PL02.3.A Survival and T-cell tumor reactivity in patients treated with nivolumab and bevacizumab for recurrent glioblastoma in the clinical trial CA209-9UP

Background

Glioblastoma (GBM) is an aggressive brain tumor with a median survival of 14.6 months. We have no standard treatment for relapse and current treatment options have limited effect. Novel treatments are necessary to improve survival and quality of life.

Material and Methods

We present data from; a phase II open label, two-armed clinical trial studying nivolumab and bevacizumab in treatment of recurrent GBM, with progression after Stupp’s regime. Patients were included in two arms depending on the possibility of salvage neurosurgical resection. All patients had biopsies for genome sequencing at primary tumor and recurrence. Both arms received nivolumab and bevacizumab administrated every second week and the surgical arm also received neoadjuvant nivolumab 7 days prior to surgery. Fresh tissue samples were collected for tumor digest, TILs (tumor infiltrating lymphocytes) for phenotype exploration and intracellular staining to test reactivity. Patients were treated until progression, death, or intolerable side effects. Toxicity screens were reported, and follow-up ended in Marts 2022.

Results

Forty-four patients were included from November 2018 to January 2022; 20 in each arm (four screen-failures). Treatment was overall well tolerated. Median (m) age at inclusion was 57,5 years (arm A) and 50,5 years (arm B), and the groups had an even distribution. The surgical and non-surgical arm had an mPFS of 5.95 and 3.83 months respectively, while the mOS was 13.96 months and 6.77 months, respectively. Multivariate analysis was performed by variables such us steroid, MGMT, gender, age at diagnosis, resection extent and arm. Steroid at inclusion was a significant negative predictor of outcome (p = 0.0378). Controls from our GBM registry (N=140), which were treated with neurosurgical resection and then bevazicumab and irinotecan in recurrent setting had an mOS of 8.64 months (log-rank p=0.0181).Furthermore, reactive tumor infiltrating lymphocytes (TIL) were detected in four of the patients who presented with a longer mOS and mPFS of 16.75 months and 9.18 months, while the 16 patients without TIL reactivity had mOS and mPFS of 12.63 months and 5.13 months, respectively (not significant).

Conclusion

We found an increased mOS in patients treated with nivolumab and bevacizumab at recurrence, compared to our controls: 13.96 months and 8.64 months, respectively. Four patients with T-cell reactivity towards tumor cells showed an even longer mPFS and mOS. Though not significant, these results warrant further research evaluation in larger patient cohorts. We are currently investigating proteomics and sequencing data to identify predictive biomarkers.

Developing the options for managing marine pests: specificity trials on the parasitic castrator, Sacculina carcini, against the European crab, Carcinus maenas, and related species

The impacts of introduced marine pests are becoming increasingly apparent, prompting interest in the possibility of their biological control. We undertook laboratory and field experiments on host selection of one potential control agent (the endoparasitic barnacle, Sacculina carcini) against its natural host (the widely invasive European shore crab, Carcinus maenas) and several confamilial and more distantly related crustaceans. For comparison, we also tested host specificity in a related parasitic barnacle, Heterosaccus lunatus. The results confirm indistinct behavioral host selection in S. carcini, indicate very different mechanisms for host selection by S. carcini and H. lunatus (which could be related to differences between the two species in attachment points), and suggest host specificity in S. carcini depends on interactions between the parasite and the host's physiology. Development of convincing safety trials for marine parasites like S. carcini, in which the infective stage is a planktonic larva, will be more difficult than for many terrestrial parasites and will require detailed knowledge of the parasite's behavior and physiological interaction with its hosts.

Tumors developing in nude mice express unusually large amounts of MHC class I antigens

Tumors were induced in athymic, T-cell-deficient nude mice and in syngeneic normal haired mice by treatment with low doses of 3-methylcholantrene (MCA). The tumors were studied for tumor cell expression of MHC class I molecules and for immunogenicity by transplantation to syngeneic haired recipients. Ten tumors were obtained by the MCA treatment, six from nude and four from haired mice. They were all fibrosarcomas as judged from their microscopic appearance. Five of the "nude" tumors expressed measurable amounts of MHC class I molecules and two of them expressed high amounts. Both were immunogenic in the sense that they evoked a cytotoxic T-cell response in transplanted haired recipients. Only one of the four "haired" tumors expressed measurable amounts of MHC class I, and none of them were immunogenic. These findings support the concept that some tumors are immunoselected at an early point of time in their existence in a host with a normal immune system and that this results in an elimination of tumor cell variants which are highly immunogenic for the T-cell system, leaving the low or non-immunogenic variants. These take over and grow and kill their host. The results suggest that tumor cell variants expressing high amounts of MHC class I are important targets in the immunoselection in hosts with a normal immune system.