444 CORRELATION BETWEEN PATHOLOGIC COMPLETE RESPONSE TO NEOADJUVANT THERAPY AND RECURRENCE IN PATIENTS WITH ESOPHAGEAL CANCER

Multimodal treatment options in carcinoma esophagus include neoadjuvant chemoradiotherapy or chemotherapy followed by surgery. The degree of pathologic response to different neoadjuvant options and its impact on the oncologic outcome is a matter of debate. With this background we carried out this study to analyze the rate of pathologic complete re-sponse (pCR) and its effect on recurrence in patients with carcinoma esophagus treated with various combinations of neoadjuvant chemotherapy/radiotherapy and surgery. Methods The records of all patients with carcinoma esophagus registered in our clinics between June 2012 and December 2014 were retrieved from a prospectively maintained database and were analyzed. of the 70 patients with histologically proven esophageal cancer who were treated with curative intent during this period, those with pCR (15) were followed up for a minimum of 5 years. These 15 patients are the subjects of this study. Results Forty eight (48) patients received neoadjuvant chemotherapy (NACT), 16 were treated with short course radiotherapy (SRT), and 3 patients received neoadjuvant chemoradiation (CRT). Four patients developed metastatic disease on neoadjuvant therapy. 66 patients (63 after neoadjuvant therapy and 3 upfront) underwent transthoracic esophagect-omy. Pathological CR was seen 12 patients (25%) in NACT-surgery arm, 2 (12%) in SRT-surgery and 1 (33%) in CRT-surgery groups. Three patients had postoperative mortality due to pulmo-nary complications. At 5 yrs, 14 out of 15 patients with pathological CR are alive and disease free. One patient developed brain metastases after 3 years and died. Conclusion Neoadjuvant therapy followed by radical surgery is a safe and effective treatment option for the management of carcinoma esophagus. Pathologic CR strongly correlates with recurrence-free survival. The relative significance of pCR after different types of neoadjuvant therapies need to be tested in future studies.

Pathological and Virological Studies of p16-Positive Oropharyngeal Carcinoma with a Good Response to Neoadjuvant Chemotherapy

Human papillomavirus (HPV)-related, p16-positive oropharyngeal carcinoma is considered to be sensitive to anticancer drugs, and the standard treatment is therefore chemoradiotherapy, rather than surgery, especially for aggressive disease. However, with this higher sensitivity, chemotherapy alone may achieve a pathological complete response (CR), making radiation therapy unnecessary. A 46-year-old man with p16-positive squamous cell carcinoma (SCC) of the lateral oropharynx (palatine tonsil) underwent neoadjuvant chemotherapy. This achieved clinically significant tumor shrinkage and therefore surgery was performed for subsequent definitive treatment. Clinical and CT findings indicated a good effect of neoadjuvant chemotherapy on the tumor. A biopsy prior to chemotherapy revealed SCC, which demonstrated p16 immunoreactivity and positive signals for high-risk HPV by RNA in situ hybridization. The post-chemotherapy surgical specimen showed pathological CR and no p16 positive cells nor positive signals for high-risk HPV those were detected in the pre-chemotherapy specimen. There are some reports of chemotherapy alone achieving pathological CR in cases of p16-positive oropharyngeal carcinoma, but none have included high-risk HPV RNA findings. This is the first report of the disappearance of cancer cells as well as p16 staining and a positive signal for high-risk HPV. Achieving pathological CR confirmed by immunohistochemistry and high-risk HPV RNA in situ hybridization in a solid tumor with chemotherapy alone suggests that chemotherapy may have both an antitumor effect and an antiviral effect. Forgoing subsequent radiotherapy and undergoing surgery might be unnecessary and follow-up instead might be sufficient in such cases. Into the future, in an optimal tailored treatment approach, the option of neoadjuvant chemotherapy should be considered for management of p16-positive oropharyngeal carcinoma. Other options such as tumor immunotherapy are also expected to be effective.

Pembrolizumab (pembro) + chemotherapy (chemo) as neoadjuvant treatment for triple negative breast cancer (TNBC): Preliminary results from KEYNOTE-173.

556 Background: Pembro has shown efficacy and acceptable safety in pts with previously treated metastatic TNBC. The phase Ib KEYNOTE-173 study (NCT02622074) evaluated pembro + chemo as neoadjuvant therapy for locally advanced TNBC. We present cohorts A and B. Methods: Women aged ≥18 y with locally advanced, nonmetastatic TNBC; ECOG PS 0/1; and no prior chemo, targeted therapy, or immunotherapy within 12 mo were eligible. Dosing in A was single-dose pembro followed by 4 cycles of pembro Q3W + nab-paclitaxel (Np) weekly followed by 4 cycles of pembro + doxorubicin + cyclophosphamide Q3W. Dosing in B was the same as in A but with carboplatin Q3W added to pembro + Np. Concentrations were pembro 200 mg; doxorubicin 60 mg/m2; cyclophosphamide 600 mg/m2; Np 125 mg/m2 in A, 100 mg/m2 in B; and carboplatin AUC 6 (1 cycle = 21 d). DLTs were assessed at cycles 1-3 and 6-7. Dose levels were deemed toxic if ≥3 of the first 6 pts or ≥4 of 10 pts had DLTs. Surgery was 3-6 wk after treatment completion/discontinuation. Primary end points were safety and recommended phase 2 dose of pembro combined with chemo. Key efficacy end points were pathological CR (pCR) rate, defined as ypT0/Tis, ypN0, and ypT0 ypN0, and ORR (RECIST v1.1, investigator). pCR analyses included all pts. Results: By Jan 6, 2017, 10 pts were in each cohort. Median age was 53 y (range 32-71); most pts had invasive ductal histology (90%), primary tumor stage ≥T2 (90%), and nodal involvement (75%). DLTs (myelosuppression) occurred in 7 pts (3 in A, 4 in B) and were unrelated to pembro. Gr 3-4 treatment-related AEs (TRAEs) occurred in 8 pts in A and 10 pts in B; none were fatal. One pt in A and 2 pts in B discontinued for a TRAE (2 ALT elevations with pembro; 1 DVT with chemo). Overall ORR (CR+PR) before surgery was 80% (90% CI, 49-96) in A and 100% (90% CI, 74-100) in B. ypT0/Tis pCR rate was 70% (90% CI, 39-91) in A and 100% (90% CI, 74-100) in B; ypT0 ypN0 pCR rate was 50% (90% CI, 22-78) in A and 90% (90% CI, 61-100) in B; and yT0/Tis ypN0 pCR rate was 60% (90% CI, 30-85) in A and 90% (90% CI, 61-100) in B. Conclusions: Preliminary data suggest that pembro + chemo as neoadjuvant therapy for TNBC results in manageable toxicity and promising antitumor activity. Clinical trial information: NCT02622074.

Phase I study of the safety and activity of formulated IL-12 plasmid administered intraperitoneally in combination with standard neoadjuvant chemotherapy in patients with newly diagnosed advanced stage ovarian cancer.

155 Background: This study evaluated weekly intraperitoneal GEN-1, an IL-12 plasmid formulated with polyethyleneglycol-polyethyleneimine cholesterol lipopolymer, in combination with dose-dense weekly taxane (T) and carboplatinum (C) every 3 weeks in newly diagnosed epithelial ovarian, fallopian tube, or primary peritoneal cancer (EOC) patients undergoing neoadjuvant therapy (NAC). The primary objective of this study was to evaluate the tolerability and safety of GEN-1 with NAC. Secondary objectives were objective clinical response and pathological complete response at interval debulking surgery (IDB). Methods: This protocol followed a standard 3+3 design. Patients received GEN-1 at escalating dose levels from 36 mg/m2, 47 mg/m2, 61 mg/m2, to 79 mg/m2 weekly for 8 treatments with concurrent T/C. After IDB, patients did not receive further GEN-1 but continued on T/C. Patients were assessed for dose limiting toxicities (DLT) and had tumor samples at a time of diagnostic laparoscopy and IDB. Translational endpoints are yet to be analyzed. Patients are being followed for every 3 months for 2 years. Results: Fifteen patients were enrolled and 9 patients received all 8 treatments with no DLTs. The 79 mg/m2GEN-1 cohort of patients are actively being treated. Two patients were screen failures; 1 patient discontinued prior to GEN-1 administration due to port site infection. Most common related toxicities were Gr 1 nausea, fatigue, abdominal pain, and vomiting. One patient experienced Gr 2 fevers associated with GEN-1 but responded to acetaminophen and fluids. One patient did not undergo IDB due to pulmonary embolism and severe deconditioning due to underlying cancer. Of the other 8 patients undergoing IDB: 3/8 had stable disease, 4/8 had partial responses (PR), and 1/8 had complete response (CR). There was 1 pathological CR, 3 micro PR, and 3 macro PR. All patients had a ≥ 89% drop in CA-125 following GEN-1. Conclusions: Adding GEN-1 to T/C is safe and appears to be active in NAC patients with newly diagnosed EOC. Updated results to be presented at meeting. Clinical trial information: NCT02480374.