Mayo Clinic Arizona, Phoenix, AZ;
Daniel Walden , Sachin Deshmukh , Felipe Batalini , Binbin Zheng-Lin , Sharon Wu , Joanne Xiu , Emil Lou , Daniel H. Ahn , Christina Wu , Sanjay Goel , Anthony Frank Shields , David Spetzler , Matthew James Oberley , Wolfgang Michael Korn , Tanios S. Bekaii-Saab
Background: HR deficient (HRD) CRC has improved outcomes following exposure to DNA damaging agent (DDA) (irinotecan, IR; oxaliplatin, OX) compared to HRP CRC. Low expression of wild type (WT) BRCA1 mRNA is associated with prolonged OS in ovarian cancer; however, this finding has not been investigated in CRC or outside of BRCA. Here, we examine the effect of low expression of HR genes in HRP CRC on post-DDA survival. Methods: 12,860 CRC samples were analyzed by NGS (592, NextSeq; WES, NovaSeq) and WTS (NovaSeq) at Caris Life Sciences (Phoenix, AZ). Samples were classified by RNA expression percentiles. Real world OS was extracted from insurance claims and calculated using Kaplan-Meier estimates for molecularly defined cohorts from first of OX or IR to last contact. Results: Post-IR survival was prolonged with low expression of ATM, CHEK2 and PALB2 in WT ATM, PALB2, and CHEK2 WT CRC, respectively (bottom vs. top 10%, bottom vs. top 25%; p<0.05). Notably, low PALB2 expression (bottom 10%) showed a 14.5-month post-IR benefit compared to high PALB2 expression (top 10%) in WT PALB2 CRC (p=0.003). Post-OX survival was not significantly prolonged with low expression of CHEK2 in WT CHEK2 CRC (bottom 10% vs top 10%, bottom 25% vs top 25%) but was with low expression of ATM (+9.7 months, p=0.02) and PALB2 (+5.6 months, p=0.03) in WT ATM and PALB2 CRC, respectively (all bottom 25% vs top 25%). Conclusions: Here we report the first findings to suggest a novel subclass of CRC defined as the low expression of mRNA of non-mutated HRD genes that exhibit sensitivity to DDA. Low expression of WT ATM, CHEK2, and PALB2 correlates with prolonged OS following IR, post-OX survival was prolonged with low expression of ATM and PALB2. Further characterization defining sensitivity of low expressing HRP genes to DDA may help guide treatment considerations in HRP CRC.
DDA | Gene | HR (95% CI) | Bottom 25% | Top 25% | ∆ (mo) | P-val | HR (95% CI) | Bottom 10% | Top 10% | ∆ (mo) | P-val |
---|---|---|---|---|---|---|---|---|---|---|---|
OX | ATM | 0.80 (0.66-0.96) | 61.2mo N=906 | 51.5mo N=998 | +9.7 | 0.02 | 0.76 (0.56-1.04) | 57.2mo N=344 | 48.9mo N=393 | +8.3 | 0.08 |
CHEK2 | 0.87 (0.73-1.03) | 61.2mo N=1025 | 55.6mo N=1041 | +5.6 | 0.11 | 0.82 (0.62-1.08) | 61.5mo N=383 | 55.6mo N=406 | +5.9 | 0.16 | |
PALB2 | 0.82 (0.69-0.98) | 61.2mo N=1050 | 56.5mo N=1101 | +4.7 | 0.03 | 0.79 (0.59-1.05) | 57.2mo N=376 | 49.4mo N=419 | +7.8 | 0.10 | |
IR | ATM | 0.79 (0.62-0.99) | 35.4mo N=463 | 31.1mo N=637 | +4.3 | 0.04 | 0.64 (0.42-0.96) | 35.4mo N=178 | 31.1mo N=271 | +4.3 | 0.03 |
CHEK2 | 0.75 (0.60-0.94) | 43.5mo N=541 | 33.5mo N=646 | +10 | 0.01 | 0.62 (0.44-0.89) | 35.3mo N=207 | 31.1mo N=270 | +4 | 0.01 | |
PALB2 | 0.79 (0.64-0.97) | 35.4mo N=570 | 31.1mo N=658 | +4.3 | 0.03 | 0.57 (0.39-0.83) | 41.1mo N=205 | 26.6mo N=271 | +14.5 | 0.003 |
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Abstract Disclosures
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