Heads Up: 2018 ASCO GI Cancers Symposium

The 2018 Gastrointestinal Cancers Symposium is gearing up for its meeting in San Francisco, January 18 through January 20. Presentations will include important studies on topics such as a new way to detect colorectal cancer early, novel surgical approaches for GI cancers, the role of immunotherapy, and long-term evaluation of outcomes of patients receiving standard therapy for colorectal cancer.

Here is a summary of some meeting highlights:

CTC Blood-Based Assay (Abstract 556)

A simple blood test to detect the presence of circulating tumor cells (CTCs) — a liquid biopsy — identifies colorectal cancer (CRC) at early treatable stages with an accuracy of 84% to 88%. This is one of the first studies using the CTC blood test to detect GI cancer at early, rather than later, stages.

Lead author, Wen-Sy Tsai, MD, Linkou Chang Gung Memorial Hospital, Taipei, Taiwan, said that the CTC blood test “may point to a solution for people who are reluctant to get an initial screening colonoscopy or are not compliant in returning stool-based test kits that they get from their doctors.”

The study enrolled 620 people over the age of 20 coming to a single center for routine colonoscopies or with a confirmed diagnosis of CRC. Based on colonoscopy and biopsy, 438 people were found to have either adenomatous polyps or early- to late-stage CRC; the remainder had no evidence of pre-cancer or cancer. All 620 people had a blood analysis for CTC using the CMx assay. Blood test results were compared with colonoscopy results in a blinded fashion.

The assay was 97.3% specific with less than a 3% probability of a false-positive test. Sensitivity of the test was 77% for detection of pre-cancerous lesions and up to 87% for stage I-IV CRC. Considering both specificity and sensitivity, the accuracy of the test ranged from 84% to 88% for pre-cancerous and cancerous samples, respectively. The CTC blood test has superior accuracy compared with the fecal occult blood test, say the authors.

The CTC test is inexpensive, and the authors envision using it to screen people in Taiwan for CRC, continuing to use colonoscopy as a definitive diagnostic test if the CTC test is positive.

Surgical Approaches (Abstracts 6, 206)

A randomized, controlled trial found that robot-assisted minimally invasive thoraco-laparoscopic esophagectomy (RAMIE) improved overall surgery-related and cardiopulmonary outcomes, postoperative pain, as well as quality of life and functional recovery compared with open transaortic esophagectomy (OTE), the current standard curative treatment for resectable esophageal cancer.

Oncologic outcomes in the 112 patients enrolled in the trial, including disease-free survival (DFS) and overall survival (OS), were similar between the two groups at 38 months of follow-up. Mean cost of RAMIE was about 5000 € less than that for OTE. Lead author was Pieter Christiaan Van Der Sluis, MD, University Medical Center, Utrecht, The Netherlands.

The Phase II TACTICS trial found that sorafenib in combination with transarterial chemoembolization (TACE) improved outcomes over TACE alone in patients with unresectable hepatocellular carcinoma (HCC). Patients randomized to TACE plus sorafenib (n=80) had improved progression-free survival (PFS) compared with TACE alone (N=76): Median PFS was 25.2 months versus 13.5 months, respectively (P=.006). Median time to progression was 24.1 months and 13.5 months, respectively. Survival is still immature. There was no unexpected toxicity.

This study provides the first evidence for the benefit of adding sorafenib to TACE in this setting. Lead author was Masatoshi Kudo MD, Kindai University Faculty of Medicine, Osaka, Japan.

Immunotherapy in GI Cancer (Abstracts 209 and 553)

The anti-PD1 inhibitor pembrolizumab achieved durable responses and favorable PFS and OS in patients with advanced hepatocellular carcinoma (HCC) previously treated with sorafenib (79.8% progressed on sorafenib and 63.5% had extra-hepatic disease). In the phase II KEYNOTE-224 trial, 104 patients were treated with pembrolizumab. At data cut-off and a median follow-up of 8.4 months, 23% of patients were still on pembrolizumab.

Objective response rate (ORR) was 16.3% and was similar across subgroups with different etiology. Median time to response was 2.1 months, and 94% of responders were estimated to have a duration of response of 6 months or longer. Disease control rate was 65% (complete response 1 [1%], partial response 16 [15.4%], and stable disease in 47 [45.2%]), and progressive disease occurred in in 34 (32.7%). Median PFS was 4.8 months, and median OS was not reached. At 6 months, PFS was 43.1% and OS was 77.9%. Treatment-related adverse events occurred in 73.1%, and no new treatment-related concerns for pembrolizumab were raised.

Andrew X. Zhu, MD, Massachusetts General Hospital, Boston, was lead author.

First reports of efficacy and safety in the nivolumab plus ipilimumab cohort of CheckMate-142 demonstrate that 85% of patients with DNA mismatch repair-deficient/microsatellite instability-high (dMMR/MSI-H) metastatic CRC had clinical benefit from the combination with manageable toxicity. This is the largest single study report of an immunotherapy regimen in patients with this disease type, and it suggests that nivolumab plus ipilimumab may represent a new standard of care, according to lead author Thierry Andre, MD, Saint-Antoine Hospital, Paris, France, and co-authors.

The study included 119 previously treated patients with dMMR/MSI-H metastatic CRC, 76% of whom received at least 2 prior lines of therapy. At a median follow-up of 13.4 months, ORR was 55% and disease control rate was 80%. CR was 3%, PR was 51%, and stable disease rate was observed in 31%. Median duration of response has not yet been reached, and 94% of responses were ongoing at data cut-off. Nine-month PFS was 76% and OS was 87%. About one third of patients reported grades 3 or 4 treatment-related adverse events. No treatment-related deaths were reported.

Outcomes Over Time (Abstract 724)

Patients with stage III colon cancer treated in the “modern era” with FOLFOX adjuvant therapy (i.e, 2004-2009 after bevacizumab was approved by the FDA) had improved OS and nearly double survival after recurrence (SAR) compared with patients treated between 1998 and 2003 (“old era”), according to a large retrospective study based on the ACCENT database that includes 6 adjuvant therapy trials including FOLFOX, with a total of 7230 patients (stage II, 1122; stage III, 6108). Thirty-two percent were treated in the old era and 68% in the new era.

Stage III patients enrolled in the new era were significantly younger, more likely to have T4/N2 disease, higher tumor grade, and left-sided tumors. In an analysis adjusted for patient characteristics, no difference in disease-free survival (DFS) was observed between the old and new eras. However, median SAR was significantly prolonged from 14.8 months in the old era to 26.4 months in the new era (P<.001) and 5-year OS was significantly higher in the new era (75.2% versus 80.2%, respectively; P=.004).

These findings suggest that the optimal duration of OS follow-up to evaluate the benefits of adjuvant therapy should be reassessed, the authors state. It is currently 5 years. The ACCENT investigators plan to conduct additional longer-term analyses using their large database.

Lead author was Mohamed E. Salem, MD, Levine Cancer Institute, Carolinas HealthCare System, Charlotte, NC.

 

by Adrian Barfield, Founder and President, Medallion Healthcare

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