QS217 - Perioperative Outcomes After Neoadjuvant Immunotherapy in MSI-H Colon Cancer

Monday, May 12, 2025

1:25 PM – 1:28 PM PT

Location: Room 9, Upper Level

Quick Shot Presenter(s)

Daniel A. Metzger, MD

Resident
Weill Cornell Medicine
New York Presbyterian/Weill Cornell
New York, NY, United States

All of the relevant financial relationships listed below have been mitigated.
This individual has no financial relationships with ineligible companies.

Author(s)

OW

Olivia Watman, MD, MBA

Resident
New York Presbyterian Brooklyn Methodist Hospital
Brooklyn, New York, United States

Disclosure information not submitted.
BG

Benjamin Greenspun, MD

Resident
Weill Cornell Medicine
New York, New York, United States

Disclosure information not submitted.
PS

Pooja S. Salvi, MD

Resident
New York Presbyterian - Weill Cornell Medical Center
New York, New York, United States

Disclosure information not submitted.
AG

Alexandra Gangi, MD

Associate Professor
Cedars Sinai Medical Center
LOS ANGELES, California, United States

Disclosure information not submitted.
JG

Jun Gong, MD

Medical Oncologist
Cedars-Sinai Medical Center
Los Angeles, California, United States

Disclosure information not submitted.
CF

Cathy Fan, MD

GI liver pancreas pathologist
Weill Cornell Medicine
Forest Hills, New York, United States

Disclosure information not submitted.
PG

Preethi Guniganti, Md

Assistant Professor of Radiology
Weill Cornell Medicine
New York, New York, United States

Disclosure information not submitted.
JH

Jini Hyun, MD, MS

Assistant Professor of Clinical Medicine
Weill Cornell Medicine, NYP-Queens
Flushing, New York, United States

Disclosure information not submitted.
DS

Despina Siolas, MD, PhD

Assistant Professor
Weill Cornell Medical College
New York, New York, United States

Disclosure information not submitted.
EH

Erika Hissong, MD

Assistant Professor of Pathology
New York Presbyterian-Weill Cornell Medicine
New York, New York, United States

Disclosure information not submitted.

Senior Author(s)

Mehraneh D. Jafari, MD (she/her/hers)

Director of Clinical Research; Department of Surgery
Weill Cornell Medicine
Weill Cornell Medicine
New York, New York, United States

All of the relevant financial relationships listed below have been mitigated.
This individual has no relevant relationships with ineligible companies.

All of the relevant financial relationships listed below have been mitigated.

Daniel A. Metzger, MD: This individual has no financial relationships with ineligible companies.

Mehraneh D. Jafari, MD: This individual has no relevant relationships with ineligible companies.

Image or Table (Do Not add text here):

Purpose/Background: Neoadjuvant immunotherapy can induce significant tumor regression in microsatellite instability-high (MSI-H) colon cancer, but its impact on surgical outcomes is not well-defined. Therefore, we report the first review of surgical outcomes after neoadjuvant immunotherapy for non-metastatic colon cancer (nmCC).

Methods/Interventions: We performed a retrospective analysis of patients with MSI-H nmCC who underwent colectomy after neoadjuvant immunotherapy between 2021-2024 as well as a control group of MSI-H colon cancer patients who did not receive neoadjuvant therapy during the same period. Perioperative outcomes were compared between the two groups. The pan-immune-inflammation value (PIV) was calculated for patients in neoadjuvant group and compared between those who had major pathologic response (MPR) (≥90%) and those who did not.

Results/Outcomes: Twenty-two patients were included, with 11 receiving neoadjuvant immunotherapy. The median age was 74 years (IQR: 67 - 82), with a balanced gender distribution. The median follow-up time was 185 days (IQR: 151 - 486). In the neoadjuvant group, 10 patients received pembrolizumab, and 1 received ipilimumab/nivolumab. MPR was seen in 7 tumors (70%), of which 6 (60%) had complete pathologic response. The median interval from immunotherapy initiation to surgery was 69 days (range: 34-209). Baseline PIV was lower in patients who had a major pathologic response to immunotherapy compared to those with incomplete or no response (362 vs 1,872; p=0.033). There were no differences between the neoadjuvant group and control group in operative time (neoadjuvant: 197 minutes vs. control: 161 minutes; p=0.6), conversion to open (neoadjuvant: 9.1% vs. control: 0%; p>0.9), length of stay (neoadjuvant: 7 days vs. control: 3 days; p=0.2), 30-day readmission rates (9.1% in both groups; p > 0.9), or Clavien-Dindo III-IV complications (neoadjuvant: 18.2% vs control: 9.1%; p>0.9). Dense adhesions near the tumor were encountered in 36% of the neoadjuvant group compared to 18% of the control group (p=0.6). There were no 90-day mortalities in either group. Adjuvant therapy was administered to 1 patient in the neoadjuvant group and 5 patients in the control group.

Conclusion/Discussion: Neoadjuvant immunotherapy was effective in inducing tumor regression in MSI-H colon cancer without compromising surgical safety and should be considered in patients with MSI-H colon cancer. Additionally, baseline PIVs may help predict response to immunotherapy.