Combining tumor deposits with the number of lymph node metastases to improve the prognostic accuracy in stage III colon cancer: a post hoc analysis of the CALGB/SWOG 80702 phase III study (Alliance)☆

BACKGROUND

In colon cancer, tumor deposits (TD) are considered in assigning prognosis and staging only in the absence of lymph node metastasis (i.e. stage III pN1c tumors). We aimed to evaluate the prognostic value of the presence and the number of TD in patients with stage III, node-positive colon cancer.

PATIENTS AND METHODS

All participants from the CALGB/SWOG 80702 phase III trial were included in this post hoc analysis. Pathology reports were reviewed for the presence and the number of TD, lymphovascular and perineural invasion. Associations with disease-free survival (DFS) and overall survival (OS) were evaluated by multivariable Cox models adjusting for sex, treatment arm, T-stage, N-stage, lymphovascular invasion, perineural invasion and lymph node ratio.

RESULTS

Overall, 2028 patients were included with 524 (26%) TD-positive and 1504 (74%) TD-negative tumors. Of the TD-positive patients, 80 (15.4%) were node negative (i.e. pN1c), 239 (46.1%) were pN1a/b (<4 positive lymph nodes) and 200 (38.5%) were pN2 (≥4 positive lymph nodes). The presence of TD was associated with poorer DFS [adjusted hazard ratio (aHR) = 1.63, 95% CI 1.33-1.98] and OS (aHR = 1.59, 95% CI 1.24-2.04). The negative effect of TD was observed for both pN1a/b and pN2 groups. Among TD-positive patients, the number of TD had a linear negative effect on DFS and OS. Combining TD and the number of lymph node metastases, 104 of 1470 (7.1%) pN1 patients were re-staged as pN2, with worse outcomes than patients confirmed as pN1 (3-year DFS rate: 65.4% versus 80.5%, P = 0.0003; 5-year OS rate: 87.9% versus 69.1%, P = <0.0001). DFS was not different between patients re-staged as pN2 and those initially staged as pN2 (3-year DFS rate: 65.4% versus 62.3%, P = 0.4895).

CONCLUSION

Combining the number of TD and the number of lymph node metastases improved the prognostication accuracy of tumor-node-metastasis (TNM) staging.

Enhanced recovery after surgery pathway in patients with soft tissue sarcoma

BACKGROUND

Patients undergoing surgery for soft tissue sarcoma have high morbidity rates, particularly after preoperative radiation therapy (RT). An enhanced recovery after surgery (ERAS) programme may improve perioperative outcomes in abdominal surgery. This study reported outcomes of an ERAS programme tailored to patients with soft tissue sarcoma.

METHODS

A prospective ERAS protocol was implemented in 2015 at a high-volume sarcoma centre. Patients treated within the ERAS programme from 2015 to 2018 were case-matched retrospectively with patients treated between 2012 and 2018 without use of the protocol, matched by surgical site, surgeon, sarcoma histology and preoperative RT treatment. Postoperative outcomes, specifically wound complications and duration of hospital stay, were reported.

RESULTS

In total, 234 patients treated within the ERAS programme were matched with 237 who were not. The ERAS group had lower wound dehiscence rates overall (2 of 234 (0·9 per cent) versus 31 of 237 (13·1 per cent); P < 0·001), after preoperative RT (0 of 41 versus 11 of 51; P = 0·004) and after extremity sarcoma surgery (0 of 54 versus 6 of 56; P = 0·040) compared with the non-ERAS group. Rates of postoperative ileus or obstruction were lower in the ERAS group (21 of 234 (9·9 per cent) versus 40 of 237 (16·9 per cent); P = 0·016) and in those with retroperitoneal sarcoma (4 of 36 versus 15 of 36; P = 0·007). Duration of hospital stay was shorter in the ERAS group (median 5 (range 0-36) versus 6 (0-67) days; P = 0·003).

CONCLUSION

Treatment within an ERAS protocol for patients with soft tissue sarcoma was associated with lower morbidity and shorter hospital stay.

Prediction of morbidity following cytoreductive surgery for metastatic gastrointestinal stromal tumour in patients on tyrosine kinase inhibitor therapy

BACKGROUND

Although cytoreductive surgery has been shown to be beneficial in carefully selected patients with metastatic gastrointestinal stromal tumours (GISTs) treated with tyrosine kinase inhibitors (TKIs), factors predictive of postoperative morbidity have not been investigated previously.

METHODS

A surgical complexity score for GIST metastasectomy (GM-SCS) composed of patient-related and surgical factors was assigned retrospectively to patients with metastatic GIST treated with TKI therapy and surgery at two institutions between 2002 and 2014. The ability of clinicopathological factors and GM-SCS to predict postoperative morbidity was assessed by means of a multivariable logistic regression model. Postoperative complications were categorized using the Clavien-Dindo classification.

RESULTS

Some 400 operations on 323 patients with metastatic GIST on TKIs were included. Complications were observed following 110 operations (27·5 per cent) including 70 major complications (grade III-V) (17·5 per cent of 400 operations). Patients were divided into low (5 points or less; 100 patients, 25·0 per cent), intermediate (6-9 points; 191, 47·8 per cent) and high (at least 10 points; 109, 27·3 per cent) complexity scoring groups based on the GM-SCS. An intermediate (odds ratio (OR) 2·88; P = 0·008) and high (OR 5·40; P < 0·001) GM-SCS were independent predictors of overall complications, whereas only a high GM-SCS was independently predictive of a major complication (OR 3·65; P = 0·018). Metastatic mitotic index was also an independent predictor of overall complications (OR 2·55; P = 0·047). GM-SCS did not predict progression-free or overall survival.

CONCLUSION

A gastrointestinal stromal tumour metastastectomy surgical complexity score can predict morbidity, which may help in preoperative risk stratification and optimal treatment planning.

Predicted vitamin D status and colon cancer recurrence and mortality in CALGB 89803 (Alliance)

Background

Observational studies suggest that higher levels of 25-hydroxyvitamin D3 (25(OH)D) are associated with a reduced risk of colorectal cancer and improved survival of colorectal cancer patients. However, the influence of vitamin D status on cancer recurrence and survival of patients with stage III colon cancer is unknown.

Patients and methods

We prospectively examined the influence of post-diagnosis predicted plasma 25(OH)D on outcome among 1016 patients with stage III colon cancer who were enrolled in a National Cancer Institute-sponsored adjuvant therapy trial (CALGB 89803). Predicted 25(OH)D scores were computed using validated regression models. We examined the influence of predicted 25(OH)D scores on cancer recurrence and mortality (disease-free survival; DFS) using Cox proportional hazards.

Results

Patients in the highest quintile of predicted 25(OH)D score had an adjusted hazard ratio (HR) for colon cancer recurrence or mortality (DFS) of 0.62 (95% confidence interval [CI], 0.44-0.86), compared with those in the lowest quintile (Ptrend = 0.005). Higher predicted 25(OH)D score was also associated with a significant improvement in recurrence-free survival and overall survival (Ptrend = 0.01 and 0.0004, respectively). The benefit associated with higher predicted 25(OH)D score appeared consistent across predictors of cancer outcome and strata of molecular tumor characteristics, including microsatellite instability and KRAS, BRAF, PIK3CA, and TP53 mutation status.

Conclusion

Higher predicted 25(OH)D levels after a diagnosis of stage III colon cancer may be associated with decreased recurrence and improved survival. Clinical trials assessing the benefit of vitamin D supplementation in the adjuvant setting are warranted.

ClinicalTrials.gov Identifier

NCT00003835.

Insulin resistance in vascular endothelial cells promotes intestinal tumour formation

The risk of several cancers, including colorectal cancer, is increased in patients with obesity and type 2 diabetes, conditions characterized by hyperinsulinemia and insulin resistance. Because hyperinsulinemia itself is an independent risk factor for cancer development, we examined tissue-specific insulin action in intestinal tumor formation. In vitro, insulin increased proliferation of primary cultures of intestinal tumor epithelial cells from Apc^Min/+ mice by over 2-fold. Surprisingly, targeted deletion of insulin receptors in intestinal epithelial cells in Apc^Min/+ mice did not change intestinal tumor number or size distribution on either a low or high-fat diet. We therefore asked whether cells in the tumor stroma might explain the association between tumor formation and insulin resistance. To this end, we generated Apc^Min/+ mice with loss of insulin receptors in vascular endothelial cells. Strikingly, these mice had 42% more intestinal tumors than controls, no change in tumor angiogenesis, but increased expression of vascular cell adhesion molecule-1 (VCAM-1) in primary culture of tumor endothelial cells. Insulin decreased VCAM-1 expression and leukocyte adhesion in quiescent tumor endothelial cells with intact insulin receptors and partly prevented increases in VCAM-1 and leukocyte adhesion after treatment with tumor necrosis factor-α. Knockout of insulin receptors in endothelial cells also increased leukocyte adhesion in mesenteric venules and increased the frequency of neutrophils in tumors. We conclude that although insulin is mitogenic for intestinal tumor cells in vitro, its action on tumor cells in vivo is via signals from the tumor microenvironment. Insulin resistance in tumor endothelial cells produces an activated, proinflammatory state that promotes tumorigenesis. Improvement of endothelial dysfunction may reduce colorectal cancer risk in patients with obesity and type 2 diabetes.

Presence of 18q loss of heterozygosity (LOH) and disease-free and overall survival in stage II colon cancer: CALGB Protocol 9581

4012

Background: LOH at 18q is associated with poorer overall survival in patients with colon cancer; however available studies are retrospective and vary in analysis methods. We recently completed an 18qLOH assay method validation study, and after standardizing technique, this prospective study investigated the role of 18qLOH among patients with low-risk stage II colon cancer. Methods: In Cancer and Leukemia Group B (CALGB) protocol 9581, we randomized 1738 stage II patients to post-operative treatment with a 500 mg loading dose of monoclonal antibody 17–1A followed by four infusions of 100 mg every 28 days or observation. The primary endpoint was overall survival (OS); disease free survival (DFS) was a secondary endpoint. Status of 18qLOH was assessed in patients with available tissue and interpretable PCR results. Patients were excluded if their tumors were uninformative for 18qLOH or if their tumors displayed microsatellite instability. Results: We report 18qLOH data on 156 patients. Patient characteristics including treatment, age, gender, performance status, site and grade of tumor, were similar between all patients enrolled and the subset of patients with tumor samples analyzed. The DFS and OS for treated and observed patients were no different (5-yr DFS: 0.81 and 0.80, p= 0.96; 5-yr OS: 0.88 and 0.86, p=0.44 at a median of 6.8 yrs of follow-up) and the data were pooled across the study's arms. Of the tumors examined, 101 (65%) were positive for 18qLOH. A significantly lower proportion of patients with 18qLOH-positive tumors had proximal tumors (46.5% vs 65.5%; p=0.02). Significantly decreased DFS and OS were observed in patients with 18qLOH-positive tumors. Five-year DFS among patients with 18qLOH-positive tumors was 0.78 vs 0.93 among patients with 18qLOH-negative tumors [HR 0.39; 95% CI (0.16, 0.94); logrank p=0.03 based on 33 events]. Five-year OS among patients with 18qLOH-positive tumors was 0.85 vs 0.98 among patients with 18qLOH-negative tumors [HR 0.25; 95% CI (0.07, 0.83); logrank p=0.01 based on 24 events]. Conclusions LOH at 18q was prognostic for DFS and OS among patients with available tissue for analysis after resection of low-risk stage II colon cancer who were not treated with chemotherapy in the adjuvant setting.

[Table: see text]

KRAS mutation, cancer recurrence, and patient survival in stage III colon cancer: Findings from CALGB 89803

4037

Purpose: KRAS mutation in stage IV colorectal cancer predicts resistance to anti-EGFR targeted treatment (cetuximab or panitumumab). However, whether the presence of KRAS mutation independently predicts the survival of colon cancer patients remains uncertain. Methods: We conducted a prospective observational study of 508 cases identified among 1264 patients with stage III colon cancer who enrolled in a randomized adjuvant chemotherapy trial (5-fluorouracil, leucovorin with or without irinotecan) between April 1999 and May 2001 (CALGB 89803; Saltz et al. J Clin Oncol 2007). KRAS mutations were detected in 178 tumors (35%) by Pyrosequencing. Kaplan-Meier and Cox proportional hazard models were used to assess the significance of KRAS mutational status and adjusted for potential confounders including age, sex, tumor location, T stage, N stage, performance status, adjuvant chemotherapy arm and microsatellite instability (MSI) status. Results: When compared to patients with wild-type KRAS, those with a mutation in KRAS did not experience any difference in disease-free (DFS), recurrence-free (RFS), or overall survival (OS) (log-rank P>0.56 for DFS, RFS, and OS). Five-year DFS was 62% for KRAS-mutated and 63% for KRAS-wild-type patients. Five-year RFS was 64% for KRAS-mutated and 66% for KRAS- wild-type patients. Five-year OS was 74% for KRAS-mutated and 73% for KRAS-wild-type patients. The effect of KRAS mutation on patient survival did not differ according to clinical features, chemotherapy arm or MSI status, and the effect of adjuvant chemotherapy assignment on outcome did not differ according to KRAS status. Conclusions: In this large clinical trial of chemotherapy in patients with stage III colon cancer, KRAS mutational status was not associated with any significant influence on disease-free or overall survival.

No significant financial relationships to disclose.

Perioperative sunitinib dosing around extensive resections of imatinib-resistant metastatic gastrointestinal stromal tumors

10044

Background: Sunitinib malate (SU) is the primary therapy for metastatic gastrointestinal stromal tumor (GIST) resistant to imatinib mesylate (IM). Its inhibition of multiple receptor tyrosine kinases (TK) raised concerns that SU may impair healing after cytoreductive procedures more than IM. We reviewed our experience to compare the spectrum of postoperative complications after SU v. IM therapy. Methods: All patients (pts) with IM-resistant metastatic GISTs enrolled in phase II/III SU protocols at our institution were reviewed. The control group underwent cytoreduction on IM. Perioperative SU dosing and complications after surgery and after resumption of SU were recorded. Complications related to healing included wound/fascial dehiscence, anastomotic leak, and fistula. Complications not attributed to wound healing included hemorrhage, abscess, seroma, and ileus. Results: We treated 188 pts with IM-resistant metastatic GISTs with SU. Twenty-six pts on SU and 46 pts on IM underwent 28 and 53 operations for disease resection, respectively ( Table ). SU was stopped a median of 5 days (range 0–26) prior to surgery and resumed a median of 33 days (range 12–183) after surgery and 20 days (range 7- 178) after hospital discharge, generally during the first postoperative clinic visit. There were 17 complications after 14 (50%) of 28 procedures on SU and 23 complications after 20 (38%) of 53 procedures on IM (p=NS). Dehiscence, leaks, or fistulas, were identified after 2 (7%) procedures on SU and 4 (8%) procedures on IM (p=NS). These 2 pts with complications on SU stopped the drug 9 and 22 days prior to surgery. No wound healing complications were noted among the 18 pts who stopped SU less than 9 days before surgery. Conclusions: Wound healing complications were not more common after extensive resections on SU than on IM, despite SU's inhibition of a wider spectrum of TKs. Our current practice is to continue SU until 1–2 days prior to surgery and to resume SU at the first postoperative visit.

[Table: see text]

No significant financial relationships to disclose.

Mechanisms of sunitinib malate (SU) resistance in gastrointestinal stromal tumors (GISTs)

10006

Background: SU, an oral, multitargeted inhibitor of KIT, PDGFRs, VEGFRs, FLT3, and RET receptor tyrosine kinases, is now the standard therapy for treatment of imatinib mesylate (IM)-resistant GIST tumors or IM-intolerant GIST patients. However, it is unclear if the clinical efficacy of SU in this setting is due to inhibition of KIT and/or PDGFRA in tumor cells, inhibition of VEGFRs and PDGFRs in endothelial cells and pericytes, respectively, or a combination of antitumor and antiangiogenic effects. In order to address this question, we studied the molecular mechanisms of SU resistance in vitro and in patient-derived tumors. Methods: We studied the in-vitro effects of IM or SU on cells with KIT exon 11 mutations, either alone or in combination with known IM-resistant secondary mutations. In addition, we analyzed tumor samples obtained from patients undergoing salvage surgery after SU treatment failure. Tumor specimens were genotyped for primary and secondary mutations. Results: SU was approximately 2–5-fold more potent than IM against typical GIST-associated KIT exon 11 mutations. In addition, the presence of secondary mutations involving the ATP/drug binding pocket (V654A or T670I) did not substantially alter SU potency. In contrast, these ATP/drug-binding-pocket mutations conferred high-level resistance to IM. However, SU had no significant inhibitory effect on the kinase activity of secondary IM-resistant mutations involving the KIT activation loop (exon 17, codons 816, 820, 822, and 823). Surgical resection was performed on two GIST patients who had clinical progression on SU. Among nine progressing lesions, substitutions were detected in codons 816, 820, and 822; a novel mutation, L783V, was also identified. In contrast, two non-progressing tumors both contained a V654A secondary mutation. Conclusions: Consistent with in-vitro studies, acquired IM-resistant mutations of the KIT activation loop in GIST are associated with clinical resistance to SU and IM. In addition, novel kinase mutations not previously associated with IM resistance may contribute to clinical SU resistance. These findings suggest that the antiangiogenic effects of SU may be insufficient to inhibit GIST progression when the targeted oncogenic kinase remains active.

[Table: see text]

Microsatellite instability predicts improved response to adjuvant therapy with irinotecan, 5-fluorouracil and leucovorin in stage III colon cancer

10003

Background: Colon cancers exhibiting a high level of microsatellite instability (MSI-H) show distinct clinicopathological features, including both better prognosis and reduced response to 5-fluorouracil (5-FU)-based chemotherapy. We investigated the impact of adjuvant chemotherapy containing irinotecan in patients with MSI-H colon cancers. Methods: CALGB protocol 89803 randomized 1264 patients with resected stage III colon cancer to receive post-operative 5-FU and leucovorin (LV) with or without irinotecan. Paraffin blocks containing primary tumor and normal tissue were collected. Microsatellite instablility was assessed using a panel of mono- and di-nucleotide markers. Disease free survival (DFS) was measured from trial entry until documented disease progression or death from any cause. A statistical significance level of 0.2 was used in screening to generate hypotheses regarding MSI status and outcome. Median follow-up at analysis was 3.8 years. Overall C89803 showed no advantage for addition of irinotecan to 5-FU/LV. Results: Patients with and without tumor samples analyzed did not differ by treatment, age, gender, primary site, T-stage, differentiation, # positive nodes, or mucinous type. Of 482 tumors analyzed, 75 (16%) demonstrated MSI-H. MSI-H cancers were more likely to be located in the proximal colon (p<0.0001), of high histologic grade (p<0.0001) and mucinous histology (p<0.0001), and also had increased numbers of tumor-containing lymph nodes (mean # positive nodes/case = 3.5 for MSI Low/Stable vs. 4.7 for MSI-H; p = 0.04). At the time of analysis 143 of 482 patients (36%) analyzed experienced tumor recurrence and/or death due to any cause. For patients with MSI-H tumors, DFS was better in those treated with irinotecan in addition to 5-FU/LV (logrank p=0.18). Among patients with MSI Low/Stable tumors there was no difference in DFS between those treated with and without irinotecan (logrank p =0.39). Conclusions: Early results from CALGB protocol 89803 indicate that addition of postoperative irinotecan to 5-FU/LV may improve DFS in patients with stage III colon cancers that exhibit MSI-H. Longer follow-up is required to confirm this finding.

[Table: see text]

Patterns of PET response after long-term sunitinib therapy in patients (pts) with imatinib (IM)-resistant gastrointestinal stromal tumors (GIST)

9547

Background: Sunitinib malate (previously known as SU11248) is an active therapy for GIST patients resistant to or intolerant of IM. During initial development, sunitinib was administered in 4–6 week cycles, with 2–4 weeks of drug dosing followed by 2 weeks off treatment. We previously reported suppression of tumor-related 18FDG avidity on PET imaging during sunitinib dosing, with rebound tumor uptake while off drug. This rebound, seen in 80% with initial PET suppression, did not correlate with lack of clinical benefit. We asked if this pattern persists in pts who benefited from long term (> 2 years) sunitinib therapy. Methods: Of 77 pts in our initial Phase I/II study, 7 remain on therapy with sunitinib for more than 2 years, 4 of whom had matched baseline PET and CT data to assess tumor metabolic activity on and off sunitinib dosing. PET scans were obtained at baseline, during initial treatment, during the off-treatment period, and again after > 2 years therapy. These 4 pts were followed for a median 39 months (range 35–45 months) and for a median of 35 cycles (range 27–47). Two achieved PR and two SD. Results: Initially, all 4 exhibited suppression of tumor FDG avidity with treatment followed by rebound during the off-treatment period. By 6 months, all showed complete suppression of FDG activity. After > 2 years on sunitinib, GIST lesions in 2 pts showed no activity on PET, even while off sunitinib, while GIST in 2 pts demonstrated rebound flare when off therapy. The GIST lesions have not progressed despite the transient metabolic rebound while off sunitinib. Conclusions: Metastatic lesions in pts with IM-resistant GIST benefiting from long-term sunitinib therapy display two patterns on PET imaging. GIST in certain pts who benefit from therapy demonstrates metabolic rebound of activity when off dosing, while lesions in other pts remain metabolically inert on PET even during the brief dosing breaks. Functional imaging may yield insights to differences in the underlying biology of GIST subtypes in different pts.

[Table: see text]

2-Methoxyestradiol induces p53-associated apoptosis of colorectal cancer cells

Menopausal estrogen replacement therapy is thought to be responsible for the recent decline in colorectal cancer (CRC) incidence among women. In the C57BL/6J-Min/+ mouse, an animal model of CRC, 17beta-estradiol (E(2)) prevents tumor formation in ovariectomized females. We examined human CRC intestinal cell lines to determine whether particular E(2) metabolites produced anti-tumor effects. Treatment of CRC cells with 2-methoxyestradiol (2-MeOE(2)) increased expression of p53 and p21(WAF1/CIP1) proteins and induced apoptosis, but did not produce changes in expression of estrogen receptor (ER)alpha or ERbeta. The finding that 2-MeOE(2) induces p53-mediated colon cell apoptosis in vitro supports a role for 2-MeOE(2) as an endogenous mediator of intestinal tumor suppression.

Progressive changes in adherens junction structure during intestinal adenoma formation in Apc mutant mice

The C57BL/6J-Min/+ (Min/+) mouse bears a mutant Apc gene and therefore is an important in vivo model of intestinal tumorigenesis. Min/+ mice develop adenomas that exhibit loss of the wild-type Apc allele (Apc(Min/-)). Previously, we found that histologically normal enterocytes bearing a truncated Apc protein (Apc(Min/+)) migrated more slowly in vivo than enterocytes with either wild-type Apc (Apc(+/+)) or with heterozygous loss of Apc protein (Apc(1638N)). To study this phenotype further, we determined the effect of the Apc(Min) mutation upon cell-cell adhesion by examining the components of the adherens junction (AJ). We observed a reduced association between E-cadherin and beta-catenin in Apc(Min/+) enterocytes. Subcellular fractionation of proteins from Apc(+/+), Apc(Min/+), and Apc(Min/-) intestinal tissues revealed a cytoplasmic localization of intact E-cadherin only in Apc(Min/+), suggesting E-cadherin internalization in these enterocytes. beta-Catenin tyrosine phosphorylation was also increased in Apc(Min/+) enterocytes, consistent with its dissociation from E-cadherin. Furthermore, Apc(Min/+) enterocytes showed a decreased association between beta-catenin and receptor protein-tyrosine phosphatase beta/zeta (RPTPbeta/zeta), and Apc(Min/-) cells demonstrated an association between beta-catenin and receptor protein-tyrosine phosphatase gamma. In contrast to the Apc(Min/+) enterocytes, Apc(Min/-) adenomas displayed increased expression and association of E-cadherin, beta-catenin, and alpha-catenin relative to Apc(+/+) controls. These data show that Apc plays a role in regulating adherens junction structure and function in the intestine. In addition, discovery of these effects in initiated but histologically normal tissue (Apc(Min/+)) defines a pre-adenoma stage of tumorigenesis in the intestinal mucosa.

Cyclooxygenase-2 as a target for prevention of colorectal cancer

COX-2 is an isoenzyme of cyclooxygenase that is increased in response to growth factors, cytokines, and other mitogenic stimuli. Upregulation of COX-2 gene expression and functional activity is an early event in colorectal tumor formation. The long-term use of cyclooxygenase inhibitors, such as aspirin and nonsteroidal anti-inflammatory drugs, is associated with a decreased rate of colorectal tumors. This observation holds across a range of experimental models, from animal genetic tumor models to large epidemiologic studies of human sporadic colorectal cancer. Selective inhibitors of COX-2 were primarily developed to treat COX-2-related inflammation with minimal side effects. These drugs, however, may also provide safe, effective chemoprevention of colorectal neoplasia.

Reciprocal expression of ERalpha and ERbeta is associated with estrogen-mediated modulation of intestinal tumorigenesis

Menopausal hormone replacement therapy has been widely used to alleviate the symptoms of menopause and to decrease the detrimental effects of ovarian hormone loss on bone density and cardiovascular health. Multiple studies of colorectal cancer epidemiology also support a role for hormone replacement therapy in prevention of colorectal cancer. We studied the effect of ovariectomy and estrogen replacement on tumor formation in C57BL/6J-Min/+ (Min/+) mice, animals that bear a germline mutation in murine Apc. These mice develop multiple intestinal tumors that show loss of wild-type Apc protein. After ovariectomy, intestinal adenomas in Min/+ mice increased by 77% (P = 0.0004). Ovariectomized Min/+ mice that were treated with a replacement dose of 17beta-estradiol had the same number of tumors as Min/+ mice that were neither castrated nor treated with estrogen replacement (P = 0.85). Examination of estrogen receptor (ER) levels in intestinal tissue by immunoblot showed changes in relative expression levels of ERalpha and ERbeta, with highest ERalpha and lowest ERbeta expression in the normal-appearing intestine of Min/+ mice, and lowest ERalpha and highest ERbeta expression in the enterocytes of animals that received 17beta-estradiol. These results suggest that endogenous estrogens protect against Apc-associated tumor formation and that tumor prevention by 17beta-estradiol is associated with an increase in ERbeta and a decrease in ERalpha expression in the target tissue.

(+)-Catechin inhibits intestinal tumor formation and suppresses focal adhesion kinase activation in the min/+ mouse

Colorectal cancer is sensitive to dietary influences. Epidemiological data linking high intake of fruits and vegetables to decreased cancer risk have prompted the search for specific plant constituents implicated in tumor prevention. This task is difficult because of the complex chemical composition of plant foods and the multifactorial nature of carcinogenesis. Researchers are aided in this effort by the C57BL/6J-Min/+ (Min/+) mouse, an animal bearing a germline defect in Apc that is similar to the initiating genetic event in the majority of human colorectal cancers. In this study, we treated Min/+ mice with (+)-catechin, a phenolic antioxidant abundant in certain fruits. Administration of (+)-catechin in an AIN-76A diet at doses of 0.1 and 1% decreased the intestinal tumor number by 75 and 71%, respectively. Mechanistic studies linked this effect to (+)-catechin-induced changes in integrin-mediated intestinal cell-survival signaling, including structural alteration of the actin cytoskeleton and decreased focal adhesion kinase (FAK) tyrosine phosphorylation. Immunoblot analysis of small intestine scrapings from Min/+ mice and Apc+/+ wild-type C57BL/6J littermates together with excised Min/+ adenomas showed increased expression of phosphorylated FAK in the macroscopically normal enterocytes of untreated Min/+ mice and adenomas. Confirming the relevance of this signaling pathway, treatment of Min/+ mice with (+)-catechin reduced the expression of phosphorylated FAK to a level similar to the wild-type littermate controls. Thus, the natural abundance and favorable bioavailability of (+)-catechin make it a promising addition to the list of potential colorectal cancer chemopreventive agents.

Combined sentinel lymphadenectomy and mohs micrographic surgery for high-risk cutaneous squamous cell carcinoma

BACKGROUND

There are subgroups of cutaneous squamous cell carcinoma (SCC) that have a higher risk for both regional and distant metastasis. When cutaneous SCC does metastasize, it typically spreads first to local nodal groups. Sentinel lymph node (SLN) localization has been successfully used to evaluate nodal metastasis in breast carcinoma, melanoma, and other select tumors. It may also be useful in certain high-risk cutaneous SCCs. Currently, Mohs micrographic surgery is the treatment of choice for these tumors.

METHODS

A patient presented with a high-risk recurrent SCC on the forehead. The regional nodal groups were clinically negative and radiographically negative by computed tomographic scan. Sentinel lymphadenectomy was performed by means of technetium 99m-radiolabeled sulfur colloid. The main tumor was resected with Mohs micrographic surgery.

RESULTS

A left preauricular SLN was localized by lymphoscintigraphy. The SLN was located intraoperatively by means of a gamma probe and excised. Subsequent pathologic evaluation of the SLN was negative for evidence of metastatic SCC by light microscopy with hematoxylin and eosin, and with immunohistochemical stains for cytokeratins AE1 and AE3. The day after SLN excision, the tumor was removed via Mohs micrographic surgery with clear surgical margins after a total of 8 stages. Aggressive subclinical spread by both subcutaneous "skating" and perineural invasion was noted.

CONCLUSION

The combination of Mohs micrographic surgery and sentinel lymphadenectomy is feasible and has theoretical utility in the management of a subset of cutaneous SCCs at high risk for metastasis. The ability of sentinel lymphadenectomy to identify regionally metastatic cutaneous SCC as well as the additive benefit of SLN and Mohs micrographic extirpation in the treatment of high-risk cutaneous SCC remain to be further clarified.

Plant phenolics decrease intestinal tumors in an animal model of familial adenomatous polyposis

Epidemiological studies consistently indicate that consumption of fruits and vegetables lowers cancer risk in humans and suggest that certain dietary constituents may be effective in preventing colon cancer. Plant-derived phenolic compounds manifest many beneficial effects and can potentially inhibit several stages of carcinogenesis in vivo. In this study, we investigated the efficacy of several plant-derived phenolics, including caffeic acid phenethyl ester (CAPE), curcumin, quercetin and rutin, for the prevention of tumors in C57BL/6J-Min/+ (Min/+) mice. These animals bear a germline mutation in the Apc gene and spontaneously develop numerous intestinal adenomas by 15 weeks of age. At a dietary level of 0.15%, CAPE decreased tumor formation in Min/+ mice by 63%. Curcumin induced a similar tumor inhibition. Quercetin and rutin, however, both failed to alter tumor formation at dietary levels of 2%. Examination of intestinal tissue from the treated animals showed that tumor prevention by CAPE and curcumin was associated with increased enterocyte apoptosis and proliferation. CAPE and curcumin also decreased expression of the oncoprotein beta-catenin in the enterocytes of the Min/+ mouse, an observation previously associated with an antitumor effect. These data place the plant phenolics CAPE and curcumin among a growing list of anti-inflammatory agents that suppress Apc-associated intestinal carcinogenesis.

Inhibition of intestinal tumors by curcumin is associated with changes in the intestinal immune cell profile

BACKGROUND

The C57BL/6J-Min/+ (Min/+) mouse bears a germline mutation in Apc and is therefore a model for familial adenomatous polyposis and sporadic colorectal cancer. Min/+ intestinal mucosa exhibits a marked tendency for spontaneous adenoma formation. Curcumin is a phenolic antioxidant known for its antitumor and immune modulatory functions in vitro. Curcumin prevents adenoma formation in Min/+ mice, through a mechanism that may be related to its immunomodulatory properties.

MATERIALS AND METHODS

To study the relationship between intestinal immunity and curcumin-induced antitumor response, we used immunohistochemistry to characterize the effect of curcumin treatment on resident intestinal immune effector cells in Min/+ mice.

RESULTS/CONCLUSION

These results show that mucosal CD4(+) T cells and B cells increase in animals treated with curcumin, suggesting that curcumin modulates lymphocyte-mediated immune functions.

APC and intestinal carcinogenesis. Insights from animal models

The APC protein is a crucial regulator of intestinal cell growth, and mutations in the APC gene are a common initial event in the process of human colorectal carcinogenesis. Animals bearing germline mutations in Apc are therefore important models for human colorectal cancer. These animals have been used both to understand the biology of human colorectal cancer and to screen for agents able to prevent malignant transformation of susceptible intestinal cells.

Colon cancer chemopreventive drugs modulate integrin-mediated signaling pathways

Epidemiological studies of colorectal cancer incidence suggest that the development of this disease can be modulated by dietary factors. Among the micronutrients showing significant efficacy in tumor prevention are polyphenolic antioxidants found in fruits and vegetables. Epidemiological studies also indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) decrease the incidence of colorectal cancer. Integrin-mediated cell-matrix contact provides critical signaling that regulates cellular proliferation, migration, and apoptosis. A signaling mediator for this system is focal adhesion kinase (FAK). Thus far, FAK has not been identified as a target for the inhibitory action of any chemopreventive drug in vivo or in vitro. However, the loss of integrin-mediated cell-matrix contact can induce apoptosis (anoikis), and effective chemopreventive agents typically increase the rate of enterocyte apoptosis. Therefore, we asked whether the NSAID, sulindac sulfide, and the phenolic antioxidant, caffeic acid phenethyl ester (CAPE), affected FAK expression or tyrosine phosphorylation in human colon carcinoma cells. We show that subapoptotic doses of both sulindac sulfide and CAPE caused a rearrangement of the actin cytoskeleton and consequently the loss of focal adhesion plaques. These drugs also reduced the tyrosine phosphorylation of FAK and an associated factor, p130Cas. Steady-state levels of these proteins, together with other relevant signaling molecules, remained unchanged after treatments. Finally, we show that both CAPE and sulindac reduced cell invasion, a functional assay for the inhibition of signaling downstream of FAK. These data strongly suggest that chemopreventive drugs can regulate FAK activity. In conclusion, these novel studies add modulation of integrin-mediated signaling to the spectrum of activity of NSAIDs and plant phenolics.

Administration of an unconjugated bile acid increases duodenal tumors in a murine model of familial adenomatous polyposis

Intestinal carcinogenesis involves the successive accumulation of multiple genetic defects until cellular transformation to an invasive phenotype occurs. This process is modulated by many epigenetic factors. Unconjugated bile acids are tumor promoters whose presence in intestinal tissues is regulated by dietary factors. We studied the role of the unconjugated bile acid, chenodeoxycholate, in an animal model of familial adenomatous polyposis. Mice susceptible to intestinal tumors as a result of a germline mutation in Apc (Min/+ mice) were given a 10 week dietary treatment with 0.5% chenodeoxycholate. Following this, the mice were examined to determine tumor number, enterocyte proliferation, apoptosis and beta-catenin expression. Intestinal tissue prostaglandin E2 (PGE2) levels were also assessed. Administration of chenodeoxycholate in the diet increased duodenal tumor number in Min/+ mice. Promotion of duodenal tumor formation was accompanied by increased beta-catenin expression in duodenal cells, as well as increased PGE2 in duodenal tissue. These data suggest that unconjugated bile acids contribute to periampullary tumor formation in the setting of an Apc mutation.

Genotype-phenotype correlation in murine Apc mutation: differences in enterocyte migration and response to sulindac

The adenomatous polyposis coli (APC) gene product mediates coordinated cell growth in the intestinal mucosa. In humans, germ-line mutations of APC are associated with colorectal carcinogenesis, a process that varies in severity depending on the length of the protein resulting from the mutant allele. In a previous study of the C57BL/6J-Min/+ (Min/+) mouse, we found that the protein fragment resulting from truncation at codon 850 of murine Apc was associated with changes in enterocyte migration, proliferation, apoptosis, and beta-catenin expression. This effect was reversed upon treatment of Min/+ mice with the chemopreventive drug sulindac sulfide. In this study, we measured enterocyte migration in the Apc1638N mouse, an animal with an Apc mutation that yields no detectable APC protein. We found no difference in enterocyte migration, proliferation, apoptosis, or beta-catenin levels in the Apc1638N mouse when compared to wild-type littermates bearing two normal Apc alleles. Furthermore, administration of sulindac sulfide to Apc1638N mice did not alter enterocyte migration. These observations suggest that a dominant negative effect altering cell migration is exerted by the truncated APC protein present in the Min/+ mouse. These data also suggest that the effectiveness of chemopreventive agents in preventing Apc-related tumor formation may depend on which type of mutation is present.

Choledochal cysts in adults: a report of two cases and review of the literature

A choledocal cyst is a dilation of some component of the biliary tract that may include both intra- and extra-hepatic sites. They are classified into six types, all of which are relatively rare. Previously, choledochal cysts were treated with biliary-enteric bypass procedures. The current recommendation is to attempt complete excision to minimize the known risk of malignancy and the development of recurrent cholangitis or pancreatitis that may occur in patients with these cystic lesions. Two cases are discussed in which type I choledochal cysts presented. One was removed from a 31-yr-old man who presented with vague abdominal complaints the other from a 32-yr-old man who presented with pancreatitis. The epidemiology, diagnosis, surgical treatment, and risk of cancer in choledochal cysts is described.

Aspirin prevents tumors in a murine model of familial adenomatous polyposis

BACKGROUND

Both human and murine studies suggest that anti-inflammatory drugs prevent intestinal neoplasia. The purpose of this study was to investigate the role of aspirin as a chemopreventive agent for colorectal cancer.

METHODS

We administered aspirin to the Min/+ mouse, an animal with a germline mutation in Apc, a gene that is essential for normal epithelial cell growth and differentiation. Apc mutation increases cytoplasmic beta-catenin, a regulatory protein associated with the cytoskeleton. Min/+ mice develop multiple intestinal adenomas and exhibit altered cell growth in the preneoplastic intestinal epithelium.

RESULTS

Aspirin decreased the rate of tumor formation in Min/+ mice by 44%. Aspirin also normalized enterocyte growth by increasing apoptosis and proliferation in the preneoplastic intestinal mucosa. Finally, aspirin produced a decrease in intracellular beta-catenin levels, suggesting that modulation of this protein is associated with tumor prevention.

CONCLUSIONS

These data confirm a role for aspirin in suppression of Apc-associated intestinal carcinogenesis.

Aspirin prevents tumors in a murine model of familial adenomatous polyposis

BACKGROUND

Both human and murine studies suggest that anti-inflammatory drugs prevent intestinal neoplasia. The purpose of this study was to investigate the role of aspirin as a chemopreventive agent for colorectal cancer.

METHODS

We administered aspirin to the Min/+ mouse, an animal with a germline mutation in Apc, a gene that is essential for normal epithelial cell growth and differentiation. Apc mutation increases cytoplasmic beta-catenin, a regulatory protein associated with the cytoskeleton. Min/+ mice develop multiple intestinal adenomas and exhibit altered cell growth in the preneoplastic intestinal epithelium.

RESULTS

Aspirin decreased the rate of tumor formation in Min/+ mice by 44%. Aspirin also normalized enterocyte growth by increasing apoptosis and proliferation in the preneoplastic intestinal mucosa. Finally, aspirin produced a decrease in intracellular beta-catenin levels, suggesting that modulation of this protein is associated with tumor prevention.

CONCLUSIONS

These data confirm a role for aspirin in suppression of Apc-associated intestinal carcinogenesis.

The sulfide metabolite of sulindac prevents tumors and restores enterocyte apoptosis in a murine model of familial adenomatous polyposis

Sulindac, a non-steroidal anti-inflammatory drug (NSAID), is effective in treating intestinal adenomas in humans with Familial Adenomatous Polyposis (FAP) and in preventing intestinal tumors in the C57Bl/6J-Min+ (Min) mouse, an animal model of FAP. Sulindac is a prodrug metabolized by the liver and intestinal flora to a sulfone, which has no anti-inflammatory activity, and a sulfide, which is the active anti-inflammatory metabolite. In this study, we determined which of these metabolites is responsible for the anti-tumor effect of sulindac in Min mice. Min mice were treated with either sulindac sulfone or sulindac sulfide (0.5 +/- 0.1 mg/day). Min mice and homozygous C57Bl/6J-(+/+) normal litter-mates lacking the Apc mutation (+/+) were used as controls. At 110 days of age, all mice were euthanized and their intestinal tracts examined. Control Min mice had 33.2 +/- 6.6 tumors per mouse compared to 0.6 +/- 0.3 tumors for sulindac sulfide-treated Min mice (P < 0.001) and 21.9 +/- 4.5 tumors per mouse for sulindac sulfone-treated Min mice (P > 0.05). Decreased enterocyte apoptosis was observed in Min control mice and Min mice treated with sulindac sulfone. Sulindac sulfide restored to normal the level of apoptosis in the mucosa of Min animals and decreased levels of PGE2 in the small intestine of treated Min animals by 59% (P < 0.001). These data suggest that the anti-tumor effect of sulindac in Apc-deficient animals is mediated by the sulfide metabolite and correlates with suppression of tissue prostaglandin synthesis.

Apc gene mutation is associated with a dominant-negative effect upon intestinal cell migration

Apc-associated intestinal tumor formation appears to require functional loss of both Apc alleles. Apc has, therefore, been classified as a tumor suppressor gene. Loss of APC protein function results in increased intracellular beta-catenin, a molecule important to both cell-cell adhesion and regulation of cellular growth. In mice bearing a germ-line Apc mutation, we found that enterocyte beta-catenin expression was also increased in histologically normal intestinal mucosa. Enterocyte crypt-villus migration was decreased by 25%, and treatment of Min/+ animals with sulindac sulfide normalized both beta-catenin expression and enterocyte migration. Our data suggest that alterations in enterocyte migration occur in cells bearing a single mutant Apc allele, and that sulindac sulfide may normalize enterocyte growth in these cells.

Colon cancer prevention: intervening in a multistage process

Colorectal cancer, one of the most common human malignancies, is also one of the best understood. The epidemiology of this disease, and its relationship to environmental influences, particularly diet, has been extensively studied. New insights into the molecular biology and genetics of colorectal cancer also provide clues to its etiology, and high-risk populations that are most likely to benefit from preventive measures can be identified. Using this information, promising strategies for prevention of colorectal cancer are under investigation. These strategies include dietary modification, screening and adenoma removal, and antitumor agents from both natural and synthetic sources.

Surgical aspects of colorectal carcinoma

Colorectal surgery remains the cornerstone of curative therapy for colorectal carcinoma. The development of new instruments permitting technical advances, however, as well as the advent of effective adjuvant therapies and the progress in staging and early detection, have changed some of the indications for surgery as well as surgical methods. Even so, emphasis has always been placed on thorough preoperative evaluation and staging. This article explores the current state of standard surgical care of the colorectal cancer patient with special attention given to preoperative evaluation, standard and controversial surgical therapies, and postoperative surveillance.

Cyclooxygenase-2 overexpression and tumor formation are blocked by sulindac in a murine model of familial adenomatous polyposis

Inducible cyclooxygenase (Cox-2), also known as prostaglandin H synthase 2 (PGH-2) is a key enzyme in the formation of prostaglandins and thromboxanes. Cox-2 is the product of an immediate-early gene that is expressed in response to growth factors, tumor promoters, or cytokines. Overexpression of Cox-2 is associated with both human colon cancers and suppression of apoptosis in cultured epithelia] cells, an activity that is reversed by the nonsteroidal anti-inflammatory drug, sulindac sulfide. To address the relationship between Cox-2, apoptosis, and tumor development in vivo, we studied C57BL/6J-Min/+(Min) mice, a strain containing a fully penetrant dominant mutation in the Apc gene, leading to the development of gastrointestinal adenomas by 110 days of age. Min mice were fed AIN-76A chow diet and given sulindac (0.5 +/- 0.1 mg/day) in drinking water. Control Min mice and homozygous C57BL/6J-+/+ normal littermates lacking the Apc mutation (+/+) were fed AIN-76A diet and given tap water to drink. At 110 days of age, all mice were sacrificed, and their intestinal tracts were examined. Control Min mice had 11.9 +/- 7.8 tumors per mouse compared to 0.1 +/- 0.1 tumors for sulindac-treated Min mice. As expected, +/+ littermates had no macroscopic tumors. Examination of histologically normal-appearing small bowel from Min animals revealed increased amounts of Cox-2 and prostaglandin E(2) compared to +/+ littermates. Using two different in situ techniques, terminal transferase-mediated dUTP nick end labeling and a direct immunoperoxidase method, Min animals also demonstrated a 27-47% decrease in enterocyte apoptosis compared to +/+ animals. Treatment with sulindac not only inhibited tumor formation but decreased small bowel Cox-2 and prostaglandin E(2) to baseline and restored normal levels of apoptosis. These data suggest that overexpression of Cox-2 is associated with tumorigenesis in the gastrointestinal epithelium, and that both are inhibited by sulindac administration.

Evidence that rapamycin inhibits interleukin-12-induced proliferation of activated T lymphocytes

Interleukin 12 is a heterodimeric cytokine involved in the regulation of natural killer cell and T lymphocyte responses. In previous studies, we found that IL-12 induces proliferation of T cells only after co-stimulation with lectin, alloantigen, or anti-CD3 antibody. The IL-2-mediated proliferation of long-term T cell lines generated in this fashion is typically insensitive to the immunosuppressive agent, cyclosporine but sensitive to rapamycin. In this study, we examined the effect of cyclosporine and rapamycin on T cells responsive to IL-12. For long-term cultured T cell lines stimulated with phytohemagglutinin, alloantigen, or solid-phase anti-CD3 antibody, rapamycin blocked IL-12-induced proliferation to background levels. Culture in cyclosporine produced minimal inhibition of IL-12-induced T cell proliferation. Freshly isolated CD3+ cells did not proliferate in response to IL-12, nor did culture of these cells in IL-12 lead to upregulation of IL-2 receptor. These data suggest that the effect of IL-12, an important growth regulator for activated T lymphocytes, may involve late cellular activation events.

Immunomodulatory effects of interleukin-12 on human tumor-infiltrating lymphocytes

Interleukin (IL)-12 is a recently described cytokine with multiple immunoregulatory effects on various lymphoid populations, including peripheral blood lymphocytes (PBL), natural killer (NK) cells, and T-cell subsets. We examined the effects of recombinant IL-12 on the immune function of human tumor infiltrating lymphocytes (TIL) from several different tumor types. At an optimal concentration of 50 IU/ml, IL-12 acted as a co-stimulant for TIL recently activated with anti-CD3 antibodies, giving stimulation indices between 2.6 and 9.9. This co-stimulatory effect was independent of IL-2 and was not inhibited by neutralizing antibody to human IL-2. When IL-2 and IL-12 were used synchronously as co-mitogenic stimuli in culture with activated TIL, the effect on proliferation was additive. This additive effect held true over a range of suboptimal concentrations of IL-2 and in different TIL populations. IL-12 did not enhance non-major histocompatibility complex (MHC)-restricted cytotoxicity in the TIL populations tested. TIL cultured with IL-12 killed more autologous tumor targets than TIL maintained in media alone at identical effector/target (E/T) ratios. This effect on cytotoxicity was not as great as that seen in TIL maintained in low-dose IL-2. Co-culture with IL-12 did not change the phenotype of TIL used in these assays. The importance of these findings and possible uses in immunotherapy are discussed.

Staged antrectomy and thoracoscopic truncal vagotomy for perforated peptic ulcer disease

We report the case of a 40-year-old man with a perforated duodenal ulcer who underwent antrectomy at laparotomy, and in whom standard truncal vagotomy was not technically possible due to an intraabdominal abscess. Thoracoscopic truncal vagotomy performed at the level of the inferior pulmonary vein was successful in completely eliminating symptoms due to peptic ulcer disease without producing clinically significant morbidity. The minimal morbidity and short hospital stay suggest that thoracoscopic truncal vagotomy provides a reasonable alternative in patients with complicated intraabdominal abscesses due to peptic ulcer disease.

IL-12 augments antigen-dependent proliferation of activated T lymphocytes

Ag-dependent T cell activation requires multiple transmembrane signals including activation of Ag-specific T cell receptor in combination with signals delivered through cytokine receptors. IL-12 is a heterodimeric cytokine involved in the regulation of NK and T lymphocyte responses. In examining the role of IL-12 in T cell activation, we found a direct relationship between Ag stimulation and IL-12-induced proliferation. Unlike IL-2, which induced proliferation of CTL either in the presence or absence of a CD3/TCR co-signal, IL-12 mediated proliferation of CTL only when the cells were recently co-stimulated with alloantigen or solid-phase anti-CD3 antibody. After culture in the absence of alloantigen or anti-CD3 for 7 to 14 days, these CTL lost the ability to proliferate to IL-12 alone. Under these conditions, however, IL-12 synergized with low-dose IL-2 to induce CTL proliferation. Restimulation with alloantigen or solid-phase anti-CD3 restored the ability of the CTL to proliferate to IL-12 alone. Not all Ag signals resulted in IL-2 independent proliferation to IL-12. For example, CTL with specificity for influenza matrix peptide proliferated best when co-cultured with peptide Ag presented on self MHC and a combination of IL-2 and IL-12. This evidence suggests that IL-12 may be useful in expanding an Ag-specific T cell population, as the culture of CTL with IL-12 and low-dose IL-2 leads to proliferation only in response to an Ag co-signal.

IL-12 augments antigen-dependent proliferation of activated T lymphocytes

Ag-dependent T cell activation requires multiple transmembrane signals including activation of Ag-specific T cell receptor in combination with signals delivered through cytokine receptors. IL-12 is a heterodimeric cytokine involved in the regulation of NK and T lymphocyte responses. In examining the role of IL-12 in T cell activation, we found a direct relationship between Ag stimulation and IL-12-induced proliferation. Unlike IL-2, which induced proliferation of CTL either in the presence or absence of a CD3/TCR co-signal, IL-12 mediated proliferation of CTL only when the cells were recently co-stimulated with alloantigen or solid-phase anti-CD3 antibody. After culture in the absence of alloantigen or anti-CD3 for 7 to 14 days, these CTL lost the ability to proliferate to IL-12 alone. Under these conditions, however, IL-12 synergized with low-dose IL-2 to induce CTL proliferation. Restimulation with alloantigen or solid-phase anti-CD3 restored the ability of the CTL to proliferate to IL-12 alone. Not all Ag signals resulted in IL-2 independent proliferation to IL-12. For example, CTL with specificity for influenza matrix peptide proliferated best when co-cultured with peptide Ag presented on self MHC and a combination of IL-2 and IL-12. This evidence suggests that IL-12 may be useful in expanding an Ag-specific T cell population, as the culture of CTL with IL-12 and low-dose IL-2 leads to proliferation only in response to an Ag co-signal.

Approaches to immunotherapy of cancer: characterization of lymphokines as second signals for cytotoxic T-cell generation

Lymphokines, the soluble molecules produced by cells of the immune system, regulate cell-cell interactions and, consequently, the functional status of the immune system. Altering immunoregulatory pathways with lymphokines in vivo may provide a mechanism for controlling a variety of immunologic disorders. Although normally produced in vivo in very small quantities, the widespread availability of recombinant lymphokines has made it possible to study the molecular signals involved in production of lymphocyte effectors with activity against tumor. For example, interleukin-2-based cancer immunotherapy programs have, in certain clinical situations, suggested that immunologic intervention can influence the regression of metastatic cancer. Ultimately the successful application of these biologic agents requires an understanding of the interaction between the immune system and tumor on a molecular level. To induce a given biologic effect, it is necessary both to classify the required lymphokines and to identify the relevant effector cell populations. This review will examine the progress made in identifying the requirements for lymphokine-induced cytotoxic T-lymphocyte function.

IL-4-supported induction of cytolytic T lymphocytes requires IL-2 and IL-6

Previous work indicated that a CTL response can be generated by the combination of IL-2 plus IL-6 or IL-4 alone. Because of the ubiquitous production of IL-6 and its apparent ability to induce IL-2, we explored the interdependence of these lymphokines in supporting a CTL response from murine thymocytes. For thymocytes cultured in IL-4, further addition of IL-6 enhanced thymocyte proliferation. In addition, a role for IL-6 in thymocyte activation was indicated by the ability of anti-IL-6 mAb to block both IL-4-directed proliferation and the cytotoxic response found in the presence of IL-4. The addition of IL-2 to limiting doses of IL-4 augmented the CTL response; however, the response to high levels of IL-4 was not augmented by addition of IL-2. Consistent with this apparent involvement of IL-2 in the IL-4-mediated response we found: (a) that mAb to IL-2 significantly reduced the CTL response generated in the presence of IL-4; (b) that IL-2 activity was present in culture supernatant following incubation of thymocytes with high levels of IL-4; and (c) that enhanced IL-2 receptor expression found in the presence of IL-4 was blocked with the addition of anti-IL-2 antibody to the thymocyte culture. In contrast to the data for proliferation, anti-IL-4 mAb had no effect on the generation of CTL in the presence of IL-2 + IL-6 but readily blocked the CTL response to IL-4. These results indicate that, for thymocyte responders, the CD8+ CTL generated in the presence of IL-4 require both IL-2 and IL-6.