No abstract

8504 Background: Neoadjuvant immune checkpoint inhibitors (ICIs) induce major pathologic response (MPR) rates of 20 to 45% in resected NSCLCs. We report the results of NEOSTAR - a phase 2 trial of neoadjuvant N or NI for NSCLCs. Methods: Pts with stage I-IIIA (single N2) resectable NSCLC (AJCC 7th), PS 0-1, were randomized to N (3 mg/kg IV, D1, 15, 29) or N plus I (1 mg/kg IV, D1) followed by surgery (n = 44). Primary endpoint: MPR (≤10% viable tumor), hypothesized to be higher than MPR to induction chemotherapy historical controls. Tumor immune infiltrates and pre- & post-ICI tumor PD-L1 % were assessed by flow cytometry & IHC. Wilcoxon ranked sum test & Fisher’s exact test were used for comparisons. Results: 44 pts were randomized, 23 N, 21 NI: mean age 66, 64% males, 18% never smokers, 59% adenocarcinomas, stages: IA 8 (18%), IB 15 (34%), IIA 7 (16%) IIB 5 (11%); IIIA 9 (20%). Only 3 pts received < 3 doses due to TRAEs (7%). 34 pts had surgery post ICIs (7 not resected [7/41], 17%, [2 N, 5 NI], 3 pending). There were 10 MPRs in 41 pts overall (24%, 4 N, 6 NI), of which 6 were path CRs (15%, 2 N [9%], 4 NI [21%]). Among 34 resected pts, MPR rate was 29% (N 20%, NI 43%). Median % of viable tumor was lower post NI vs N (20% vs 65%, p = .097). ORR (RECIST v1.1) was 22% (8 PRs [5 N, 3 NI], 1 CR [NI]); 15% of pts had PD (3 N, 3 NI). The proportion of CR+PR in MPR+ was higher than in MPR- (6 [60%] vs 2 [7%], p < .001). Surgical complications included 2 bronchopleural fistulas (BPFs) in N & 8 air leaks (5 N, 3 NI). G3-G5 TRAEs included a death due to BPF post steroid-treated pneumonitis (G5, N); G3 pneumonia, hypoxia, hypermagnesemia (1 each, all N), G3 diarrhea (1 NI). CD3+ & CD103+ tissue resident memory CD8+ TILs were higher in NI- vs N-treated tumors (CD3+ 81.2% vs 54.4%, p = .028; CD8+ 56.2% vs 38.3%, p = .069). Median pre-treatment tumor PD-L1 was higher in responders (MPR+, CR+PR) vs non-responders (80% vs 1%, p = .024), and the % of viable tumor was lower in tumors with PD-L1 > 1% vs PD-L1 ≤1% (median 20% vs 80%, p = .046). Conclusions: Overall a 24% MPR rate to neoadjuvant ICIs was observed. NI induced a higher % of non-viable tumor and of tissue resident memory TILs vs N. Antitumor activity was associated with higher pre-treatment PD-L1 levels. Clinical trial information: NCT03158129.

Limited clinical activity has been seen in osteosarcoma (OS) patients treated with immune checkpoint inhibitors (ICI). To gain insights into the immunogenic potential of these tumors, we conducted whole genome, RNA, and T-cell receptor sequencing, immunohistochemistry and reverse phase protein array profiling (RPPA) on OS specimens from 48 pediatric and adult patients with primary, relapsed, and metastatic OS. Median immune infiltrate level was lower than in other tumor types where ICI are effective, with concomitant low T-cell receptor clonalities. Neoantigen expression in OS was lacking and significantly associated with high levels of nonsense-mediated decay (NMD). Samples with low immune infiltrate had higher number of deleted genes while those with high immune infiltrate expressed higher levels of adaptive resistance pathways. PARP2 expression levels were significantly negatively associated with the immune infiltrate. Together, these data reveal multiple immunosuppressive features of OS and suggest immunotherapeutic opportunities in OS patients.

Highlights d Upregulated PHGDH in osteosarcoma correlates with poor survival d Inhibiting PHGDH attenuates osteosarcoma proliferation without causing cell death d TCA cycle blockade and accumulation of metabolites results in mTORC1 activation d PHGDH inhibition combined with non-rapalog mTORC1 inhibition is synergistic

Radiographic imaging is the standard approach for evaluating the disease involvement of lymph nodes in patients with operable NSCLC although the impact of neoadjuvant immune checkpoint inhibitors (ICIs) on lymph nodes has not yet been characterized. Herein, we present an ad hoc analysis of the NEOSTAR trial (NCT03158129) where we observed a phenomenon we refer to as “nodal immune flare” (NIF) in which patients treated with neoadjuvant ICIs demonstrate radiologically abnormal nodes post-therapy that upon pathological evaluation are devoid of cancer and demonstrate de novo non-caseating granulomas. Abnormal lymph nodes are analyzed by computed tomography and 18F-fluorodeoxyglucose positron emission tomography/computer tomography to evaluate the size and the maximum standard uptake value post- and pre-therapy in NEOSTAR and an independent neoadjuvant chemotherapy cohort. NIF occurs in 16% (7/44) of patients treated with ICIs but in 0% (0/28) of patients after neoadjuvant chemotherapy. NIF is associated with an inflamed nodal immune microenvironment and with fecal abundance of genera belonging to the family Coriobacteriaceae of phylum Actinobacteria, but not with tumor responses or treatment-related toxicity. Our findings suggest that this apparent radiological cancer progression in lymph nodes may occur due to an inflammatory response after neoadjuvant immunotherapy, and such cases should be evaluated by pathological examination to distinguish NIF from true nodal progression and to ensure appropriate clinical treatment planning.