Genomic and transcriptomic correlates of immunotherapy response within the tumor microenvironment of leptomeningeal metastases.

Leptomeningeal disease (LMD) is a devastating complication of solid tumor malignancies, with dire prognosis and no effective systemic treatment options. Over the past decade, the incidence of LMD has steadily increased due to therapeutics that have extended the survival of cancer patients, highlighting the need for new interventions. To examine the efficacy of immune checkpoint inhibitors (ICI) in patients with LMD, we completed two phase II clinical trials. Here, we investigate the cellular and molecular features underpinning observed patient trajectories in these trials by applying single-cell RNA and cell-free DNA profiling to longitudinal cerebrospinal fluid (CSF) draws from enrolled patients. We recover immune and malignant cell types in the CSF, characterize cell behavior changes following ICI, and identify genomic features associated with relevant clinical phenomena. Overall, our study describes the liquid LMD tumor microenvironment prior to and following ICI treatment and demonstrates clinical utility of cell-free and single-cell genomic measurements for LMD research.

Clinical outcomes of non-small cell lung cancer patients with leptomeningeal metastases after immune checkpoint inhibitor treatments.

OBJECTIVE: Leptomeningeal metastases (LM) occur in up to 5% of non-small cell lung cancer (NSCLC) patients and often develop after previous systemic treatments. In this article, we explored whether immune checkpoint inhibitors (ICIs) enhanced the dismal survival of patients with LM. MATERIALS AND METHODS: Data on NSCLC patients with LM prescribed ICIs were collected at the Guangdong Lung Cancer Institute. Furthermore, relevant literature was reviewed. RESULTS: A total of 255 NSCLC patients diagnosed with LM were screened from January 2015 to March 2020 at our institute. Cases reported by literature were also included. Finally, 32 NSCLC patients received ICIs after LM diagnosis; their median age was 55 years. Druggable genes were detected in 37.5% of all patients. The ICI regimens included nivolumab (n = 21), pembrolizumab (n = 9), and atezolizumab (n = 2). Ultimately, 62.5% of patients evidenced neurological symptom controlled. Two patients exhibited both intracranial and extracranial complete tumour response; one patient showed both intracranial and extracranial partial response (PR), one patient indicated intracranial PR and a systemic PR, and one patient showed central nervous system PR without extracranial response reported. The median progression-free survival (PFS) in the single-agent subgroup was 2.1 months (95% confidence interval [CI]: 1.4-2.9 months), and the median overall survival (OS) was 4.0 months (95% CI: 0.1-13.3 months). In the combined subgroup, the median PFS and OS were 3.0 months (95% CI: 1.1-4.9 months) and 5.4 months (95% CI: 0.5-10.3 months), respectively. Three patients exhibited remarkable PFS of over 20 months: all patients had ICI single agent, received cranial radiotherapy before ICI prescription, and took ICIs as second-line therapy, and two patients were EGFR/ALK wild type. Multivariate analysis showed that a better Eastern Cooperative Oncology Group Performance Status (ECOG-PS) score was associated with prolonged PFS (P = 0.04). No difference in survival was seen between monotherapy and combination therapy groups. CONCLUSION: NSCLC patients with LM may benefit from ICIs of both monotherapy and combination with other therapies, especially those with good ECOG-PS scores. Further work in this regard is required.

Antigen Mass May Influence Trastuzumab Concentrations in Cerebrospinal Fluid After Intrathecal Administration.

Intravenous administration of monoclonal antibodies leads to low concentrations in the central nervous system, which is a serious concern in neuro-oncology, especially in leptomeningeal carcinomatosis of HER2-overexpressing breast cancer. Case reports of i.t. administrations of trastuzumab have shown promising results in these patients but dosing regimens are empirical in absence of pharmacokinetic (PK) study. With a population PK approach, we described the fate of trastuzumab after i.t. administration in 21 women included in a phase I-II clinical trial. Trastuzumab was administered by i.t. route every week for 8 weeks and both cerebrospinal fluid (CSF) and serum were sampled to measure trough concentrations. Some patients showed noticeable CSF concentration fluctuations predicted using a target-mediated drug disposition. This target was latent and produced with a delayed feedback. Apparent volumes of distribution were close to physiological volumes (V1  = 3.25 L, V2  = 0.644 L, for serum and CSF, respectively). Estimated (constant) transfer from serum to CSF was very slow (k12  = 0.264 mg/day) whereas estimated half-life of transfer from CSF to serum was rapid (2.2 days). From the individual parameters of patients, a single i.t. administration of 150 mg of trastuzumab corresponded to median mean residence times of 3.8 days and 15.6 days in CSF and serum, respectively. Survival without neurological relapse was not related to trastuzumab exposure. This study confirms that transfer of trastuzumab from serum to CSF is very limited and that this monoclonal antibody, when administered by i.t. route, is rapidly transferred to the serum.