Phase I Study of Bortezomib, Fludarabine, and Melphalan, with or without Total Marrow Irradiation as Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation in Patients with High-Risk or Relapsed/Refractory Multiple Myeloma

PURPOSE/OBJECTIVE(S)

Though outcomes of patients with multiple myeloma (MM) have improved, cure remains elusive. Allogeneic hematopoietic stem cell transplantation (allo-sCT) is associated with a lower relapse rate, but its role is hindered due to toxicities. We hypothesized that targeted total body irradiation in the form of total marrow irradiation (TMI) could safely facilitate allo-SCT via an improved toxicity profile. Therefore, we conducted a phase I study to investigate the safety and feasibility of a bortezomib (BTZ), fludarabine (FLU), and melphalan (MEL), with or without TMI, prior to allo-SCT for patients with high-risk (HR) or relapsed/refractory (R/R) MM.

MATERIALS/METHODS

Between 2012 and 2018 this study enrolled patients with HR or R/R MM on one of two strata, each comprising BTZ dose-escalation cohorts. Patients aged 18-60 with no prior radiation (RT) received TMI at 900 cGy (in 6 fractions delivered twice-daily), FLU, and MEL conditioning, with BTZ added in the second cohort (stratum I). Patients aged 18-70 with prior RT received FLU, MEL, and BTZ, without TMI (stratum II). The primary endpoint was feasibility of escalating doses of BTZ, with or without TMI, defined using a 3+3 design. Dose-limiting toxicity (DLT) was defined as any Grade 3+ Bearman toxicity or prolonged CTCAE v4.0 Grade 4+ neutropenia. Secondary endpoints included treatment response, time to neutrophil and platelet engraftment, incidence of acute (a) and chronic (c) graft-versus-host disease (GVHD), progression-free-survival (PFS), and overall survival (OS).

RESULTS

Eight patients were enrolled on stratum I. One of three patients in the first cohort of stratum I experienced DLT, which led to expansion to three more patients with no DLT. Cohort 2 enrolled only 2 patients due to low accrual, with BTZ added at 0.5 mg/m2; neither experienced DLT. Nine patients were enrolled on stratum II. Three patients were enrolled on cohort 1 (BTZ 0.5 mg/m2) and none experienced DLT. Three were enrolled on cohort 2 (bortezomib 0.7 mg/m2), and one experienced DLT. Therefore, the cohort expanded to three more patients. One more patient experienced DLT and 0.5 mg/m2 was considered the maximum tolerated dose. There were no primary or secondary graft failures. Complete response was achieved in 7 and 4 patients in strata I and II, respectively. Median follow-up for all patients was 30.7 months (mos) and was 99.8 mos for surviving patients. Median overall survival (OS) on strata I and II were 44.5 mos and 21.6 mos, respectively. Median PFS on strata I and II were 18.1 mos and 8.9 mos, respectively. In strata I, 5 patients developed Grade 2+ aGVHD and 8 developed extensive cGVHD. In strata II, 4 patients developed Grade 2+ aGVHD and 6 developed extensive cGVHD.

CONCLUSION

The TMI 900 cGy, FLU, and MEL conditioning regimen is considered safe as conditioning for allo-SCT and may warrant further investigation due to favorable response rates and survival; the conditioning regimen of FLU, MEL, and BTZ (0.7 mg/m2) is associated with unacceptable toxicities.

Six-month abdominal transplant recipient outcomes from donation after circulatory death heart donors: A retrospective analysis by procurement technique

Standard US practice for donation after circulatory death (DCD) abdominal organ procurement is superrapid recovery (SRR). A newer approach using thoracoabdominal normothermic regional perfusion (TA-NRP) shows promise for better recipient outcomes for all organs, but there are few reports of abdominal recipient outcomes from TA-NRP donors. We used the United Network for Organ Sharing data to identify all cardiac DCD donors from October 1, 2020, to May 20, 2022, and categorized them by recovery procedure (SRR vs TA-NRP). We then identified all liver, kidney, and pancreas recipients of these donors for whom 6-month outcome data were available and compared patient and graft survival, kidney delayed graft function (DGF), and biliary complications between TA-NRP DCD and SRR DCD organ recipients. Patient and graft survival did not differ significantly between groups for either kidney or liver recipients. Significantly fewer TA-NRP kidney recipients developed DGF (12.7% [15/118] vs 42.0% [84/200], P <.001), and TA-NRP and pumped kidneys had lower odds for DGF on multivariate analysis. No liver recipients in either group had biliary complications or were relisted for transplantation for ischemic cholangiopathy. Although long-term outcomes need to be investigated, our early results show similar outcomes for recipients of TA-NRP DCD abdominal organs versus recipients of SRR DCD abdominal organs. We believe that TA-NRP is an effective approach to expand the use of DCD organs.

Global solutions of aggregation equations and other flows with random diffusion

Aggregation equations, such as the parabolic-elliptic Patlak–Keller–Segel model, are known to have an optimal threshold for global existence versus finite-time blow-up. In particular, if the diffusion is absent, then all smooth solutions with finite second moment can exist only locally in time. Nevertheless, one can ask whether global existence can be restored by adding a suitable noise to the equation, so that the dynamics are now stochastic. Inspired by the work of Buckmaster et al. (Int Math Res Not IMRN 23:9370–9385, 2020) showing that, with high probability, the inviscid SQG equation with random diffusion has global classical solutions, we investigate whether suitable random diffusion can restore global existence for a large class of active scalar equations in arbitrary dimension with possibly singular velocity fields. This class includes Hamiltonian flows, such as the SQG equation and its generalizations, and gradient flows, such as those arising in aggregation models. For this class, we show global existence of solutions in Gevrey-type Fourier–Lebesgue spaces with quantifiable high probability.

The results of rapid source control laparotomy or open abdomen for acute diverticulitis

INTRODUCTION

Rapid source control laparotomy (RSCL) for the management of non-traumatic intra-abdominal emergencies has increased over the past 25 years when it was advocated for trauma patients. Little data, however, support its widespread use. We hypothesize that the patients with RSCL will have poorer outcomes than those treated with primary fascial closure (PFC).

METHODS

Patients operated for acute diverticulitis from 2014 to 2016 using The American College of Surgeons sponsored National Surgical Quality Improvement Program (NSQIP) data were reviewed. Two groups were identified: PFC, patients with their closed fascia but skin left open (PFC) and RSCL, patients with their left open fascia after the initial operation. The primary outcome of the study was 30-day mortality, with secondary analyses evaluating complications, discharge location and length of stay. Univariate analysis was initially performed followed by propensity score matching.

RESULTS

A total of 460 patients were surgically treated for Hinchey IV diverticulitis of whom 101 (21.9%) had RSCL. The length of stay of the RSCL patients was significantly longer (15 versus 12 days, p, 0.02) than patients in the PFC group. Similarly, the discharge destination for the PFC group was twice as likely to be discharged home as the RSCL group.

CONCLUSION

RSCL for acute diverticulitis is a widely used but is associated with prolonged hospitalizations resulting in high rates of discharge to skilled nursing or rehabilitation facilities. Its routine use for diverticulitis should be limited.

Pregnancy after CMV infection following uterus transplantation: A case report from the Dallas Uterus Transplant Study

Uterus transplantation is a repeatedly proven treatment for women with absolute uterine-factor infertility, which is the congenital or acquired absence of the uterus, who desire to carry, and ultimately deliver, a child. No stranger to the field of transplant or obstetrics is cytomegalovirus. Cytomegalovirus is both a frequent complication after transplant, presenting as an opportunistic infection, and a common congenital disease in the newborn child from pregnancy. To date, there have been no reported cases of pregnancy following uterus transplantation from cytomegalovirus-positive donors into cytomegalovirus-negative recipients. We present a case report describing our experience of a cytomegalovirus-negative recipient, transplanted with a uterus from a cytomegalovirus-positive living donor, and subsequently diagnosed with active cytomegalovirus infection despite prophylactic treatment. She was treated for infection prior to embryo transfer and carried a healthy child to term. This case suggests transplanting a cytomegalovirus-positive uterus into a negative donor is possible to do safely.

Are the Benefits of Rapid Source Control Laparotomy Realized after Acute Colonic Perforation?

Background: The indications for damage-control laparotomy (DCL) in patients with intra-abdominal injuries have evolved from its use in trauma patients with hypothermia, coagulopathy, and acidosis to use in general surgical patients with acute intestinal perforations. Whereas some patients may be acidotic, most are not hypothermic or afflicted with coagulopathies. Recent study suggests the benefits to patients of rapid source-control laparotomy (RSCL) are not realized in patients with acute abdominal emergencies. Methods: Three years of data (2014-2016) from The American College of Surgeons National Surgical Quality Improvement Program (ACSNSQIP) were assessed. The patient populations were separated into RSCL patients who had their fascia left open after the initial source control operation and those who had primary fascial closure (PFC). The principal outcome of interest in this study was death within thirty days. A secondary analysis was performed evaluating complications and length of stay. Results: Of the 1,381 patients who qualified for the study, 396 (28.7%) were managed with RSCL and the remaining 985 patients had PFC. After a univariable analysis, propensity score matching was performed. The median hospital length of stay was 20 days (95% confidence interval [CI] 18-22) versus 14 (95% CI 13-16; p < 0.001) in RSCL and PFC, respectively. A larger number of patients having RSCL went to a rehabilitation facility than those having PFC (18.7%; versus 11.2%; p = 0.014). The 30-day mortality rate in patients in the RSCL group was significantly higher than in the PFC group ((32.6% versus 16.9%; p < 0.001). Conclusion: These data provide strong evidence that RSCL may not be beneficial for routine use in perforated colon surgery.

Recurrent hyperactive ESR1 fusion proteins in endocrine therapy-resistant breast cancer

Background

Estrogen receptor-positive (ER-positive) metastatic breast cancer is often intractable due to endocrine therapy resistance. Although ESR1 promoter switching events have been associated with endocrine-therapy resistance, recurrent ESR1 fusion proteins have yet to be identified in advanced breast cancer.

Patients and methods

To identify genomic structural rearrangements (REs) including gene fusions in acquired resistance, we undertook a multimodal sequencing effort in three breast cancer patient cohorts: (i) mate-pair and/or RNAseq in 6 patient-matched primary-metastatic tumors and 51 metastases, (ii) high coverage (>500×) comprehensive genomic profiling of 287-395 cancer-related genes across 9542 solid tumors (5216 from metastatic disease), and (iii) ultra-high coverage (>5000×) genomic profiling of 62 cancer-related genes in 254 ctDNA samples. In addition to traditional gene fusion detection methods (i.e. discordant reads, split reads), ESR1 REs were detected from targeted sequencing data by applying a novel algorithm (copyshift) that identifies major copy number shifts at rearrangement hotspots.

Results

We identify 88 ESR1 REs across 83 unique patients with direct confirmation of 9 ESR1 fusion proteins (including 2 via immunoblot). ESR1 REs are highly enriched in ER-positive, metastatic disease and co-occur with known ESR1 missense alterations, suggestive of polyclonal resistance. Importantly, all fusions result from a breakpoint in or near ESR1 intron 6 and therefore lack an intact ligand binding domain (LBD). In vitro characterization of three fusions reveals ligand-independence and hyperactivity dependent upon the 3' partner gene. Our lower-bound estimate of ESR1 fusions is at least 1% of metastatic solid breast cancers, the prevalence in ctDNA is at least 10× enriched. We postulate this enrichment may represent secondary resistance to more aggressive endocrine therapies applied to patients with ESR1 LBD missense alterations.

Conclusions

Collectively, these data indicate that N-terminal ESR1 fusions involving exons 6-7 are a recurrent driver of endocrine therapy resistance and are impervious to ER-targeted therapies.

Abstract P1-17-10: The impact of age and adjuvant chemotherapy modifications on disease-free and overall survival among African American women with breast cancer

Background: During chemotherapy for breast cancer, African American women receive less relative dose intensity with more dose reductions and early chemotherapy cessation compared to Caucasian women. Other research has found that older breast cancer patients are most at risk for treatment modifications; however, it is unclear if this remains true for African American patients. Furthermore, the clinical implications of treatment modifications and delays on survival is uncertain, particularly in African American patients.

Purpose: The purpose of this study was to investigate whether age (diagnosis &lt;55 vs. diagnosis ≥55) was a moderator for the association between treatment modifications (dose held, dose delayed, and early cessation) and overall survival (OS) and disease-free survival (DFS) in African American women with breast cancer.

Methods: A retrospective cohort study of early stage African American breast cancer patients treated with adjuvant chemotherapy was employed. Dose held, dose delayed and early cessation were examined as dichotomous variables: any adjustment to the initially prescribed treatment plan was considered a modification. Medical record data extraction was utilized to gather this information. The sample was divided into two groups: those diagnosed &lt;55 years of age and those diagnosed ≥55 years of age. A Cox's proportional hazards regression model was used to examine the interaction between age group and treatment modifications for OS and DFS, while controlling for stage and ER and HER2 status.

Results: In the study of 115 participants, 58 (50.4%) were diagnosed before the age of 55, and 57 (49.6%) were diagnosed age 55 or older. Across the entire sample, 43 (37.4%) patients experienced a treatment modification. There were no significant differences in the proportions of treatment modifications between the two age groups. We found no interaction between age group and treatment modifications for OS. However, there was a significant interaction between age group and held dose for DFS (p=0.045). Specifically, those diagnosed at 55 years of age and older, who had doses of chemotherapy held, experienced worse DFS compared to those who did not (hazard ratio (HR)=3.390, 95% CI (1.013,11.34)). In contrast, there was no difference in DFS between those who did and did not have doses held in patients diagnosed below 55 years of age (HR=0.563, 95%CI (0.159, 1.986)).

Conclusions: African American women receiving adjuvant chemotherapy for treatment of early stage breast cancer have high levels of treatment modifications across all age groups. However, held doses of chemotherapy in older African American patients were associated with worse DFS. Further research is needed to elucidate the clinical implications of adjuvant chemotherapy treatment modifications, particularly in African American patients, and the subgroups of patients who are at greatest risk.

Citation Format: Nugent BD, Ren D, Bender C, Rosenzweig M. The impact of age and adjuvant chemotherapy modifications on disease-free and overall survival among African American women with breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-17-10.

Abstract P2-08-48: Features associated with long-term survival in metastatic breast cancer

Background: 5-10% of women with metastatic breast cancer (MBC) survive ≥5 years. Predictors of long-term survival are not clearly elucidated. We used data from 122 long-term MBC survivors (≥5-year survival from date of MBC diagnosis) and 191 short-term MBC survivors (≤2-year survival from date from MBC diagnosis) to identify clinico-pathologic and socioeconomic features associated with MBC survival.

Methods: Women initially diagnosed with breast cancer (BC) in or after 1999, and diagnosed with MBC at Magee Women's Cancer Program of UPMC were included (N=313). Data abstracted from medical records included: stage at initial BC diagnosis, body mass index (BMI), Charlson Comorbidity Index (CCI), age, menopausal status at initial BC diagnosis, tumor receptor status at initial BC diagnosis, site of initial metastases, time to recurrence between initial diagnosis and MBC, household income, race, employment status, and partner status. Differences between groups were assessed using t-tests and Chi-square or Fisher's exact tests. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariate logistic regression models.

Results: Long-term survivors were significantly (P&lt;0.05) younger, had more ER positive, PR positive, and Her2 positive disease, lower CCI, more often premenopausal at initial diagnosis, lower rates of visceral metastases, higher household income, and more often partnered than short-term survivors. The association of premenopausal status at initial diagnosis with long-term survival remained significant after adjustment for stage at initial diagnosis, tumor receptor status, and CCI (OR: 1.96, 95% CI 1.02- 3.79). Long-term term survivors were also significantly more often diagnosed with de novo MBC compared to short-term survivors. The association of de novo MBC with long-term survival remained significant after adjustment for age, tumor receptor status, and CCI (OR: 3.0, 95% CI 1.6-5.4). Time to recurrence between initial diagnosis and MBC, BMI, race, and employment status were not associated with survival.

Conclusions: Diagnosis of de novo MBC, ER-, PR- and/or Her2-positive primary tumor, lower rates of visceral metastases, higher household income, younger age, lower CCI, premenopausal status, and having a partner are associated with long-term survival after diagnosis of MBC. This is one of the first studies to show a survival benefit in MBC for patients with de novo MBC, premenopausal status at initial diagnosis, positive partner status, and higher household income.

Citation Format: Klar NJ, Rosenzweig M, Diergaarde B, Brufsky A. Features associated with long-term survival in metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-48.

Colo-ovarian fistula

Colo-ovarian fistula is a rare entity. The case of a 54-year-old female with a colo-ovarian fistula is presented. We describe our experience in managing this complication of diverticulitis and propose a workup and treatment plan. Initial imaging and diagnostic studies are described. En-bloc resection of the sigmoid colon and ovary was performed. A review of the literature is presented.

Tension pneumoperitoneum caused by blunt thoracic trauma

Tension pneumoperitoneum is a rare entity that occurs when free air under pressure accumulates in the abdominal cavity compromising visceral function and blood flow. The case of a 23-year-old man whose chest was run over by the wheels of a truck is presented. He arrived with a severely distended abdomen, significant thoracic trauma, hypoxemia, and elevated airway pressures following intubation. Imaging studies revealed massive intraperitoneal free air. He was treated with a decompressive laparotomy but was not found to have a hollow viscus nor diaphragmatic injury. We hypothesize a possible, as yet unpublished, mechanism: secondary to the patient’s rib fractures and significant torso soft tissue shearing, a defect in the parietal pleura allowed air to track from the thorax inferiorly along subcutaneous and fascial planes, eventually entering into the peritoneal cavity through a violated parietal peritoneum. We present a review of the literature on tension pneumoperitoneum.

Long-term treatment with intravenous bisphosphonates in metastatic breast cancer (MBC)

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Background: Intravenous bisphosphonates (IV BPs) are safe and effective in reducing skeletal related events in MBC. The effects of IV BPs after 24 months of therapy are unknown. The incidence of osteonecrosis of the jaw (ONJ) and renal insufficiency (RI) among women with MBC receiving >= 24 months of IV BPs is also poorly defined. We studied the long term effect of IV BPs in a cohort of women with MBC. Methods: We maintain an ongoing prospective database of >600 women with MBC diagnosed and treated at our institution from January 1999. A long-term cohort (LTC) of 159 women with metastatic breast cancer to bone treated for >= 24 months with pamidronate (n = 9), zoledronic acid (n = 110), or both (n = 40) was identified. A control cohort (CC) of 62 women with MBC to bone treated with IV BPs for 12–23 months was also identified. RI was defined as an increase in serum creatinine (scr) of > 0.5 mg/dl or an absolute level of scr >1.5mg/dl; ONJ was diagnosed by dental consultation. Results: Median follow-up of the LTC was 39 months (range 24–99) months. Median overall survival in this cohort was 43 months (range 24–114). The vast majority of women in the LTC (140/159, 88.1%) continued to receive IV BPs at standard dose every 3–4 weeks. The incidence of ONJ in the LTC was 6/159 (3.8%), after a mean 42.2 treatment cycles, with a median time to ONJ of 44 months. Three of six patients with ONJ (50%) underwent surgical resection, and 3/6 (50%) were managed conservatively, and 3/6 (50%) resumed IV BPs after a mean 12 month hold. The incidence of RI (all pts had baseline scr < 1.4 mg/dl) in the LTC was 19/159 (11.9%), occurring after a mean 43.4 treatment cycles, with a median time to RI of 43 months. Eleven of 19 patients (57.9%) recovered to baseline scr and 7/19 (36.7%) patients showed partial recovery. Seventeen of 19 patients (89.4%) were able to resume therapy after temporary discontinuation, decreasing the dose, or increasing the interval of the IV BP. Incidence of ONJ in the CC was 1/62 (1.6%) and RI in the CC was 6/62 (9.7%). Conclusions: Long term (>=24 month) IV BP use in MBC is well tolerated and safe, with relatively low incidence of ONJ and RI. Most patients were able to resume IV BP therapy after a therapy hold without further complication.

No significant financial relationships to disclose.

Febrile reactions occurring with second cycle of high-dose melphalan and SCT in patients with AL amyloidosis: a 'melphalan recall' reaction

Aggressive treatment with high-dose i.v. melphalan followed by auto-SCT (HDM/SCT) is effective in inducing hematological and clinical remissions, and in extending survival in AL amyloidosis. Tandem cycles of HDM/SCT have been shown to increase hematologic complete response rates in patients with AL amyloidosis. Between April 1994 and July 2008, 57 patients with AL amyloidosis at the Boston University Medical Center were treated with a second cycle of HDM/SCT after failing to achieve a complete response after a first transplantation. A total of 11 of 57 patients (19%) treated with tandem transplantation developed high fever 12-24 h after melphalan administration. The average peak temperature was 39.1 degrees C. Other clinical features include hypotension, acute renal failure and skin rash. No infectious etiology was identified. One of the patients had serum available for measurement of cytokines before, during and after the febrile reaction. The concentration of several pro-inflammatory cytokines, including IL-6 and TNFalpha, increased significantly, showing a clear physiological response correlating with the clinical findings. We conclude that an unusual cytokine-mediated febrile reaction can occur in patients with AL amyloidosis exposed to a second cycle of high-dose melphalan, which we have termed a 'melphalan recall' reaction.

Women with Her2 unamplified but chromosome 17 hyperploid metatstatic breast cancer (MBC) respond to traztuzumab

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Background: Guidelines for the interpretation of Her2 testing by FISH in determining therapy for Her2 positive metatstatic breast cancer generally suggest that only women with Her2 to chromosome 17 (CEP 17) amplification ratios of greater than 2.0 will benefit from traztuzumab. However, hyperploidy of chromosome 17 may lead to increased Her2 copy number despite a normal HER2/CEP 17 ratio, which may also predict response. We sought to examine hyperploid frequency in a well defined Her2 positive MBC population. We also sought to determine the time to progression (TTP) on first chemotherapy for MBC in such women, as well as their overall survival (OS) with MBC. Methods: A tissue mircoarray (TMA) with 3-fold redundancy was constructed using 0.6mm cores from primary or metatstatic paraffin embedded tumor from 124 cases which were Her2 2+ or 3+ by IHC, or amplified by FISH, on pathology report. Four micron thick TMA sections were used for HER2 IHC and HER2 FISH analysis. HER2/CEP 17 ratios of 2.0 or more was considered as amplification. If the tumor was 2+ or 3+ by IHC, greater than or equal to 3 signals for chromosome 17 were seen in a majority of cell nuclei, and the HER2/CEP17 ratio was less than 2.0, the tumor was considered hyperploid Her2 FISH negative. Results: Tissue blocks from 52 tumors delivered clearly interpretable amplification for Her2 by FISH. An additional 10 tumors (8%) were hyperploid, IHC positive (2+ or 3+), and FISH negative. Median survival (Kaplan-Meier) was 39 months (95% CI, 21–62) for women with hyperploid FISH negative tumors and 41 months (95% CI, 25–53) for women with FISH positive tumors (p=0.63, NS, Wilcoxon). Median time to progression (Kaplan-Meier) on first therapy for metastatic disease was 14 months (95% CI, 8–20) for hyperploid FISH negative tumors and 15 months (95% CI, 12–18) for women with FISH positive tumors (p=0.41, NS, Wilcoxon). Conclusions: In this analysis, women with hyperploid Her2 FISH negative IHC positive tumors had similar TTP and OS as women with Her2 FISH positive tumors. These women, although Her2 FISH negative, appeared to respond well to traztuzumab. These provocative results should be repeated on larger data sets.

No significant financial relationships to disclose.

Topoisomerase II-alpha (TOP2A) gene co-amplification does not predict response to therapy and survival in Her-2 neu positive metastatic breast cancer

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Background: Preliminary data from a phase III trial of adjuvant traztuzumab (BCIRG, SABCS 2005, abstract 1045) suggested that co-amplification of the genes for HER2 and topisomerase II alpha (TOP2A) on chromosome 17 resulted in improved disease free survival with chemotherapy regimens containing both and anthracycline and traztuzumab. We sought to determine if co-amplification of HER2 and TOP2A was a predictor of response and benefit (or lack thereof) to herceptin containing chemotherapy in the metastatic setting, since few women receive both therapies concurrently for MBC. Methods: A tissue mircoarray (TMA) with 3-fold redundancy was constructed using 0.6mm cores from primary or metatstatic paraffin embedded tumor from 124 cases from Magee-Women's Hospital which were Her2 2+ or 3+ by IHC, or amplified by FISH, on pathology report. Four micron thick TMA sections were used for HER2 immunohistochemical (CB11 monoclonal antibody, Ventana Medical Systems, Tucson, AZ) and HER2 and TOP2A FISH analysis (HER2/CEP 17 and TOP2A/CEP 17 dual color probes from Vysis Inc. Downers Grove, IL). HER2 (or TOP2A) gene to chromosome 17 ratios of 2.0 or more was considered as amplification. Results: Tissue blocks from 52 tumors delivered clearly interpretable amplification for Her2 by FISH on reanalysis. The remaining 72 tumors are undergoing further reanalysis. Of the 52 tumors with Her2 amplification, 15 (29%) had co- amplification of TOP2A. Median survival was 44 months (95% CI, 31–69) for women with TOP2A coamplified tumors and 35 months (95% CI, 29- 63) for women with non-coamplified tumors (p=0.448, NS). Median time to progression on first therapy was 17 months (95% CI, 14–20) for women with TOP2A coamplified tumors and 15 months (95% CI, 12–17) for women with non-coamplified tumors (p=0.939, NS) Conclusions: In this analysis, TOP2A and HER2 gene co-amplification did not correlate with worse TTP on first metatstatic therapy or worse OS from metatstatic disease.

No significant financial relationships to disclose.

Clinical and molecular characteristics of patients with non-amyloid light chain deposition disorders, and outcome following treatment with high-dose melphalan and autologous stem cell transplantation

Light chain deposition disease (LCDD) is caused by a clonal plasma cell disorder in which fragments of monoclonal immunoglobulin light chains form non-fibrillary deposits in various tissues resulting in organ dysfunction. Crystal storing histiocytosis (CSH) is another light chain deposition disorder in which monoclonal light chains form intracytoplasmic crystals. Both are uncommon diseases for which there is limited treatment experience. Between 2003 and 2005, five patients with LCDD and one with CSH were treated at Boston University Medical Center with high-dose melphalan and autologous peripheral blood stem cell transplantation (HDM/SCT). Five of the six patients had predominantly renal involvement, and one patient with LCDD had biopsy-proven deposits in the myocardium. Molecular characterization revealed that the pathologic light chains were kappa in four of the six patients, and sequence analysis revealed unusual germline donor genes and high rates of amino-acid substitutions. One light chain sequence encoded a new potential N-linked glycosylation site, and another showed evidence of antigen selection. All patients are alive and five of the six patients are in complete hematologic remission at a median follow-up of 12 months (range 4-29 months) after HDM/SCT. In our experience, HDM/SCT is a feasible and effective treatment approach for these disorders.

A phase II trial of lenalidomide for patients with AL amyloidosis

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Introduction: A phase II trial was designed to evaluate the toxicity and response rate of lenalidomide (Revlimid, CC-5013), alone and in combination with dexamethasone in patients with AL amyloidosis. Patients with this plasma cell disorder have organ dysfunction that makes them more susceptible to drug toxicity. Methods: Planned enrollment, 35 patients. Regimen: 3 cycles of lenalidomide at 25 mg/d for 21d, with dexamethasone 10 mg bid for 4 days, 3 times a month, every other month, for those patients not responding to lenalidomide alone. Toxicity and responses were evaluated after 1, 3, 6, 9, and 12 months of treatment. Hematologic responses were based upon qualitative and quantitative measures of clonal plasma cell disease. Organ responses were scored according to published criteria. Results: 24 patients have been enrolled to date, age range is 47–76, M:F 18:6, κ:λ 7:17. Organ involvement: 75% renal, 38% cardiac, 18% hepatic or gastrointestinal, 17% neuropathy, 13% soft tissue or lymph node. 22 had been treated previously, and 12 had undergone treatment with HDM/SCT. After none of the first 6 patients tolerated 3 treatment cycles at 25 mg/day, the starting dose was reduced to 15 mg/day. A total of 112 cycles have been administered (1–14 cycles per patient). 2 patients were removed from study because of rashes; one because of gout and severe fatigue; one by choice; and one patient died in the first treatment cycle, apparently due to complications of the underlying disease. Grade 3 toxicities observed included fatigue (33%), hypoalbuminemia (29%), worsening performance status (29%), neutropenia (21%), rash (21%), dizziness (13%), gout (13%), dyspnea (8%), muscle weakness (8%), and pneumonia (8%). One patient (4%) had a DVT on lenalidomide and dexamethasone. 8 out of 13 have had a measureable hematologic response, of which 3 were complete or near complete. 8 patients had elevated free light chains (FLC) with a skewed κ:λ ratio, and 4 of these had ≥50% reduction in FLC level. 4 of 14 patients with proteinuria improved. Conclusion: Lenalidomide is reasonably well-tolerated in patients with AL amyloidosis, and alone or in combination with dexamethasone, can induce excellent hematologic responses and improvement in organ disease.

No significant financial relationships to disclose.

Symptom distress, quality of life and challenges of illness according to race and income in women with metastatic breast cancer

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Background: Response to a diagnosis of metastatic breast cancer (MBC) may vary according to race and income. The aims of this study were: 1) to identify quality of life, symptom distress and challenges of illness during MBC treatment and 2) to determine if these variables differ according to race and income. Methods: The study was a 2×2 prospective design conducted at an urban breast cancer center. Women with MBC were categorized into four groups based on race and income: white low (WL), white high (WH), African American high (AAH) and African American low (AAL). Instruments were 1) Symptom Distress Scale (SDS), (higher scores /worse distress) 2) Functional Assessment of Cancer Therapy (FACT), (higher scores/better QOL) and a 3) semi structured interview assessing patient perspectives of MBC. Interview analysis utilized grounded theory. Results: Preliminary results are for 51 women. Mean age was 58.2 years, with mean 24 months since MBC diagnosis. Quantitative data indicated worse quality of life in AA than white women. (P=0.06), with AALI women exhibiting worse symptom distress (P=0.03) as compared to white women. Qualitative data (n=48) corroborated quantitative data. The most prevalent themes among all sociodemographic groups were of hope (33/48 - 69%), faith (28/48 - 58%) and progressive loss (29/48, 60%). Each racial/economic delineation expressed unique themes: AALI talked about physical (7/7,100%)and social distress (6/7, 86%) as well as uncertainty regarding “whether treatment was worth it” (6/7 - 86%). WLI women verbalized an overall optimism, describing themselves as “lucky” (6/14 - 43%), with minimization of symptoms (10/14 - 71%). WHI women articulated a sense of betrayal at their progressive illness (9/20 - 45%) and fear of physical and economic dependence. Conclusion: Race and economic delineation brings unique symptom experience, quality of life and patient perspective to the metastatic breast cancer experience. These findings will advise tailored intervention.

[Table: see text]

No significant financial relationships to disclose.

Expansion of HPCs from cord blood in a novel 3D matrix

BACKGROUND

An optimal system for the expansion of pluripotent HPCs would ideally eliminate the use of cytokines and animal-derived serum. We have shown previously that a 3D, tantalum-coated porous biomaterial (Cytomatrix) supports the maintenance and expansion of human BM HPCs in the absence of cytokines.

METHODS

Umbilical cord blood (UCB) derived HPC were cultured in the Cytomatrix in the absence of exogenous cytokines. Phenotype was determined using FACS. Colony-forming units (CFU) activity was evaluated. Engraftment capacity was evaluated by transplanting the expanded cells into non-obese diabetic (NOD)/SCID mice.

RESULTS

We describe the expansion of HPCs from UCB using the Cytomatrix system. When UCB-derived CD34(+) cells were cultured in the Cytomatrix system for 2 weeks we observed an increase in the number of nucleated cells (3-fold) and CFU (2.6-fold). The number of CD45(+) and CD34(+) cells both increased three-fold. Trends demonstrated an increase in the frequency of CD34(+)C38(-) cells, and an increase in both CD34(+)C33(+) cells and CD34(+)C61(+) cells. No expansion of T or B lymphocytes was observed. When expanded UCB cells from the Cytomatrix were injected into sub-lethally irradiated NOD/SCID mice, human cells were detected in the murine peripheral blood and BM 6 weeks post-transplantation.

DISCUSSION

This unique approach to the expansion of UCB cells in a serum-free, cytokine-free environment may provide expansion of HPCs with multi-lineage engraftment capability that could be used clinically.

T-cell differentiation of human and non-human primate CD34+ hematopoietic progenitor cells using porcine thymic stroma

Transplantation of swine thymic tissue has been proposed as an approach to reconstitute the immune system of HIV-infected individuals. This is an attractive strategy because miniature swine are readily available as donors and porcine tissue is resistant to infection with HIV-1. Demonstration that porcine thymus tissue supports primate T-cell differentiation is critical to the ultimate utility of this approach. Using a thymic stroma culture system we have previously described [Rosenzweig M, Marks DF, Zhu H et al. In vitro T lymphopoiesis of human and rhesus CD34+ progenitor cells. Blood 1996; 87: 4040], we demonstrate that porcine thymus tissue is able to promote the in vitro T-lymphocyte differentiation of both human and non-human primate hematopoietic progenitor cells. CD34+ hematopoietic progenitors differentiated into both double positive (CD4+CD8+) and single positive thymocytes expressing CD4 or CD8 alone. A polyclonal T-cell repertoire was evident. In addition, the T cells responded appropriately to mitogen and were permissive to infection with simian immunodeficiency virus (SIV). These data demonstrate the ability of porcine thymus to support T-cell differentiation of both human and non-human hematopoietic progenitor cells and support in vivo studies of transplantation of swine thymic tissue as a strategy for immune reconstitution in AIDS.

Induction of cytotoxic T lymphocyte and antibody responses to enhanced green fluorescent protein following transplantation of transduced CD34(+) hematopoietic cells

Genetic modification of hematopoietic stem cells often results in the expression of foreign proteins in pluripotent progenitor cells and their progeny. However, the potential for products of foreign genes introduced into hematopoietic stem cells to induce host immune responses is not well understood. Gene marking and induction of immune responses to enhanced green fluorescent protein (eGFP) were examined in rhesus macaques that underwent nonmyeloablative irradiation followed by infusions of CD34(+) bone marrow cells transduced with a retroviral vector expressing eGFP. CD34(+) cells were obtained from untreated animals or from animals treated with recombinant human granulocyte colony-stimulating factor (G-CSF) alone or G-CSF and recombinant human stem cell factor. Levels of eGFP-expressing cells detected by flow cytometry peaked at 0.1% to 0.5% of all leukocytes 1 to 4 weeks after transplantation. Proviral DNA was detected in 0% to 17% of bone marrow--derived colony-forming units at periods of 5 to 18 weeks after transplantation. However, 5 of 6 animals studied demonstrated a vigorous eGFP-specific cytotoxic T lymphocyte (CTL) response that was associated with a loss of genetically modified cells in peripheral blood, as demonstrated by both flow cytometry and polymerase chain reaction. The eGFP-specific CTL responses were MHC-restricted, mediated by CD8(+) lymphocytes, and directed against multiple epitopes. eGFP-specific CTLs were able to efficiently lyse autologous CD34(+) cells expressing eGFP. Antibody responses to eGFP were detected in 3 of 6 animals. These data document the potential for foreign proteins expressed in CD34(+) hematopoietic cells and their progeny to induce antibody and CTL responses in the setting of a clinically applicable transplantation protocol. (Blood. 2001;97:1951-1959)

Cytokine-augmented culture of haematopoietic progenitor cells in a novel three-dimensional cell growth matrix

Studies aimed at the in vitro expansion of haematopoietic progenitor cells (HPCs) have suffered from the conflict of increasing cell numbers while maintaining long-term repopulating ability. We have developed a long-term bone marrow bioreactor culture system resembling the marrow-microenvironment that cultures HPCs in an inert, three-dimensional, porous biomatrix termed Cellfoam. Previous studies have shown that the short-term culture of CD34(+)cells in Cellfoam improved the maintenance and multipotency of haematopoietic stem cells compared to cells cultured on plastic dishes. In this study, we examined the effects of low concentrations of cytokines including stem cell factor (SCF), IL-3, and Flk-2/Flt-3 ligand, on the maintenance, preservation and multipotency of CD34(+) cells cultured for 3 or 6 weeks in Cellfoam. Analysis of cell yields using flow cytometry showed that in SCF and Flk-2/Flt-3 ligand-supplemented cultures as well as cytokine-free cultures, a higher number of CD45(+)34(+) and CD45(+)34(+)38(-) cells is observed in Cellfoam cultures as compared to plastic cultures. The function of cultured cells was evaluated in colony-forming assays. The data demonstrate that Cellfoam cultures supplemented with SCF and Flk-2/Flt-3 ligand resulted in a higher output of colony activity compared to plastic cultures. Analysis of CAFC (29 days) activity also demonstrated that primitive progenitors were maintained to a greater extent in Cellfoam cultures containing either no cytokines or low concentrations of early-acting cytokines. These data suggest that culture of HPCs in three-dimensional bioreactors such as Cellfoam for extended periods may benefit from the addition of low levels of early-acting cytokines, including SCF and Flk-2/Flt-3 ligand, resulting in high yields of cells that are enriched for multipotent haematopoietic progenitors. These findings demonstrate that a three-dimensional matrix promotes the survival of primitive HPCs in culture and may modulate the in vitro effects of cytokines.

Identification of primitive hematopoietic progenitor cells in the rhesus macaque

The close phylogenetic relationship of macaques to humans has resulted in their widespread use as a preclinical model for bone marrow transplantation and stem cell gene therapy. To facilitate further use of this model, we undertook analysis of hematopoietic cells using multiparametric flow cytometric analysis. Rhesus CD34+CD38- cells displayed a number of characteristics of primitive hematopoietic cells, including low forward and orthogonal scatter and the lack of expression of lineage-specific markers or human lymphocyte antigen-DR. Four-color flow cytometric analysis demonstrated that rhesus CD34+CD38- cells were heterogenous with respect to Thy-1 expression and were CD59dim. Quantitative limiting dilution long-term culture-initiating cell (LTC-IC) analysis demonstrated that CD34+CD38- cells were approximately 150-fold enriched for LTC-IC as compared with unfractionated bone marrow, and occurred at a frequency similar to that previously reported in humans. Thus, as in humans, the CD34+38- population of rhesus macaque bone marrow is enriched for primitive, multipotent hematopoietic progenitor cells.

Mechanisms for adaptation of simian immunodeficiency virus to replication in alveolar macrophages

In contrast to the simian immunodeficiency virus SIVmac239, which replicates poorly in rhesus monkey alveolar macrophages, a variant with nine amino acid changes in envelope (SIVmac239/316E) replicates efficiently and to high titer in these same cells. We examined levels of viral DNA, RNA, antigen, and infectious virus to identify the nature of the block to SIVmac239 replication in these cells. Low levels of viral antigen (0.1 to 1.0 ng of p27 per ml) and infectious virus (100 to 1,000 infectious units per ml) were produced in the supernatant 1 to 4 days after SIVmac239 infection, but these levels did not increase subsequently. SIVmac239 DNA was synthesized in these macrophage cultures during the initial 24 h after infection, but the levels did not increase subsequently. Quantitation of the numbers of infectious cells in cultures over time and the results of experiments in which cells were reexposed to SIVmac239 after the initial exposure indicated that only a small proportion of cells were susceptible to SIVmac239 infection in these alveolar macrophage cultures and that the vast majority (>95%) of cells were refractory to SIVmac239 infection. In contrast to the results with SIVmac239, the levels of viral antigen, infectious virus, and viral DNA increased exponentially 2 to 7 days after infection by SIVmac239/316E, reaching levels greater than 100 ng of p27 per ml and 100,000 infectious units per ml. Since SIVmac239/316E has previously been described as a virus capable of infecting cells in a relatively CD4-independent fashion, we examined the levels of CD4 expression on the surface of fresh and cultured alveolar macrophages from rhesus monkeys. The levels of CD4 expression were extremely low, below the limit of detection by flow cytometry, on greater than 99% of the macrophages. CCR5(+) cells were profoundly depleted only from alveolar macrophage cultures infected with SIVmac239/316E. High concentrations of an antibody to CD4 delayed but did not block replication of SIVmac239/316E. The results suggest that the adaptation of SIVmac316 to efficient replication in alveolar macrophages results from its ability to infect these cells in a CD4-independent fashion or in a CD4-dependent fashion even at extremely low levels of surface CD4 expression. Since resident macrophages in brains and lungs of humans also express little or no CD4, our findings predict the presence of human immunodeficiency virus type 1 that is relatively CD4 independent in the lung and brain compartments of infected people.

Characterization of lymphocyte subsets in rhesus macaques during the first year of life

Establishing reliable phenotypic data sets from the analysis of peripheral blood lymphocytes of normal animals is required to assess disease states. The rhesus macaque animal model is well established with respect to adult animals, but limited data are available that characterizes lymphocyte subsets in normal neonates. To address this, we used four-color flow cytometric analysis to follow phenotypic changes in 29 normal rhesus animals through their first ten months of life. From birth to 44 wk of age, the white cell count and absolute lymphocyte count were both elevated compared to adults. CD4+ cells constituted over 80% of all T cells at birth, a percentage that declined gradually over the first 12 wk of life, coincidental with increases in the percentages of CD8+ T cells, CD3-8+ natural killer cells and CD20+ B cells. This difference in relative frequency of CD4 and CD8 results in a significant skewing of CD4:CD8 ratio from 0.7:1 in adults to 3.5:1 in neonates. In addition, the predominant population of T lymphocytes consisted of CD45RA+CD62L+ naive cells. This subset continues to be the predominant phenotype for at least the first year of age. After birth the expression of activation markers (CD25) increased particularly on CD4+ T cells, although these levels generally reached a frequency similar to that observed in adults between 12 and 20 weeks after birth. These results are similar to those seen in humans and further confirm the reliability of the rhesus macaque animal model to study human diseases.

Mechanisms associated with thymocyte apoptosis induced by simian immunodeficiency virus

Despite considerable research, the mechanisms by which HIV disrupts thymic function remain controversial. We have described the phenotypic changes that occur in the thymus of SIV-infected macaques during acute SIV infection. In this study, we analyzed the effects of SIV infection on apoptotic pathways in thymic tissue from newborn macaques infected with SIV. Thymocyte apoptosis was accompanied by a modest increase in surface Fas expression, a profound decrease in the frequency of bcl-2-positive cells, as well as the amount of bcl-2 per cell. With control of viral replication, levels of bcl-2 and Fas returned to baseline together with a return to basal levels of apoptosis. In the thymus, SIV infection resulted in depletion of CD4+CD8+ thymocytes, an increase in apoptosis of thymocytes, and a down-regulation of MHC class I molecules. These changes peaked 14-21 days after infection at or just after peak viremia. This data further suggests disruption of the antiapoptotic pathway regulated by bcl-2 plays a critical role in SIV-induced apoptosis of thymocytes.

Clomipramine augmentation in treatment-resistant depression

In depression that is resistant to tricyclic antidepressant (TCA) therapy, the substitution of a selective serotonin re-uptake inhibitor (SSRI), clomipramine, or a monoamine oxidase (MAO) inhibitor has been recommended. However, adding an additional antidepressant medication from a different drug class may produce even more rapid efficacy. In this regard, the combination of a MAO inhibitor or a SSRI plus a TCA has been shown to be of value in treatment-resistant depression (TRD). In this report, we examined the efficacy of clomipramine augmentation in 20 patients who failed to respond to either a MAO inhibitor or fluoxetine therapy for at least a 6-week period, and compared this to a third group given MAO inhibitor plus a conventional TCA. Two out of 9 (22%) MAO inhibitor/clomipramine patients and 4 out of 11 (36%) fluoxetine/clomipramine patients improved (Fisher's Exact test, P = ns), compared to 3 out of 7 (43%) patients taking MAO inhibitor/TCA (P = ns). However, the MAO inhibitor/clomipramine group experienced significantly more adverse events which necessitated stopping treatment (56%) when compared to the fluoxetine/clomipramine (9%) and compared to the MAO inhibitor/TCA group (0%) (chi 2 = 8.9, df = 2, P < 0.05). These adverse events included several cases of serotonin syndrome of mild to moderate severity. These observations indicate that clomipramine augmentation of a failed MAO inhibitor trial is of marginal efficacy (compared to augmentation with a conventional TCA) and should be employed with extreme caution.

Efficient generation of human T cells from a tissue-engineered thymic organoid

Biocompatible inorganic matrices have been used to enhance bone repair by integrating with endogenous bone architecture. Hypothesizing that a three-dimensional framework might support reconstruction of other tissues as well, we assessed the capacity of a tantalum-coated carbon matrix to support reconstitution of functioning thymic tissue. We engineered a thymic organoid by seeding matrices with murine thymic stroma. Co-culture of human bone marrow-derived hematopoietic progenitor cells within this xenogeneic environment generated mature functional T cells within 14 days. The proportionate T-cell yield from this system was highly reproducible, generating over 70% CD3+ T cells from either AC133+ or CD34+ progenitor cells. Cultured T cells expressed a high level of T-cell receptor excision circles (TREC), demonstrating de novo T lymphopoiesis, and function of fully mature T cells. This system not only facilitates analysis of the T-lymphopoietic potential of progenitor cell populations; it also permits ex vivo genesis of T cells for possible applications in treatment of immunodeficiency.

Efficient gene transfer to hematopoietic progenitor cells using SV40-derived vectors

We used recombinant SV40 (rSV40)-derived vectors to deliver transgenes to human and simian hematopoietic progenitor cells in culture, and in vivo after transduction ex vivo. rSV40 are highly efficient vectors that are made in very high titers. They infect almost all cells, whether resting or dividing. Two rSV40s were used: SV(HBS), carrying hepatitis B surface antigen as a marker; and SV(Aw) carrying IN#33, a single chain Fv antibody against HIV-1 integrase. CD34+ cells derived from human fetal bone marrow (HFBM) and rhesus macaque bone marrow were transduced once with SV(HBS) without selection. On average 60% of colonies derived from transduced CD34+ cells carried and expressed HBsAg, as assessed by PCR and immunochemistry. Transgene carriage persisted following differentiation of transduced rhesus CD34+ cells into T lymphocytes. In an effort to increase the percentage of gene-marked cells, three sequential treatments of CD34+ cells were done using SV(Aw), without selection. Two weeks later, >95% of colonies expressed IN#33. Unselected SV(Aw)-transduced CD34+ cells from HFBM were transplanted into sublethally irradiated SCID mice. Bone marrow harvested 3 months later showed that >50% of bone marrow cells expressed IN#33. This is comparable with the percentage of human cells in these animals' bone marrow as judged by immunostaining for human CD45. The stability and longevity of transduction in this setting suggests that rSV40 vectors integrate into the cellular genome. This possibility was supported by finding that PCR of genomic DNA using primer pairs with one cellular and one viral primer yielded PCR products only in transduced, but not control, cells. These PCR products hybridized with an SV40 DNA fragment. Thus, rSV40 vectors transduce normal human and primate bone marrow progenitor cells effectively without selection, and maintain transgene expression in vivo following reimplantation. Such high efficiency transduction may be useful in treating diseases of CD34+ cells and their derivatives.

Quantification of thymic function by measuring T cell receptor excision circles within peripheral blood and lymphoid tissues in monkeys

The thymus is the primary organ responsible for the production of mature TCR alpha / beta T cells. Quantification of a DNA excision circle that is produced during TCR rearrangement, termed a signal joint TCR rearrangement excision circle (sjTREC) can be used as a measure of thymic function. Here sjTREC measurement has been applied to two monkey species used as animal models of human disease, rhesus macaques (Asian origin) and sooty mangabeys (African origin). Initial PCR analysis determined that the TCR deltaRec-PsiJalpha rearrangement leading to sjTREC formation occurs in both species. Primers to a DNA sequence conserved in macaques, mangabeys and humans were used in a quantitative competitive PCR assay to quantify sjTREC. We found that as in humans, sjTREC in these two monkey species decline with age. sjTREC are first generated in thymocytes during the early stages of TCR rearrangement. Lymph node CD4(+) and CD8(+) T cells contain more sjTREC than peripheral blood T cell populations, suggesting that recent thymic emigrants home to the lymphoid tissues. The sjTREC level is significantly higher within the peripheral blood CD4(+) and CD8(+) T cells of mangabeys compared to macaques. Removal of the thymus in four macaques led to a profound decrease in peripheral blood sjTREC level by 1 year post-thymectomy, indicating the lack of a significant extra-thymic source of peripheral naive T cells in macaques. Our results indicate that production, trafficking, and proliferation of recent thymic emigrants in these two monkey species represents a useful animal model system for understanding human immunological disorders.

Immunological memory and acquired immunodeficiency syndrome pathogenesis

Infection with the human immunodeficiency virus results in profound perturbations in immunological memory, ultimately resulting in increased susceptibility to opportunistic infections and acquired immunodeficiency syndrome (AIDS). We have used rhesus macaques infected with the simian immunodeficiency virus (SIV) as a model to understand better the effects of AIDS virus infection on immunological memory. Acute infection with SIV resulted in significant deficits in CD4+ helper responses to cytomegalovirus (CMV) as well as CMV-specific cytotoxic T-lymphocyte and neutralizing antibody responses. Reactivation of CMV was associated with high levels of SIV replication and suppression of both T-helper and cytotoxic responses to CMV. We have also studied the effects of SIV infection on T-cell turnover in non-human primates. T-cell turnover was evaluated using the nucleoside analogue bromodeoxyuridine (BrdU) in combination with five-colour flow cytometric analysis. T cells in normal animals turned over at relatively rapid rates, with memory cells turning over more quickly than naive cells. In SIV-infected animals, the labelling and elimination rates of both CD4+ and CD8+ BrdU-labelled cells were increased by two- to threefold compared with normal controls. Further analysis of immunological memory in non-human primates should offer the opportunity to extend immunological insights from murine models to the pathogenesis and prevention of AIDS.