Poster Walks: Cancers of the Colon, Rectum, and Anus

George A. Fisher Jr., MD, PhD—Poster Walk Leader
Stanford University

Abstract 563: A phase II study of GVAX colon vaccine with cyclophosphamide and pembrolizumab in patients with mismatch repair–proficient (MMR-p) advanced colorectal cancer.
First Author: Mark Yarchoan, MD

Conclusions: GVAX/Cy plus pembrolizumab is well tolerated in advanced MMRp CRC and resulted in CEA responses but not radiographic responses. PFS and OS compare favorably to historical controls in this small cohort. CEA responses were not observed with PD1 monotherapy in MMRp CRC, suggesting GVAX can modulate the antitumor immune response. Clinical trial information: NCT02981524

Abstract 564: Genetic variants in the lipopolysaccharide (LPS) receptor complex and TLR4 expression levels to predict efficacy of cetuximab (cet) in patients (pts) with metastatic colorectal cancer (mCRC): Data from the FIRE-3 phase III trial.
First Author: Francesca Battaglin, MD

Conclusions: Our results provide the first evidence that polymorphisms in the LPS receptor complex and TLR4 expression levels may have a predictive value in mCRC pts receiving first-line cetuximab-based treatment and, overall, contribute to resistance to anti-EGFRs.

Abstract 589: Characterisation of chemoradiation-induced changes in immune cells and targets for personalized therapy in locally advanced rectal cancer (LARC).
First Author: Elisa Fontana, MD

Conclusions: The expression of immune-related genes is significantly modified by CRT in LARC. With the caveat of small numbers, we identified differentially expressed immune targets at baseline which may justify immune-CRT combinations in neoadjuvant setting in selected pts to modulate the CRT effect and ultimately increase response.

Abstract 619: A systematic review and network meta-analysis of regorafenib and TAS-102 in refractory metastatic colorectal cancer.
First Author: Mohamad Bassam Sonbol, MD

Conclusions: Regorafenib 160 and TAS-102 appear to have similar efficacy. Rego 80+ is shown to be superior to BSC. A trend for improved OS was observed with Rego 80+ versus Rego 160 or TAS 102.

Abstract 670: Safety and clinical activity of durvalumab monotherapy in patients with microsatellite instability–high (MSI-H) tumors.
First Author: Neil Howard Segal, MD, PhD

Conclusions: Durvalumab had a tolerable safety profile, and showed promising antitumor activity and overall survival in patients with MSI-H tumors. Clinical trial information: NCT01693562 and NCT02227667.

 

Marcia Cruz-Correa, MD, PhD—Poster Walk Leader
The University of Puerto Rico and MD Anderson Cancer Center

Abstract 505: Gene-specific features (MLH1, MSH2, MSH6, PMS2) of mismatch repair (MMR) protein expression and somatic mutations (muts), microsatellite instability (MSI) and tumor mutational burden (TMB) in MSI-H and MMR-mutated tumor genomic profiles (TGPs).
First Author: Michael J. Hall, MD, MS

Conclusions: MSI-H and MMR mutated tumors demonstrate marked gene-specific heterogeneity in IHC patterns, TMBs, and somatic muts that may be relevant to treatment selection, resistance, and response.

Abstract 515: Microsatellite instability detection from plasma of colorectal cancer patients.
First Author: Jing Sun, MD, PhD

Conclusions: We developed a sensitive algorithm which can reliably detect MSI status with ctDNA fraction greater than 0.4% with a sensitivity of 93.3% and specificity of 100%.

Abstract 604: Comprehensive landscape of gene amplifications (amps) in tissue and circulating tumor DNA (ctDNA) in metastatic colorectal cancer (mCRC).
First Author: Kanwal Pratap Singh Raghav, MD, MBBS

Conclusions: While individually uncommon, amps occur across key oncogenic pathways in mCRC and after adjusting for ctDNA shedding, are seen at similar prevalence in tissue and plasma. Amps in RTKs are seen in 10-12% of RB WT tumors, suggesting clinically relevant roles as oncogenic effectors and targets. After EGFRi, a number of amps emerge, including PIK3CA and FGFR1 amps, not previously implicated in acquired resistance.

Abstract 606: Characteristics of colorectal cancer (CRC) patients with BRCA1 and BRCA2 mutations.
First Author: Madiha Naseem, MD

Conclusions: This is the first study to show that BRCA1/2 mutations are more frequent in MSI-H, and independently associated with higher TMB, pathogenic POLE mutations, and right-sided tumors in MSI-H CRCs. Given their relationship with TMB, the presence of BRCA1/2 mutations may be potential predictive biomarkers for checkpoint or PARP inhibitors in CRC, a finding that should be prospectively evaluated.

Abstract 618: Timing of first surveillance colonoscopy in stage I colon cancer patients and the association with colon cancer-specific survival.
First Author: Robert Brooks Hines, PhD

Conclusions: Although stage I colon cancer patients have a good prognosis, patients who received colonoscopy within one year of cancer-directed surgery experienced significantly better survival than patients who did not receive colonoscopy within 3 years of surgery. The results of this study justify efforts to ensure that stage I colon cancer patients receive colonoscopic surveillance testing approximately 1 year following cancer-directed surgery.