Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia: Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE

Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients.

PATIENTS AND METHODS

In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients.

RESULTS

Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 μg h/mL, 2.52 μg h/mL, and 2.66 μg h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children.

CONCLUSION

Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.

The genomic landscape of acute lymphoblastic leukemia with intrachromosomal amplification of chromosome 21

Intrachromosomal amplification of chromosome 21 defines a subtype of high-risk childhood acute lymphoblastic leukemia (iAMP21-ALL) characterized by copy number changes and complex rearrangements of chromosome 21. The genomic basis of iAMP21-ALL and the pathogenic role of the region of amplification of chromosome 21 to leukemogenesis remains incompletely understood. In this study, using integrated whole genome and transcriptome sequencing of 124 patients with iAMP21-ALL, including rare cases arising in the context of constitutional chromosomal aberrations, we identified subgroups of iAMP21-ALL based on the patterns of copy number alteration and structural variation. This large data set enabled formal delineation of a 7.8 Mb common region of amplification harboring 71 genes, 43 of which were differentially expressed compared with non-iAMP21-ALL ones, including multiple genes implicated in the pathogenesis of acute leukemia (CHAF1B, DYRK1A, ERG, HMGN1, and RUNX1). Using multimodal single-cell genomic profiling, including single-cell whole genome sequencing of 2 cases, we documented clonal heterogeneity and genomic evolution, demonstrating that the acquisition of the iAMP21 chromosome is an early event that may undergo progressive amplification during disease ontogeny. We show that UV-mutational signatures and high mutation load are characteristic secondary genetic features. Although the genomic alterations of chromosome 21 are variable, these integrated genomic analyses and demonstration of an extended common minimal region of amplification broaden the definition of iAMP21-ALL for more precise diagnosis using cytogenetic or genomic methods to inform clinical management.

Inferring clonal heterogeneity in cancer using SNP arrays and whole genome sequencing

MOTIVATION

Clonal heterogeneity is common in many types of cancer, including chronic lymphocytic leukemia (CLL). Previous research suggests that the presence of multiple distinct cancer clones is associated with clinical outcome. Detection of clonal heterogeneity from high throughput data, such as sequencing or single nucleotide polymorphism (SNP) array data, is important for gaining a better understanding of cancer and may improve prediction of clinical outcome or response to treatment. Here, we present a new method, CloneSeeker, for inferring clinical heterogeneity from sequencing data, SNP array data, or both.

RESULTS

We generated simulated SNP array and sequencing data and applied CloneSeeker along with two other methods. We demonstrate that CloneSeeker is more accurate than existing algorithms at determining the number of clones, distribution of cancer cells among clones, and mutation and/or copy numbers belonging to each clone. Next, we applied CloneSeeker to SNP array data from samples of 258 previously untreated CLL patients to gain a better understanding of the characteristics of CLL tumors and to elucidate the relationship between clonal heterogeneity and clinical outcome. We found that a significant majority of CLL patients appear to have multiple clones distinguished by copy number alterations alone. We also found that the presence of multiple clones corresponded with significantly worse survival among CLL patients. These findings may prove useful for improving the accuracy of prognosis and design of treatment strategies.

AVAILABILITY AND IMPLEMENTATION

Code available on R-Forge: https://r-forge.r-project.org/projects/CloneSeeker/.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

A prospective comparison of UroVysion FISH and urine cytology in bladder cancer detection

Background

UroVysion fluorescence in situ hybridization (uFISH) was reported to have superior sensitivity to urine cytology. However uFISH studies are limited by varying definitions of what is considered a positive result, absence of histopathology and small sample size. The aim of our study was to better determine the performance characteristics of uFISH and urine cytology by overcoming some of the deficiencies of the current literature.

Methods

Intraoperative bladder wash cytology and uFISH were collected prospectively on all patients. Strict definitions for positivity of uFISH and cytology were determined before initiating the study. A re-review of false-negative uFISH specimens was performed to analyze potential sources of error. Sixteen bladder tumors embedded in paraffin were analyzed by uFISH and compared with the result in the urine.

Results

One hundred and twenty-nine specimens were analyzed. Sensitivity was 67% and 69% (p = 0.54); specificity was 72% and 76% (p = 1.0), for uFISH and cytology, respectively. Thirty-two false negative uFISH samples were re-reviewed. Low grade tumors often showed cells with abnormal morphology and patchy DAPI staining but diploid chromosomal counts and a few high grade tumors had tetraploid counts but less than needed to interpret uFISH as positive. uFISH study of the tumors revealed three categories; positive in both tumor and urine (9), negative in both tumor and urine (5) and positive in tumor but negative in urine (2).

Conclusion

In a pathologically-confirmed analysis of bladder washed urine specimens, uFISH does not outperform urine cytology in cancer detection.

Abstract 4729: Frequency of actionable gene fusions in patients with Philadelphia chromosome-like (Ph-like) B-acute lymphoblastic leukemia (ALL): A retrospective study from the Children's Oncology Group (COG)

Introduction: While cure rates exceed 80%, many children with B-ALL still relapse. Many of these patients (pts) display a Ph-like gene expression profile (GEP), but lack canonical BCR-ABL1 fusion. We have identified alternate kinase fusions in Ph-like ALL that induce cell proliferation sensitive to tyrosine kinase inhibitors (TKI) (Roberts, NEJM 2014). We report retrospective analyses of 1390 B-ALL pts, 885 NCI high risk and 505 standard risk B-ALL pts with elevated minimal residual disease.

Methods: Cases were screened using an 8-gene Taqman low-density array (LDA) PCR assay to identify the Ph-like GEP (Harvey, ASH 2013). Ph-like cases with elevated CRLF2 expression were tested for CRLF2 rearrangement (CRLF2-R; P2RY8-CRLF2 by Taqman PCR on the LDA card and IGH-CRLF2 by FISH). JAK mutations in CRLF2-R cases were tested by Sanger sequencing. Ph-like cases without CRLF2-R were tested for previously identified kinase fusions involving ABL1, ABL2, CSF1R, JAK2, NTRK3, and PDGFRB by RT-PCR. Ph-like cases without detected fusions underwent RNA-sequencing, either using standard Illumina library preparation or a customized kinome capture kit (Agilent).

Results: 339 (24%) pts were Ph-like. BCR-ABL1 (N = 45) and ETV6-RUNX1 (N = 11) were excluded from further analyses, as the former already receives TKI therapy and ETV6-RUNX1 ALL lacks targetable kinase fusions (unpublished). Of the remaining 283 Ph-like cases, 153 were CRLF2high (defined by CRLF2 expression levels on the LDA card). 61 (40%) had P2RY8-CRLF2 fusion, and of the remaining 91 CRLF2high cases, 56 of 69 tested had CRLF2-R (55 to IGH, 1 to an unknown partner). Thus, 117/130 (90%) CRLF2high Ph-like cases had a documented CRLF2 genomic lesion and 52 (44%) of these had a JAK mutation. Of the 130 Ph-like CRLF2low cases, 61 (47%) had a previously reported targetable TK fusion identified by RT-PCR, kinome capture or RNA sequencing. These included: 38 ABL class fusions (17 ABL1, 5 ABL2, 3 CSF1R, 13 PDGFRB) sensitive to imatinib/dasatinib; 14 JAK2 and 8 EPOR fusions sensitive to ruxolitinib; and 1 NTRK3 fusion sensitive to crizotinib. Nine cases had known fusions with new alternate breakpoints, and an additional 9 cases had fusions of novel N-terminal partners with known actionable C-terminal kinase genes. RNA sequencing identified 8 cases with IGH-EPOR fusions not previously captured by the kinome assay, indicating the cryptic and complex nature of this rearrangement.

Conclusion: Almost half of Ph-like pediatric B-ALL pts lacking CRLF2-R harbor altered TKs with compelling pre-clinical data that they are likely amenable to targeted therapy using FDA-approved TKIs. The COG will start real-time screening with this algorithm in 2015 and allocate pts with ABL class fusions to treatment with chemotherapy plus dasatinib.

Citation Format: Shalini C. Reshmi, Richard C. Harvey, Amy Smith, I-Ming Chen, Marc Valentine, Yu Liu, Yongjin Li, Jinghui Zhang, Kathryn G. Roberts, Ying Shao, John Easton, Debbie Payne-Turner, Meenakshi Devidas, Nyla Heerema, Andrew J. Carroll, Elizabeth A. Raetz, Michael J. Borowitz, Brent L. Wood, Anne L. Angiolillo, Michael M. Burke, Wanda L. Salzer, Patrick A. Zweidler-McKay, Karen R. Rabin, William L. Carroll, Mignon L. Loh, Stephen P. Hunger, Charles G. Mullighan, Cheryl L. Willman, Julie M. Gastier-Foster. Frequency of actionable gene fusions in patients with Philadelphia chromosome-like (Ph-like) B-acute lymphoblastic leukemia (ALL): A retrospective study from the Children's Oncology Group (COG). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4729. doi:10.1158/1538-7445.AM2015-4729

Abstract CT132: Long-term treatment with single-agent ibrutinib 420 mg leads to durable responses including complete responses in CLL

Background: Ibrutinib (ibr), a first-in-class, once-daily, oral, covalent inhibitor of Bruton's tyrosine kinase, has single-agent efficacy and acceptable toxicity in treatment-naïve (TN) [Lancet Oncology 2013] and previously-treated chronic lymphocytic leukemia (CLL)/small lymphocytic leukemia (SLL) patients (pts) [NEJM 2014]. Ibrutinib (Imbruvica®) is indicated for treatment of pts with CLL receiving one prior therapy and for pts with del17p CLL. We present efficacy and safety data with up to 45 months of follow-up for pts receiving ibr at the approved 420 mg dose.

Methods: Analysis included all pts receiving ibr 420 mg/day, dosed until disease progression in the phase I/IIb study PCYC-1102, and the PCYC-1103 extension study. Best overall response rate (ORR), including partial response with lymphocytosis (PR-L) was assessed by investigator using iwCLL criteria. Adverse event (AE) collection focused on ≥grade 3 and serious AEs.

Results: Of 94 CLL/SLL pts (27 TN, 67 relapsed/refractory [R/R]) receiving ibr, median age was 68 years (range, 37-84), with 44 (47%) pts aged ≥70 years. 25 (27%) pts (2 TN, 23 R/R) had del17p and 22 (23%, all R/R) had del11q. R/R pts had a median of 4 (range, 1-12) prior therapies. Best ORR was 91% including 14% complete responses (CR) for all pts (CR 26% TN, 9% R/R). Median DOR and PFS were not reached for all pts. Median time on treatment was 25 mos (range, 0-45) for all pts (30 mos TN, 22 mos R/R). The most common ≥grade 3 AEs reported over this follow-up were hypertension (23%), pneumonia (15%), neutropenia (13%), atrial fibrillation (7%), and diarrhea (7%). 50 (53%) pts (22 [81%] TN, 28 [42%] R/R) remained on treatment for >2 years. At analysis, 22 (81%) TN and 40 (60%) R/R pts continued on ibrutinib. During follow-up, 12 pts discontinued treatment due to disease progression and 12 due to an AE.

Conclusions: Single-agent ibrutinib led to durable responses including 14% CRs in pts with TN or R/R CLL/SLL, with up to 45 months of follow-up.

Efficacy parameterTNR/R(n = 27)(n = 67)ORR23 (85%)63 (94%)CR7 (26%)6 (9%)PR/PR-L16 (59%)57 (85%)DOR, mos (95% Cl)NR (NE, NE)NR (36, NE)30-mo PFS (95% Cl)96% (74, 99)76% (63, 85)30-mo OS rate (95% Cl)96% (78, 99)87% (76, 93)DOR, duration of response; NE, not estimated; NR, not reached; PFS, progression-free survival; OS, overall survival

Citation Format: Steven Coutre, Richard Furman, Ian Flinn, Jan Burger, Kristie Blum, Jeff Sharman, Jeffrey Jones, William Wierda, Weiqiang Zhao, Nyla Heerema, Amy Johnson, Anh Tran, Cathy Zhou, Elizabeth Bilotti, Danelle James, John Byrd, Susan O'Brien. Long-term treatment with single-agent ibrutinib 420 mg leads to durable responses including complete responses in CLL. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT132. doi:10.1158/1538-7445.AM2015-CT132

Amplification of distant estrogen response elements deregulates target genes associated with tamoxifen resistance in breast cancer

A causal role of gene amplification in tumorigenesis is well known, whereas amplification of DNA regulatory elements as an oncogenic driver remains unclear. In this study, we integrated next-generation sequencing approaches to map distant estrogen response elements (DEREs) that remotely control the transcription of target genes through chromatin proximity. Two densely mapped DERE regions located on chromosomes 17q23 and 20q13 were frequently amplified in estrogen receptor-α-positive luminal breast cancer. These aberrantly amplified DEREs deregulated target gene expression potentially linked to cancer development and tamoxifen resistance. Progressive accumulation of DERE copies was observed in normal breast progenitor cells chronically exposed to estrogenic chemicals. These findings may extend to other DNA regulatory elements, the amplification of which can profoundly alter target transcriptome during tumorigenesis.

Early versus delayed autologous stem cell transplant in patients receiving novel therapies for multiple myeloma

Autologous stem cell transplant (ASCT) is an effective treatment for multiple myeloma (MM). However, the timing of ASCT in the era of novel agents (lenalidomide, thalidomide, bortezomib) is unknown. We retrospectively reviewed the outcome of patients with MM who received novel agent-based induction treatment and received first ASCT within 12 months of diagnosis (early ASCT, n = 102) or at a later date (late ASCT, n = 65). Median time to ASCT was 7.9 months vs. 17.7 months in early vs. late ASCT. The 3- and 5-year overall survival (OS) from diagnosis was 90 and 63% vs. 82 and 63% in early and late ASCT, respectively (p = 0.45). Forty-one and 36 patients in the early and late ASCT groups have relapsed or progressed, with median time to relapse of 28 and 23 months (p = 0.055). On multivariable analysis, factors predictive of increased risk for progression were International Scoring System (ISS) stage III (p = 0.007), and less than a very good partial response (< VGPR) post-ASCT (p < 0.001). A factor predictive of worst outcome for OS was being on hemodialysis (p = 0.037). No superiority of one agent was seen. In summary, early or late ASCT is a viable option for patients with MM receiving induction treatment with novel targeted therapies.

A multi-institutional phase II study of the efficacy and tolerability of lapatinib in patients with advanced hepatocellular carcinomas

BACKGROUND

Hepatocellular carcinoma (HCC) is on the rise worldwide. HCC responds poorly to chemotherapy. Lapatinib is an inhibitor of epidermal growth factor receptor and HER2/NEU both implicated in hepatocarcinogenesis. This trial was designed to determine the safety and efficacy of lapatinib in HCC.

METHODS

A Fleming phase II design with a single stage of 25 patients with a 90% power to exclude a true response rate of <10% and detect a true response rate of > or =30% was used. The dose of lapatinib was 1,500 mg/day administered orally in 28-day cycles. Tumor and blood specimens were analyzed for expression of HER2/NEU/CEP17 and status of downstream signal pathway proteins.

RESULTS

Twenty-six patients with HCC enrolled on this study. Nineteen percent had one prior therapy. Most common toxicities were diarrhea (73%), nausea (54%), and rash (42%). No objective responses were observed. Ten (40%) patients had stable disease as their best response including six (23%) with stable disease lasting >120 days. Median progression-free survival was 1.9 months and median overall survival was 12.6 months. Patients who developed a rash had a borderline statistically significant longer survival. Tissue and blood specimens were available on >90% of patients. No somatic mutations in EGFR (exons 18-21) were found. In contrast to our previous findings, we did not find evidence of HER2/NEU somatic mutations. PTEN, P-AKT, and P70S6K expression did not correlate with survival.

CONCLUSIONS

Lapatinib is well-tolerated but seems to benefit only a subgroup of patients for whom predictive molecular or clinical characteristics are not yet fully defined.

A phase I/II study of rituximab and etanercept in patients with chronic lymphocytic leukemia and small lymphocytic lymphoma

Rituximab has modest activity in relapsed chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma but is associated with tumor necrosis factor-alpha (TNF-alpha) release that can cause CLL proliferation and inhibit apoptosis. We examined whether disruption of TNF-alpha by etanercept improves response to rituximab in CLL. Eligible patients had previously treated CLL with performance status 0-3. Patients received etanercept 25 mg subcutaneously twice weekly (weeks 1-5) and rituximab 375 mg/m(2) intravenously thrice weekly (weeks 2-5) using a phase I/II design. Primary end points were response and toxicity. The 36 enrolled patients had a median of two prior treatments; 50% were fludarabine refractory and 22% had del(17p13.1). Of the 34 response-evaluable patients, 10 (29%) responded, including 9 partial responses and 1 complete remission. Response was not affected by prior rituximab or fludarabine-refractory status, but no patients with del(17p13.1) responded. Median progression-free survival for responders was 9.0 months (range 1-43). Ten patients have had treatment-free intervals exceeding 12 months, including four who have remained untreated for 32, 43, 46 and 56 months. Adverse events were mild, including mild infusion reactions, transient cytopenias and grade 3 infections in 14% of the patients. The combination of etanercept and thrice weekly rituximab produces durable remissions in non-del(17p13.1) CLL patients and is well tolerated.

Abstract LB-306: A Phase II study of the efficacy and tolerability of Lapatinib in patients with advanced hepatocellular carcinomas

Background: Hepatocellular carcinoma (HCC) is on the rise in the US and the rest of the world. HCC responds poorly to systemic chemotherapy. EGFR 1 and 2 are both overexpressed in HCC. We reported that HER2/NEU (EGFR2) somatic mutations in HCC may predict response to EGFR-targeted agents. Lapatinib is an oral inhibitor of EGFR and HER2/NEU with evidence of activity in a number of tumor types. This trial was designed to determine the efficacy of lapatinib in HCC patients. Methods: A Fleming phase II design resulting in a single stage of 25 patients was utilized with a 90% power to detect a true response rate &gt;20%. Adequate hematologic, renal and hepatic function were required. Eligible pts included Child’s A or favorable B group and ECOG PS of 0-1. One prior treatment regimen was allowed. Lapatinib dose was 1,500 mg/d orally without interruption. One cycle was 28 days and radiological assessment was done every 8 weeks. Tumor and blood specimens were analyzed for expression of EGFR/EGFRP, HER2/NEU/CEP17, status of downstream signal pathway molecules (including PTEN, P-Akt, cyclin D, p27 and p70S6K, p53 and others) and correlated to response. Results: 26 pts with HCC were accrued with the following characteristics: Males (17 pts), ECOG PS 0/1 (12/14 pts), median age of 58 yrs (range 29-83). A median of 2 cycles were administered (range 1-12). The most common toxicities were: diarrhea (69%) and nausea ( 54% ). Grade 3/4 toxicities were noted in 3 patients including diarrhea, rash and acute renal failure. There was no evidence of cardiac dysfunction. In 25 patients with HCC, no objective responses were observed. However, 8 (31%) patients had stable disease (SD) including 2 (7.6%) with SD lasting &gt; 6 months. Survival data is being analyzed. The overall goal of correlative studies underway is to attempt to understand the molecular biology of this tumor and guide directed therapy for subsets of patients with hepatocellular carcinoma that may benefit from EGFR inhibition. Tissue and blood specimens were available on &gt;95% of patients. No mutations in EGFR (exons 18-21) were found, consistent with our previous findings, although three single nucleotide polymorphisms (SNP) were found that correlate with SNPs in the NCBI SNP database. We did not find evidence of HER2/NEU somatic mutations. HER2/NEU copy number may be elevated in one patient with stable disease using FISH and is currently being confirmed by IHC staining. Studies are currently underway to assess the expression of EGFR/EGFR-P protein expression and the genes that regulate the cell cycle and apoptosis, which are either downstream of or cross-talk with the EGFR signaling pathway. KRAS mutational status is also underway as it is hypothesized that KRAS mutations will correlate with resistance to EGFR directed-treatment. Conclusions: Lapatinib is well-tolerated and may have some activity, mainly stabilization of disease, in HCC. Source of support: NCI-NO1-CM-62207.

A novel Raji-Burkitt's lymphoma model for preclinical and mechanistic evaluation of CD52-targeted immunotherapeutic agents

PURPOSE

To date, efforts to study CD52-targeted therapies, such as alemtuzumab, have been limited due to the lack of stable CD52 expressing transformed B-cell lines and animal models. We describe generation and utilization of cell lines that stably express CD52 both in vitro and in vivo.

EXPERIMENTAL DESIGN

By limiting dilution, we have established several clones of Raji-Burkitt's lymphoma cell line that express surface CD52. Immunophenotype and cytogenetic characterization of these clones was done. In vivo usefulness of the CD52(high) cell line to evaluate the therapeutic efficacy of CD52-directed antibody was investigated using a SCID mouse xenograft model.

RESULTS

Stable expression of CD52 was confirmed in cells cultured in vitro up to 52 weeks of continuous growth. The functional integrity of the expressed CD52 molecule was shown using alemtuzumab, which induced cytotoxic effects in vitro in the CD52(high) but not the CD52(low) clone. Compared with control antibody, alemtuzumab treatment in CD52(high) inoculated mice resulted in significantly increased median survival. Comparable levels of CD52-targeted direct cytotoxicity, complement-dependent cytotoxicity, and antibody-dependent cytotoxicity and anti-CD52 immunoliposome-mediated delivery of synthetic oligodeoxyribo nucleotides in CD52(high) clone and primary B-chronic lymphocytic leukemia cells implicated potential in vivo application of this model for evaluation of CD52-targeted antibody and immunoliposomes encapsulating therapeutic agents.

CONCLUSIONS

These results show the in vitro utility of the cloned Raji cell lines that stably express high levels CD52. The disseminated leukemia-lymphoma mouse model described herein using these stable cell lines can serve as an excellent system for in vivo therapeutic and mechanistic evaluation of existing and novel antibodies directed against CD52 molecule.

Different lineages of P1A-expressing cancer cells use divergent modes of immune evasion for T-cell adoptive therapy

Tumor evasion of T-cell immunity remains a significant obstacle to adoptive T-cell therapy. It is unknown whether the mode of immune evasion is dictated by the cancer cells or by the tumor antigens. Taking advantage of the fact that multiple lineages of tumor cells share the tumor antigen P1A, we adoptively transferred transgenic T cells specific for P1A (P1CTL) into mice with established P1A-expressing tumors, including mastocytoma P815, plasmocytoma J558, and fibrosarcoma Meth A. Although P1CTL conferred partial protection, tumors recurred in almost all mice. Analysis of the status of the tumor antigen revealed that all J558 tumors underwent antigenic drift whereas all P815 tumors experienced antigenic loss. Interestingly, although Meth A cells are capable of both antigenic loss and antigenic drift, the majority of recurrent Meth A tumors retained P1A antigen. The ability of Meth A to induce apoptosis of P1CTL in vivo alleviated the need for antigenic drift and antigenic loss. Our data showed that, in spite of their shared tumor antigen, different lineages of cancer cells use different mechanisms to evade T-cell therapy.

T-cell prolymphocytic leukemia: An aggressive T cell malignancy with frequent cutaneous tropism

BACKGROUND

T-cell prolymphocytic leukemia (T-PLL), formerly categorized as T-cell chronic lymphocytic leukemia, is a rare and aggressive hematologic malignancy. Although the skin is characteristically involved, it is not a well-recognized entity in the dermatologic literature.

METHODS

Six cases of cutaneous T-PLL are presented from a clinical, light microscopic, and phenotypic perspective.

RESULTS

The patient population comprised 2 women and 4 men, with a mean age of 69.8 years. The disease was associated in all with skin involvement with facial preference; edema, purpura, and lesional symmetry were characteristic. The skin biopsies demonstrated a largely non-epidermotropic angiocentric lymphocytic infiltrate with accompanying hemorrhage. The cells showed irregular- to reniform-shaped nuclei with small nucleoli and eosinophilic rims of cytoplasm. Phenotypic studies revealed three prevailing profiles: CD4 dominant in 4, CD8 dominant in one, and co-expression of CD4 and CD8 in one. CD3 loss was seen in one case. All expressed T-cell leukemia 1 (TCL-1) and CD7; cutaneous lymphocyte antigen expression was discernible in a dot-like perinuclear array. All cases tested excluding one expressed TCL-1 and CD52. In two cases tested, T-cell receptor beta rearrangements were observed. Cytogenetic studies demonstrated a paracentromeric chromosome 14 inversion. Polysomy 8 and MYC amplification was seen in one case, manifesting an aggressive clinical course. Four patients died from their disease within 18 months of diagnosis.

LIMITATIONS

Cytogenetic MYC amplification, FISH, and TCR beta studies were conducted on each of 2 cases, respectively, due to limitations of tissue block samples and/or peripheral blood. cMYC translocation studies were conducted on 3 of the 6 cases, again due to limitations imposed by the tissue samples on the cases. The last case was recently diagnosed and, therefore, long-term follow-up is not possible.

CONCLUSION

T-PLL is a distinctive post-thymic T-cell malignancy with frequent cutaneous tropism. A diagnosis is possible in almost all cases based on characteristic clinical, light microscopic, phenotypic, and cytogenetic features. While a chromosome 14 inversion is highly characteristic, additional inherent cytogenetic differences, such as trisomy 8 with CMYC over-amplification, may account for some case to case variation in clinical course.

Pre-B cell proliferation and lymphoblastic leukemia/high-grade lymphoma in E(mu)-miR155 transgenic mice

MicroRNAs (miRNAs) represent a newly discovered class of posttranscriptional regulatory noncoding small RNAs that bind to targeted mRNAs and either block their translation or initiate their degradation. miRNA profiling of hematopoietic lineages in humans and mice showed that some miRNAs are differentially expressed during hematopoietic development, suggesting a role in hematopoietic cell differentiation. In addition, recent studies suggest the involvement of miRNAs in the initiation and progression of cancer. miR155 and BIC, its host gene, have been reported to accumulate in human B cell lymphomas, especially in diffuse large B cell lymphomas, Hodgkin lymphomas, and certain types of Burkitt lymphomas. Here, we show that E(mu)-mmu-miR155 transgenic mice exhibit initially a preleukemic pre-B cell proliferation evident in spleen and bone marrow, followed by frank B cell malignancy. These findings indicate that the role of miR155 is to induce polyclonal expansion, favoring the capture of secondary genetic changes for full transformation.

No prognostic effect of additional chromosomal abnormalities in children with acute lymphoblastic leukemia and 11q23 abnormalities

This study characterized the additional chromosomal abnormalities (ACA) associated with 11q23 rearrangements in 450 infants and children with acute lymphoblastic leukemia (ALL) and examined the impact of these ACA on survival. Overall, 213 (47%) cases had ACA but the incidence varied according to patient age and 11q23 subgroup. Infants and patients with t(4;11)(q21;q23) had the lowest incidence of ACA (50/182 (27%) and 57/216 (26%) respectively), whereas patients with del(11)(q23) had the highest incidence (66/93 (71%)). Del(11)(q23) abnormalities were heterogeneous and occasionally secondary to t(9;22)(q34;q11.2). Thus, patients with del(11)(q23) comprised a separate biological entity, which was clearly distinct from those with an 11q23 translocation. The most frequent specific ACA were trisomy X (n = 38), abnormal 12p (n = 32), abnormal 9p (n = 28) and del(6q) (n = 19). The presence of ACA did not change the 5 year event-free survival estimates among children (56% (95% Cl 46-65%) vs 62% (54-69%)) or infants (22% (15-29%) vs 18% (9-29%)), nor when the different 11q23 subgroups were analyzed separately. This study has conclusively demonstrated that there is no prognostic effect of secondary chromosomal changes in association with 11q23 abnormalities in childhood ALL. However, characterization of these ACA is important to determine their potential role in initiation of MLL driven leukemogenesis.

Polypoid endobronchial Hodgkin lymphoma with an initial response to photodynamic therapy

Endobronchial presentation of Hodgkin lymphoma is rare and can be confused clinically and radiographically with pulmonary small cell carcinoma. We present a case of an obstructive endobronchial presentation of nodular sclerosing classic Hodgkin lymphoma, initially misdiagnosed as small cell carcinoma, with endobronchial vasculitis and associated hemoptysis. Photodynamic therapy relieved the obstruction before induction of tumor-specific therapy. This case demonstrates the successful use of photodynamic therapy in obstructive endobronchial Hodgkin lymphoma.

Clinical heterogeneity in childhood acute lymphoblastic leukemia with 11q23 rearrangements

To assess the clinical heterogeneity among patients with acute lymphoblastic leukemia (ALL) and various 11q23 abnormalities, we analyzed data on 497 infants, children and young adults treated between 1983 and 1995 by 11 cooperative groups and single institutions. The substantial sample size allowed separate analyses according to age younger or older than 12 months for the various cytogenetic subsets. Infants with t(4;11) ALL had an especially dismal prognosis when their disease was characterized by a poor early response to prednisone (P=0.0005 for overall comparison; 5-year event-free survival (EFS), 0 vs 23+/-+/-12% s.e. for those with good response), or age less than 3 months (P=0.0003, 5-year EFS, 5+/-+/-5% vs 23.4+/-+/-4% for those over 3 months). A poor prednisone response also appeared to confer a worse outcome for older children with t(4;11) ALL. Hematopoietic stem cell transplantation failed to improve outcome in either age group. Among patients with t(11;19) ALL, those with a T-lineage immunophenotype, who were all over 1 year of age, had a better outcome than patients over 1 year of age with B-lineage ALL (overall comparison, P=0.065; 5-year EFS, 88+/-+/-13 vs 46+/-14%). In the heterogeneous subgroup with del(11)(q23), National Cancer Institute-Rome risk criteria based on age and leukocyte count had prognostic significance (P=0.04 for overall comparison; 5-year EFS, 64+/-+/-8% (high risk) vs 83+/-+/-6% (standard risk)). This study illustrates the marked clinical heterogeneity among and within subgroups of infants or older children with ALL and specific 11q23 abnormalities, and identifies patients at particularly high risk of failure who may benefit from innovative therapy.

Expression of TEL-AML1 fusion transcripts and response to induction therapy in standard risk acute lymphoblastic leukemia

We prospectively examined the frequency of the t(12;21)TEL-AML1 fusion in 504 children with newly diagnosed standard risk ALL using RT-PCR assays. Cells from 95 patients (18.8%) were TEL-AML1+. There was a significantly higher frequency of pseudodiploidy among the TEL-AML1+ cases (39.4% versus 14.1%, P = 0.001), primarily because structural abnormalities involving 12p and del(6q) occurred more frequently in the TEL-AML1+ group. TEL-AML1+ ALL was more sensitive to the induction chemotherapy than TEL-AML1- ALL. The percentage of "rapid early responders", i.e., patients who achieved an M1 (< 5% blasts) or M2 (5-25% blasts) marrow status on day 7 of induction chemotherapy, was significantly higher among TEL-AML1+ cases. The quality of remission of RT-PCR positive cases was excellent, as evidenced by the very low to absent MRD burden of their end-of-induction bone marrow specimens. TEL-AML1+ patients also had an excellent early EFS outcome. The probability of EFS at 30 months from study entry were 98.9 +/- 1.0% for the TEL-AML1+ group and 92.1 +/- 1.5% for the TEL-AML1- group (P = 0.0001). This prospective study significantly expands the knowledge gained from previous studies regarding the prognostic significance of t(12;21)TEL-AML1 fusion in pediatric ALL.

Expression of dominant-negative and mutant isoforms of the antileukemic transcription factor Ikaros in infant acute lymphoblastic leukemia

Ikaros, a zinc finger-containing DNA-binding protein, is required for normal lymphocyte development, and germline mutant mice that express only non-DNA binding dominant-negative "leukemogenic" Ikaros isoforms lacking critical N-terminal zinc fingers develop an aggressive form of lymphoblastic leukemia 3-6 months after birth. Therefore, we sought to determine whether molecular abnormalities involving the Ikaros gene could contribute to the development of acute lymphoblastic leukemia (ALL) in infants. Primary leukemic cells were freshly obtained from 12 infants (<1 year of age) with newly diagnosed ALL. In leukemic cells from each of the 12 infants with ALL, we found high level expression of dominant-negative isoforms of Ikaros with abnormal subcellular compartmentalization patterns. PCR cloning and nucleotide sequencing were used to identify the specific Ikaros isoforms and detect Ikaros gene mutations in these cells. Leukemic cells from seven of seven infants with ALL, including five of five MLL-AF4(+) infants, expressed dominant-negative Ikaros isoforms Ik-4, Ik-7, and Ik-8 that lack critical N-terminal zinc fingers. In six of seven patients, we detected a specific mutation leading to an in-frame deletion of 10 amino acids (Delta KSSMPQKFLG) upstream of the transcription activation domain adjacent to the C-terminal zinc fingers of Ik-2, Ik-4, Ik-7, and Ik-8. In contrast, only wild-type Ik-1 and Ik-2 isoforms with normal nuclear localization were found in normal infant bone marrow cells and infant thymocytes. These results implicate the expression of dominant-negative Ikaros isoforms and the disruption of normal Ikaros function in the leukemogenesis of ALL in infants.

Distinct in vivo engraftment and growth patterns of t(1;19)+/E2A-PBX1+ and t(9;22)+/BCR-ABL+ human leukemia cells in SCID mice

The SCID mouse represents a valuable tool for assessing growth characteristics and drug sensitivity of human leukemic cells. We have examined differences in the engraftment patterns in SCID mice of primary human leukemic cells isolated from children (< 21 years old) with either t(1;19)+/E2A-PBX1+ or t(9;22)+/BCR-ABL+ acute lymphoblastic leukemia. Leukemic cells from 13/24 t(1;19)+/E2A-PBX1+ patients caused overt leukemia in SCID mice. Macroscopic lesions were evident in 6/13 cases, with multiple sites involved in some mice: hepatomegaly,(3) splenomegaly(4), thymic enlargement; liver tumors(1), kidney tumors(1), abdominal tumors(1). Microscopic lesions in SCID mouse organs were present in all 13 cases and involved the bone marrow, brain, heart, gut, liver, kidney, lung, ovary, pancreas, skeletal muscle, spleen, and thymus. Leukemic cells from 5/20 t(9;22)+/BCR-ABL+ patients caused overt leukemia in SCID mice. Notably, macroscopic lesions (splenomegaly; leukemic bones; hepatic tumors) were observed in only 1 case. In all 5 cases, microscopic lesions were found in the mouse bone marrow. Additional microscopic lesions were restricted to skeletal muscle, spleen, and mesentery (1 case) or thymus (1 case). These findings differ markedly from those of t(1;19)+/E2A-PBX1+ leukemic cells due to the lack of involvement of major organs such as liver, pancreas, kidney, skin, or brain. These data illustrate the biological heterogeneity of childhood ALL and suggest that the differential risks associated with t(1;19)+/E2A-PBX1+ and t(9;22)+/BCR-ABL ALL might arise from unique engraftment and proliferation capabilities of the respective leukemic cell populations.

Clinical significance of MLL-AF4 fusion transcript expression in the absence of a cytogenetically detectable t(4;11)(q21;q23) chromosomal translocation

Leukemic cells from bone marrow (BM) of 17 infants and 127 children with newly diagnosed ALL, as well as fetal liver and BM and normal infant BM samples, were analyzed for presence of a t(4;11) translocation using standard cytogenetic techniques and expression of an MLL-AF4 fusion transcript using standard reverse transcriptase-polymerase chain reaction (RT-PCR) assays as well as nested RT-PCR that is 100-fold more sensitive than standard RT-PCR. Overall, 9 of 17 infants and 17 of 127 noninfant pediatric ALL patients were positive for expression of MLL-AF4 fusion transcripts, as determined by standard and/or nested RT-PCR assays. None of the MLL-AF4(+) cases were positive for E2A-PBX1 or BCR-ABL fusion transcript expression. Although 8 of 9 MLL-AF4(+) infants had cytogenetically detectable t(4;11)(q21;q23), 15 of the 17 MLL-AF4(+) noninfants were t(4;11)-. Infants with MLL-AF4(+) ALL had poor outcomes, whereas non-infant MLL-AF4(+)/t(4;11)- patients had favorable outcomes similar to MLL-AF4(-) patients. Notably, MLL-AF4 transcripts also were detected by nested RT-PCR in 4 of 16 fetal BMs, 5 of 13 fetal livers, and 1 of 6 normal infant BMs, but not in any of the 44 remission BM specimens from pediatric ALL patients. Our results provide unprecedented evidence that MLL-AF4 fusion transcripts can be present in normal hematopoietic cells, indicating that their expression is insufficient for leukemic transformation of normal lymphocyte precursors.

mdm-2 oncoprotein expression associated with deletion of the long arm of chromosome 12 in a case of mantle cell lymphoma with blastoid transformation [corrected]

We report a unique case of mantle cell lymphoma in blastoid transformation associated with deletion of the long arm of chromosome 12 and with 90 kDa mdm-2 protein overexpression. Neither the mantle cells nor their blastoid counterparts expressed p53 gene product by immunohistochemical analysis. This seems to be the first reported case of this subtype of lymphoma associated with these specific cytogenetic and molecular genetic abnormalities.

Uniform approach to risk classification and treatment assignment for children with acute lymphoblastic leukemia

PURPOSE

To define more uniform criteria for risk-based treatment assignment for children with acute lymphoblastic leukemia (ALL), the Cancer Therapy Evaluation Program (CTEP) of the National Cancer Institute (NCI) sponsored a workshop in September 1993. Participants included representatives from the Childrens Cancer Group (CCG), Pediatric Oncology Group (POG), Dana-Farber Cancer Institute (DFCI), St Jude Children's Research Hospital (SJCRH), and the CTEP.

METHODS

Workshop participants presented and reviewed data from ALL clinical trials, using weighted averages to combine outcome data from different groups.

RESULTS

For patients with B-precursor (ie, non-T, non-B) ALL, the standard-risk category (4-year event-free survival [EFS] rate, approximately 80%) will include patients 1 to 9 years of age with a WBC count at diagnosis less than 50,000/microL. The remaining patients will be classified as having high-risk ALL (4-year EFS rate, approximately 65%). For patients with T-cell ALL, different treatment strategies have yielded different conclusions concerning the prognostic significance of T-cell immunophenotype. Therefore, some groups/institutions will classify patients with T-cell ALL as high risk, while others will assign risk for patients with T-cell ALL based on the uniform age/WBC count criteria. Workshop participants agreed that the risk category of a patient may be modified by prognostic factors in addition to age and WBC count criteria, and that a common set of prognostic factors should be uniformly obtained, including DNA index (DI), cytogenetics, early response to treatment (eg, day-14 bone marrow), immunophenotype, and CNS status.

CONCLUSIONS

The more uniform approach to risk-based treatment assignment and to collection of specific prognostic factors should increase the efficiency of future ALL clinical research.

Pediatric leukemia/lymphoma with t(8;14)(q24;q11)

A variety of chromosomal translocations occur in pediatric T-cell acute lymphoblastic leukemia (T-ALL) in which a cellular oncogene or growth-related gene is translocated to the alpha/delta locus of the T-cell receptor gene. The t(8;14)(q24;q11) has been described at the cytogenetic and molecular level, but the disease associated with this translocation has not been defined clinically. Fifteen pediatric cases of leukemia/lymphoma with a t(8;14)(q24;q11) chromosomal translocation were collected from previous publications and institutional records. The estimated prevalence of this abnormality among all cases of ALL was 1%. The t(8;14)(q24;q11) disease was characterized by male predominance (10/15), a median age of 5.5 years (range 1.8-17 years), high white blood cell count (median 95 x 10(9)/l), central nervous system infiltration (4/11), bulky extramedullary leukemia (10/11), and T-cell immunophenotype (12/15). The median event-free survival was 4 months, and the median survival, 11 months. Seven cell lines with t(8;14)(q24;q11) were established from six of the cases; four were T-lymphoblastic, one was T-lymphoblastic, but expressed myeloid-related antigens, and two were predominantly myeloid. t(8;14)(q24;q11) leukemia/lymphoma and other ALLs involving 13(q11) have in common a high tumor burden, early spread to extramedullary sites, a propensity to form T-lymphoblastic or T-myeloid cell lines and, usually, an aggressive clinical course.

Deletions in chromosome 2 and fragile sites

We report on 2 patients with de novo deletions of 2q and chromosome constitutions of 46,XY,del(2)(q32.3q33.3) and 46,XX,del(2) (q21q23.2), respectively. Comparisons of breakpoints of interstitial deletions show frequent correspondence to common fragile sites.

Hematologic neoplasia associated with primary mediastinal germ-cell tumors

Between September 1983 and December 1988, we observed 16 cases of hematologic neoplasia associated with mediastinal germ-cell tumors. Twenty-eight similar cases have been reported in the literature. A review of the clinical and cytogenetic details in these patients suggests that the hematologic neoplasia is not the result of cisplatin-based chemotherapy of the mediastinal germ-cell cancer. This syndrome was found only in patients with nonseminomatous mediastinal germ-cell tumors, particularly those with serologic or histologic evidence of yolk-sac elements. The two most common hematologic neoplasms seen in this syndrome were acute megakaryoblastic leukemia and malignant histiocytosis. Consistent cytogenetic abnormalities have not yet been identified, but the finding of the marker chromosome isochromosome (12p) in the mediastinal germ-cell tumor and associated leukemic blasts in one patient suggests that these tumors may arise from a common progenitor cell.

Biochemically directed therapy of leukemia with tiazofurin, a selective blocker of inosine 5'-phosphate dehydrogenase activity

Tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide, NSC 286193), a selective inhibitor of the activity of IMP dehydrogenase (EC 1.1.1.205), the rate-limiting enzyme of de novo GTP biosynthesis, provided in end stage leukemic patients a rapid decrease of IMP dehydrogenase activity and GTP concentration in the blast cells and a subsequent decline in blast cell count. Sixteen consecutive patients with end stage acute nonlymphocytic leukemia or myeloid blast crisis of chronic granulocytic leukemia were treated with tiazofurin. Allopurinol was also given to inhibit xanthine oxidase activity to decrease uric acid excretion and to elevate the serum concentration of hypoxanthine, which should competitively inhibit the activity of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8), the salvage enzyme of guanylate synthesis. Assays of IMP dehydrogenase activity and GTP concentration in leukemic cells provided a method to monitor the impact of tiazofurin and allopurinol and to adjust the drug doses. In this group of patients with poor prognosis, five attained a complete hematological remission and one showed a hematological improvement. A marked antileukemic effect was seen in two other patients. All five evaluable patients with myeloid blast crisis of chronic granulocytic leukemia reentered the chronic phase of their disease. Five patients with acute nonlymphocytic leukemia were refractory to tiazofurin and three were unevaluable for hematological effect because of early severe complications. Responses with intermittent 5- to 15-day courses of tiazofurin lasted 3-10 months. Tiazofurin had a clear antiproliferative effect, but the pattern of hematological response indicated that it appeared to induce differentiation of leukemic cells. In spite of toxicity with severe or life-threatening complications in 11 of 16 patients, tiazofurin was better tolerated in most patients than other antileukemic treatment modalities and provided a rational, biochemically targeted, and biochemically monitored chemotherapy which should be of interest in the treatment of leukemias and as a paradigm in enzyme pattern-targeted chemotherapy.

Localization of the human gene for the El alpha subunit of branched chain keto acid dehydrogenase (BCKDHA) to chromosome 19q13.1----q13.2

The gene encoding the El alpha subunit of branched chain keto acid dehydrogenase (BCKDHA) was mapped to human chromosome region 19q13.1----q13.2 using 3H-labeled cDNA hybridized in situ to human chromosomes.

Evidence for the clonal nature of hypereosinophilic syndrome

Hypereosinophilic syndrome (HES) is a disease process of unknown pathogenesis. Although some cases are believed to be primary hematologic malignancies, this issue remains unsolved. We present a case of HES in whom we have observed a clone of cytogenetically abnormal cells in the bone marrow in parallel with a clinical picture of a hematologic disorder characterized by progressive proliferation and organ infiltration by eosinophils. The cytogenetic abnormality 46,XY,t(7;12)(q11;p11) is previously unreported. Our case, plus other evidence present in the literature, supports the concept that HES is a hematologic malignant neoplasia.

A variant t(X;15)(p11;q22) translocation in acute promyelocytic leukemia

Nonrandom reciprocal translocations involving chromosomes #15 and #17 are characteristic anomalies in a great majority of cases of acute promyelocytic leukemia (APL). Other complex translocations in APL that invariably involve chromosome #17 also have been described. We describe a patient with clinical and morphologic characteristics of APL but with a previously undescribed acquired karyotype, t(X;15)(p11;q22). This is the first translocation in APL described in which chromosome #17 is not involved. Although a comparative structure/function analysis of potentially relevant genes to the translocation breakpoints in both t(X;15) and t(15;17) APL showed no major alterations, the enhanced expression of the c-Ki-ras oncogene observed in t(X;15) APL supports the concept of heterogeneity in APL at the cytogenetic and molecular levels.

Cellular control of in vitro progression of murine myeloid leukemia: progression accompanies acquisition of independence from growth factor and stromal cells

The ability of bone marrow stroma cells of normal WCB6F1 (+/+) mice versus their congenic Sl/Sld stromal-defective littermates to support sustained proliferation and leukemic transformation of the growth factor-dependent myeloid cell line FDC-P1 was studied. Extensive proliferation of factor-dependent cells occurred on (+/+) normal long-term marrow culture stroma without the addition of growth factor, whereas factor-dependent cells dissipated from Sl/Sld stromal cultures after addition. The sustained proliferation that occurred on +/+ stromal layers later resulted in the appearance of factor-independent cell lines that were no longer dependent upon stroma. Factor-independent cell lines were cloned by limiting dilution and analyzed for expression of cell surface antigens to prove their origin from FDC-P1. Factor-independent cells, but not factor-dependent cells, formed tumors in syngeneic mice. These studies demonstrate a critical role for marrow stroma in the stepwise development of murine leukemia and are concordant with the previous data obtained in in vivo studies by McCool et al. that the splenic stroma of irradiated Sl/Sld mice do not support growth of Friend virus-induced preleukemic cell colonies. The present data demonstrate in a preleukemia model not induced by Friend virus complex that normal (+/+) stromal cells promote the in vitro proliferation of factor-dependent preleukemic cells and their subsequent transition to factor-independent leukemia cells, but Sl/Sld defective stroma do not efficiently promote this transition.

DNA linkage analysis of X chromosome-linked chronic granulomatous disease

Chronic granulomatous disease (CGD) is a disorder of phagocytes that is usually inherited as an X chromosome-linked trait. Previous family studies suggested that the CGD locus resides on the distal short arm (Xp22-Xpter). Using cloned, polymorphic DNA probes we have performed a linkage analysis within CGD families that suggests a more proximal location (Xp21). In addition, the CGD locus is proximal to the Duchenne muscular dystrophy locus and lies within a broad region of Xp in which recombination appears to be greater than anticipated on the basis of physical distance between markers. Regional localization of the X chromosome CGD locus should facilitate molecular cloning of the CGD gene and molecular dissection of the phagocyte oxidase system.

Effect of temperature variation on sister-chromatid exchange and cell-cycle duration in cultured human lymphocytes

The relation of temperature variation and cell-cycle duration and their influence on SCE frequencies in human peripheral blood lymphocytes was studied. The results indicate that the frequency of SCEs is affected by variation in temperature. Either increase or decrease in the incubation temperature of cells leads to a higher frequency of SCEs than in control cultures grown at 37 degrees C. With a decrease in temperature to 35 degrees C the increase in SCE is accompanied by prolonged cell cycle. No significant difference in cell cycle was observed with the increase of temperature to 39 degrees C.