe a patient with essential thrombocythaemia who developed an acute leukaemia of T cell phenotype following hydroxyurea therapy. The T cell phenotype of the blasts suggests the target cell for leukaemic transformation was a pluripotential stem cell.