Many developing neural systems with peripheral projections depend on their target for trophic support during a critical period of natural cell death. Much less is known about central systems. That dopaminergic neurons of the substantia nigra may depend on their target, the striatum, during development is suggested by the presence of a natural apoptotic cell death event in these neurons that can be augmented by an early developmental axon-sparing striatal injury. To further assess the target dependence of these neurons, we have used the selective neurotoxin 6-hydroxydopamine to lesion their terminals within the striatum during development, while sparing intrinsic striatal target neurons. This lesion results in an induction of apoptotic cell death in phenotypically defined dopaminergic neurons that appears on the third postlesion day and persists until the tenth. This inducibility of cell death is dependent on developmental age: it is most marked before postnatal day (PND) 14. As late as PND42, inducibility is still detectable but much less so. In addition, at day 42 the morphology of cell death changes and becomes nonapoptotic in some cells. We conclude that terminal injury during a critical period of postnatal development, like axon-sparing target injury, induces augmented apoptotic death in mesencephalic dopaminergic neurons. These results suggest that these neurons have a period of target dependence. Regulation of this dependence is likely to influence the mature adult number of dopaminergic neurons.

BackgroundNivolumab is approved for patients with metastatic renal cell carcinoma (mRCC) refractory to prior antiangiogenic therapy. The clinical activity of nivolumab in patients with non-clear cell RCC subtypes remains unknown as these patients were excluded from the original nivolumab trials.MethodsPatients from 6 centers in the United States who received at least one dose of nivolumab for non-clear cell mRCC between 12/2015 and 06/2017 were identified. A retrospective analysis including patient characteristics, objective response rate according to RECIST v1.1 and treatment-related adverse events (TRAEs) was undertaken.ResultsForty-one patients were identified. Median age was 58 years (33–82), 71% were male, and majority had ECOG PS 0 (40%) or 1 (47%). Histology included 16 papillary, 14 unclassified, 5 chromophobe, 4 collecting duct, 1 Xp11 translocation and 1 MTSCC (mucinous tubular and spindle cell carcinoma). Among 35 patients who were evaluable for best response, 7 (20%) had PR and 10 (29%) had SD. Responses were observed in unclassified, papillary and collecting duct subtypes. In the entire cohort, median follow-up was 8.5 months and median treatment duration was 3.0 months. Median PFS was 3.5 months and median OS was not reached. Among responders, median time to best response was 5.1 months, and median duration of response was not reached as only 2 out of 7 responders had disease progression during follow-up. TRAEs of any grade were noted in 37% and most commonly included fatigue (12%), fever (10%) and rash (10%). Nivolumab treatments were postponed in 34% and discontinued in 15% of patients due to intolerance. No treatment-related deaths were observed.ConclusionsNivolumab monotherapy demonstrated objective responses and was well tolerated in a heterogeneous population of patients with non-clear cell mRCC. In the absence of other data in this treatment setting, this study lends support to the use of nivolumab for patients with metastatic non-clear cell renal cell carcinoma.

Lung cancer remains a leading cause of mortality with 1.69 million deaths worldwide. Activating mutations in epidermal growth factor receptor (EGFR), predominantly exon 19 deletions and exon 21 L858R mutations, are known oncogenic drivers identified in 20–40% of non-small-cell lung cancers (NSCLC). 70% of EGFR-mutant NSCLC patients develop brain metastases (BM), compared to 38% in EGFR wild-type patients. First-generation tyrosine kinase inhibitors (TKIs), such as erlotinib and gefitinib have proven to be superior to chemotherapy in the front-line treatment of EGFR-mutant NSCLC, as has afatinib, a second-generation TKI. The most common acquired resistance mechanism is the development of a gatekeeper mutation in exon 20 T790M. Osimertinib has emerged as a third-generation EGFR TKI with proven activity in the front-line setting as well as in patients with a T790M acquired resistance mutation with remarkable CNS activity. As long-term survival outcomes in EGFR-mutant NSCLC continue to improve, the burden of BM becomes a greater challenge. Here, we review the literature related to the management of BM in EGFR-mutant NSCLC including the role of the three generations of EGFR TKIs, immunotherapy, and brain radiation.

PURPOSE COSMIC-021 is evaluating cabozantinib plus atezolizumab in patients with solid tumors. We report results from patients with advanced clear cell (cc) and non–clear cell (ncc) renal cell carcinoma (RCC). METHODS This phase Ib study ( NCT03170960 ) enrolled patients age ≥ 18 years with advanced RCC. A dose-escalation stage was followed by expansion cohorts. For cohort expansion, prior systemic therapy was not permitted for ccRCC but allowed for nccRCC. Patients received oral cabozantinib 40 mg once a day (ccRCC and nccRCC) or 60 mg once a day (ccRCC only) plus atezolizumab (1,200 mg intravenously, once every 3 weeks). The primary end point was investigator-assessed objective response rate (ORR) per RECIST v1.1; the secondary end point was safety. RESULTS A total of 102 patients were enrolled. Median follow-up was 25.8, 15.3, and 13.3 months for the 40-mg ccRCC, 60-mg ccRCC, and nccRCC groups, respectively. ORR was 53% (80% CI, 41 to 65) in the 40-mg ccRCC group (n = 34) and 58% (80% CI, 46 to 70) in the 60-mg ccRCC group (n = 36), 3% and 11%, respectively, with complete response; median progression-free survival (exploratory end point) was 19.5 and 15.1 months, respectively. In nccRCC (n = 32), ORR was 31% (80% CI, 20 to 44), all partial responses; median progression-free survival was 9.5 months. Grade 3 or 4 treatment-related adverse events (TRAEs) were reported by 71% of patients in the 40-mg ccRCC group, 67% in the 60-mg ccRCC group, and 38% in the nccRCC group; TRAEs leading to discontinuation of both agents occurred in 15%, 6%, and 3% of patients, respectively. There were no grade 5 TRAEs. CONCLUSION The novel combination of cabozantinib plus atezolizumab demonstrated encouraging clinical activity and acceptable tolerability in patients with advanced ccRCC and nccRCC. Disease control was observed across dose levels and histologic subtypes.