Advances in Human Epidermal Growth Factor Receptor 2-Targeted Therapy in Upper Gastrointestinal Cancers

The Trastuzumab for Gastric Cancer (ToGA) trial marked a pivotal moment in the adoption of trastuzumab for treating advanced human epidermal growth factor receptor 2 (HER2)-positive esophagogastric (EG) cancer. The KEYNOTE-811 trial brought to light the synergistic effect of immune modulation and HER2 targeting. Additionally, the emergence of trastuzumab deruxtecan (T-DXd) highlighted the potential of new pharmaceutical technologies to extend response, particularly for patients who have advanced beyond initial HER2-targeted therapies. This review aims to navigate through both the successes and challenges encountered historically, as well as promising current trials on innovative and transformative therapeutic strategies, including promising first-in-class and novel first-in-human agents.

Trastuzumab deruxtecan in patients in the USA and Europe with HER2-positive advanced gastric or gastroesophageal junction cancer with disease progression on or after a trastuzumab-containing regimen (DESTINY-Gastric02): primary and updated analyses from a single-arm, phase 2 study

BACKGROUND

Approximately 15-20% of advanced gastric and gastro-oesophageal junction cancers overexpress HER2. In DESTINY-Gastric01, the HER2-targeted antibody-drug conjugate trastuzumab deruxtecan improved response and overall survival versus chemotherapy in patients from Japan and South Korea with locally advanced or metastatic HER2-positive gastric or gastro-oesophageal junction cancer whose disease progressed after two lines of previous therapy including trastuzumab. Here, we report primary and updated analyses of the single-arm, phase 2 DESTINY-Gastric02 trial, which aimed to examine trastuzumab deruxtecan in patients living in the USA and Europe.

METHODS

DESTINY-Gastric02 is a single-arm, phase 2 study in adult patients from 24 study sites in the USA and Europe (Belgium, Spain, Italy, and the UK). Eligible patients were aged at least 18 years and had an Eastern Cooperative Oncology Group performance status of 0 or 1, pathologically documented unresectable or metastatic gastric or gastro-oesophageal junction cancer, progressive disease on or after first-line therapy with a trastuzumab-containing regimen, with at least one measurable lesion per Response Evaluation Criteria in Solid Tumours (version 1.1), and centrally confirmed HER2-positive disease on a postprogression biopsy. Patients were given 6·4 mg/kg of trastuzumab deruxtecan intravenously every 3 weeks until disease progression, withdrawal by patient, physician decision, or death. The primary endpoint was confirmed objective response rate by independent central review. The primary endpoint and safety were assessed in the full analysis set (ie, participants who received at least one dose of study drug). Here, we report the primary analysis of this study, with a data cutoff of April 9, 2021, and an updated analysis, with a data cutoff of Nov 8, 2021. This trial is registered with ClinicalTrials.gov, NCT04014075, and is ongoing.

FINDINGS

Between Nov 26, 2019, and Dec 2, 2020, 89 patients were screened and 79 were enrolled and subsequently treated with trastuzumab deruxtecan (median age 60·7 years [IQR 52·0-68·3], 57 [72%] of 79 were male, 22 [28%] were female, 69 [87%] were White, four [5%] were Asian, one [1%] was Black or African American, one [1%] was Native Hawaiian or Pacific Islander, one had missing race, and three [4%] were other races). At the primary analysis (median follow-up 5·9 months [IQR 4·6-8·6 months]), confirmed objective response was reported in 30 (38% [95% CI 27·3-49·6]) of 79 patients, including three (4%) complete responses and 27 (34%) partial responses, as assessed by independent central review. As of data cutoff for the updated analysis (median follow-up 10·2 months [IQR 5·6-12·9]), a confirmed objective response was reported in 33 (42% [95% CI 30·8-53·4]) of 79 patients, including four (5%) complete responses and 29 (37%) partial responses, as assessed by independent central review. The most common grade 3 or worse treatment-emergent adverse events were anaemia (11 [14%]), nausea (six [8%]), decreased neutrophil count (six [8%]), and decreased white blood cell count (five [6%]). Drug-related serious treatment-emergent adverse events occurred in ten patients (13%). Deaths determined to be associated with study treatment occurred in two patients (3%) and were due to interstitial lung disease or pneumonitis.

INTERPRETATION

These clinically meaningful results support the use of trastuzumab deruxtecan as second-line therapy in patients with HER2-positive advanced gastric or gastro-oesophageal junction cancer.

FUNDING

Daiichi Sankyo and AstraZeneca.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of gastrointestinal cancer

Gastrointestinal (GI) cancers, including esophageal, gastroesophageal junction, gastric, duodenal and distal small bowel, biliary tract, pancreatic, colon, rectal, and anal cancer, comprise a heterogeneous group of malignancies that impose a significant global burden. Immunotherapy has transformed the treatment landscape for several GI cancers, offering some patients durable responses and prolonged survival. Specifically, immune checkpoint inhibitors (ICIs) directed against programmed cell death protein 1 (PD-1), either as monotherapies or in combination regimens, have gained tissue site-specific regulatory approvals for the treatment of metastatic disease and in the resectable setting. Indications for ICIs in GI cancer, however, have differing biomarker and histology requirements depending on the anatomic site of origin. Furthermore, ICIs are associated with unique toxicity profiles compared with other systemic treatments that have long been the mainstay for GI cancer, such as chemotherapy. With the goal of improving patient care by providing guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop this clinical practice guideline on immunotherapy for the treatment of GI cancer. Drawing from published data and clinical experience, the expert panel developed evidence- and consensus-based recommendations for healthcare professionals using ICIs to treat GI cancers, with topics including biomarker testing, therapy selection, and patient education and quality of life considerations, among others.

HERIZON-GEA-01: Zanidatamab + chemo ± tislelizumab for 1L treatment of HER2-positive gastroesophageal adenocarcinoma

HER2-positive gastroesophageal adenocarcinomas (GEAs) are common cancers with high mortality and the treatment options for advanced/metastatic disease are limited. Zanidatamab and tislelizumab are novel monoclonal antibodies targeting HER2 and PD-1, respectively, and have shown encouraging antitumor activity in early phase studies in multiple cancers, including GEA. Preliminary data suggest that dual targeting of the HER2 and PD-1 pathways could further improve upon the results achieved with targeting either pathway alone. Here, we describe the design of HERIZON-GEA-01, a global, randomized, open-label, active-comparator, Phase III study to evaluate and compare the efficacy and safety of zanidatamab plus chemotherapy with or without tislelizumab to the standard of care (trastuzumab plus chemotherapy) as first-line treatment for patients with advanced/metastatic HER2-positive GEAs.

Oligometastases After Curative Esophagectomy Are Not One Size Fits All

BACKGROUND

More than one-half of patients treated with esophagectomy for esophageal cancer experience recurrence. Oligometastasis, a proposed intermediate state of isolated local or solid organ recurrence that occurs before widespread systemic disease, is a potential target for aggressive local intervention. This study investigated presentation and prognosis among solid organ recurrence sites.

METHODS

Patients with isolated solid organ recurrence at the liver, lung, or brain who underwent R0 esophagectomy from 1995 to 2016 were identified. Clinicopathologic characteristics and outcomes were compared among sites of recurrence. Overall survival was quantified using the Kaplan-Meier approach and Cox proportional hazards models.

RESULTS

In total, 104 patients were included (site: brain, 37; lung, 27; liver, 40). Eighty percent of liver, 51% of brain, and 44% of lung oligometastases occurred in the first 12 months after esophagectomy. Despite the limited use of aggressive therapy, patients with lung oligometastasis had significantly longer median overall survival (2.41 years; 95% confidence interval [CI], 1.58 to 3.31) than did patients with brain (0.95 years; 95% CI, 0.62 to 1.49) or liver (0.95 years; 95% CI, 0.82 to 1.41) oligometastasis (P < .001). This difference remained after patient and tumor characteristics were adjusted for (brain: hazard ratio, 4.48; 95% CI, 2.24 to 8.99; liver: hazard ratio, 2.94; 95% CI, 1.48 to 5.82).

CONCLUSIONS

Presentations and prognoses differ by site of esophageal cancer recurrence. Lung oligometastases are associated with a more indolent course, and patients with these lesions may benefit from more aggressive treatment to improve their more favorable outcomes further. These differences by site of recurrence advocate for moving beyond a standardized palliative approach to all esophageal cancer recurrences.

Prognostic significance of T-cell-inflamed gene expression profile and PD-L1 expression in patients with esophageal cancer

Purpose

The ability of the T‐cell–inflamed gene expression profile (GEP) to predict clinical outcome in esophageal cancer (EC) is unknown. This retrospective observational study assessed the prognostic value of GEP and programmed death ligand 1 (PD‐L1) expression in patients with EC treated in routine clinical practice.

Methods

Tumor samples of 294 patients from three centers in Denmark, South Korea, and the United States, collected between 2005 and 2017, were included. T‐cell–inflamed GEP score was defined as non‐low or low using a cutoff of −1.54. A combined positive score (CPS) ≥10 was defined as PD‐L1 expression positivity. Associations between overall survival (OS) and GEP status and PD‐L1 expression were explored by Cox proportional hazards models adjusting for age, sex, histology, stage, and performance status.

Results

Median age was 65 years; 63% of patients had adenocarcinoma (AC) and 37% had squamous cell carcinoma (SCC). Thirty‐six percent of tumors were GEP non‐low, with higher prevalence in AC (46%) than SCC (18%). Twenty‐one percent were PD‐L1–positive: 32% in South Korean samples versus 16% in non‐Asian samples and 26% in SCC versus 18% in AC. GEP scores and PD‐L1 CPS were weakly correlated (Spearman’s R = 0.363). OS was not significantly associated with GEP status (non‐low vs low; adjusted hazard ratio, 0.91 [95% CI, 0.69–1.19]) or PD‐L1 expression status.

Conclusion

Neither GEP nor PD‐L1 expression was a prognostic marker in Asian and non‐Asian patients with EC.

Phase II Single-arm Study of Durvalumab and Tremelimumab with Concurrent Radiotherapy in Patients with Mismatch Repair-proficient Metastatic Colorectal Cancer

PURPOSE

Immune checkpoint inhibition (ICI) alone is not active in mismatch repair-proficient (MMR-P) metastatic colorectal cancer (mCRC), nor does radiotherapy alone result in objective systemic benefit. However, combined radiotherapy plus ICI can induce systemic antitumor immunity in preclinical and clinical models.

PATIENTS AND METHODS

In this single-center, phase II study, patients with chemotherapy-refractory MMR-P mCRC received durvalumab 1,500 mg plus tremelimumab 75 mg every 4 weeks plus radiotherapy. The primary endpoint was objective response rate (ORR) in nonirradiated lesions. Treatment and efficacy were correlated with peripheral immune cell profiles.

RESULTS

We enrolled 24 patients, and report outcomes after a median follow-up of 21.8 (range: 15.9-26.3) months. The ORR was 8.3% (2 patients) [95% confidence interval (CI), 1.0-27.0]. The median progression-free survival was 1.8 (95% CI, 1.7-1.9) months, median overall survival was 11.4 (95% CI, 10.1-17.4) months. Twenty five percent of patients (n = 6) had treatment-related grade 3-4 adverse events. We observed increased circulating CD8⁺ T lymphocyte activation, differentiation, and proliferation in patients with objective response.

CONCLUSIONS

This combination of radiotherapy plus ICI study did not meet the prespecified endpoint criteria to be considered worthwhile for further study. However, rare instances of systemic immune augmentation and regression in nonirradiated lesions were observed (an abscopal response). Combination durvalumab and tremelimumab plus radiotherapy is feasible in MMR-P mCRC with a manageable safety profile. Further studies of novel immunotherapy combinations, and identification of biomarkers predictive of abscopal response are warranted.

Abstract CT057: Safety and efficacy of durvalumab in combination with tremelimumab in patients with advanced gastric cancer with elevated tumor interferon-γ gene signature

Background: Anti-PD-L1 and anti-CTLA-4 agents have demonstrated clinical activity in gastric and gastroesophageal junction cancer (GC/GEJC) tumors. However, response rates are low suggesting clinical benefit in only a subset of the population. This study prospectively evaluated the ability of a tumor-based interferon (IFN)-γ gene signature to identify a subset of GC/GEJC patients more likely to respond to checkpoint inhibitor therapy.

Methods: Second and third-line patients were prescreened using archival formalin-fixed paraffin-embedded tissue to assess IFN-γ gene signature (comprising IFNy, CD274, LAG3, and CXCL9) status with a custom, targeted RNA sequencing assay using Ion AmpliSeq (Thermo Fisher Scientific) sequencing technologies. The cutoff for positive was established at the upper tertile of expression from an existing data set. Patients who were positive during prescreening were eligible to screen. Enrolled patients received durvalumab 20 mg/kg and tremelimumab 1 mg/kg IV every 4 weeks (Q4W) for 4 cycles, followed by durvalumab 10 mg/kg Q2W for ≤12 months. Disease assessments were performed every 8 weeks according to Response Evaluation Criteria In Solid Tumors (RECIST) v1.1.

Results: As of August 24, 2018, 176 patients were prescreened. In these patients, the IFN-γ gene signature assay had a 70% rate for providing actionable data; 37.5% of prescreened patients had high expression. The primary failure reason was insufficient tissue, resulting in insufficient nucleic acid. 19 patients were enrolled, with a median follow-up of 5.8 months. Drug-related adverse events (AEs) occurred in 8 patients (42%); 4 (21%) had grade 3/4 AEs (fatigue, elevated lipase, decreased appetite, and interstitial lung disease, the latter of which led to treatment discontinuation). There were no drug-related deaths. Objective response rate (ORR) was 15.8% (95% CI, 3.4%-39.6%), including 1 complete response and 2 partial responses; 1 patient had stable disease. Duration of response was 13.3 weeks (range, 8.1-16.3 w). Median progression-free survival (PFS) was 1.8 months (95% CI, 1.6-1.9 mo), and median overall survival (OS) was 7 months (95% CI, 2.4-7.5 mo).

Conclusions: Prospective screening of patients using a novel RNA-based IFN-γ gene expression signature was feasible for patient selection with predictable assay performance. Clinical activity of durvalumab + tremelimumab was increased, with a higher ORR in enrolled patients, compared with unselected populations receiving durvalumab and/or tremelimumab (presented at ASCO 2018); however, PFS and OS remained similar. Given the added complexity of patient preselection and lack of substantial improvement in clinical outcomes, these results, while encouraging, do not support further implementation of the IFN-γ gene signature for patient selection in this indication and treatment regimen.

Citation Format: Geoffrey Ku, Jeeyun Lee, Heinz-Josef Lenz, Cheng Ean Chee, Takeshi Omori, Keun-Wook Lee, Yee Chao, Daniel Catenacci, Michael Gibson, Deirdre Cohen, Zev Wainberg, Philip Z. Brohawn, Peng He, Siddharth Sheth, Judson Englert, Ronan Kelly, Yung-Jue Bang. Safety and efficacy of durvalumab in combination with tremelimumab in patients with advanced gastric cancer with elevated tumor interferon-γ gene signature [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT057.

Safety and Efficacy of Pembrolizumab Monotherapy in Patients With Previously Treated Advanced Gastric and Gastroesophageal Junction Cancer: Phase 2 Clinical KEYNOTE-059 Trial

Importance

Therapeutic options are needed for patients with advanced gastric cancer whose disease has progressed after 2 or more lines of therapy.

Objective

To evaluate the safety and efficacy of pembrolizumab in a cohort of patients with previously treated gastric or gastroesophageal junction cancer.

Design, Setting, and Participants

In the phase 2, global, open-label, single-arm, multicohort KEYNOTE-059 study, 259 patients in 16 countries were enrolled in a cohort between March 2, 2015, and May 26, 2016. Median (range) follow-up was 5.8 (0.5-21.6) months.

Intervention

Patients received pembrolizumab, 200 mg, intravenously every 3 weeks until disease progression, investigator or patient decision to withdraw, or unacceptable toxic effects.

Main Outcomes and Measures

Primary end points were objective response rate and safety. Objective response rate was assessed by central radiologic review per Response Evaluation Criteria in Solid Tumors, version 1.1, in all patients and those with programmed cell death 1 ligand 1 (PD-L1)-positive tumors. Expression of PD-L1 was assessed by immunohistochemistry. Secondary end points included response duration.

Results

Of 259 patients enrolled, most were male (198 [76.4%]) and white (200 [77.2%]); median (range) age was 62 (24-89) years. Objective response rate was 11.6% (95% CI, 8.0%-16.1%; 30 of 259 patients), with complete response in 2.3% (95% CI, 0.9%-5.0%; 6 of 259 patients). Median (range) response duration was 8.4 (1.6+ to 17.3+) months (+ indicates that patients had no progressive disease at their last assessment). Objective response rate and median (range) response duration were 15.5% (95% CI, 10.1%-22.4%; 23 of 148 patients) and 16.3 (1.6+ to 17.3+) months and 6.4% (95% CI, 2.6%-12.8%; 7 of 109 patients) and 6.9 (2.4 to 7.0+) months in patients with PD-L1-positive and PD-L1-negative tumors, respectively. Forty-six patients (17.8%) experienced 1 or more grade 3 to 5 treatment-related adverse events. Two patients (0.8%) discontinued because of treatment-related adverse events, and 2 deaths were considered related to treatment.

Conclusions and Relevance

Pembrolizumab monotherapy demonstrated promising activity and manageable safety in patients with advanced gastric or gastroesophageal junction cancer who had previously received at least 2 lines of treatment. Durable responses were observed in patients with PD-L1-positive and PD-L1-negative tumors. Further study of pembrolizumab for this group of patients is warranted.

Trial Registration

clinicaltrials.gov Identifier: NCT02335411.

Targeted first-line therapies for advanced colorectal cancer: a Bayesian meta-analysis

BACKGROUND

Colorectal cancer is common and deadly. First-line treatments for patients with metastatic disease include FOLFIRI and FOLFOX, which have been combined with anti-EGFR or anti-VEGF antibodies to achieve benefit in selected populations. However, optimal therapy remains unclear.

RESULTS

Fifteen publications on 10 trials were identified. There was a lack of decisive evidence that FOLFIRI or FOLFOX impact efficacy of either anti-EGFR or anti-VEGF, across mutational status groups. On the other hand, evidence suggests both anti-EGFR and anti-VEGF may be more effective for KRAS WT than MT patients. KRAS WT results provided evidence that anti-EGFR treatments may be more effective than anti-VEGF treatments when combined with FOLFIRI or FOLFOX. Further, evidence suggests that both anti-EGFR and anti-VEGF therapies, when combined with FOLFIRI or FOLFOX, may be harmful as compared to chemotherapy for KRAS MT patients.

MATERIALS AND METHODS

Literature was searched for randomized trials comparing anti-EGFR or anti-VEGF antibodies, paired with FOLFIRI or FOLFOX, as first-line therapy for advanced colorectal cancer. Meta-estimates were generated via Bayesian hierarchical log-linear model. The primary endpoint was overall survival.

CONCLUSIONS

Further studies examining impact of all-RAS mutation status, left or right side location of primary tumor, and combination anti-VEGF with modern bolus fluoropyrimidine are needed.

Ex Vivo Lymphadenectomy During Gastrectomy for Adenocarcinoma Optimizes Lymph Node Yield

INTRODUCTION

Variability in surgical and pathological techniques in Western centers may lead to inconsistency in lymph node staging in patients with gastric adenocarcinoma. We hypothesize that ex vivo dissection (EVD) after gastrectomy for adenocarcinoma increases lymph node yield.

METHODS

We retrospectively reviewed 222 consecutive patients who underwent gastrectomy with curative intent for adenocarcinoma between November 2010 and June 2014. In August of 2012, we began performing EVD of nodes in surgical specimens (EVD group, N = 111), as opposed to submitting specimens en bloc with lymph node basins attached to the specimen (No EVD group, N = 111). Primary end point was lymph node yield.

RESULTS

The median number of lymph nodes procured was significantly higher in the EVD compared to that in the No EVD group (30 vs. 21 lymph nodes, respectively; P < 0.0001). Moreover, 28% of the No EVD group were not adequately staged (defined by ≤15 nodes), compared to 5% of the EVD group (P < 0.0001). Stage-for-stage overall survival was not significantly different.

CONCLUSION

EVD may be a useful tool to maximize lymph node yield. However, this had no impact on staging or survival. This is an interesting finding that warrants further investigation.

Prognostic significance of PET assessment of metabolic response to therapy in oesophageal squamous cell carcinoma

Objectives:

The role of maximum standard uptake value (SUVmax) at baseline and after induction chemotherapy (CT) on positron emission tomography (PET) as an imaging biomarker has not been well established in oesophageal squamous cell carcinoma (SCC). In this retrospective analysis, we investigated the prognostic significance of various PET metrics in oesophageal SCC patients treated with induction chemotherapy followed by concurrent chemoradiotherapy (CRT).

Methods:

A total of 57 patients were treated with CRT; 52 patients received induction chemotherapy and 10 patients underwent surgery following CRT. Scans were independently analysed by a nuclear medicine physician blinded to patient outcome. Using region of interest analysis, SUVmax and metabolic tumour volume (MTV) were calculated for the index lesion and lymph node metastases in each patient. Kaplan–Meier analysis was used to evaluate overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS) and distant metastasis-free survival (DMFS). Cox proportional hazards regression was used to assess correlation between outcomes and PET metrics.

Results:

Median follow-up for those who are alive was 4.4 years, with a median survival for all patients of 2.9 years. The 3-year OS, DFS, DMFS and LRFS rates were 47, 40, 44 and 36%, respectively. Using a pre-established cutoff of a 35% decrease in SUVmax from baseline to post-induction PET, 3-year OS for responders (⩾35% decrease from baseline) was 64%, whereas non-responders (<35% decrease from baseline) had a 3-year OS of 15% (P=0.004).

Conclusions:

The pre-specified 35% decrease in SUVmax after induction chemotherapy was prognostic for OS. Baseline and post-induction PET metrics provide prognostic information for oesophageal SCC.

Preoperative CTLA-4 blockade: tolerability and immune monitoring in the setting of a presurgical clinical trial

PURPOSE

Cytotoxic T lymphocyte associated antigen (CTLA-4) blockade is being explored in numerous clinical trials as an immune-based therapy for different malignancies. Our group conducted the first preoperative clinical trial with the anti-CTLA-4 antibody ipilimumab in 12 patients with localized urothelial carcinoma of the bladder.

EXPERIMENTAL DESIGN

Six patients were treated with 3 mg/kg/dose of anti-CTLA-4 and six patients were treated with 10 mg/kg/dose of antibody. Primary end points of the study were safety and immune monitoring.

RESULTS

Most drug-related adverse events consisted of grade 1/2 toxicities. All patients had measurable immunologic pharmacodynamic effects, consisting of an increased frequency of CD4+ICOShi T cells in tumor tissues and the systemic circulation. To determine if CD4+ICOShi T cells could be a correlative marker for clinical outcome after treatment with anti-CTLA-4, a cohort of metastatic melanoma patients was studied retrospectively for frequency of CD4+ICOShi T cells and survival. Data from this small cohort of patients indicated that an increased frequency of CD4+ICOShi T cells, sustained over a period of 12 weeks of therapy, correlates with increased likelihood of clinical benefit consisting of overall survival.

CONCLUSIONS

Our trial shows that anti-CTLA-4 therapy has a tolerable safety profile in the presurgical setting and that a preoperative model can be used to obtain biological data on human immune responses, which can efficiently guide the monitoring of patients treated in the metastatic disease setting.

Cytokine changes in castrate metastatic prostate cancer (CPMC) patients (pts) treated with ipilimumab (Ipi)

e16149

Background: Ipilimumab (Ipi) is a human IgG1 monoclonal antibody that blocks the inhibitory action of the checkpoint molecule CTLA-4. Recent data [Proc Amer Soc Clin Onc, Abstr#5004, 2008] from castrate metastatic PC pts suggested that Ipi was active but was associated with grade 3 autoimmune adverse events (AEs), such as colitis, hepatitis, hypophysitis or rash, which required high dose steroids. We studied pts who were treated on a clinical trial with Ipi 10 mg/kg alone or with radiation to a single site in bone to determine whether there was any correlation between serum cytokine levels and autoimmune AEs. Methods: Thirteen pts were treated, of whom 10 had sufficient specimens for analysis. Of the 10 pts, 8 had ≥1 AE during treatment. Pts were stratified by ascertainment of clinical benefit (CB) vs. no clinical benefit (NCB) based on time-to-PSA-baseline relapse (TTBR) and also by toxicity (tox) using standard NCI tox criteria. TTBR was defined as time from study entry until the time when a PSA measurement reached or exceeded the baseline value. Pts with a TTBR greater than the median value were judged to have CB; those with a TTBR less than the median value had NCB. Pts with grade (gd) 0/1/2 tox were termed “low tox” while those with gd 3/4 tox were “high tox”. Sera at serial time points were analyzed for interferon-gamma (IFN-γ), tumor necrosis factor α and interleukins (IL)-1b, 2, 4, 8, 10, 12, 13 with the Meso Scale Discovery Multiplex Assay (MSD, Gaithersburg, MD). Results: IFN-γ was the predominant cytokine produced in 4 of 5 pts with CB and AEs; it increased at week 4 or 7 after two doses of Ipi, then declined. Four of 5 pts with NCB had minimal IFN-γ production. There was no difference in IL-10 production between those with CB vs. NCB or high vs. low tox. However, there was a suggestion that the IFN-γ /IL-10 ratio may be increased in pts who had high tox and/or CB vs. pts with low tox and NCB. This awaits confirmation. Conclusions: While this experience with Ipi in PC is small, there may be differences between pts with CB vs. NCB and pts with low vs. high tox. Investigation of the immunophenotype of pts who remain in follow- up and continue to be enrolled is ongoing as well as the impact of prior chemotherapy on development of toxicities.

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Life-threatening coagulopathy associated with use of Campath (alemtuzumab) in maintenance steroid-free renal transplant given before surgery

We report a case in which an alarming coagulopathy occurred during the operation in a patient receiving a kidney from his spouse. Campath was used for induction of immunosuppression immediately before surgery. There was catastrophic intra-abdominal bleeding associated with severe hypotension, respiratory failure, prolonged partial thrombin time (PTT), normal prothrombin time (PT) and absence of signs of disseminated intravascular coagulation. Multiple tranfusions of blood and blood products were given. Repeated explorations were carried out to secure hemostasis and removal of intra-abdominal blood clots. The coagulopathy improved after 24 h, but recurred within 3 h after the second dose of Campath, given exactly 24 h after the first dose. The coagulopathy also resulted in graft dysfunction, bilateral basal pneumonia, pleural effusions and prolonged abdominal ileus. In spite of the above, the patient went into diuresis and was discharged well after 3 weeks. He was on Prograf (tacrolimus), the sole maintenance immunosuppressor. The pathogenesis of the Campath-related coagulopathy is unclear. We wish to alert the transplant community to this unusual, but catastrophic, complication. We also advocate administering intravenous Campath following the operation, when surgical wounds are more secure and the patient is in a more stable environment.

The novel IMPDH inhibitor VX-497 prolongs skin graft survival and improves graft versus host disease in mice

VX-497 is the first inosine-5'-monophosphate dehydrogenase (IMPDH) inhibitor generated in a structure-based drug design program specifically addressing the tolerability problems of currently available immunosuppressive drugs. The pharmacological activity of the compound has been examined in murine skin transplantation and graft versus host disease (GVHD) models. In the skin transplant study, trunk skin grafts from Balb/c mice were grafted onto C57Bl/6 mice. Mice were administered vehicle or VX-497 twice daily until day 10. Mean survival of skin grafts on vehicle-treated animals was 9.9 +/- 0.9 days. Graft survival was prolonged significantly in animals treated with VX-497 to 13.2 +/- 1.2 (p < 0.001, Kaplan Meier Log-Rank test) days in the 50 mg/kg group and 13.9 +/- 1.0 (p < 0.001) days in the 85 mg/kg group. In the GVHD study, 150 x 10(6) nonadherent splenocytes from B6 mice were injected intravenously into the F1 hybrid strain B6DBA/2. Groups of animals (n = 6) were administered vehicle or 50 or 100 mg/kg VX-497 b.i.d for 8 days. Animals were sacrificed and spleen weights and interferon-gamma (IFN-gamma) serum levels were determined by enzyme-linked immunosorbent assay. In addition, spontaneous spleen cell proliferation was measured using a 3H-thymidine uptake assay. Isografted F1 animals served as controls. GVHD developed in the vehicle-treated allografted F1 mice and treatment with VX-497 improved all manifestations of the disease significantly. The 2.9-fold increase in spleen weight in allografted animals was reduced to a 1.6-fold increase in the VX-497-treated mice. Serum IFN-gamma levels were increased 54-fold in the vehicle group while there was a 7.4-fold increase in VX-497-treated animals. Spontaneous spleen cell proliferation was increased 9.9-fold in the absence of VX-497 and there was a 3.5-fold increase in its presence. Thus, VX-497 has been shown to be effective in both a skin transplantation and a GVHD model in the mouse. The demonstrated pharmacological activity of VX-497 in these murine transplantation models warrants further evaluation of the drug in transplantation indications.

A dendritic cell vaccine induces protective immunity to intracranial growth of glioma

The central nervous system is an immunologically privileged site hidden behind the blood brain barrier. Nevertheless, immune effector cells induced peripherally can be recruited into the central nervous system. Active immunotherapy of intracranial malignancies is thus potentially feasible. In this study we describe a vaccine regimen, based on bone marrow-derived dendritic cells pulsed with the RNA derived from GL261 glioma cells that induces a specific T cell response and protection against intracerebrally implanted GL261 tumors. Immunohistochemical analysis of brain tumors from vaccinated mice was characterized by pronounced intratumoral infiltrates predominantly of CD4+ as well as CD8+ T cells. The efficacy of the vaccine was improved further by administration of recombinant interleukin-12 into the vaccine regimen.

Microwave-induced thermoacoustic tomography: reconstruction by synthetic aperture

We have applied the synthetic-aperture method to linear-scanning microwave-induced thermoacoustic tomography in biological tissues. A nonfocused ultrasonic transducer was used to receive thermoacoustic signals, to which the delay-and-sum algorithm was applied for image reconstruction. We greatly improved the lateral resolution of images and acquired a clear view of the circular boundaries of buried cylindrical objects, which could not be obtained in conventional linear-scanning microwave-induced thermoacoustic tomography based on focused transducers. Two microwave sources, which had frequencies of 9 and 3 GHz, respectively, were used in the experiments for comparison. The 3 GHz system had a much larger imaging depth but a lower signal-noise ratio than the 9 GHz system in near-surface imaging.

Microwave-induced thermoacoustic tomography using multi-sector scanning

A study of microwave-induced thermoacoustic tomography of inhomogeneous tissues using multi-sector scanning is presented. A short-pulsed microwave beam is used to irradiate the tissue samples. The microwave absorption excites time-resolved acoustic waves by thermoelastic expansion. The amplitudes of the acoustic waves are strongly related to locally absorbed microwave-energy density. The acoustic waves may propagate in all spatial directions. A focused ultrasonic transducer is employed to acquire temporal acoustic signals from multiple directions. Each detected signal is converted into a one-dimensional (1D) image along the acoustic axis of the transducer. The cross-sectional images of the tissue samples are calculated by combining all of the 1D images acquired in the same planes.

Tumor necrosis factor receptor deletion reduces nuclear factor-kappaB activation, cellular inhibitor of apoptosis protein 2 expression, and functional recovery after traumatic spinal cord injury

Tumor necrosis factor-alpha (TNF-alpha) expression has been documented extensively in animal models of traumatic spinal cord injury (SCI). However, the pathophysiological significance of TNF-alpha expression in the injured cord remains to be delineated. The TNF receptor (TNFR)-nuclear factor-kappaB (NF-kappaB) signal transduction pathway is important for maintaining cell viability. NF-kappaB exerts anti-apoptotic effects via an endogenous caspase inhibitory system mediated by cellular inhibitor of apoptosis protein 2 (c-IAP2). NF-kappaB transactivates c-IAP2 to inhibit caspase-3 activation. Progressive cell death, including morphological and biochemical features suggestive of apoptosis, has been noted after SCI. We explored the effects of TNFR1 or TNFR2 deletion on the apoptotic events downstream of NF-kappaB in relation to SCI pathology and functional recovery. Nuclear proteins from the injured cords of the TNFR1(-/-) mice had a reduced NF-kappaB binding activity compared with the wild-type controls. This decrease in NF-kappaB activation was accompanied by a reduction in c-IAP2 expression and an increase in the active form of caspase-3 protein. After SCI the TNFR1(-/-) mice had greater numbers of apoptotic cells, a larger lesion size, and worse functional recovery than wild-type mice. TNFR2-deficient mice had a similar, although not as pronounced, consequence as the TNFR1(-/-) mice. These findings support the argument that the TNFR-NF-kappaB pathway is beneficial for limiting apoptotic cell death after SCI and that a defective TNFR-NF-kappaB pathway results in a poorer neurological outcome. A worse functional outcome in TNFR(-/-) mice suggests that an endogenous apoptosis inhibitory mechanism mediated by TNFR activation, NF-kappaB, and c-IAP2 may be of pathophysiological importance.

ICE/Caspase-1 inhibitors as novel anti-inflammatory drugs

In recent years, several strategies that selectively inhibit pro-inflammatory cytokines, have yielded effective protein-based therapies for inflammatory disorders, validating the therapeutic hypothesis that intervention in cytokine signalling can provide clinical benefit. However, these protein-based products must be administered by injection, a constraint associated with inconvenience, adverse effects and expense for patients, caregivers and insurers. Besides interfering with the effects of cytokines such as TNF-alpha or IL-1beta that have already been produced, inhibition of pro-inflammatory cytokine production or signalling with low-molecular weight orally-active drugs would combine the convenience of conventional pharmaceuticals with the focused efficacy of the protein therapies. Reducing IL-1beta and IL-18 production by inhibition of IL-1beta converting enzyme (ICE, caspase-1) is one promising strategy because of the key roles of these cytokines in many inflammatory diseases. Pralnacasan, the first orally available, potent and selective ICE inhibitor to enter clinical trials, is currently under investigation in rheumatoid arthritis.

Amyloid beta peptide-induced cerebral endothelial cell death involves mitochondrial dysfunction and caspase activation

Amyloid beta peptide (A beta), a 39 to 43 amino acid fragment of the beta-amyloid precursor protein (betaAPP), forms insoluble fibrillar accumulation in neurofibrillary tangles and vascular plaques. A beta has been implicated in neuronal and vascular degeneration in brain regions susceptible to plaque formation because of its cytotoxic effect on neurons and endothelial cells (ECs). The authors used a murine cerebral endothelial cell (CEC) line and primary cultures of bovine CECs to explore the cytotoxic mechanism of A beta. A beta 1-40 and A beta 25-35 peptides caused cell death in a dose-dependent and time-dependent manner. Exposure to either A beta 25-35 or A beta 1-40 at 10 micromol/L for 48 hours caused at least 40% cell death. Cerebral endothelial cell death was characterized by nuclear condensation, mitochondrial dysfunction, and nuclear and mitochondrial DNA damage. A beta 25-35 activated both caspase-8 and caspase-3 in murine CECs. zVAD-fmk, a broad-spectrum caspase inhibitor, prevented A beta 25-35-induced increase in caspase-3 activity and CEC death. N-acetyl-cysteine, an antioxidant, also prevented A beta-induced cell death. Together, these findings indicate that A beta-mediated CEC death is an apoptotic process that is characterized by increased oxidative stress, caspase activation, mitochondrial dysfunction, and nuclear and mitochondrial DNA damage.

iNOS and nitrotyrosine expression after spinal cord injury

Secondary tissue damage after spinal cord injury (SCI) may be due to inflammatory mediators. After SCI, the nuclear factor-kappaB (NF-kappaB) transcription factor can activate many pro-inflammatory genes, one of which is inducible nitric oxide synthase (iNOS). iNOS catalyzes the synthesis of nitric oxide (NO), a key inflammatory mediator, which in turn reacts with superoxide to generate peroxynitrite. Peroxynitrite is a strong oxidant that can damage cellular enzymes, membranes, and subcellular organelles through the nitration of tyrosine residues on proteins. The presence of nitrotyrosine (NT) is an indirect chemical indicator of toxic NO and peroxynitrite-induced cellular damage. Using a New York University (NYU) impactor to induce SCI in adult rats, we examined the temporal and cellular expression of iNOS and NT. We observed a progressive increase in iNOS expression in the injured cord starting at day 1 with maximal expression occurring at day 7, as determined by Western blot analysis. iNOS expression corresponded temporally to an increase in iNOS enzyme activity after SCI. In parallel with the progressive increase in iNOS activity, NT expression also increased with time after SCI. The iNOS and NT immunoreactivity was localized in neurons, astrocytes, endothelial cells and ependymal cells at the epicenter and adjacent to the region of spinal cord impact and injury. Results from the present study suggest that increased iNOS and peroxynitrite anion, as reflected by the progressive accumulation of NT in the injured impacted spinal cord, may contribute to the secondary injury process after SCI.

Scanning microwave-induced thermoacoustic tomography: signal, resolution, and contrast

Scanning thermoacoustic tomography was explored in the microwave region of the electromagnetic spectrum. Short microwave pulses were used to induce acoustic waves by thermoelastic expansion in biological tissues. Cross sections of tissue samples were imaged by a linear scan of the samples while a focused ultrasonic transducer detected the time-resolved thermoacoustic signals. Based on the microwave-absorption properties of normal and cancerous breast tissues, the piezoelectric signals in response to the thermoacoustic contrast were investigated over a wide range of electromagnetic frequencies and depths of tumor locations. The axial resolution is related to the temporal profile of the microwave pulses and to the impulse response of the ultrasonic transducer. The lateral resolution is related to the numerical aperture of the ultrasonic transducer as well as to the frequency spectra of the piezoelectric signals in the time window corresponding to the axial resolution. Gain compensation, counteracting the microwave attenuation, was applied to enhance the image contrast.

Amyloid-beta peptides are cytotoxic to oligodendrocytes

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive dementia. Amyloid-beta peptide (Abeta), a 39-43 amino acid peptide derived from beta-amyloid precursor protein, forms insoluble fibrillar aggregates that have been linked to neuronal and vascular degeneration in AD and cerebral amyloid angiopathy. Here we demonstrate that Abeta 1-40 and a truncated fragment, Abeta 25-35, induced death of oligodendrocytes (OLGs) in vitro in a dose-dependent manner with similar potencies. Abeta-induced OLG death was accompanied by nuclear DNA fragmentation, mitochondrial dysfunction, and cytoskeletal disintegration. Abeta activation of redox-sensitive transcription factors NF-kappaB and AP-1 and antioxidant prevention of Abeta-mediated OLG death suggest that oxidative injury contributes to Abeta cytotoxicity in OLGs. Recent demonstration of Abeta deposition and white matter abnormalities in AD implies a potential pathophysiological role for Abeta-mediated cytotoxicity of OLGs in this neurodegenerative disease.

iNOS expression inhibits hypoxia-inducible factor-1 activity

Hypoxia-inducible factor-1 (HIF-1) activates genes important in vascular function such as vascular endothelial growth factor (VEGF), erythropoietin (EPO), and inducible nitric oxide synthase (iNOS). iNOS catalyzes the synthesis of nitric oxide (NO), a free radical gas that mediates a number of cellular processes, including regulation of gene expression, vasodilatation, and neurotransmission. Here we demonstrate that iNOS expression inhibits HIF-1 activity under hypoxia in C6 glioma cells transfected with an iNOS gene and a VEGF promoter-driven luciferase gene. HIF-1 induction of VEGF-luciferase activity in C6 cell is also inhibited by sodium nitroprusside (SNP). Furthermore, pretreatment of C6 cells with N-acetyl-l-cysteine (NAC), an antioxidant, nullified the inhibitory effect of iNOS on HIF-1 binding. These results demonstrate that NO generated by iNOS expression inhibits HIF-1 activity in hypoxic C6 cells and suggest a negative feedback loop in the HIF-1 --> iNOS cascade.

Astrocytes and central nervous system endothelial cells do not express B7-1 (CD80) or B7-2 (CD86) immunoreactivity during experimental autoimmune encephalomyelitis

The identity of cell types within the central nervous system (CNS) capable of activating T lymphocytes is a fundamental issue in the understanding of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). To become fully activated, a T cell must recognize its antigen and receive co-stimulation, the latter being optimally delivered via B7-1 and/or B7-2 molecules expressed by the antigen presenting cell (APC). There are conflicting reports regarding whether astrocytes or CNS endothelial cells (EC) can act as fully competent APCs. The present studies were performed to determine whether astrocytes or CNS EC express B7-1 or B7-2 immunoreactivity during EAE. No expression of B7-1 or B7-2 by either astrocytes or EC was detected during acute, remitting, relapsing or chronic EAE, whether EAE was induced by active immunization or cell transfer using five different myelin antigens. These results suggest that neither astrocytes nor CNS EC can deliver co-stimulatory signals via B7 molecules in the setting of murine EAE, rendering them incapable of acting as fully competent APCs.

Coadministration of interleukin-18 and interleukin-12 induces a fatal inflammatory response in mice: critical role of natural killer cell interferon-gamma production and STAT-mediated signal transduction

The administration of therapeutic doses of recombinant cytokines to patients with malignant disease can be complicated by systemic toxicities, which in their most severe form may present as a systemic inflammatory response. The combination of interleukin (IL)-18 and IL-12 has synergistic antitumor activity in vivo yet has been associated with significant toxicity. The effects of IL-18 plus IL-12 were examined in a murine model, and it was found that the daily, simultaneous administration of IL-18 and IL-12 resulted in systemic inflammation and 100% mortality within 4 to 8 days depending on the strain employed. Mice treated with IL-18 plus IL-12 exhibited unique pathologic findings as well as elevated serum levels of proinflammatory cytokines and acute-phase reactants. The actions of tumor necrosis factor-alpha did not contribute to the observed toxicity, nor did T or B cells. However, toxicity and death from treatment with IL-18 plus IL-12 could be completely abrogated by elimination of natural killer (NK) cells or macrophages. Subsequent studies in genetically altered mice revealed that NK-cell interferon-gamma mediated the fatal toxicity via the signal transducer and activator of transcription pathway of signal transduction. These data may provide insights into methods of ameliorating cytokine-induced shock in humans. (Blood. 2000;96:1465-1473)

The T-cell receptor regulates Akt (protein kinase B) via a pathway involving Rac1 and phosphatidylinositide 3-kinase

The serine/threonine kinase Akt (also known as protein kinase B) (Akt/PKB) is activated upon T-cell antigen receptor (TCR) engagement or upon expression of an active form of phosphatidylinositide (PI) 3-kinase in T lymphocytes. Here we report that the small GTPase Rac1 is implicated in this pathway, connecting the receptor with the lipid kinase. We show that in Jurkat cells, activated forms of Rac1 or Cdc42, but not Rho, stimulate an increase in Akt/PKB activity. TCR-induced Akt/PKB activation is inhibited either by PI 3-kinase inhibitors (LY294002 and wortmannin) or by overexpression of a dominant negative mutant of Rac1 but not Cdc42. Accordingly, triggering of the TCR rapidly stimulates a transient increase in GTP-Rac content in these cells. Similar to TCR stimulation, L61Rac-induced Akt/PKB kinase activity is also LY294002 and wortmannin sensitive. However, induction of Akt/PKB activity by constitutive active PI 3-kinase is unaffected when dominant negative Rac1 is coexpressed, placing Rac1 upstream of PI 3-kinase in the signaling pathway. When analyzing the signaling hierarchy in the pathway leading to cytoskeleton rearrangements, we found that Rac1 acts downstream of PI 3-kinase, a finding that is in accordance with numerous studies in fibroblasts. Our results reveal a previously unrecognized role of the GTPase Rac1, acting upstream of PI 3-kinase in linking the TCR to Akt/PKB. This is the first report of a membrane receptor employing Rac1 as a downstream transducer for Akt/PKB activation.

Scanning thermoacoustic tomography in biological tissue

Microwave-induced thermoacoustic tomography was explored to image biological tissue. Short microwave pulses irradiated tissue to generate acoustic waves by thermoelastic expansion. The microwave-induced thermoacoustic waves were detected with a focused ultrasonic transducer. Each time-domain signal from the ultrasonic transducer represented a one-dimensional image along the acoustic axis of the ultrasonic transducer similar to an ultrasonic A-scan. Scanning the system perpendicularly to the acoustic axis of the ultrasonic transducer would generate multi-dimensional images. Two-dimensional tomographic images of biological tissue were obtained with 3-GHz microwaves. The axial and lateral resolutions were characterized. The time-domain piezo-electric signal from the ultrasonic transducer in response to the thermoacoustic signal was simulated theoretically, and the theoretical result agreed with the experimental result very well.

A guanine nucleotide exchange factor-independent function of Vav1 in transcriptional activation

T cell antigen receptor (TCR) stimulation induces the tyrosine phosphorylation of several intracellular proteins including the protooncogene Vav1. Vav1 expression is necessary for normal T cell development and activation. We previously showed that overexpression of Vav1 in Jurkat T cells potentiates the activity of the transcription factor nuclear factor of activated T cells (NF-AT). The mechanism by which Vav1 participates in TCR signaling events is not clear. Vav1 contains a guanine nucleotide exchange factor (GEF) domain that has specificity for Rac and other Rho GTPases that have been recently implicated in T cell activation events. Significantly, in vitro tyrosine phosphoryation of Vav1 by Lck activates its exchange activity. This Lck-mediated phosphorylation of Vav1 has been reported to depend upon Tyr-174 in Vav1, a site implicated in Vav1 function by other studies as well. In this report, we demonstrated that Tyr-174 is not required for the TCR-induced phosphorylation of Vav1 in vivo. Moreover, mutation of Tyr-174 augmented the ability of Vav1 to up-regulate NF-AT activation as well as the Vav1 GEF function leading to Rac activation. However, we also showed that the GEF activity of Vav1 was neither sufficient nor necessary for potentiation of NF-AT, and thereby we identify a GEF-independent role of Vav1 in potentiating NF-AT-driven transcription. Oncogenic Vav1 in which the amino-terminal 67 amino acids were deleted had elevated GEF activity but did not potentiate NF-AT when overexpressed in Jurkat cells. We also showed that a GEF mutant form of Vav1 that had impaired GEF function could still potentiate NF-AT. These studies reveal a previously unrecognized negative regulatory function of Tyr-174 in Vav1 and suggest that domains other than the Vav1 GEF domain contribute to TCR signals leading to NF-AT activation.

T cells are the main cell type expressing B7-1 and B7-2 in the central nervous system during acute, relapsing and chronic experimental autoimmune encephalomyelitis

T cell co-stimulation through the CD28 receptor on T cells is critical to the induction of experimental autoimmune encephalomyelitis (EAE). In this study, expression of the co-stimulatory ligands B7-1 (CD80) and B7-2 (CD86), as well as the receptors CD28 and CTLA-4, were quantitated in central nervous system (CNS) tissues from mice at various stages of EAE. Immunohistochemistry and flow cytometry of CNS-infiltrating cells revealed a high percentage of infiltrating T cells expressing B7-1 and B7-2 during acute, chronic and relapsing EAE. Of the infiltrating cells 10-20% were CTLA-4(+), most of which were CD4(+) T cells. B7-1 and B7-2 expression within the CNS during active EAE might increase the potential for local activation of autoimmune T cells; however, the high level of expression of B7 molecules may also provide a mechanism for the autoregulation of activated CTLA-4(+) T cells.