PURPOSE Immune checkpoint inhibitor (ICI) therapy often is suspended because of immune-mediated diarrhea and colitis (IMDC). We examined the rate of and risk factors for IMDC recurrence after ICI resumption. METHODS This retrospective multicenter study examined patients who resumed ICI therapy after improvement of IMDC between January 2010 and November 2018. Univariable and multivariable logistic regression analyses assessed the association of clinical covariates and IMDC recurrence. RESULTS Of the 167 patients in our analysis, 32 resumed an anti–cytotoxic T-cell lymphocyte-4 (CTLA-4) agent, and 135 an anti–programmed cell death 1 or ligand 1 (PD-1/L1) agent. The median age was 60 years (interquartile range [IQR], 50-69 years). The median duration from IMDC to restart of ICI treatment was 49 days (IQR, 23-136 days). IMDC recurred in 57 patients (34%) overall (44% of those receiving an anti–CTLA-4 and 32% of those receiving an anti–PD-1/L1); 47 of these patients (82%) required immunosuppressive therapy for recurrent IMDC, and all required permanent discontinuation of ICI therapy. The median duration from ICI resumption to IMDC recurrence was 53 days (IQR, 22-138 days). On multivariable logistic regression, patients who received anti–PD-1/L1 therapy at initial IMDC had a higher risk of IMDC recurrence (odds ratio [OR], 3.45; 95% CI, 1.59 to 7.69; P = .002). Risk of IMDC recurrence was higher for patients who required immunosuppression for initial IMDC (OR, 3.22; 95% CI, 1.08 to 9.62; P = .019) or had a longer duration of IMDC symptoms in the initial episode (OR, 1.01; 95% CI, 1.00 to 1.03; P = .031). Risk of IMDC recurrence was lower after resumption of anti–PD-1/L1 therapy than after resumption of anti–CTLA-4 therapy (OR, 0.30; 95% CI, 0.11 to 0.81; P = .019). CONCLUSION One third of patients who resumed ICI treatment after IMDC experienced recurrent IMDC. Recurrence of IMDC was less frequent after resumption of anti–PD-1/L1 than after resumption of anti–CTLA-4.

Background: Bone metastases and skeletal-related events (SREs) are a frequent cause of morbidity in patients with metastatic non–small cell lung cancer (mNSCLC). Data are limited on bone metastases and SREs in patients with mNSCLC treated using immune checkpoint inhibitors (ICIs), and on the efficacy of bone-modifying agents (BMAs) in this setting. Here we report the incidence, impact on survival, risk factors for bone metastases and SREs, and impact of BMAs in patients with mNSCLC treated with ICIs in a multi-institutional cohort. Patients and Methods: We conducted a retrospective study of patients with mNSCLC treated with ICIs at 2 tertiary care centers from 2014 through 2017. Overall survival (OS) was compared between patients with and without baseline bone metastases using a log-rank test. A Cox regression model was used to evaluate the association between OS and the presence of bone metastases at ICI initiation, controlling for other confounding factors. Results: We identified a cohort of 330 patients who had received ICIs for metastatic disease. Median patient age was 63 years, most patients were treated in the second line or beyond (n=259; 78%), and nivolumab was the most common ICI (n=211; 64%). Median OS was 10 months (95% CI, 8.4–12.0). In our cohort, 124 patients (38%) had baseline bone metastases, and 43 (13%) developed SREs during or after ICI treatment. Patients with bone metastases had a higher hazard of death after controlling for performance status, histology, line of therapy, and disease burden (hazard ratio, 1.57; 95% CI, 1.19–2.08; P=.001). Use of BMAs was not associated with OS or a decreased risk of SREs. Conclusions: Presence of bone metastases at baseline was associated with a worse prognosis for patients with mNSCLC treated with ICI after controlling for multiple clinical characteristics. Use of BMAs was not associated with reduced SREs or a difference in survival.

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2633 Background: Emerging data suggest that concomitant medications (CM) influence response to ICI. CM impact the host microbiome which may mitigate tumor-immune responsiveness. PPI use in patients treated with ICI has been associated with worse survival. Few data exist regarding the effects of PPI use in terms of prior chemotherapy or in risk for immune related adverse events (irAE) (e.g., colitis). Methods: This retrospective study of patients with advanced cancer treated with ICI between 2011 and 2019 was conducted at The Ohio State University. Patients who received ICI as either single agent or combination were included. Clinical data was abstracted from chart review, including CM, toxicity, and survival. Overall survival (OS) was evaluated to date of death or last contact. Associations between OS and proton pump inhibitor (PPI) use were studied using log-rank tests and Cox regression analyses overall and by the groups of whether prior chemotherapy was administered and timing from chemotherapy to ICI. The associations between PPI and incidence of irAE (overall and colitis) were assessed by chi-square tests. Results: We identified 1,091 patients treated with ICI, of whom 415 (38%) received PPI at time of ICI. Most common cancers were NSCLC and melanoma; most common therapy was PD1/L1 (Table). PPI use was associated with shorter OS in patients treated as first line therapy (HR = 1.46, 95% CI = [1.11, 1.91], p=0.006) and in second line and beyond (HR = 1.30, 95% CI = [1.10, 1.53], p=0.002). PPI use was associated with shorter OS in patients treated with ICI for those without prior chemotherapy (HR = 1.47, 95% CI = [1.17, 1.86], p=0.001). When evaluated by timing from chemotherapy to ICI, PPI use was associated with shorter OS only in patients where last chemotherapy was > 1 year from ICI (HR = 1.99, 95% CI [1.15, 3.45], p=0.014) but not for patients with chemotherapy within 1 year of ICI (HR = 1.01, 95% CI = [0.79, 1.29], p=0.960). The use of PPI was not associated with incidence of irAE (p=0.317) or colitis in particular (p=0.781). Conclusions: PPI use was associated with shorter survival in patients treated with ICI across a broad variety of cancers and in first line of therapy or beyond. In patients with recent chemotherapy (<1 year), PPI use was not associated with survival, which may be due to disruption of the microbiome by chemotherapy. Further study is needed to determine the impact of CM (e.g, PPI), on outcomes of patients treated with ICI.[Table: see text]

Acute undifferentiated leukemia (AUL) is a subtype of acute leukemias of ambiguous lineage. There is no standard treatment approach for AUL, although acute lymphoblastic leukemia–like regimens for induction therapy have been used. Additional data suggest that AUL may be better treated as acute myeloid leukemia (AML), given their similarities in genetic, cytogenetic, and gene expression patterns. Somatic mutations of IDH1 are found in 7% to 14% of patients with AML; however, the patient in this study was the first patient with IDH1-mutated AUL treated with ivosidenib. In this case, a woman aged 39 years was found to have anemia and thrombocytopenia after presenting to her primary care physician with fatigue, weight loss, and persistent infections. During further workup of the cytopenia, she was diagnosed with AUL and received 7+3 (daunorubicin, 60 mg/m2/d intravenously on days 1–3, and cytarabine, 100 mg/m2 24-hour continuous intravenous infusion on days 1–7) due to the presence of the IDH1 mutation. Bone marrow biopsy performed on day 14 of 7+3 showed persistent disease, and ivosidenib was initiated due to severe HLA alloimmunization (panel-reactive antibody, 100%) and significant bleeding complications. The patient achieved a complete morphologic and molecular remission on ivosidenib monotherapy despite critical bleeding complications during induction. Targeted therapy using ivosidenib may represent an encouraging therapeutic option in patients with AUL and IDH1 mutations. Additional evaluation of ivosidenib in this subgroup of patients with AUL is needed.

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