Clinical trial designs for rare diseases: studies developed and discussed by the International Rare Cancers Initiative

BACKGROUND

The past three decades have seen rapid improvements in the diagnosis and treatment of most cancers and the most important contributor has been research. Progress in rare cancers has been slower, not least because of the challenges of undertaking research.

SETTINGS

The International Rare Cancers Initiative (IRCI) is a partnership which aims to stimulate and facilitate the development of international clinical trials for patients with rare cancers. It is focused on interventional--usually randomized--clinical trials with the clear goal of improving outcomes for patients. The key challenges are organisational and methodological. A multi-disciplinary workshop to review the methods used in ICRI portfolio trials was held in Amsterdam in September 2013. Other as-yet unrealised methods were also discussed.

RESULTS

The IRCI trials are each presented to exemplify possible approaches to designing credible trials in rare cancers. Researchers may consider these for use in future trials and understand the choices made for each design.

INTERPRETATION

Trials can be designed using a wide array of possibilities. There is no 'one size fits all' solution. In order to make progress in the rare diseases, decisions to change practice will have to be based on less direct evidence from clinical trials than in more common diseases.

Rituximab, methotrexate, procarbazine, and vincristine followed by consolidation reduced-dose whole-brain radiotherapy and cytarabine in newly diagnosed primary CNS lymphoma: final results and long-term outcome

PURPOSE

A multicenter phase II study was conducted to assess the efficacy of rituximab, methotrexate, procarbazine, and vincristine (R-MPV) followed by consolidation reduced-dose whole-brain radiotherapy (rdWBRT) and cytarabine in primary CNS lymphoma.

PATIENTS AND METHODS

Patients received induction chemotherapy with R-MPV (five to seven cycles); those achieving a complete response (CR) received rdWBRT (23.4 Gy), and otherwise, standard WBRT was offered (45 Gy). Consolidation cytarabine was given after the radiotherapy. The primary end point was 2-year progression-free survival (PFS) in patients receiving rdWBRT. Exploratory end points included prospective neuropsychological evaluation, analysis of magnetic resonance imaging (MRI) white matter changes using the Fazekas scale, and evaluation of the apparent diffusion coefficient (ADC) as a prognostic factor.

RESULTS

Fifty-two patients were enrolled, with median age of 60 years (range, 30 to 79 years) and median Karnofsky performance score of 70 (range, 50 to 100). Thirty-one patients (60%) achieved a CR after R-MPV and received rdWBRT. The 2-year PFS for this group was 77%; median PFS was 7.7 years. Median overall survival (OS) was not reached (median follow-up for survivors, 5.9 years); 3-year OS was 87%. The overall (N = 52) median PFS was 3.3 years, and median OS was 6.6 years. Cognitive assessment showed improvement in executive function (P < .01) and verbal memory (P < .05) after chemotherapy, and follow-up scores remained relatively stable across the various domains (n = 12). All examined MRIs (n = 28) displayed a Fazekas score of ≤ 3, and no patient developed scores of 4 to 5; differences in ADC values did not predict response (P = .15), PFS (P = .27), or OS (P = .33).

CONCLUSION

R-MPV combined with consolidation rdWBRT and cytarabine is associated with high response rates, long-term disease control, and minimal neurotoxicity.

Subdural hematoma in patients with cancer

BACKGROUND

Subdural hematoma (SDH) in patients with cancer is poorly described, and its frequency and causes may have changed with recent oncologic advances.

OBJECTIVE

We conducted an analysis of the clinical and radiographic features, etiologies, treatments, and outcomes of patients with SDHs and cancer.

METHODS

We retrospectively identified patients at Memorial Sloan-Kettering Cancer Center with a diagnosis of SDH and cancer from January 2000 to December 2007. We analyzed clinical and radiographic data; multivariate Cox regression was performed to associate tumor type and etiology with survival outcome.

RESULTS

There were 90 patients; 66 had acute or subacute SDHs, 9 chronic SDHs, 11 subdural hygromas, and 4 SDHs of unclear chronicity. Gliomas (16%), leukemias (14%), and prostate cancers (14%) were the most frequent malignancies. The most common single etiologies were coagulopathy (27%) and trauma (11%). SDHs with multiple etiologies occurred in 25 patients (28%) with the combination of coagulopathy and trauma occurring in 15. Sixty patients (67%) were either completely or partially independent after SDH, and 1-year survival was 43% (95% confidence interval: 32.1-52.9). Overall survival correlated with etiology (P < .0001) and whether the malignancy was in remission (P = .005). Trauma was associated with the best overall survival compared with coagulopathy.

CONCLUSION

Leukemia and prostate cancer are the most common systemic cancers associated with SDH, and gliomas may predispose to SDH more often than previously recognized. Coagulopathy is common and associated with the worst outcome, but many patients experience good functional outcome and survival.

Pharmacokinetics and tolerability of exemestane in combination with raloxifene in postmenopausal women with a history of breast cancer

PURPOSE

Raloxifene is a second-generation selective estrogen receptor modulator that reduces the incidence of breast cancer in postmenopausal women. Exemestane, a steroidal aromatase inhibitor, decreases contralateral new breast cancers in postmenopausal women when taken in the adjuvant setting. Preclinical evidence suggests a rationale for coadministration of these agents to achieve complete estrogen blockade.

EXPERIMENTAL DESIGN

We tested the safety and tolerability of combination exemestane and raloxifene in 11 postmenopausal women with a history of hormone receptor-negative breast cancer. Patients were randomized to either raloxifene (60 mg PO daily) or exemestane (25 mg PO daily) for 2 weeks. Patients then initiated combination therapy at the same dose levels for a minimum of 1 year. Pharmacokinetic and pharmacodynamic data for plasma estrogens, raloxifene, exemestane, and their metabolites were collected at the end of single-agent therapy and during combination therapy.

RESULTS

Plasma concentration-time profiles for each drug were unchanged with monotherapy versus combination therapy. Raloxifene did not affect plasma estrogen levels. Plasma estrogen concentrations were suppressed below the lower limit of detection by exemestane as monotherapy and when administered in combination with raloxifene. The most common adverse events of any grade included arthralgias, hot flashes, vaginal dryness and myalgias.

CONCLUSIONS

In this small study, coadministration of raloxifene and exemestane did not affect the pharmacokinetics or pharmacodynamics of either agent to a significant degree in postmenopausal women. The combination of estrogen receptor blockade and suppression of estrogen synthesis is well tolerated and warrants further investigation.

Immunization of high-risk breast cancer patients with clustered sTn-KLH conjugate plus the immunologic adjuvant QS-21

PURPOSE

To determine the clinical toxicities and antibody response against sTn and tumor cells expressing sTn following immunization of high-risk breast cancer patients with clustered sTn-KLH [sTn(c)-KLH] conjugate plus QS-21.

EXPERIMENTAL DESIGN

Twenty-seven patients with no evidence of disease and with a history of either stage IV no evidence of disease, rising tumor markers, stage II (>or=4 positive axillary nodes), or stage III disease received a total of five injections each during weeks 1, 2, 3, 7, and 19. Immunizations consisted of sTn(c)-KLH conjugate containing 30, 10, 3, or 1 microg sTn(c) plus 100 microg QS-21. Induction of IgM and IgG antibodies against synthetic sTn(c) and natural sTn on ovine submaxillary mucin were measured before and after therapy. Fluorescence-activated cell sorting analyses assessed reactivity of antibodies to LSC and MCF-7 tumor cells.

RESULTS

The most common toxicities were transient local skin reactions at the injection site and mild flu-like symptoms. All patients developed significant IgM and IgG antibody titers against sTn(c). Antibody titers against ovine submaxillary mucin were usually of lower titers. IgM reactivity with LSC tumor cells was observed in 21 patients and with MCF-7 cells in 13 patients. There was minimal IgG reactivity with LSC cells.

CONCLUSION

Immunization with sTn(c)-KLH conjugate plus QS-21 is well tolerated and immunogenic in high-risk breast cancer patients. Future trials will incorporate sTn(c) as a component of a multiple antigen vaccine.

Adjuvant (adj) bevacizumab (B) plus dose-dense (dd) doxorubicin/cyclophosphamide (AC) followed by nanoparticle albumin- bound paclitaxel (nab-p) in early stage breast cancer (BC) patients (pts): Cardiac safety

567

Background: Dose dense, q2 wk AC-paclitaxel (T) is superior to q3 wk therapy (Rx) (Citron, JCO 2003). The risk of congestive heart failure (CHF) with ddAC-T is not increased at <1%. In MBC, B improves PFS when added to T (Miller, SABCS 2005). It is unclear if doxorubicin plus B increases risk of CHF. Hence, we are testing the cardiac safety of ddAC-nab-p with concurrent B as adj therapy. Based upon the accepted cardiac event (CE) rate of ≤4% in trials with adj trastuzumab (an agent with known cardiac toxicity), we designed this study with similar monitoring & tolerability thresholds. The primary endpoint is cardiac safety, defined as discontinuation of B due to cardiac death from LV dysfunction or symptomatic CHF (dyspnea and LVEF<50%). Secondary endpoints: toxicity, disease-free & overall survival. Methods: Eligible pts have resected HER2(-) BC and normal LVEF. Rx consists of q2wk AC (60/600 mg/m2) ×4 then nab-p (260 mg/m2) x4 with pegfilgrastim on Day 2 plus B for one year (10mg/kg IV q2wk ×8 with chemoRx then B 15mg/kg q3wk); radiation & endocrine Rx per standard of care. MUGA obtained at baseline & mos. 2, 6, 9, 18. Pts with significant asymptomatic ↓LVEF during Rx may have B held per protocol. These pts are not counted as CEs but will have long-term cardiac monitoring. Accrual goal is 75 pts. If ≥3 CE (∼4.7%) or >1 cardiac death from LV dysfunction, B + ddAC-nab-p will not be considered safe. Results: 44 pts have enrolled, median (med) age 46.5 yrs (33–67). 28 pts have baseline & month 2 LVEF data: med baseline LVEF 68% (61–82), med LVEF at mo. 2 after ddAC+B 68% (53–75); 1 pt had an 18 point asymptomatic drop to 53% - B held but reinitiated in 4 wks with repeat LVEF 63%. 12 pts completed nab-p+B but none have reached the 6 mo. MUGA. Rx-related Gr 3/4 toxicity: neutropenia gr4 (6.8%), diarrhea gr3 (2.3%), hypertension gr3 (2.3%), neuropathy gr 3 (2.3%), fatigue gr 3 (2.3%), mucositis gr 3 (2.3%). 4 pts have withdrawn from study Rx, but only 1 due to toxicity including gr3 fatigue, mucositis & neuropathy. Conclusions: No LV dysfunction has been observed with B + ddAC-nab-p; this trial is on-going. Long-term follow-up and analysis of troponin, renin and circulating endothelial & tumor cells are planned.

No significant financial relationships to disclose.

Phase II trial of extended-dosing temozolomide in patients with melanoma

8531

Background: To test the hypothesis that the ∼30% response rate we observed in metastatic melanoma (mel) patients (pts) treated with temozolomide (TMZ) using an extended dosing schedule with either thalidomide or interferon was largely due to TMZ alone, we conducted a phase II trial of TMZ alone. We also hypothesized that mel expression of methylguanine methyltransferase (MGMT) would correlate with drug resistance. Methods: Stage IV mel pts without brain metastases or prior chemotherapy were stratified into two cohorts based on whether or not they had stage M1c disease. Each cycle consisted of TMZ 75 mg/m2/day for 6 weeks followed by 2 weeks with no treatment. Treatment cycles were repeated as long as pts did not progress. The primary endpoint was the proportion of complete or partial responses by RECIST criteria. The trial was powered to exclude the null hypothesis that the response rate in each cohort was <30%. MGMT promoter methylation status was assessed by methylation-specific pyrosequencing. In pts with insufficient tumor material for pyrosequencing, MGMT expression was measured by immunohistochemistry using the monoclonal antibody MT3.1. Results: To date we have accrued 48 pts, 23 in the M1c cohort. 7 pts are still receiving treatment and are not yet evaluable for response. There have been 4 partial responses observed, 2 in each cohort. The median number of cycles was 2 (range 1–6). 9/41 pts (22%) were stable for =6 months and received =3 cycles. 56% of pts developed CD4+ lymphopenia (<500/μl) during treatment; 37% of pts developed CD4+ lymphopenia <200/μl and received PCP prophylaxis. Opportunistic infections were not observed. Conclusions: The overall response rate is 9.8% (95% CI 0.8%-19%). The estimated median survival is 11 months for the stage III/M1a/b cohort and 9.7 months for the M1c cohort. To date, the response proportion to TMZ alone appears to be <30%. There would need to be 3 more responses in a cohort to reject the null hypothesis for that cohort. MGMT analyses are ongoing and will be used to determine if promoter methylation status correlates with objective response rate or time to progression. The study was supported by Schering-Plough.

No significant financial relationships to disclose.

In vitro expansion of Ag-specific T cells by HLA-A*0201-transfected K562 cells for immune monitoring

BACKGROUND

Development of a practical and sensitive assay for evaluating immune responses against cancer Ag has been a challenge for immune monitoring of patients. We have established a reproducible method using peptide-pulsed K562-A*0201 cells as APC to expand Ag-specific T cells in vitro. This method may be applied for monitoring T-cell responses in cancer immunotherapy clinical trials.

METHODS

Autologous PBMC from HLA-A*0201+ healthy donors and patients with melanoma were stimulated with peptide-pulsed K562-A*0201 cells under varying conditions. We investigated (1) different culture conditions, including the requirements for serum and cytokines for expansion of CD8+ T lymphocytes; (2) a range of peptide concentrations for Ag loading; (3) phenotypic characterization of responding T cells; and (4) APC:responder ratios and their effects on T-cell expansion. We validated these conditions by ELISPOT and intracellular cytokine staining (ICS) assays using peptides from influenza, Epslein-Barr Virus (EBV) and tyrosinase.

RESULTS

Conditions for optimal T-cell expansion using K562-A*0201 APC included input of 2 x 10(6) PBMC, a 10 microg/mL peptide concentration to pulse K562-A*0201 cells, a 1:30 APC:responder T-cell ratio and culture in 10% autologous plasma supplemented with IL-2 and IL-15. In these conditions, Ag-specific T cells expanded >100-fold over a 10-day culture period (peak at day 12).

DISCUSSION

This bulk culture method is simple and reliable for expanding human Ag-specific T cells using peptide-pulsed K562-A*0201 cells. This HLA-matched APC line can be adapted to other HLA haplotypes, and has advantages for monitoring clinical trials of immunotherapy with limited availability of autologous APC and PBMC from patients.

The serum IL-12:IL-6 ratio reliably distinguishes infectious from non-infectious causes of fever during autologous stem cell transplantation

BACKGROUND

Fever during neutropenia and after neutrophil engraftment (post-engraftment fever) occurs commonly during autologous transplantation (ASCT), but infections are infrequently identified. Tests that reliably exclude infection may reduce the cost and toxicity of unnecessary diagnostic testing and empiric treatment. We assessed whether serum levels of inflammatory cytokines could distinguish infectious from non-infectious causes of fever in patients undergoing ASCT.

METHODS

Serum levels of IL-1beta, IL-2, IL-6, IL-8, IL-10, IL-12(p70), TNF-alpha and IFN-gamma were measured by sandwich ELISA at multiple pre-determined times and at the onset of the first fever during neutropenia and after neutrophil engraftment in patients with hematologic malignancies undergoing ASCT. Standard clinical criteria were used to assess for the presence of infection.

RESULTS

Seventy-two febrile episodes occurred in 54 of 65 enrolled patients; 29 (40%) of the episodes occurred after neutrophil engraftment. Infections were identified as the cause of 28% and 24% of the neutropenic and post-engraftment febrile episodes, respectively. The level of IL-12 decreased and that of IL-6 increased significantly during fever because of infection, such that the IL-12:IL-6 ratio accurately excluded infection. The area under the ROC curve for the IL-12:IL-6 ratio was 0.88 (95% CI 0.79-0.97). The sensitivity, specificity, positive predictive and negative predictive values associated with a cut-off ratio of 4.1 were 95%, 75%, 60%, and 97%, respectively.

DISCUSSION

The IL-12:IL-6 ratio effectively discriminates infectious from non-infectious causes of fever during ASCT. It may be useful in assessing the probability of infection in patients with post-engraftment fever.

Phase II trial of extended-dosing temozolomide in patients with melanoma

8042

Background: We previously reported a 30% response rate in metastatic melanoma (mel) patients (pts) treated with temozolomide (TMZ) using an extended dosing schedule of 6 weeks on/ 2 weeks off with either thalidomide or interferon. We hypothesized that these responses were largely due to TMZ alone and conducted a phase II trial using extended dosing TMZ alone. We also tested the hypothesis that a) mel expression of methylguanine methyltransferase (MGMT) would correlate with drug resistance, and b) TMZ would cause decreased CD4+ T cell function during the first cycle of therapy. Methods: A phase II trial stratified metastatic mel patients into two cohorts based on whether or not they had stage IV M1c. 25 patients/cohort are planned. No brain metastases or prior chemotherapy were allowed. Each cycle consisted of TMZ 75mg/m2/day for 6 weeks followed by 2 weeks with no treatment. Primary endpoint was the proportion of objective responses by RECIST criteria. The trial was powered to exclude the null hypothesis that the response rate in each cohort was ≤10%. MGMT promoter methylation status was assessed by methylation-specific PCR. MGMT tumor expression was measured by immunohistochemistry (IHC). CD4+ T cell function was assessed by measuring interferon-γ responses to CMV by intracellular cytokine FACS analysis (FastImmune, BD Biosciences) at pretreatment, week 4 and week 8 of cycle 1. Results: To date 19 evaluable pts, 8 in the M1c cohort, have progressed with no objective responses; 6 other patients are currently on study. 4/19 pts who have gone off study because of progression were stable for 6 months and received ≥3 cycles. To date, 14/15 tumors analyzed for MGMT promoter methylation were unmethylated (≤15%). Promoter methylation of 21% was seen in one tumor. Conclusions: The MGMT promoter of metastatic mel tumors are hypomethylated predicting expression of the enzyme. This is being assessed directly by IHC and will be correlated with promoter methylation and clinical response. The effect of TMZ on anti-CMV CD4+ T cell function is being assessed. Accrual is ongoing and will be completed in Spring 2006. The study was supported by Schering-Plough.

No significant financial relationships to disclose.

Estimating survival probability in stage III melanoma: A multivariable individualized patient risk assessment nomogram

8020

Background: Recent revisions in the AJCC staging system have increased its complexity without comparable improvement in prognostic accuracy for patients with Stage III melanoma. Furthermore, there remains significant prognostic heterogeneity, even within Stages IIIA, IIIB, and IIIC. The current study was undertaken to develop a model for individual patient risk assessment, both to facilitate patient care, and to help define prognostically homogeneous patient populations for entry into clinical trials. Methods: Patients with AJCC Stage III melanoma were identified from a prospective single institution database. Overall survival was calculated from the date of Stage III to last followup. A multivariate Cox model of independent prognostic factors was developed, and a multivariable individualized patient risk assessment nomogram was built from that model. Results: Among 1,064 patients with Stage III melanoma, 535 have died, at a median followup of 44 months. Independent predictors of overall survival are shown in the table. Individual patient three and five year survival was predicted by incorporating all eight variables into a prognostic nomogram. The nomogram was superior to the AJCC Staging system in predicting outcome in Stage III melanoma patients. Conclusions: Individual patient risk assessment is more accurate than traditional AJCC staging in predicting outcome in Stage III melanoma. This approach, which can be easily incorporated into a handheld computing environment, offers potential advantages for both patient care and clinical research, and should be explored in the next iteration of the AJCC staging system.

[Table: see text]

No significant financial relationships to disclose.

Letrozole (L) with bevacizumab (B) is feasible in patients (pts) with hormone receptor-positive metastatic breast cancer (MBC)

3050

Background: Bevacizumab added to chemotherapy (CRx) prolongs PFS in pts with MBC. Data suggest that estrogen (E2) modulates VEGF-induced angiogenesis in physiologic and pathologic conditions. E2-induced VEGF expression may promote breast cancer growth therefore combination therapy with an aromatase inhibitor (AI) and an antibody to VEGF may be more effective than either agent alone. We performed a feasibility study testing B with L for the treatment (tx) of hormone receptor-positive MBC. Methods: Eligible pts have MBC and are candidates for AI therapy. Prior non-steroidal AI (NSAI) use without progression is permitted. Premenopausal pts undergo ovarian suppression/oophorectomy prior to tx. Therapy consists of L (2.5 mg daily) and B (15 mg/kg IV q3 weeks). The primary endpoint is frequency of Grade (Gr) 4 toxicity. Secondary endpoints include response rate, stable disease (SD) ≥ 6 mo and time to tumor progression. Using a two-stage design, 19 pts were accrued. Because <3 pts had Gr 4 toxicity, the 2nd stage is now enrolling an additional 23 pts. If <5 of the 42 pts have Gr 4 toxicity, the regimen will be considered feasible. Results: Thirty two pts are currently accrued and 28 are now evaluable. Medians: Age 49.5 yrs (32–77) and ECOG PS 0 (0–1). Sites of MBC: bone only 11/28, visceral 16/28, chest wall/soft tissue/lymph nodes 11/28. All are ER and/or PR (+); none are HER2 (+). Prior therapy: adjuvant CRx 20; adjuvant tamoxifen 14. Twenty five pts received an NSAI as first-line tx of MBC, starting a median of 23 wks (1–213) before B. Three pts received first-line tamoxifen; one pt had prior CRx for MBC. After a median of 8 cycles (1–20), tx-related toxicities: Gr 2: hypertension (HTN) 4, headache (HA) 4, proteinuria 3, fatigue 6, joint pain 5, hot flashes 1, epistaxis 1; Gr 3: HTN 5, HA 1, proteinuria 1. There has been no tx-related Gr 4/5 toxicity. Tx-related withdrawals: HTN 1 and headache 1. Twenty five pts are evaluable for response: PR 2, SD ≥ 6 mo 13, SD 4, progression 6. Conclusions: Combination L and B is well tolerated and will be studied in a randomized CALGB trial. Circulating endothelial and tumor cell data is reported separately. Supported in part by Genentech and Novartis.

[Table: see text]

Sentinel lymph node biopsy for patients with cutaneous desmoplastic melanoma

BACKGROUND

Although desmoplastic melanoma (DM) often presents at a locally advanced stage, nodal metastases are rare. We describe our experience with lymphatic mapping and sentinel lymph node biopsy (SLNB) in patients with DM to characterize the biological behavior of these tumors.

METHODS

Twenty-seven patients with cutaneous DM underwent wide excision and attempted SLNB between 1996 and 2001. All pathology was reviewed by a single dermatopathologist (KB). Clinical and histological features were recorded.

RESULTS

There were 20 male and 7 female patients. The median age was 64 years (range, 35-83 years). The head and neck was the most commonly involved anatomical region (n = 14). The median Breslow thickness was 2.2 mm. Twenty-four patients underwent successful SLNB. No patient had a positive sentinel node. At a median follow-up of 27 months, five patients recurred (four systemic and one local); all five had undergone successful SLNB. Two of these patients died of disease, two are alive with disease, and one remains alive and disease free. No patient experienced failure in a regional nodal basin.

CONCLUSIONS

DM is a biologically distinct form of melanoma, with a very low incidence of regional lymph node metastases, either at presentation or in long-term follow-up. This biology should be considered when designing rational treatment strategies for these patients.

Vaccination of high-risk breast cancer patients with mucin-1 (MUC1) keyhole limpet hemocyanin conjugate plus QS-21

Our objective was to determine whether an immune response can be generated against MUC1 peptide and against tumor cell MUC1 after vaccination with MUC1-keyhole limpet hemocyanin (KLH) conjugate plus QS-21 in breast cancer patients. Nine patients with a history of breast cancer but without evidence of disease were treated with MUC1-KLH conjugate plus QS-21, containing 100 microg of MUC1 and 100 microg of QS-21. s.c. vaccinations were administered at weeks 1, 2, 3, 7, and 19. Peripheral blood was drawn at frequent intervals to assess antibody titers. Skin tests were placed at weeks 1, 3, 9, and 21 to determine delayed type hypersensitivity reactions. Common toxicities included a local skin reaction at the site of the vaccine, usually of 4-5 days' duration, and mild flu-like symptoms usually of 1-2 days' duration. High IgM and IgG antibody titers against synthetic MUC1 were detected. IgG antibody titers remain elevated from a minimum of 106-137 weeks after the first vaccination. Binding of IgM antibody to MCF-7 tumor cells was observed in seven patients, although there was minimal binding of IgG antibody. Two patients developed significant antibody titers post-high-dose chemotherapy and stem cell reinfusion. There was no evidence of T cell activation. This MUC1-KLH conjugate plus QS-21 was immunogenic and well tolerated in breast cancer patients. Additional trials are ongoing to determine the optimal MUC1 peptide for use in larger clinical trials. Further investigation of vaccine therapy in high-risk breast cancer is warranted.

Wound tensile strength and contraction rate are not affected by laparotomy or pneumoperitoneum

BACKGROUND

Many cellular elements responsible for wound healing are affected by laparotomy. The aim of this study was to evaluate the effects of laparotomy and CO2 pneumoperitoneum on wound healing.

METHODS

Male Sprague Dawley rats were randomly assigned to one of three experimental groups. Anesthesia control rats underwent no procedure. Pneumoperitoneum group rats were insufflated with CO2 gas. Laparotomy group rats underwent a 7-cm midline laparotomy incision. The interventions were 30 min long. For the incisional study (n = 30), a 4-cm dorsal full-thickness skin incision was made on each rat and then closed with staples. On postoperative days 7 and 14, an equal number of rats were sacrificed from each group, and wound tensile strength measurements were performed. For the excisional study (n = 45), each group of 15 rats underwent a 2-cm diameter circular dorsal full-thickness skin excision. Blinded measurements of wound area were performed every other day until wounds closed.

RESULTS

Wound tensile strength values were not significantly different among experimental groups at either time point. The study had a power of 80% to find a 30% difference at POD 7 and a power of 80% to find a 23% difference at POD 14 to a confidence level of p < 0.05. Wound contraction data from the excisional model were analyzed with the Generalized Estimation Equations statistical approach. When we modeled the treatment group as a covariate, no statistical difference was found between groups, demonstrating equal slopes across time.

CONCLUSIONS

From the results of these studies, we conclude that wound healing in this model is not significantly diminished following laparotomy or peritoneal insufflation, as compared to anesthesia control.