Whole-genome and transcriptome analysis enhances precision cancer treatment options.

BACKGROUND: Recent advances are enabling delivery of precision genomic medicine to cancer clinics. While the majority of approaches profile panels of selected genes or hotspot regions, comprehensive data provided by whole-genome and transcriptome sequencing and analysis (WGTA) present an opportunity to align a much larger proportion of patients to therapies. PATIENTS AND METHODS: Samples from 570 patients with advanced or metastatic cancer of diverse types enrolled in the Personalized OncoGenomics (POG) program underwent WGTA. DNA-based data, including mutations, copy number and mutation signatures, were combined with RNA-based data, including gene expression and fusions, to generate comprehensive WGTA profiles. A multidisciplinary molecular tumour board used WGTA profiles to identify and prioritize clinically actionable alterations and inform therapy. Patient responses to WGTA-informed therapies were collected. RESULTS: Clinically actionable targets were identified for 83% of patients, of which 37% of patients received WGTA-informed treatments. RNA expression data were particularly informative, contributing to 67% of WGTA-informed treatments; 25% of treatments were informed by RNA expression alone. Of a total 248 WGTA-informed treatments, 46% resulted in clinical benefit. RNA expression data were comparable to DNA-based mutation and copy number data in aligning to clinically beneficial treatments. Genome signatures also guided therapeutics including platinum, poly-ADP ribose polymerase inhibitors and immunotherapies. Patients accessed WGTA-informed treatments through clinical trials (19%), off-label use (35%) and as standard therapies (46%) including those which would not otherwise have been the next choice of therapy, demonstrating the utility of genomic information to direct use of chemotherapies as well as targeted therapies. CONCLUSIONS: Integrating RNA expression and genome data illuminated treatment options that resulted in 46% of treated patients experiencing positive clinical benefit, supporting the use of comprehensive WGTA profiling in clinical cancer care.

The ECHELON-2 Trial: 5-year results of a randomized, phase III study of brentuximab vedotin with chemotherapy for CD30-positive peripheral T-cell lymphoma.

BACKGROUND: For patients with peripheral T-cell lymphoma (PTCL), outcomes using frontline treatment with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like therapy are typically poor. The ECHELON-2 study demonstrated that brentuximab vedotin plus cyclophosphamide, doxorubicin, and prednisone (A+CHP) exhibited statistically superior progression-free survival (PFS) per independent central review and improvements in overall survival versus CHOP for the frontline treatment of patients with systemic anaplastic large cell lymphoma or other CD30-positive PTCL. PATIENTS AND METHODS: ECHELON-2 is a double-blind, double-dummy, randomized, placebo-controlled, active-comparator phase III study. We present an exploratory update of the ECHELON-2 study, including an analysis of 5-year PFS per investigator in the intent-to-treat analysis group. RESULTS: A total of 452 patients were randomized (1 : 1) to six or eight cycles of A+CHP (N = 226) or CHOP (N = 226). At median follow-up of 47.6 months, 5-year PFS rates were 51.4% [95% confidence interval (CI): 42.8% to 59.4%] with A+CHP versus 43.0% (95% CI: 35.8% to 50.0%) with CHOP (hazard ratio = 0.70; 95% CI: 0.53-0.91), and 5-year overall survival (OS) rates were 70.1% (95% CI: 63.3% to 75.9%) with A+CHP versus 61.0% (95% CI: 54.0% to 67.3%) with CHOP (hazard ratio = 0.72; 95% CI: 0.53-0.99). Both PFS and OS were generally consistent across key subgroups. Peripheral neuropathy was resolved or improved in 72% (84/117) of patients in the A+CHP arm and 78% (97/124) in the CHOP arm. Among patients who relapsed and subsequently received brentuximab vedotin, the objective response rate was 59% with brentuximab vedotin retreatment after A+CHP and 50% with subsequent brentuximab vedotin after CHOP. CONCLUSIONS: In this 5-year update of ECHELON-2, frontline treatment of patients with PTCL with A+CHP continues to provide clinically meaningful improvement in PFS and OS versus CHOP, with a manageable safety profile, including continued resolution or improvement of peripheral neuropathy.

Canadian cohort expanded-access program of nivolumab plus ipilimumab in advanced melanoma.

Background: The combination of nivolumab and ipilimumab is approved in several jurisdictions (United States, European Union, Canada) for the first-line treatment of patients with advanced melanoma. CheckMate 218 is a North American expanded-access program (eap) of nivolumab plus ipilimumab in patients with advanced melanoma. Here, we report safety and survival outcomes for the Canadian cohort in the eap. Methods: Eligible patients were those 18 years of age or older with unresectable stage iii or iv melanoma, an Eastern Cooperative Oncology Group performance status of 0 or 1, and no prior anti-PD-1 or anti-ctla-4 therapy. Patients were treated with nivolumab 1 mg/kg and ipilimumab 3 mg/kg every 3 weeks for 4 cycles (induction phase); they then continued with nivolumab 3 mg/kg every 2 weeks (maintenance phase) until progression, unacceptable toxicity, or a maximum of 48 weeks, whichever occurred first. Safety and overall survival (os) data were collected. Results: Of 194 patients enrolled, 174 were treated, and 51% continued on nivolumab maintenance. Median follow-up was 12.9 months. All-grade and grades 3-4 treatment-related adverse events were reported in 98% and 60% of patients respectively and led to treatment discontinuation in 40% and 28% of patients. Two treatment-related deaths were reported. The 12- and 18-month os rates were 80% [95% confidence interval (ci): 73% to 86%] and 76% (95% ci: 67% to 82%) respectively. Conclusions: In this Canadian population, nivolumab plus ipilimumab demonstrated a safety profile and survival outcomes consistent with phase ii and iii clinical trial data.

Observation as the initial management strategy in patients with mantle cell lymphoma.

BACKGROUND: Patients with mantle cell lymphoma (MCL) follow a heterogeneous clinical course. While they generally require treatment initiation shortly after diagnosis, it is unclear whether deferring treatment in selected patients with an indolent clinical behavior affects their overall outcome. PATIENTS AND METHODS: In this population-based study, all patients diagnosed with MCL during 1998-2014 were identified in the British Columbia Cancer Agency Lymphoid Cancer Database. The associations between clinico-pathologic characteristics, including the expression of Ki67, SOX11, and TP53, and time to treatment (TtT) and OS were analyzed. RESULTS: A total of 440 patients with MCL were evaluated: 365 (83%) received early treatment and 75 (17%) were observed ≥3 months. In the observation group, 54 (72%) patients had a nodal presentation, 16 (21%) a non-nodal presentation, and 5 (7%) had only gastrointestinal involvement. Characteristics associated with deferred treatment included good performance status, no B symptoms, low LDH, non-bulky disease, non-blastoid morphology, and lower Ki67 values. The median TtT in the observation group was 35 months (range 5-79), and 60 (80%) patients were observed beyond 12 months. The median OS was significantly longer in the observation group than in the early treatment group (72 versus 52.5 months, respectively, P = 0.041). In multivariable analysis, treatment decision was not associated with OS [HR 0.804 (95% CI 0.529-1.221), P = 0.306]. CONCLUSIONS: A subgroup of patients with MCL may be safely observed from diagnosis without negatively impacting their outcomes, including patients with non-nodal presentation as well as asymptomatic patients with low burden nodal presentation and a low proliferative rate.

ABVD chemotherapy with reduced radiation therapy rates in children, adolescents and young adults with all stages of Hodgkin lymphoma.

Background: We adopted ABVD chemotherapy with risk-adapted radiation therapy (RT) as first-line therapy for children, adolescents and young adults with Hodgkin lymphoma (HL) in British Columbia in 2004. Patients and methods: Patients ≤ 25 years diagnosed from 2004 to 2013 with all stages of HL who received ABVD as initial therapy were included. Results: Among 55 children (age < 18 year) and 154 young adults (18-25 year), there were no significant differences among age groups for sex, histologic subtype, tumour bulk, B symptoms, prognostic risk groups or treatment received. The rates of complete response, partial response and progressive disease were 84%, 7% and 10% for children and 95%, 4% and 1% for young adults (P=0.01), respectively. Treatment failures in children all occurred within one year of completion, while 8/21 (38%) relapses in young adults occurred later (P=0.04). With a median follow-up of 66 months the 5-year progression-free (PFS) and overall survival (OS) were 85 ± 3% and 97 ± 1%, respectively. For limited stage disease, PFS was 90 ± 7% for children and 93 ± 3% for young adults (P=0.65); OS was 100% for both. For advanced stage patients, PFS and OS were also similar for the children and young adults (77 ± 7% versus 81 ± 4%; P=0.38 and OS 90 ± 6% versus 97 ± 2%; P=0.17). The rate of consolidative RT was low (21%) and did not differ between age groups. Conclusion: ABVD is an effective treatment in children, adolescents and young adults with HL. Children were less likely to achieve complete response and demonstrated earlier relapses compared to young adults. RT may be omitted for the majority of patients while maintaining excellent 5-year OS.

Effect of nivolumab on health-related quality of life in patients with treatment-naïve advanced melanoma: results from the phase III CheckMate 066 study.

BACKGROUND: Nivolumab has shown significant survival benefit and a favorable safety profile compared with dacarbazine chemotherapy among treatment-naïve patients with metastatic melanoma in the CheckMate 066 phase III study. Results from the health-related quality of life (HRQoL) analyses from CheckMate 066 are presented. PATIENTS AND METHODS: HRQoL was evaluated at baseline and every 6 weeks while on treatment using the European Organisation for Research and Treatment of Care (EORTC) Core Quality of Life Questionnaire (QLQ-C30) and the EuroQoL Five Dimensions Questionnaire (EQ-5D). Via a multi-step statistical plan, data were analyzed descriptively, cross-sectionally, and longitudinally, adjusting for baseline covariates, in patients having baseline plus ≥1 post-baseline assessment. RESULTS: Baseline-adjusted completion rates for all HRQoL questionnaires across treatment arms were 65% and 70% for dacarbazine and nivolumab, respectively, and remained similar throughout treatment. The mean baseline HRQoL scores were similar for patients treated with nivolumab and dacarbazine. Baseline HRQoL levels with nivolumab were maintained over time. This exploratory analysis showed a between-arm difference in favor of nivolumab on the EQ-5D utility index and clinically meaningful EQ-5D improvements from baseline at several time points for patients receiving nivolumab. Patients treated with nivolumab did not show increased symptom burden as assessed by the EORTC QLQ-C30. No HRQoL change was noted with dacarbazine patients up to week 43, although the high attrition rate after week 13 did not allow any meaningful analyses. Patients receiving nivolumab deteriorated significantly later than those receiving dacarbazine on several EORTC QLQ-C30 scales and the EQ-5D utility index. CONCLUSIONS: In addition to prolonged survival, these exploratory HRQoL results show that nivolumab maintains baseline HRQoL levels to provide long-term quality of survival benefit, compared with dacarbazine in patients with advanced melanoma.

The value of routine bone marrow biopsy in patients with diffuse large B-cell lymphoma staged with PET/CT: a Danish-Canadian study.

BACKGROUND: The added diagnostic and prognostic value of routine bone marrow biopsy (BMB) in patients with diffuse large B-cell lymphoma (DLBCL) undergoing positron emission tomography combined with computed tomography (PET/CT) staging is controversial. PATIENTS AND METHODS: Patients with newly diagnosed DLBCL who underwent both staging PET/CT and BMB were retrospectively identified in British Columbia, Aalborg, and Copenhagen. Original written PET/CT and pathology reports were retrospectively reviewed to determine Ann Arbor stage and outcomes, with and without the contribution of BMB. RESULTS: A total of 530 patients were identified: 146 (28%) had focal bone marrow (BM) lesions on PET/CT and 87 (16%) had positive BMB. Fifty-two of 146 patients (36%) with positive PET/CT had a positive BMB [39 DLBCL, 13 indolent non-Hodgkin lymphoma (iNHL)], while 35 of 384 patients (9%) with negative PET/CT had positive BMB (12 DLBCL, 23 iNHL). BMB upstaged 12/209 (6%) of stage I/II patients to stage IV, although this was the case for only 3 (1%) patients with DLBCL in the BMB. PET/CT identified BM involvement by BMB with sensitivity 60%, specificity 79%, positive predictive value 36%, and negative predictive value 91%. Concordant histological involvement of the BM by DLBCL was associated with worse overall survival and progression-free survival than discordant or no involvement in univariate and multivariate analyses. CONCLUSIONS: In patients with DLBCL, staging PET/CT can miss BM involvement with concordant DLBCL (less common) or discordant iNHL (more common). Routine BMB does not add relevant diagnostic or prognostic value over PET/CT alone in the majority of patients with DLBCL.

Outcome of patients with primary refractory diffuse large B cell lymphoma after R-CHOP treatment.

Primary refractory diffuse large B cell lymphoma (DLBCL) following R-CHOP chemotherapy is a major concern. We identified 1126 patients with DLBCL treated with R-CHOP from 2000 to 2009, of whom 166 (15 %) had primary refractory disease. Of the 75/166 (45 %) who were age <70 years and had been planned for stage-directed curative therapy, 43 (57 %) were primary nonresponders and 32 (43 %) relapsed within 3 months of completing R-CHOP. Thirty of 75 (40 %) patients had serious comorbidity and organ dysfunction precluding intensive treatment and had palliative treatment only. Twelve of 45 (27 %) patients responded to second-line treatment and underwent ASCT. The median overall survival for the 75 patients was 10 months with only seven patients alive without evidence of disease at follow-up ranging from 14 to 106 months. Primary refractory DLBCL after R-CHOP has a very poor outcome with only anecdotal survivors independent of the intended treatment approach.

Chemoresistance can be overcome with high-dose chemotherapy and autologous stem-cell transplantation for relapsed and refractory Hodgkin lymphoma.

BACKGROUND: High-dose therapy and autologous stem-cell transplant (HDT/ASCT) is the preferred treatment of chemosensitive relapsed/refractory Hodgkin lymphoma (HL). The role for HDT/ASCT in chemoresistant HL is less well defined. We evaluated long-term outcomes of relapsed/refractory HL patients whose disease was refractory to secondary chemotherapy preceding HDT/ASCT. PATIENTS AND METHODS: All HL patients who underwent HDT/ASCT in British Columbia for primary progression (PP, defined as progression within 3 months of initial therapy completion) or first relapse (REL1) were reviewed. Patients were grouped based on response to secondary chemotherapy as sensitive (S), resistant (R), and untested/unknown (U). RESULTS: A total of 256 patients underwent HDT/ASCT for PP (35%) or REL1 (65%) between 1985 and 2011. At median follow-up of 11.7 years, 58% were alive without HL, 36% relapsed; 6% died of transplant-related mortality, 3% secondary malignancies, and 3% unrelated causes. For PP/S, PP/R, and PP/U groups, 10-year FFS were 47%, 31%, and 38%; 10-year OS were 52%, 29%, and 37%, respectively. For REL1/S, REL1/R, and REL1/U groups, 10-year FFS were 64%, 51%, and 81%; 10-year OS were 71%, 59%, and 79%, respectively. In multivariate analysis, resistance to secondary chemotherapy predicted for post-transplant mortality in the PP (P = 0.04) but not REL1 (P = 0.16) groups. CONCLUSION: In this large uniformly treated cohort of HL patients with long-term follow-up, chemoresistance preceding HDT/ASCT was identified as a poor prognostic factor; however, this factor can be partially overcome by HDT/ASCT, resulting in cure in 30%-50% of patients. HDT/ASCT should therefore be considered in all transplant eligible patients, regardless of responsiveness to salvage chemotherapy.

Incidence of transformation to aggressive lymphoma in limited-stage follicular lymphoma treated with radiotherapy.

BACKGROUND: The established treatment of limited-stage follicular lymphoma is radiotherapy (RT). There is an inherent risk of transformation of follicular lymphoma to aggressive lymphoma; however, the frequency and impact on the outcome are unknown in limited-stage patients. MATERIALS AND METHODS: We identified 237 patients with limited-stage follicular lymphoma treated with curative intent RT. Cases were reviewed to determine the frequency of transformation and subsequent survival. RESULTS: With a median follow-up of 7.4 years, the 10-year risk of transformation was 18.5%. With a median follow-up after transformation of 4.7 years, the 3-year post-transformation progression-free survival (PFS) and overall survival (OS) were 42% and 44%, respectively. The addition of rituximab improved the 3-year post-transformation PFS and OS compared with combination chemotherapy alone (78% versus 15%, P < 0.00001) and (87% versus 38.5%, P < 0.00001), respectively. In multivariate analysis, only rituximab was associated with OS [HR 0.07 (95% CI 0.015-0.312, P = 0.001)] and PFS [HR 0.19 (95% CI 0.55-0.626, P = 0.007)] following transformation. CONCLUSIONS: There is a moderate risk of transformation in limited-stage follicular lymphoma treated with curative intent RT, and it substantially impacts outcome in these patients. Treatment with rituximab at the time of transformation appears to improve survival in this otherwise poor-risk population.

Patients' and physicians' roles in detecting recurrent Hodgkin lymphoma following complete remission.

BACKGROUND: Optimal post-treatment surveillance for patients with Hodgkin lymphoma in first complete remission (CR) is unknown. Guidelines are based on consensus rather than high-quality evidence. It is unknown if routine screening leads to earlier relapse detection or translates into better outcomes. PATIENTS AND METHODS: We identified 258 patients with relapse after CR and determined whether the recurrence was detected as a result of patient-detected symptoms (PT group) or through exams or tests ordered by the physician in the absence of symptoms (MD group). RESULTS: Of 258 recurrences, 182 (71%) were in the PT group. The median time to diagnosis of recurrence was similar in both groups (PT group = 1.65 years; MD group = 1.95 years; P = 0.69). Neither the postrelapse progression-free (PFS, P = 0.26) nor overall survival (OS, P = 0.40) differed significantly between the groups. CONCLUSION: Patients are much more likely to detect recurrence than their physicians employing routine follow-up testing. There is no difference in PFS or OS between patients whose recurrence is self-diagnosed versus those whose recurrence is diagnosed by physician through routine screening. We found no benefit for detection of HL recurrence in asymptomatic patients and thus cannot support the routine use of costly, anxiety-provoking or potentially harmful tests in the absence of symptoms.

Incidence and risk factors for central nervous system relapse in patients with diffuse large B-cell lymphoma: the impact of the addition of rituximab to CHOP chemotherapy.

BACKGROUND: The addition of rituximab to CHOP (R-CHOP; CHOP, cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy improves outcome in patients with diffuse large B-cell lymphoma (DLBCL). We evaluated the risk of central nervous system (CNS) relapse in the R-CHOP in a population-based cohort of patients with DLBCL. METHODS: Patients with DLBCL diagnosed from 1 September 1999 to 14 January 2005 at the British Columbia Cancer Agency (BCCA) were identified. Patients were included if they were > or =16 years old with advanced stage or any stage with testicular involvement and were treated with CHOP (1999-2001) or R-CHOP (2001-2005) with curative intent. RESULTS: Four hundred and thirty-five patients were identified; 126 (29%) were treated with CHOP and 309 (71%) with R-CHOP. With a median follow-up of 5.7 years, there were 31 CNS relapses in total with a trend to a reduced likelihood of CNS relapse in R-CHOP-treated patients (3-year risk 9.7% versus 6.4, P = 0.085). In multivariate analysis, the use of rituximab significantly reduced the risk of CNS relapse [hazard ratio (HR) 0.45, P = 0.034]; this benefit was more striking in patients who achieved a complete response (HR 0.18, P = 0.005). CONCLUSION: The use of R-CHOP appears to reduce the overall risk of CNS relapse in patients with DLBCL particularly in patients who achieve a complete response.

Favorable outcome of primary mediastinal large B-cell lymphoma in a single institution: the British Columbia experience.

BACKGROUND: Primary mediastinal large B-cell lymphoma (PMBCL) is a distinct clinico-pathological subtype of diffuse large B-cell lymphoma (DLBCL). The optimal treatment is unknown, with some studies suggesting a superior outcome with dose-intensive chemotherapy regimens, and the role of radiotherapy remains ill-defined. PATIENTS AND METHODS: The British Columbia Cancer Agency lymphoma database was searched and records reviewed to identify those patients presenting with a prominent mediastinal mass and considered to be PMBCL based on the current REAL/WHO classifications. Patients were treated based on era-specific BCCA guidelines (1980-1992 MACOPB/VACOPB; 1992-2001 CHOP-type; 2001-present CHOP-R). Beginning in January 1998 involved-field radiotherapy was recommended to be routinely administered following chemotherapy. Prior to this, use of radiotherapy was individualized in advanced disease. RESULTS: In total, 153 patients with newly diagnosed PMBCL were identified between 28 July 1980 and 30 June 2003. The median age was 37 years (range 13-82) and the majority had stage I/II (74%), bulky mediastinal disease (75%). Overall (OS) and progression-free (PFS) survival at 5 years for the entire cohort were 75% and 69%, respectively. In direct comparison with a cohort of patients with DLBCL (n = 1273), OS (P = 10(-4)) and PFS (P = 0.0001) favored PMBCL. The age-adjusted International Prognostic Index (aaIPI) was not predictive of survival (P = 0.18). Five-year OS in patients < 65 years old treated with MACOPB/VACOPB, CHOP-R and CHOP-type was 87%, 81% and 71% respectively (P = 0.048). In pair-wise survival comparisons, only MACOPB/VACOPB and CHOP-type treated patients were significantly different (P = 0.016). In Cox multiple regression analysis, poor performance status remained the only predictor of survival, with treatment received demonstrating a trend to worse outcome for patients treated with CHOP-type regimens (P = 0.09). In an intention-to-treat analysis comparing the era before radiotherapy was routinely administered with after, there was no significant difference in 5-year PFS (74% versus 62%; P = 0.09) or OS (78% versus 69%; P = 0.14). CONCLUSIONS: In this single institution, population-based retrospective study, we found that PMBCL patients have excellent survival rates and a distinct plateau is observed in PFS, in striking comparison to DLBCL. The aaIPI was not predictive of survival in this population, suggesting that other prognostic models may be better suited for risk stratification. Dose-intensified chemotherapy with MACOPB or VACOPB demonstrated a trend to superior outcome over CHOP-type chemotherapy. However, further randomized studies are needed and the impact of rituximab on these comparisons must be considered. Finally, the routine addition of radiotherapy does not improve survival.

Characterization of peripheral T-cell lymphomas in a single North American institution by the WHO classification.

BACKGROUND: All peripheral T-cell lymphomas (PTCLs) diagnosed at a single institution were evaluated to determine the unique clinical features and outcome of specific entities and test the predictive validity of the International Prognostic Index (IPI). PATIENTS AND METHODS: Cases of PTCL seen at the British Columbia Cancer Agency between 1981 and 2000 were identified. Pathologic material was re-assessed and classified according to the WHO classification, and patients were staged and treated uniformly according to era-specific guidelines. In total, there were 199 patients with PTCL and the most common subtypes were peripheral T-cell lymphoma unspecified (PTCL-US) (59%), anaplastic large-cell lymphoma, systemic type (ALCL) (17%) and extranodal NK/T-cell lymphoma, nasal and nasal-type (NASAL) (9%). Most patients were treated with CHOP-type chemotherapy. RESULTS: Three distinct prognostic subgroups were notable on survival analysis: favorable (cutaneous ALCL), 5-year overall survival (OS) 78%; intermediate [PTCL, ALCL and angioimmunoblastic lymphoma (AILT)], 5-year OS 35-43%; unfavorable [NASAL and enteropathy-type T-cell lymphoma (ETTL)], 5-year OS 22-24%. Furthermore, in PTCL-US and ALCL clinical separation of patients into good risk (IPI 0,1) and poor risk (IPI > or =2) subsets was demonstrated. CONCLUSIONS: A large proportion of PTCL patients have poor risk disease and/or a histologically aggressive subtype with frequent relapse and unfavorable outcome. For these patients, treatment with CHOP chemotherapy is only minimally effective and new strategies need to be developed, an effort that will require a multi-institution international collaboration due to the rarity of most subtypes.

Outpatient use of low molecular weight heparin (Dalteparin) for the treatment of deep vein thrombosis of the upper extremity.

Upper extremity deep vein thrombosis (DVT) is now recognized as a major cause of morbidity and mortality. There is little information regarding the most effective treatment of this condition. We report a prospective cohort study of the use of low molecular weight heparin (LMWH) in the outpatient management of upper extremity DVT. Forty-six patients were managed as outpatients for objectively documented upper extremity DVT with dalteparin (200 aXa u/kg), for a minimum of five days. Warfarin was usually initiated on the first day with a target INR of 2.0-3.0. Most patients had an underlying malignancy or a history of a central line. All patients were followed for 12 weeks from diagnosis. Only one patient had a major bleed. No patients developed pulmonary emboli. One patient had a recurrence of DVT during the treatment with LMWH with extension of the existing thrombus. Seven patients died, all due to their underlying disease. This study supports the safety and effectiveness of dalteparin in the treatment of upper extremity DVT. Given that these patients were treated as outpatients, there is a potential for huge cost savings.

Receptor recognition sites reside in both lobes of human serum transferrin.

The binding of iron by transferrin leads to a significant conformational change in each lobe of the protein. Numerous studies have shown that the transferrin receptor discriminates between iron-saturated and iron-free transferrin and that it modulates the release of iron. Given these observations, it seems likely that there is contact between each lobe of transferrin and the receptor. This is the case with chicken transferrin, in which it has been demonstrated unambiguously that both lobes are required for binding and iron donation to occur [Brown-Mason and Woodworth (1984) J. Biol. Chem. 259, 1866-1873]. Further support to this contention is added by the ability of both N- and C-domain-specific monoclonal antibodies to block the binding of a solution containing both lobes [Mason, Brown and Church (1987) J. Biol. Chem. 262, 9011-9015]. In the present study a similar conclusion is reached for the binding of human serum transferrin to the transferrin receptor. With the use of recombinant N- and C-lobes of human transferrin produced in a mammalian expression system, we show that both lobes are required to achieve full binding. (Production of recombinant C-lobe in the baby hamster kidney cell system is reported here for the first time.) Each lobe is able to donate iron to transferrin receptors on HeLa S3 cells in the presence of the contralateral lobe. The results are not identical with the chicken system, because the C-lobe alone shows a limited ability to bind to receptors and to donate iron. Further complications arise from the relatively weak re-association between the two lobes of human transferrin compared with the re-association of the ovotransferrin lobes. However, domain-specific monoclonal antibodies to either lobe block the binding of N- and C-lobe mixtures in the human system, thus substantiating the need for both.

Association of the two lobes of ovotransferrin is a prerequisite for receptor recognition. Studies with recombinant ovotransferrins.

Different recombinant N-lobes of chicken ovotransferrin (oTF/2N) have been isolated from the tissue-culture medium of baby hamster kidney cells transfected with the plasmid pNUT containing the relevant DNA coding sequence. Levels of up to 40, 55 and 30 mg/1 oTF/2N were obtained for constructs defining residues 1-319, 1-332 and 1-337-(Ala)3 respectively. In addition, a full-length non-glycosylated oTF was expressed at a maximum of 80 mg/1 and a foreshortened oTF consisting of residues 1-682 was expressed at a level of 95 mg/l. These preparations were then used to produce, proteolytically, two different C-lobes (oTF/2C) comprising residues 342-686 and 342-682. The purified recombinant N-lobes (oTF/2N) are similar to the proteolytically derived half-molecule with regard to immunoreactivity and spectral properties; they show some interesting differences in thermal stability. A sequence analysis of the cDNA revealed six changes at the nucleotide level that led to six differences in the amino acid sequence compared with that reported by Jeltsch and Chambon [(1982) Eur. J. Biochem. 122, 291-295]. Electrospray mass spectrometry gives results consistent with these six changes. Interaction between the various N- and C-lobes was measured by titration calorimetry. Studies show that only those lobes that associate in solution are able to bind to the receptors on chick embryo red blood cells. These findings do not support a previous report by Oratore et al.

Expression of glycosylated and nonglycosylated human transferrin in mammalian cells. Characterization of the recombinant proteins with comparison to three commercially available transferrins.

The coding sequence for human serum transferrin was assembled from restriction fragments derived from a full-length cDNA clone isolated from a human liver cDNA library. The assembled clone was inserted into the expression vector pNUT and stably transfected into transformed baby hamster kidney (BHK) cells, leading to secretion of up to 125 mg/L recombinant protein into the tissue culture medium. As judged by mobility on NaDodSO4-PAGE, immunoreactivity, spectral properties (indicative of correct folding and iron binding), and the ability to bind to receptors on a human cell line, initial studies showed that the recombinant transferrin, is identical to three commercial human serum transferrin samples. Electrospray mass spectrometry (ESMS), anion-exchange chromatography, and urea gel analysis showed that the recombinant protein has an extremely complex carbohydrate pattern with 16 separate masses ranging from 78,833 to 80,802 daltons. Mutation of the two asparagine carbohydrate linkage sites to aspartic acid residues led to the expression and secretion of up to 25 mg/L nonglycosylated transferrin. ESMS, anion-exchange chromatography, and urea gel analysis showed a single molecular species that was consistent with the expected theoretical mass of 75,143 daltons. In equilibrium binding experiments, the nonglycosylated mutant bound to HeLa S3 cells with the same avidity and to the same extent as the glycosylated protein and the three commercial samples. These studies demonstrate conclusively that carbohydrate has no role in this function.