Astrid Reiser

Prognostic value of MACC1 and proficient mismatch repair status for recurrence risk prediction in stage II colon cancer patients: the BIOGRID studies

Background We assessed the novel MACC1 gene to further stratify stage II colon cancer patients with proficient mismatch repair (pMMR). Patients and methods Four cohorts with 596 patients were analyzed: Charité 1 discovery cohort was assayed for MACC1 mRNA expression and MMR in cryo-preserved tumors. Charité 2 comparison cohort was used to translate MACC1 qRT-PCR analyses to FFPE samples. In the BIOGRID 1 training cohort MACC1 mRNA levels were related to MACC1 protein levels from immunohistochemistry in FFPE sections; also analyzed for MMR. Chemotherapy-naïve pMMR patients were stratified by MACC1 mRNA and protein expression to establish risk groups based on recurrence-free survival (RFS). Risk stratification from BIOGRID 1 was confirmed in the BIOGRID 2 validation cohort. Pooled BIOGRID datasets produced a best effect-size estimate. Results In BIOGRID 1, using qRT-PCR and immunohistochemistry for MACC1 detection, pMMR/MACC1-low patients had a lower recurrence probability versus pMMR/MACC1-high patients (5-year RFS of 92% and 67% versus 100% and 68%, respectively). In BIOGRID 2, longer RFS was confirmed for pMMR/MACC1-low versus pMMR/MACC1-high patients (5-year RFS of 100% versus 90%, respectively). In the pooled dataset, 6.5% of patients were pMMR/MACC1-low with no disease recurrence, resulting in a 17% higher 5-year RFS [95% confidence interval (CI) (12.6%-21.3%)] versus pMMR/MACC1-high patients (P = 0.037). Outcomes were similar for pMMR/MACC1-low and deficient MMR (dMMR) patients (5-year RFS of 100% and 96%, respectively). Conclusions MACC1 expression stratifies colon cancer patients with unfavorable pMMR status. Stage II colon cancer patients with pMMR/MACC1-low tumors have a similar favorable prognosis to those with dMMR with potential implications for the role of adjuvant therapy.

Immunogenicity testing of therapeutic antibodies in ocular fluids after intravitreal injection.

AIM High drug concentrations in ocular fluids after intravitreal administration preclude the use of drug-sensitive immunoassays. A drug-tolerant immunoassay is therefore desirable for immunogenicity testing in ophthalmology. EXPERIMENTAL Immune complex (IC) antidrug antibody (ADA) assays were established for two species. The assays were compared with the bridging assay in ocular and plasma samples from two preclinical studies. RESULTS The IC assays showed high drug tolerance, which enabled a reliable ADA detection in ocular fluids after intravitreal administration. The IC assays were superior to the bridging assay in the analysis of ocular fluids with high drug concentrations. CONCLUSION The IC assay allows a reliable ADA detection in matrices with high drug concentrations, such as ocular fluids.

Abstract 2778: Combination of DNA mismatch repair status and MACC1 expression in patients with stage II colon cancer: The BIOGRID studies

We have previously identified the gene Metastasis-Associated in Colon Cancer 1 (MACC1). MACC1 acts a prognostic biomarker for tumor progression, metastasis and patient survival for a broad variety of solid cancer types. Here we assessed if the MACC1 gene could separate stage II colon cancer patients with proficient mismatch repair (pMMR) into high- and low-risk groups who might benefit from or be spared adjuvant chemotherapy based on their prognosis. In the Charite 1 discovery cohort (n=61), MACC1 expression and MSI status were assayed by qRT-PCR in cryo-preserved tumors from CRC patients. MSS/MSI-low/MACC1-low tumors showed better survival vs. MSS/MSI-low/MACC1-high (Pl0.0001). Patients with MSS/MSI-low/MACC1-low tumors had a similar prognosis as patients with MSI-H tumors. The Charite 2 comparison cohort (n=40) was used to translate MACC1 qRT-PCR analyses to FFPE samples. MACC1 expression was significantly higher in metachronously metastasizing tumors linked to shorter relapse-free survival (RFS), independent of the tissue type analyzed (cryo-preserved or FFPE). Next we translated MACC1 mRNA levels from qRT-PCR to MACC1 protein levels from immunohistochemistry (IHC) by comparing them in consecutive FFPE tumor sections in the BIOGRID 1 training cohort (n=189) enriched for disease recurrence. Chemotherapy-naive patients with unfavorable pMMR status separated into MACC1-high and -low groups. Better RFS was seen in the pMMR/MACC1-low vs. pMMR/MACC1-high group using MACC1 mRNA and protein expression. pMMR/MACC1-low expression was seen in 12% and 8% of patients by qRT-PCR and IHC; interestingly, they had the same favorable prognosis as the deficient MMR (dMMR) group. Prognostic and predictive findings from BIOGRID 1 were confirmed in the independent BIOGRID 2 validation cohort (n=306) unenriched for recurrence. Better RFS was again seen in chemotherapy-naive patients in the pMMR/MACC1-low (6%) vs. pMMR/MACC1-high group. No patients with pMMR/MACC1-low phenotype had disease recurrence. Remarkably, pooling BIOGRID 1 and 2, 5-year RFS was 100% and thus significantly longer in the pMMR/MACC1-low vs. pMMR/MACC1-high group (P=0.037). Taken together, MACC1 expression, measured by qRT-PCR or IHC, differentiates patients with unfavorable pMMR status. Patients with stage II colon cancer and pMMR/MACC1-low tumor status have a similar favorable prognosis as those patients with dMMR status who might not benefit from adjuvant therapy. Citation Format: Ulrich-Peter Rohr, Pia Herrmann, Katharina Ilm, Hai Zhang, Sabine Lohmann, Astrid Reiser, Andrea Muranyi, Janice Smith, Susen Burock, Marc Osterland, Katherine Leith, Shalini Singh, Patrick Brunhoeber, Rebecca Bowermaster, Jeanne Tie, Michael Christie, Hui-Li Wong, Paul Waring, Kandavel Shanmugam, Peter Gibbs, Ulrike S. Stein. Combination of DNA mismatch repair status and MACC1 expression in patients with stage II colon cancer: The BIOGRID studies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2778. doi:10.1158/1538-7445.AM2017-2778