Differential Spatial Gene and Protein Expression Associated with Recurrence Following Chemoradiation for Localized Anal Squamous Cell Cancer

The identification of transcriptomic and protein biomarkers prognosticating recurrence risk after chemoradiation of localized squamous cell carcinoma of the anus (SCCA) has been limited by a lack of available fresh tissue at initial presentation. We analyzed archival FFPE SCCA specimens from pretreatment biopsies prior to chemoradiation for protein and RNA biomarkers from patients with localized SCCA who recurred (N = 23) and who did not recur (N = 25). Tumor cells and the tumor microenvironment (TME) were analyzed separately to identify biomarkers with significantly different expression between the recurrent and non-recurrent groups. Recurrent patients had higher mean protein expression of FoxP3, MAPK-activation markers (BRAF, p38-MAPK) and PI3K/Akt activation (phospho-Akt) within the tumor regions. The TME was characterized by the higher protein expression of immune checkpoint biomarkers such as PD-1, OX40L and LAG3. For patients with recurrent SCCA, the higher mean protein expression of fibronectin was observed in the tumor and TME compartments. No significant differences in RNA expression were observed. The higher baseline expression of immune checkpoint biomarkers, together with markers of MAPK and PI3K/Akt signaling, are associated with recurrence following chemoradiation for patients with localized SCCA. These data provide a rationale towards the application of immune-based therapeutic strategies to improve curative-intent outcomes beyond conventional therapies for patients with SCCA.

Survival benefit to immunotherapy according to site of organ involvement in metastatic anal cancer

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Background: For patients with metastatic anal cancer, demonstration of anti-tumor activity by anti-PD-(L)1 antibodies has expanded the treatment landscape. To date, there are no predictive biomarkers associated with clinical benefit to immunotherapy in this setting. In the absence of clinical trials directly comparing chemotherapy and immunotherapy for metastatic anal cancer, the optimal sequencing of therapeutic lines remains undefined because historical series have been limited to cytotoxic chemotherapy. We evaluated the survival outcomes of patients with metastatic anal cancer following treatment with immunotherapy and with chemotherapy. Methods: We reviewed retrospectively the MD Anderson Cancer Center database for patients with unresectable and/or metastatic anal cancer diagnosed between 6/2014 and 11/2021. Median survival was estimated using the Kaplan-Meier method and compared between subpopulations of interest with a log-rank test. Results: Among 82 patients with metastatic anal cancer, 68 (83%) were female, and the median age was 60 years (range, 39-81). With a median follow-up time of 24.6 months, the median lines of systemic therapy were 2 (range, 1-5). 58 (71%) received anti-PD-(L)1 immunotherapy, either alone (N=51) or in combination with bevacizumab or with MEDI-0457 on a clinical trial (N=7). Median progression-free survival times (PFS) for lines 1, 2, and 3 of systemic therapy were 7.2 months (95% CI (Confidence Interval) 5.3-9.1; N=82), 3.6 months (95% CI 2.4-4.8; N=58), and 4.1 months (95% CI 2.8-5.4; N=34), respectively. In the treatment-refractory setting, no difference in median PFS between chemotherapy and immunotherapy was observed (4.7 months vs 2.9 months, respectively; hazard ratio (HR) 0.9, 95% CI 0.5-1.4); p=.17). Median overall survival (OS) was estimated at 33.9 months (95% CI, 24.0-34.8). For patients with metastatic anal cancer treated with immunotherapy, involvement of only distant lymph nodes (N=10/58, 17%) was associated with improved median PFS (11.3 months vs 2.8 months; HR 3.5, 95% CI 1.8-6.6; p=.002) and median OS (45.2 months vs 27.1 months; HR 2.9, 95% CI 1.3-6.5, p=.02) than other sites of distant organ involvement (N=48/58, 83%). Conclusions: In this single-institution retrospective study at a large academic referral center, both chemotherapy and immune checkpoint blockade were effective treatment options for patients with metastatic anal cancer. These data provide historical context in estimating median PFS necessary for future trial design in patients with metastatic anal cancer. Lymph node-only distribution of distant metastatic disease was predictive for improved survival with immunotherapy. Pending further validation, these data provide novel identification of a potential predictive factor associated with benefit to immunotherapy in patients with metastatic anal cancer.