Establishment and characterization of a common acute lymphoblastic leukemia cell line with a deletion of chromosome 3 band q26.

This paper describes the establishment and characterization of a new cell line (SUP-B7) which was established from a child with "common" acute lymphoblastic leukemia. The SUP-B7 cells (and the patient's tumor) have been characterized by cytochemical staining, monoclonal antibodies, enzyme analyses, gene rearrangement studies, and karyotype analysis. The SUP-B7 cells are periodic acid-Schiff positive, common acute lymphoblastic leukemia antigen positive, and terminal deoxynucleotidyl transferase positive, and they lack the Epstein-Barr virus genome. In addition, the SUP-B7 cells lack cytoplasmic and surface immunoglobulins, and the immunoglobulin gene rearrangement studies showed rearranged heavy chain genes with germ line light chain genes. Concordance between the cell line and the patient's tumor was established by the immunoglobulin gene rearrangement studies. Using Southern blot analysis of the DNA from the patient's tumor and the SUP-B7 cells, there was comigration of the bands representing the rearranged immunoglobulin heavy chain gene. In addition, the SUP-B7 cells possess a single chromosome abnormality: del(3)(q26q28), with the chromosome breakpoint at or near the transferrin receptor gene. Since the SUP-B7 cell line is concordant with the patient's malignancy and since these cells possess a single chromosomal abnormality, the SUP-B7 cell line may be a useful tool in determining the biological significance of the chromosome deletion: del(3)(q26q28).

Use of alanosine as a methylthioadenosine phosphorylase-selective therapy for T-cell acute lymphoblastic leukemia in vitro.

Methylthioadenosine phosphorylase (MTAP) is an important enzyme for the salvage of adenine and methionine and is deficient in a variety of cancers including T-cell acute lymphocytic leukemia (T-ALL). Previously, we reported that the MTAP gene was deleted in over 30% of T-ALL patients at both diagnosis and relapse. We now report that MTAP-primary T-ALL cells are more sensitive to the toxicity of L-alanosine, an inhibitor of de novo AMP synthesis, than are MTAP+ primary T-ALL cells. As measured by [3H]thymidine incorporation, DNA synthesis in all seven MTAP-primary T-ALL cells was inhibited by L-alanosine with a mean IC50 of 4.8+/-5.3 ILM (range, 0.3-11.3 microM). On the other hand, the IC50 for 60% (12 of 20) of MTAP+ primary T-ALL was 19+/-18 microM (range, 1.7-67 microM; P = 0.02), whereas the remaining 40% (8 of 20) had an IC50 of >80 microM4. Furthermore, normal lymphocytes and MTAP+ primary T-ALL cells were rescued from L-alanosine toxicity by the MTAP substrate 5'-deoxyadenosine, but MTAP-T-ALL cells were not. These results indicate that normal cells, which are intrinsically MTAP+, would be protected from L.-alanosine toxicity, whereas MTAP-tumor cells would be killed. Thus, our results support the use of L-alanosine alone or in combination with a salvage agent as a MTAP-selective therapy and therefore lay the foundation for the initiation of clinical trials for the treatment of T-ALL and other MTAP-deficient malignancies with L-alanosine.

Cranial nerve involvement in children with leukemia and lymphoma.

Between 1965 and 1982, 52 children with acute lymphoblastic leukemia or non-Hodgkin's lymphoma were found to have central nervous system involvement of their disease. Of this group, 20 developed clinically apparent cranial nerve paresis or palsy. The cranial nerve most frequently affected was No. VII. With therapy, 16 of the patients had objective control of their central nervous system disease. Among these 16 patients, cranial nerve palsies resolved completely in 14, and only two children were left with residual cranial nerve dysfunction. Seven patients received intrathecal chemotherapy before radiation therapy was instituted in an attempt to control their cranial nerve palsies. Cranial nerve palsy resolved in only two of these seven patients. However, the addition of whole-brain irradiation in the remaining five patients reversed cranial nerve dysfunction in four of them. The combination of intrathecal chemotherapy and central nervous system irradiation was successful in reversing cranial nerve dysfunction in 11 of 13 patients in whom central nervous system disease was ultimately controlled. As cranial nerve dysfunction is associated with distressing signs and symptoms, the combination of central nervous system irradiation and intrathecal chemotherapy is important palliative therapy to initiate promptly. Intrathecal therapy alone appears to be inadequate therapy for prompt and durable reversal of symptoms in this group of patients.

Allogeneic bone marrow transplantation as therapy for primary induction failure for patients with acute leukemia.

The survival of patients with acute leukemia who do not achieve a remission with primary therapy is very poor. High-dose chemoradiotherapy followed by allogeneic bone marrow transplantation (BMT) has been shown to be effective therapy for patients with acute and chronic leukemia. Therefore, we determined the long-term disease-free survival of patients who did not achieve a remission and were then treated with high-dose therapy and bone marrow allografting from matched sibling donors. Twenty-one patients (median age, 28 years) who did not achieve a remission with induction chemotherapy were subsequently treated with allogeneic BMT. After BMT, 90% achieved a complete remission. Six died of complications of the therapy, and six patients relapsed between 27 and 448 days after BMT. Nine patients (43%; median age, 25 years) are alive between 556 and 4,174 days after BMT. The cumulative probability of disease-free survival at 10 years is 43%. This study suggests that allogeneic BMT can be an effective therapy to achieve long-term control of acute leukemia, even in those patients who do not achieve a remission with primary therapy.

Influence of age on the outcome of 500 autologous bone marrow transplant procedures for hematologic malignancies.

PURPOSE: To determine the effect of age on the outcome of autologous bone marrow transplantation (ABMT) and/or peripheral-blood progenitor-cell (PBPC) transplantation. PATIENTS AND METHODS: A retrospective analysis was performed on 500 consecutive patients who ranged in age from 1 to 65 years (median, 40) with non-Hodgkin's lymphoma (NHL), Hodgkin's disease (HD), multiple myeloma (MM), or acute nonlymphoblastic leukemia (AML) who underwent autologous hematopoietic-cell transplant procedures at Stanford University Medical Center. RESULTS: The actuarial 5-year event-free survival (EFS) rate was 44%, the relapse rate 47%, and the regimen-related mortality (RRM) rate 8.6%. Disease status at time of transplantation, categorized as either minimal or advanced disease, was the strongest predictive factor for EFS (relative risk (RR) for advanced-disease group, 1.8; P < .0003) and relapse rate (RR for advanced-disease group, 1.9; P < .0004). Patients with minimal or advanced disease had an EFS rate of 48% and 30% and relapse rates of 43% and 72%, respectively. The EFS rate of patients less than 50 years verus > or = 50 years of age was 46% versus 34% (P = .03). Cox regression analysis showed that age was predictive for EFS (RR for patients 50 to 65 years, 1.4; P = .03). The actuarial RRM rate for these age groups was 7.4% versus 12.7% (P = .07), respectively. Multivariate analysis demonstrated that age (odds ratio [OR] for patients 50 to 65 years, 1.9; P < .05) and period of transplantation (OR for most recent years [1991 to 1995], 0.6; P = .06) were the most predictive factors for RRM. CONCLUSION: Although age greater than 50 years is associated with an inferior outcome following autologous hematopoietic-cell transplantation, it does not appear to be warranted to limit this potentially curative procedure based solely on age. The upper age limit of high-dose therapy with autologous progenitor-cell and/ or bone marrow support remains to be defined.

Bone marrow stroma-supported culture of T-lineage acute lymphoblastic leukemic cells predicts treatment outcome in children: a Pediatric Oncology Group study.

Significant predictors of treatment outcome are poorly defined for patients with T-lineage acute lymphoblastic leukemia (T-ALL). A high WBC at diagnosis, which has traditionally been a predictor of poor response in T-ALL, has considerably weakened prognostic significance in the face of modern, more intensive chemotherapy. To test the hypothesis that bone marrow stroma-supported leukemic cell recovery might identify children at high risk for relapse, we measured the ex vivo recovery of T-ALL lymphoblasts from 29 newly diagnosed patients using a stromal cell co-culture assay. In all cases the T-ALL lymphoblasts showed an increase in recovery of T-ALL cells (RTC), ranging from 4 to 343%, in comparison to samples maintained without stroma. Since we were blinded to patient outcome in this case-control study, we then correlated patient outcome with RTC. The RTC for 18 patients in complete continuous remission (CCR) for greater than 4 years was stochastically larger than for the 11 patients who eventually relapsed (P = 0.011, by the two-sided Wilcoxon test). Furthermore, 100% of patients with an RTC of more than 26% had a CCR greater than 4 years while 78% of the patients with an RTC of less than 25% relapsed within 4 years. This is the first report to show that higher lymphoblast recovery may predict a more favorable outcome for children with T-ALL. A prospective study is needed to test whether stroma-supported leukemic cell recovery might serve as a basis for assigning risk-adjusted therapy.

Slow disappearance of peripheral blood blasts is an adverse prognostic factor in childhood T cell acute lymphoblastic leukemia: a Pediatric Oncology Group study.

The rapidity of response to induction therapy is emerging as an important prognostic factor in children and adolescents with acute lymphoblastic leukemia (ALL). We studied the relationship between rapidity of reduction in peripheral blood blast count and treatment outcome in children with T cell ALL (T-ALL). Initial systemic chemotherapy included prednisone, vincristine, doxorubicin and cyclophosphamide. A Cox analysis evaluated the correlation between the length of time that the peripheral blood absolute blast count (ABC) remained above 1000/mm3 following the start of treatment and event-free survival (EFS). Data were available for 281 patients. Patients for whom the ABC remained >1000/mm3 for 3 or more days following administration of intensive therapy had an estimated 5-year EFS of 34.2% (s.e. = 7.2) vs 58.3% (3.5) for those whose ABC was <1000/mm3 within 0-2 days, with a hazard ratio (HR) of failure of 2.03 (95% CI = 1.35-3.06, P < 0.001) for the slower responding patients. Pre-treatment of some type (usually with prednisone) occurred in 128 patients (average duration 1.7 days). When this was accounted for, patients with an ABC >1000/mm3 for 5 or more days following the start of treatment of any kind had a HR for failure of 2.27 (95% CI = 1.38-3.72, P < 0.001) compared to those responding within 0-4 days. Inclusion of other clinical and biological factors in a multivariate analysis did not alter the prognostic importance of slower blast clearance. Pediatric patients with T-ALL who have a circulating blast count >1000/mm3 at diagnosis and a relatively slower response to initial treatment are at increased risk of treatment failure. Rapidity of response may therefore be a clinically useful prognostic factor for patients with T-ALL.

Intensive high-dose asparaginase consolidation improves survival for pediatric patients with T cell acute lymphoblastic leukemia and advanced stage lymphoblastic lymphoma: a Pediatric Oncology Group study.

This study was designed to test the hypothesis that high-dose asparaginase consolidation therapy improves survival in pediatric patients with T cell acute lymphoblastic leukemia and advanced stage lymphoblastic lymphoma. Five hundred and fifty-two patients (357 patients with T cell acute lymphoblastic leukemia (ALL) and 195 patients with advanced stage lymphoblastic lymphoma) were enrolled in POG study 8704 (T-3). Treatment included rotating combinations of high-dose myelosuppressive chemotherapy agents proven to be effective in T cell ALL in other POG group-wide or local institutional protocols (including vincristine, doxorubicin, cyclophosphamide, prednisone, asparaginase, teniposide, cytarabine and mercaptopurine). After achieving a complete remission (CR), patients were randomized to receive or not receive high-dose intensive asparaginase consolidation (25,000 IU/m2) given weekly for 20 weeks by intramuscular injection. Intrathecal chemotherapy (methotrexate, hydrocortisone and cytarabine) was given to prevent CNS disease, and CNS irradiation was used only for patients with leukemia and an initial WBC of >50,000/microl or patients with active CNS disease at diagnosis. CR was achieved in 96% of patients. The high-dose asparaginase regimen was significantly superior to the control regimen for both the leukemia and lymphoma subgroups. Four-year continuous complete remission rate (CCR) for the leukemia patients was 68% (s.e. 4%) with asparaginase as compared to 55% (s.e. 4%) without. For the lymphoma patients, 4-year CCR was 78% (s.e. 5%) with asparaginase and 64% (s.e. 6%) in the controls. The overall one-sided logrank test had a P value <0.001 favoring asparaginase, while corresponding values were P = 0.002 for ALL and P = 0.048 lymphoblastic lymphoma. Toxicities were tolerable, but there were 18 failures due to secondary malignancies (16 with non-lymphocytic leukemia or myelodysplasia). Neither WBC at diagnosis (leukemia patients) nor lymphoma stage were major prognostic factors. We conclude that when added to a backbone of effective rotating agents, repeated doses of asparaginase during early treatment improve the outcome for patients with T cell leukemia and advanced stage lymphoblastic lymphoma.

Glutathione S-transferase genotypes in children who develop treatment-related acute myeloid malignancies.

Epipodophyllotoxin-associated secondary myeloid leukemia is a devastating complication of acute lymphoblastic leukemia (ALL) therapy. The risk factors for treatment-related myeloid leukemia remain incompletely defined. Genetic deficiencies in glutathione S-transferase (GST) activities have been linked to higher frequencies of a number of human malignancies. Our objective was to determine whether the null genotype for GSTM1, GSTT1, or both, was more frequent in children with ALL who developed treatment-related myeloid malignancies as compared to those who did not. A PCR technique was used to assay for the null genotype for GSTM1 and GSTT1 in 302 children with ALL, 57 of whom also subsequently developed treatment-related acute myeloid leukemia or myelodysplastic syndrome. Among children with ALL who did not develop treatment-related myeloid malignancies, the frequencies of GSTM1 and GSTT1 wild-type, GSTM1 null-GSTT1 wild-type, GSTM1 wild-type-GSTT1 null, and GSTM1 and GSTT1 null genotypes were 40%, 42%, 9% and 9%, respectively. The corresponding frequencies for patients who developed acute myeloid malignancies were 42%, 32%, 11% and 16%, respectively (P = 0.26). A statistically significant increase in the frequency of the GST null genotype was observed in male patients who developed myeloid malignancies as compared to male ALL control patients (P = 0.036), but was not observed in female patients (P = 0.51). Moreover, a logistic regression analysis of possible predictors for myeloid malignancies, controlling for gender and race, did not reveal an association of GSTM1 or GSTT1 null genotypes (P = 0.62 and 0.11, respectively) with treatment-related malignancies. Our data suggest that GSTM1 and GSTT1 null genotypes may not predispose to epipodophyllotoxin-associated myeloid malignancies.

Long-term follow-up of 23 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia treated with allogeneic bone marrow transplant in first complete remission.

Between 1984 and 1997, 23 consecutive patients with Philadelphia chromosome-positive acute lymphoblastic leukemia in first complete remission were treated with allogeneic bone marrow transplants from HLA-matched siblings. All patients but one were conditioned with fractionated total body irradiation (1320 cGy) and high-dose etoposide (60 mg/kg). One patient received high-dose cyclophosphamide instead of etoposide, and another patient received both drugs. Nine patients died following BMT, two from relapsed leukemia, and seven from transplant-related causes. The 3-year probabilities of disease-free survival and relapse are 65% and 12%, respectively. For patients transplanted after 1992, these probabilities are 81% (48-95%, 95% confidence interval) and 11% (2-50%), respectively. The relatively low relapse rate in this group of patients compared to published reports may reflect the enhanced anti-leukemic activity of etoposide in combination with FTBI compared to other conditioning regimens. The enhancement in overall survival for patients transplanted after 1992 may reflect improvements in supportive care, in particular, the prophylaxis of serious fungal and viral infections.

Varicella zoster antibody titers after the administration of intravenous immune serum globulin or varicella zoster immune globulin.

Varicella is a serious infection in the immunocompromised patient. Prophylaxis with varicella zoster immune globulin is known to decrease the incidence of severe varicella infection. The titers of antibody to varicella zoster virus were compared in patients who received either varicella zoster immune globulin or intravenous immune globulin, 4 ml or 6 ml/kg per dose. The titers of antibody to varicella zoster virus were comparable in each group.

Identifying early predictors of mortality in pediatric patients with acute leukemia and pneumonia.

STUDY OBJECTIVE: To identify clinical variables of pneumonia in children with acute leukemia that predicted respiratory failure and mortality. DESIGN: A retrospective chart review of children with acute leukemia admitted to the hospital with the diagnosis of pneumonia or ARDS from March 1991 to April 1994. SETTING: Lucile Salter Packard Children's Hospital at Stanford, a 168-bed teaching hospital and regional tertiary referral center for children in northern California. PATIENTS: During this study period, 20% of the 174 admissions of children with acute leukemia had pneumonia at the time of admission or during the course of the hospitalization for a total of 36 admissions. The mean age of these children was 9.2 +/- 1.1 years. RESULTS: Eleven percent of the children with pulmonary infiltrates in one quadrant on the chest x-ray film at the onset of pneumonia and 53% of the children with pulmonary infiltrates in more than one quadrant at the onset of pneumonia died. Fifteen percent of the children without sepsis at the onset of pneumonia and 70% of the children with sepsis at onset died. Eighteen percent of the children without shock at the onset of pneumonia and 75% of the children with shock at the onset died. None of the children died who required < or = 3L/min of O2 to maintain SO2 > or = 95%, but 79% of the children who required > 3L/min O2 died. Using the criteria "> 3 L/min O2 by nasal cannula to maintain SO2 > or = 95%" to identify the nonsurvivors had a sensitivity of 100% and specificity of 88%. This specificity was not increased by combining the criteria "O2 requirements at any time" and "the extent of pulmonary infiltrates at the onset of pneumonia." All children who required mechanical ventilatory support for respiratory failure had previously received > 3 L/min O2 by nasal cannula to maintain SO2 > or = 95% for 37.8 +/- 12.9 h (range 3 to 96 h). Nine of the 10 children in our study who received mechanical ventilation died. CONCLUSION: In children with acute leukemia and pneumonia, the amount of O2 required to maintain SO2 > or = 95% may identify those who are likely to develop respiratory failure hours before mechanical ventilatory support is needed. The ability to identify children at risk for respiratory failure is not increased by combining the risk factors "oxygen requirements" and "extent of pulmonary infiltrates at the onset of pneumonia". Finally, only 10% of the children who required mechanical ventilatory support survived.

Role of etoposide (VP-16) in preparatory regimens for patients with leukemia or lymphoma undergoing allogeneic bone marrow transplantation.

In 1983, we began a series of clinical trials with the goal of reducing the relapse rate following allogeneic BMT for hematologic malignancies. Because of its anti-leukemic activity, the drug VP-16 was chosen and combined with total body irradiation (TBI). The first series (trial I) consisted of patients who had advanced leukemia. This trial showed a relapse rate of 32% and a disease-free survival rate of 43%. Thereafter, this regimen was tested in a randomized trial (trial II) under the auspices of the Southwest Oncology Group (SWOG study 8612). The FTBI/VP-16 regimen was compared with the combination of busulfan and cyclophosphamide (BU/CY). A recent analysis indicates a disease-free advantage for patients prepared with FTBI/VP-16; however this difference is not statistically significant. In another trial (trial III), patients in their first remission of leukemia were prepared with the FTBI/VP-16 regimen and long-term disease-free survival was found to be 60-70% with a relapse rate of approximately 10%. These results compare favorably with data obtained with alternative preparatory regimens. The FTBI/VP-16 regimen is currently being compared to the 'standard' regimen, FTBI/CY, in a prospective trial (trial IV). Since the regimen-related toxicity has been relatively low, we have added one dose of CY 60 mg/kg to the FTBI/VP-16 combination. This regimen (trial V) is currently being tested in patients with advanced leukemia. The preliminary results of this ongoing trial indicate further improvement in disease-free survival through a reduction of the post-transplant relapse rate.

Treatment of T-lineage acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia is an aggressive disease that responds poorly to "standard" therapy designed for the more common B-lineage ALLs in childhood. The principles of this "standard" therapy were derived from empiric clinical trials. Thus, it is not surprising that the therapy that had the greatest impact on survival in the group as a whole would be found to be most successful for the most common subset of patients. T-cell malignant lymphoblasts share many biologic features that set them apart from the more common B-lineage lymphoblasts. Some of these biologic features suggest therapeutic approaches that should be particularly successful in treating patients with T-cell leukemia. The use of aggressive, multiple-agent "pulse" chemotherapy has been shown through empiric trials to have relative efficacy in T-cell lymphoblastic leukemia, presumably because of the rapid generation time and high growth fraction. Future studies will (1) determine the optimal dose and schedule of cytosine arabinoside needed to exploit the increased Ara-CTP accumulation in T-cell blasts, (2) determine the efficacy of a new agent, deoxycoformycin, an inhibitor of adenosine deaminase, to exploit the biochemical phenotype of T-cell blasts, and (3) assess the ability of conjugated anti-T monoclonal antibodies to deliver a cytotoxic agent, thus exploiting unique antigenic determinants at the cell surface. As more is learned about the biology of T-cell malignancies, further treatment strategies may be suggested to exploit the new features that are discovered. Similarly, it is hoped that the unique features of the B-lineage leukemias will suggest treatment strategies that will improve survival in those patients as well. Certainly, improved survival has already been achieved in the case of the B-cell leukemias and Burkitt's lymphomas, and improvement may also be possible for the pre-B and early pre-B phenotypes of lymphoblastic leukemia.

Prednisone stimulation of erythropoiesis in leukemic children during remission.

Children with acute leukemia in remission manifest reticulocytosis and a significant increase in hemoglobin concentration (mean increment of 2.3 +/- 1.1 g/dl) following prednisone pulse therapy. This hemoglobin increment is not associated with changes in serum erythropoietin activity. It is speculated that this stimulation of red cell production may be a direct effect of steroids on erythroid progenitor cells.

Repopulation of marrow after transplantation: MR imaging with pathologic correlation.

Sixty-seven magnetic resonance (MR) studies of the lumbar spine were performed in 15 patients with bone marrow transplants, and the appearance of marrow regeneration on MR images was correlated with results of bone marrow biopsy and pathologic examination. After transplantation, T1-weighted MR images of vertebral marrow showed a characteristic band pattern consisting of a peripheral zone of intermediate signal intensity and a central zone of bright signal intensity. Reciprocal changes were identified on short inversion time inversion recovery images. At histologic examination the central zone corresponded to fatty marrow; the peripheral zone corresponded to a zone of regenerating hematopoietic cells. Posttransplantation T1 and T2 relaxation times of the entire vertebral marrow were calculated from the spin-echo images; no statistically significant trends in relaxation times were noted. Knowledge of the normal MR pattern of marrow regeneration after transplantation may be useful in screening for residual marrow disease, determining marrow engraftment, and differentiating marrow repopulation with normal versus malignant cells.

Allogeneic bone marrow transplant in pediatric patients with high-risk hematopoietic malignancies early in the course of their disease.

PURPOSE: The purpose of this study was to investigate the role of bone marrow transplant (BMT) early in the course of disease for pediatric patients with high-risk leukemia using a preparatory regimen of fractionated total body irradiation (FTBI) and etoposide (VP-16). PATIENTS AND METHODS: Those studied were 33 patients aged < or =18 years with either acute leukemia in first complete remission (CR) (n = 29) or chronic myelogenous leukemia (CML) in first chronic phase (n = 4) who received 1,320 cGy FTBI followed by high-dose VP-16 (60 mg/kg) as a preparatory regimen for BMT from matched sibling donors. Patients with acute leukemia included 18 with acute nonlymphocytic leukemia (ANLL), one with biphenotypic acute leukemia (BAL), and 10 with selected "high-risk" acute lymphocytic leukemia (ALL). Patients with ALL were selected for a high risk for recurrence: those who failed standard remission induction chemotherapy, had a t(9;22) or t(4;11) chromosomal translocation, or had certain clinical high-risk features. RESULTS: At the time of analysis, 28 patients are alive, all of them in continued complete remission for 1.1-7.8 years (median, 5.3 years; mean, 4.9 years). The Kaplan-Meier projected event-free survival (EFS) is 84.5% at 7 years, and the actuarial recurrence hazard is 6.5%. All surviving patients have a performance status of >80%. CONCLUSION: This result of early BMT in a two-institution study of pediatric patients with hematopoietic malignancies suggests that (a) matched sibling allogeneic BMT after conditioning with FTBI and high-dose VP-16 is an excellent treatment for pediatric patients with high-risk leukemia, and (b) children may have a better prognosis than adults treated with allogeneic BMT. Larger multiinstitutional cooperative trials for pediatric patients are needed to confirm this result.

Clinical and biologic characterization of T-cell neoplasias with rearrangements of chromosome 7 band q34.

In T cell malignancy, rearrangements of chromosome 14 have been observed with a break in the band that contains the alpha chain gene for the T cell receptor (TCR). Because the beta chain TCR gene is in chromosome band 7q34, we searched for and report finding specific rearrangements of 7q34 exclusively in T cell malignancies. The rearrangements were reciprocal translocations between 7q34 and other points: 1p34, 9q32, 9q34, 15q22, and 19p13. The malignancies containing a 7q34 translocation were either T cell acute lymphoblastic leukemias or T cell lymphoblastic lymphomas that had similarities in clinical, enzyme, immunologic, and cellular characteristics. Hybridization using a probe to the beta-TCR gene disclosed unique rearrangements consistent with clonality in every case. A common pattern with chromosome breakpoints involving TCR genes may be emerging in T cell neoplasia.