Cancer is a leading cause of mortality worldwide. According to Cancer Research UK, the total deaths from cancer globally in 2018 were 9.6 million led by lung, liver, stomach and bowel cancers. There were 18 million new cancer cases in 2018; 9.5 million cases for men and 8.5 million for women.

World Cancer Day 2019, which is held annually on 4 February, was set up in 2000 to promote research and development (R&D) into cancers themselves and possible treatments, improve patient services, and mobilise the global community to continue working against cancer.

Global cancer R&D spending reached the $100bn mark in 2014, up $25bn from 2010, according to an IMS Health oncology report. The US National Cancer Institute’s 2018 budget was $5.7bn, and this is projected to increase to $6.5bn by 2020.

Rare cancers might be uncommon individually, but collectively they represent approximately 20% of all cancer cases. Taken as a whole, rare cancers represent a huge source of largely unmet clinical need.

Rare cancers are defined as fewer than six incidences per 100,000 people. There are approximately 200 different types of rare cancer with around 22% occurring in the blood and lymphatic system, 18% in the female reproductive system and 14% both in the digestive system and the head and neck.

Patients with rare cancers struggle with misdiagnosis, as well as a lack of access to appropriate therapies and clinical expertise due to lack of interest as the market is small and a limited number of patients who can participate in clinical trials.

Below is an exploration of three promising pipeline treatments for rare cancers that currently have limited treatment options.

Investigating efficacy of ADT in salivary gland cancer

Salivary gland cancers often start in the parotid glands and are uncommon since approximately 75% of lumps found in the glands are benign. Roughly 720 people are diagnosed with this type of cancer in the UK every year, according to Cancer Research UK.

The common standard of care for salivary gland cancers is surgery followed by radiotherapy and chemotherapy.

Researchers sponsored by the European Organisation for Research and Treatment of Cancer (EORTC) are currently conducting a study comparing chemotherapy with androgen deprivation therapy (ADT) in both chemo-naïve patients and pre-treated patients.

The androgen receptor has been identified as a target for the disease, because androgen expression has been found in salivary duct carcinoma and adenocarcinomas.

Androgen receptors are part of the steroid and nuclear receptor group that are activated by binding to androgenic hormones, such include testosterone and dihydrotestrone. It blocks DNA-binding transcription factor regulating gene expression.

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They are commonly used as drug targets for prostate cancer; for example, Johnson & Johnson subsidiary Janssen’s Erleada is an anti-androgen medicine approved for non-metastatic castration-resistant prostate cancer and being investigated in combination with ADT for metastatic castration-sensitive prostate cancer.

EORTC’s multi-centre, randomised trial, which is expected to be completed in 2021, is testing for progression-free survival over 37 months in chemo-naïve patients and a response rate over 37 months for pre-treated patients.

Understanding drug resistance of NUT midline carcinoma

Researchers from the Brigham and Women’s Hospital (BWH) in Boston, US, have started to explore the cancer drivers that can lead to NUT midline carcinoma becoming resistant to bromodomain and extraterminal (BET) domain inhibitors.

NUT midline carcinoma is defined by rearrangements in the NUT gene. In 75% of case the NUTM1 gene disconnects and fuses with the BET protein, hence why BET inhibitors have usually been the standard of care for these patients.

The team discovered six general classes of genes that seemed to drive cancer resistance to the BET inhibitors; the most interesting was genes targeted by CDK4/6 inhibitors, which seemed to be involved in drug resistance.

Pre-clinical studies combining BET inhibitors and CDK4/6 inhibitors showed the drugs stopped tumours from growing, so these findings present the possibility of new, improved clinical trial designs and outcomes for NUT midline carcinoma.

BWH Department of Pathology professor Christopher French, who has studied NUT midline carcinoma, said: “The Elledge lab discovery provides a scientifically rational direction to improve the efficacy of BET inhibitors, by combination with CDK4/6 inhibitors. I think you will see the impact of their findings in the next round of BET-inhibitor based clinical trials for this disease and others.”

Studying pembrolizumab’s efficacy in small bowel adenocarcinoma

The US National Cancer Institute is currently contributing to a Phase II study of monoclonal antibody pembrolizumab – marketed by Merck as Keytruda – in treating patients with small bowel adenocarcinoma (SBA) that has metastasised or cannot be removed by surgery.

SBA is the most common type of small bower cancer, which originates in the lining of the organ. Only around 1,500 people in the UK are diagnosed with any type of small bowel cancer, according to Macmillan Cancer Support.

The disease has often been treated using drugs developed for colon cancer, but studies have suggested SBA has a distinct genomic profile and therefore needs different types of treatment.

Pembrolizumab is an immunotherapy that targets and blocks a protein called programmed death ligand-1 (PD-1) on the surface of immune T cells, which stimulates T cells to find and kill cancer cells.

The drug is approved for a variety of cancers, including non-small cell lung cancer, melanoma, head and neck squamous cell cancer and Hodgkin lymphoma.

Pembrolizumab is being observed for anti-tumour activity measured by response rate, as well as overall survival and profession free survival. Initial findings from the study are expected in 2019, with full results in 2022.