Immunotherapy in advanced Merkel cell carcinoma: Sydney west cancer network experience

Immunotherapy in advanced cutaneous squamous cell carcinoma: Sydney west cancer network experience

BACKGROUND

Cutaneous squamous cell carcinoma (CSCC) is the second most common malignancy in the Caucasian population. A minority of cases are inoperable at presentation, recur or develop metastatic disease with a historical 5-year overall survival of ~10%. Treatment options in this setting are generally palliative. Immunotherapy has emerged as a new paradigm in managing these patients.

METHODS

Patients presenting to Sydney West Cancer Network with locally advanced or metastatic CSCC treated with the anti-PD1 agent cemiplimab were identified. Response to treatment was objectively assessed based on RECIST1.1 or PERCIST criteria. Primary end point was objective response rate (ORR). Secondary end points included progression-free survival (PFS), overall survival (OS), therapy toxicity, and predictors of treatment response.

RESULTS

A total of 19 patients were identified with a median age of 76 (range 56-94) and 4 immunosuppressed. The longest follow up duration was 28 months. ORR, complete response (CR), and partial response (PR) were 68% (13/19), 53% (10/19), and 16% (3/19), respectively. Median PFS was 12 months (95% CI 9-14) whilst median OS was not reached by end of study. Responders (CR or PR) had significantly superior OS compared to those with no response (P < 0.01). A primary site of head and neck cancer was significantly associated with ORR (P = 0.04). A single patient experienced Grade 3 toxicity with the rest being Grades 0-1.

CONCLUSION

This study confirms the clinical efficacy of cemiplimab in patients with advanced CSCC with many experiencing a durable response and an acceptable adverse effect profile.

Transcriptional and functional analyses of neoantigen-specific CD4 T cells during a profound response to anti-PD-L1 in metastatic Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) often responds to PD-1 pathway blockade, regardless of tumor-viral status (~80% of cases driven by the Merkel cell polyomavirus (MCPyV)). Prior studies have characterized tumor-specific T cell responses to MCPyV, which have typically been CD8, but little is known about the T cell response to UV-induced neoantigens.

METHODS

A patient in her mid-50s with virus-negative (VN) MCC developed large liver metastases after a brief initial response to chemotherapy. She received anti-PD-L1 (avelumab) and had a partial response within 4 weeks. Whole exome sequencing (WES) was performed to determine potential neoantigen peptides. Characterization of peripheral blood neoantigen T cell responses was evaluated via interferon-gamma (IFNγ) ELISpot, flow cytometry and single-cell RNA sequencing. Tumor-resident T cells were characterized by multiplexed immunohistochemistry.

RESULTS

WES identified 1027 tumor-specific somatic mutations, similar to the published average of 1121 for VN-MCCs. Peptide prediction with a binding cut-off of ≤100 nM resulted in 77 peptides that were synthesized for T cell assays. Although peptides were predicted based on class I HLAs, we identified circulating CD4 T cells targeting 5 of 77 neoantigens. In contrast, no neoantigen-specific CD8 T cell responses were detected. Neoantigen-specific CD4 T cells were undetectable in blood before anti-PD-L1 therapy but became readily detectible shortly after starting therapy. T cells produced robust IFNγ when stimulated by neoantigen (mutant) peptides but not by the normal (wild-type) peptides. Single cell RNAseq showed neoantigen-reactive T cells expressed the Th1-associated transcription factor (T-bet) and associated cytokines. These CD4 T cells did not significantly exhibit cytotoxicity or non-Th1 markers. Within the pretreatment tumor, resident CD4 T cells were also Th1-skewed and expressed T-bet.

CONCLUSIONS

We identified and characterized tumor-specific Th1-skewed CD4 T cells targeting multiple neoantigens in a patient who experienced a profound and durable partial response to anti-PD-L1 therapy. To our knowledge, this is the first report of neoantigen-specific T cell responses in MCC. Although CD4 and CD8 T cells recognizing viral tumor antigens are often detectible in virus-positive MCC, only CD4 T cells recognizing neoantigens were detected in this patient. These findings suggest that CD4 T cells can play an important role in the response to anti-PD-(L)1 therapy.

Skin cancer biology and barriers to treatment: Recent applications of polymeric micro/nanostructures

Background

Skin cancer has been the leading type of cancer worldwide. Melanoma and non-melanoma skin cancers are now the most common types of skin cancer that have been reached to epidemic proportion. Based on the rapid prevalence of skin cancers, and lack of efficient drug delivery systems, it is essential to surge the possible ways to prevent or cure the disease.

Aim of review

Although surgical modalities and therapies have been made great progress in recent years, however, there is still an urgent need to alleviate its increased burden. Hence, understanding the precise pathophysiological signaling mechanisms and all other factors of such skin insults will be beneficial for the development of more efficient therapies.

Key scientific concepts of review

In this review, we explained new understandings about onset and development of skin cancer and described its management via polymeric micro/nano carriers-based therapies, highlighting the current key bottlenecks and future prospective in this field. In therapeutic drug/gene delivery approaches, polymeric carriers-based system is the most promising strategy. This review discusses that how polymers have successfully been exploited for development of micro/nanosized systems for efficient delivery of anticancer genes and drugs overcoming all the barriers and limitations associated with available conventional therapies. In addition to drug/gene delivery, intelligent polymeric nanocarriers platforms have also been established for combination anticancer therapies including photodynamic and photothermal, and for theranostic applications. This portfolio of latest approaches could promote the blooming growth of research and their clinical availability.