Clinical tools do not predict pathological complete response in patients with esophageal squamous cell cancer treated with definitive chemoradiotherapy.

Chemoradiotherapy for locally advanced esophageal squamous cell carcinoma is associated with high rates of pathological complete response. A pathological complete response is recognized to be an important predictor of improved survival, to the extent that observation rather than surgery is advocated by some in patients with presumed pathological complete response based on their clinical response. The goal of this study was to look at the ability of clinical variables to predict pathological complete response after chemoradiotherapy for locally advanced esophageal squamous cell carcinoma. We reviewed retrospectively patients with locally advanced esophageal squamous cell carcinoma who underwent chemoradiotherapy followed by surgery and compared those with pathological complete response to patients with residual disease. Between January 1996 and December 2010, 116 patients met inclusion criteria. Fifty-six percent of patients had a pathological complete response and a median survival of 128.1 months versus 28.4 months in patients with residual disease. When compared with patients with residual disease, patients with a pathological complete response had a lower post-neoadjuvant positron emission tomography (PET) maximum standardized uptake value (SUVmax), a larger decrease in PET SUVmax, a less thick tumor on post-chemoradiotherapy computed tomography and a higher rate of normal appearing post-chemoradiotherapy endoscopy with benign biopsy of the tumor bed. However, none of these characteristics alone was able to correctly identify patients with a pathological complete response, and none has significant specificity. Although the rate of pathological complete response after chemoradiotherapy is high in patients with esophageal squamous cell carcinoma, the ability of identifying patients with pathological complete response is limited. A reduction of the PET SUVmax by >70%, a normal appearing endoscopic examination, and no residual disease on biopsy all were seen in >65% of the patients with a pathological complete response. Even if these findings were unable to confirm the absence of residual disease in the primary tumor, they can help guide expectant management in high-risk patients.

Recurrence and survival after pathologic complete response to preoperative therapy followed by surgery for gastric or gastrooesophageal adenocarcinoma.

BACKGROUND: To characterise recurrence patterns and survival following pathologic complete response (pCR) in patients who received preoperative therapy for localised gastric or gastrooesophageal junction (GEJ) adenocarcinoma. METHODS: A retrospective review of a prospective database identified patients with pCR after preoperative chemotherapy for gastric or preoperative chemoradiation for GEJ (Siewert II/III) adenocarcinoma. Recurrence patterns, overall survival, recurrence-free survival, and disease-specific survival were analysed. RESULTS: From 1985 to 2009, 714 patients received preoperative therapy for localised gastric/GEJ adenocarcinoma, and 609 (85%) underwent a subsequent R0 resection. There were 60 patients (8.4%) with a pCR. Median follow-up was 46 months. Recurrence at 5 years was significantly lower for pCR vs non-pCR patients (27% and 51%, respectively, P=0.01). The probability of recurrence for patients with pCR was similar to non-pCR patients with pathologic stage I or II disease. Although the overall pattern of local/regional (LR) vs distant recurrence was comparable (43% LR vs 57% distant) between pCR and non-pCR groups, there was a significantly higher incidence of central nervous system (CNS) first recurrences in pCR patients (36 vs 4%, P=0.01). CONCLUSION: Patients with gastric or GEJ adenocarcinoma who achieve a pCR following preoperative therapy still have a significant risk of recurrence and cancer-specific death following resection. One third of the recurrences in the pCR group were symptomatic CNS recurrences. Increased awareness of the risk of CNS metastases and selective brain imaging in patients who achieve a pCR following preoperative therapy for gastric/GEJ adenocarcinoma is warranted.

The evaluation of adenoviral p53-mediated bystander effect in gene therapy of cancer.

Because many tumors have mutated p53, one potential strategy proposed for cancer gene therapy is the introduction of the wild-type p53 gene into tumor cells. One puzzling aspect of this approach is that currently available gene transfer protocols result in a small percentage of tumor cells being transduced in vivo, thus implicating a "bystander effect" to achieve therapeutic efficacy. Because bystander effects in the context of p53-mediated gene therapy have not been well characterized, we evaluated the role of in vitro and in vivo bystander effects of adenovirally delivered p53 (AdWTp53). Using human tumor cell lines that did not express p53 protein but were infectible with adenovirus and showed sensitivity to p53-mediated apoptosis, we were unable to demonstrate an AdWTp53-mediated in vitro bystander effect, despite seeing strong bystander effects when cells were infected with an adenovirus containing the suicide gene herpes simplex virus thymidine kinase and treated with ganciclovir. In contrast, in vivo flank mixing studies using one of these cell lines showed a weak but significant p53-mediated bystander effect (a 40% inhibition of tumor growth). This bystander effect translated into a small survival advantage in an established intraperitoneal tumor model when tumor burden was low at the time of viral instillation. The survival advantage was lost, however, when tumor burden was increased. This study indicates that treatment of human tumors using AdWTp53 may be possible; however, because of the weak bystander effect in vivo, effective treatment will likely require a large percentage of tumor cells to be transduced.

Use of a "replication-restricted" herpes virus to treat experimental human malignant mesothelioma.

Modified, nonneurovirulent herpes simplex viruses (HSVs) have shown promise in the treatment of brain tumors. However, HSV-1 can infect and lyse a wide range of cell types. In this report, we show that HSV-1716, a mutant lacking both copies of the gene coding ICP-34.5, can effectively treat a localized i.p. malignancy. Human malignant mesothelioma cells supported the growth of HSV-1716 and were efficiently lysed in vitro. i.p. injection of HSV-1716 into animals with established tumor nodules reduced tumor burden and significantly prolonged survival in an animal model of non-central nervous system-localized human malignancy without dissemination or persistence after i.p. injection into SCID mice bearing human tumors. These findings suggest that this virus may be efficacious and safe for use in localized human malignancies of nonneuronal origin such as malignant mesothelioma.