Gandhi, Leena

29 Background: CRS-207 is a live, attenuated, double-deleted Listeria monocytogenes (LADD) engineered to stimulate immune response to mesothelin. In a phase I trial of 60 MPM patients, 34% of subjects had tumor reduction (range -1 to -47%) following 2 doses of CRS-207 alone. In KEYNOTE-028 pembro showed activity in PDL1+ (≥1% by IHC) MPM, with an objective response rate (ORR) of 20% (5/25) and stable disease in 52% of subjects who had failed or did not receive chemotherapy. Subsequent studies of pembro have shown similar results in MPM. Results from a pre-clinical murine lung tumor model (CT26hMeso) showed anti-PD-1 enhanced LADD-induced tumor response. The study described here evaluated the efficacy of combination therapy of CRS-207/pembro. Methods: Adults with epithelial/biphasic MPM, ≤2 prior lines, progression on pemetrexed and platinum-based therapy, and no prior immunotherapies were enrolled. CRS-207/pembro were administered IV Q3W for 4 cycles, after which pembro continued Q3W and CRS-207 changed to Q6W. Response was assessed Q6W by modified RECIST for MPM (Byrne and Nowak, 2004). The primary endpoint was ORR; secondary endpoints included DOR, disease control rate (DCR), progression-free survival (PFS) and overall survival. Pre- and on-treatment blood and tumor samples were collected. Shedding and blood clearance of CRS-207 were evaluated. Results: 9/10 subjects were evaluable for response. No responses were observed; DCR was 11% (1/9 with SD) and PFS ranged from 3.4 to 8.9 weeks. Most common treatment related adverse events were chills, pyrexia and nausea. 3/10 subjects evaluated were PDL-1 negative by IHC. Of 6 subjects who underwent clearance and shedding evaluation, CRS-207 was detected in blood in 1 at 18-24 hrs after the first CRS-207 dose and cleared by the next evaluation at Day 4; shedding samples (urine, fecal, and saliva) tested negative. Conclusions: The toxicity profile of CRS-207/pembro combination was consistent with the safety profile of each component alone. No evidence of clinical activity was observed. Based on the results and an overall evaluation of the program, the clinical development of CRS-207 was discontinued. (NCT01675765) (NCT02054806). Clinical trial information: NCT03175172.

Assessment of tumor-infiltrating lymphocytes (TILs) in histopathologic specimens can provide important prognostic information in diverse solid tumor types, and may also be of value in predicting response to treatments. However, implementation as a routine clinical biomarker has not yet been achieved. As successful use of immune checkpoint inhibitors and other forms of immunotherapy become a clinical reality, the need for widely applicable, accessible, and reliable immunooncology biomarkers is clear. In part 1 of this review we briefly discuss the host immune response to tumors and different approaches to TIL assessment. We propose a standardized methodology to assess TILs in solid tumors on hematoxylin and eosin sections, in both primary and metastatic settings, based on the International Immuno-Oncology Biomarker Working Group guidelines for TIL assessment in invasive breast carcinoma. A review of the literature regarding the value of TIL assessment in different solid tumor types follows in part 2. The method we propose is reproducible, affordable, easily applied, and has demonstrated prognostic and predictive significance in invasive breast carcinoma. This standardized methodology may be used as a reference against which other methods are compared, and should be evaluated for clinical validity and utility. Standardization of TIL assessment will help to improve consistency and reproducibility in this field, enrich both the quality and quantity of comparable evidence, and help to thoroughly evaluate the utility of TILs assessment in this era of immunotherapy.

Assessment of the immune response to tumors is growing in importance as the prognostic implications of this response are increasingly recognized, and as immunotherapies are evaluated and implemented in different tumor types. However, many different approaches can be used to assess and describe the immune response, which limits efforts at implementation as a routine clinical biomarker. In part 1 of this review, we have proposed a standardized methodology to assess tumor-infiltrating lymphocytes (TILs) in solid tumors, based on the International Immuno-Oncology Biomarkers Working Group guidelines for invasive breast carcinoma. In part 2 of this review, we discuss the available evidence for the prognostic and predictive value of TILs in common solid tumors, including carcinomas of the lung, gastrointestinal tract, genitourinary system, gynecologic system, and head and neck, as well as primary brain tumors, mesothelioma and melanoma. The particularities and different emphases in TIL assessment in different tumor types are discussed. The standardized methodology we propose can be adapted to different tumor types and may be used as a standard against which other approaches can be compared. Standardization of TIL assessment will help clinicians, researchers and pathologists to conclusively evaluate the utility of this simple biomarker in the current era of immunotherapy.