PhD Scientific Days 2025

Pathological and Oncological Sciences II.

Comparison of immune-checkpoint inhibitor therapy efficacy according to the predictive marker tests, microsatellite instability (MSI) and mismatch-repair deficiency (dMMR), used for patient selection

Name of the presenter

Nádorvári Maja Lilla

Institute/workplace of the presenter

Patológiai, Igazságügyi és Biztosítási Orvostani Intézet

Authors

Maja Lilla Nádorvári¹, István Kenessey¹, Erzsébet Rásó¹, Judit Kocsis², György Bodoky³, Zsuzsanna Pápai⁴, Magdolna Dank⁵, Mónika Nádorvári⁶, Anikó Maráz⁷, Katalin Boér⁸, József Tímár¹

1: Department of Pathology, Forensic and Insurance Medicine, Semmelweis University
2: Department of Oncoradiology, Bács-Kiskun County Hospital, Kecskemét, Hungary
3: Department of Oncology, St László Teaching Hospital, Budapest, Hungary
4: Military Hospital Budapest, Department of Oncology
5: Department of Internal Medicine and Oncology, Semmelweis University, Budapest, Hungary
6: Department of Oncoradiology, Jósa András Szabolcs-Szatmár-Bereg County Hospital and University Teaching Hospital, Nyíregyháza, Hungary
7: Department of Oncotherapy, University of Szeged, Szeged, Hungary
8: Department of Medical Oncology, Szent Margit Hospital Budapest, Hungary

Text of the abstract

Background/objectives. International guideline recommendations consider
immunohistochemistry (IHC) for dMMR or molecular techniques (PCR, NGS) for MSI-high
determination equal, although there are scattered reports contradicting to this
presumption. Here we aimed to analyze if the efficacy of ICI (immune-checkpoint inhibitor)
therapies is influenced by the diagnostic method based on patient selection.
Materials and Methods. In this multi-center retrospective analysis, we have directly
compared 84 anti-PD1 immune-checkpoint inhibitor treated patients’ OS (overall survival)
and PFS (progression free survival) according to the qualifying diagnostic method: four MMR
protein IHC or Pentaplex MSI-PCR. 35 patients were diagnosed with MMR IHC and 49 with
MSI PCR tests. 30 male and 54 female patients were involved in the study and 62 patients
had colorectal cancer. The mean age of the patients was 68 years ±9 years, and 67±10 years
for the colorectal part of the cohort. The follow-up was set for four years. (SE-RKEB37/2024)
Results. For the entire cohort, the PFS of the MSI group at 48 month was 52.6% as compared
to the 59.5% of the dMMR group. Concerning OS, at 48 months 72.4% of MSI patients were
alive compared to 69.9% of the dMMR group. The Kaplan-Meier analysis did not show
significant differences neither in PFS (p=0.751) nor in OS (p=0.454). This analysis was
repeated for the colorectal cancer subcohort (n=62). At 48 months, the PFS of MSI patients
was 57.0% compared to 71.5% of the dMMR group. At 48 months, the OS of the colorectal
cancer patients was 77.9% for the MSI group and 75.5% for the dMMR group. The Kaplan-
Meier analysis again, did not demonstrate significant differences, neither in PFS (p=0.757)
nor in OS (p=0.529).
Conclusion. Our study demonstrated that the therapeutic efficacy of the anti-PD1 antibodies
in cancer patients is independent from the predictive markers used for patient selection
(MSI-PCR, MMR-IHC).