This week in our colorectal cancer mini-series we have covered the validation of Immunoscore as a tool for determining which patients have high T cells in their tuours and are therefore candidates for single agent immunotherapy (Link), as well as microsatellite instability (MSI) and mismatch-repair deficient tumours and how they can respond immunotherapy (Link).
What happens in the majority (95%) of patients, the microsatellite stable (MSS) disease who are mismatch-repair proficient though? They don’t respond well to checkpoint blockade so how can we help them?
In Chicago, BSB interviewed Dr Johanna Bendell from the Sarah Cannon Research Institute in Nashville, Tennessee to find out more about what she and her colleagues have been doing and where they plan to go next.
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Continuing part two of our mini-series on colorectal cancer, today we move from the big scale Immunoscore study to small subsets of disease that are looking interesting in several ways.
For years, advanced colorectal cancer has been dominated by chemotherapy (FOLFOX or FOLFIRI) with and without targeted therapies (VEGF and EGFR antibodies), with very little new to talk about. Part of the challenge here is how do you add something the existing standard of care and move the needle significantly. In front-line, for example, the OS is already out 2-plus years, so these are long and risky trials to undertake. Not surpisingly, many companies have sought to evaluate their agents in tumour types where they consider the risk of development to be lower.
Unless… we can find creative approaches that turn the paradigm on its head and identify a clearly defined niche that can be carved out separately from allcomers.
This is where we’re at now – identifying subsets that might respond exquisitely to novel approaches based on a rational understanding of the underlying biology. One obvious subset might be BRAF, which can be treated with a BRAF inhibitor with or without other targeted therapies as Dr Pietrantonio and colleagues (2016) literally just showed for example, but what about others of potential interest?
Colorectal cancer with microsatellite stable (MSS) disease represents 95% of metastatic patients. These are people whose mismatched repair system is proficient and actively functional in fixing the DNA strand breaks that occur during the course of life.
In contrast, those with microsatellite instability (MSI) are the minority of people with colon cancer (and some other cancers too) whose mismatched repair system is deficient and unable to adequately repair the DNA strand breaks. Ironically, this leads to thousands of mutations that can be recognised by the immune system to help detect the presence of cancer. It also tends to occur in hereditary cancers such as Lynch Syndrome.
We’ve been following the MSI vs MSS story for a while now, but at ASCO this year there was more data available and things appear to be getting clearer on the commercial front too.
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We’ve been following the work of Dr Jérôme Galon, a French immunologist, on Immunoscore for a while now, and many readers will remember the last interview he kindly gave BSB from the European Cancer Conference in September [Link].
In 2015 the large global trial to validate Immunoscore as a biomarker was still ongoing, so if you want some background to this important concept, do check out Dr Galon’s interview as it’s well worth reading as a primer on immunosurveillance, the importance of immune cells – the type, density and location, as well as background on the Immunoscore test as a marker of outcome.
Since then, the group have also published some related data that both moves the field forward and offers a way to unify some important concepts in colorectal cancer.
In Chicago, the really good news was that the final results of a large global study involving nearly 4,000 patients were presented to a packed audience in the main hall where the plenary is held. It’s not often you see the gastrointestinal oral session allocated the prime time room over lung or breast cancers – the atmosphere was certainly electric with anticipation!
This week’s post ASCO mini series focuses on colorectal cancer, with a look at several important aspects of this disease as we learn more about the underlying biology, as well as how the immune system functions and how we can use that scientific knowledge to improve outcomes for patients, sometimes in a dramatic way.
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After exploring the science behind chemotherapy improving T cell trafficking into the tumour yesterday – which is one of the key rate limiting issues that need to be addressed with immunotherapies such as checkpoint blockade – some obvious follow-up questions comes to mind:
- Does the compelling data in mice translate to humans?
- Can chemotherapy turn a cold tumour into a hot one?
- Will patients have improved outcomes as a result – or not?
It’s easy to dismiss traditional therapies in favour of appealing new developments, but what happens when we combine them? Do we get additive effects, synergies or a negative impact?
As part of our ongoing AACR coverage, we explored this conundrum in the context of new data readouts, as well as the broader competitive landscape.
What we found was really interesting!
BMS, Merck and Genentech/Roche all have trials ongoing in the metastatic colorectal cancer space, with very different approaches being taken. Does it matter? Which one’s driving the bus? We summarise these trials and offer some strategic insights on this niche.
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One thing has become very clear in the oncology space over the last year… checkpoint inhibitors are insufficient on their own for the vast majority of tumour types and patients that they have been explored in to date. There are a number of reasons for this, but the main one is lack of T cells in the tumour, which enable an effective immune response to be mounted.
This begs the question – how can we address that issue and manipulate the tumour microenvironment in our favour, thereby making subsequent checkpoint blockade more effective?
There are a number of different ways to do this.
In the past, we’ve discussed several methods including innate immunotherapies such as Aduro’s STING or Biothera’s immunotherapeutic, Imprime PGG. Other approaches include vaccines, which we have discussed in detail, t-cell receptors (TCR) or even monoclonal antibodies, such as AdaptImmune’s approach with their ImmTac technology.
There are other novel strategies currently being investigated by numerous companies too.
In this article – and also the second part of the latest miniseries – which will post tomorrow, we straddle our final reviews of interesting data from the European Cancer Conference (ECC) in Vienna with the upcoming one from the Society of Immunotherapy for Cancer (SITC) being held in National Harbor, Maryland.
Today’s post explores the concept of immunocytokines, engineered antibodies that are designed to boost the immune system, so that subsequent therapies will be more effective.
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For some time now there has been much debate about finding a predictive biomarker of response for EGFR monoclonal antibodies used in the treatment of advanced colorectal cancer. These include cetuximab (Erbitux) and panitumumab (Vectibix).
After all, we know that they tend to work in wild type disease (as shown in the US label below) and that KRAS and NRAS mutations on codon 12 and 13 on exon 2, as well as others on exon 3 and 4 tend to portend resistance to therapy, but beyond that not much is known.
At the European Cancer Conference in Vienna last month I was intrigued to see some new data emerge that may help researchers better understand and predict which people with metastatic colon cancer are more likely to respond in the future.
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New Orleans – At the 2015 annual meeting of the American Association of Immunologists (AAI) leading experts came together to share their insights on the “Promise of Cancer Immunotherapy.”
The audience at #AAI2015, in an artic chilled hall, heard from an outstanding panel of speakers, many of whom flew in specially:
- Immunologic Checkpoint Blockade: Combinations and Mechanisms, Jedd Wolchok (MSKCC)
- Immune Checkpoint Therapy: Clinical Success and Next Steps, Padmanee Sharma (MD Anderson)
- Improving Cancer Treatment Through Immunotherapy Combinations: Combination MAb Therapy: Dual tumor & Immune Targeting, Holbrook Kohrt (Stanford Cancer Institute)
- Curative Potential of T-Cell Transfer Immunotherapy for Cancer, Steven Rosenberg (Surgery Branch, NCI)
- PD-1 pathway blockade in cancer therapy: new frontiers, Suzanne Topalian (Johns Hopkins)
Dr Steven Rosenberg (NCI)
Cancer Immunotherapy is such a fast-evolving field that at Immunology 2015, we heard data that wasn’t at the annual meeting of the American Association for Cancer Research (AACR), just a few weeks ago.
Several presenters also put in context data that will published at the forthcoming ASCO annual meeting.
If you’d like to hear more about some of the checkpoint inhibitor data at AACR15, do listen to the first episode of the Novel Targets podcast (if you haven’t already done so).
It’s available as a free download on SoundCloud and on iTunes.
This post offers a top-line summary of some of the key messages we heard in the #AAI2015 symposium.
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Continuing our series on the ASCO GI meeting, today marks the end of the conference coverage with an interesting look at overcoming resistance to EGFR therapies such as Erbitux and Vectibix.
One of the hallmarks of EGFR monotherapy in colorectal cancer is stable disease with eventual relapse, but few dramatic responses. This suggests that other factors may play a role in driving oncogenic activity.
Dr Tejpar, Leuven
Recently, patient derived xenografts (PDX) have begun to play an increasingly important role in helping to understand the biology of the disease and facilitate improved trial design.
Earlier this week, we discussed the molecular characterisation of the disease based on the keynote talk by Dr Sabine Tejpar. Her group in Belgium as well as others in Italy and Spain have been very active in European translational work in this area to identify and map the pathways influencing EGFR therapy in GI cancers.
What can we learn from the latest findings in this space?
The answer may well surprise you.
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Over the last decade or so, we’ve seen a lot of new targeted agents approved in a variety of different tumour types. Of the big five cancers (breast, lung, melanoma, prostate, and colorectal) one clearly stands out as missing out on exciting new developments in the last 5 years.
In fact, we haven’t really seen anything startlingly new in the colorectal cancer (CRC) space since 2004, when the FDA approved cetuximab (Erbitux) and bevacizumab (Avastin) to much fanfare a few weeks apart at the beginning of that year. Sure, there have been other EGFR and VEGF inhibitors approved since, including panitumumab (Vectibix), z-aflibercept (Zaltrap) and regorafenib (Stivarga) in various lines of therapy, but you could argue that they’re all more of the same (type of inhibitors) and incremental in their improvements, rather truly game changing or disruptive.
Why is this? Why the discrepancy?
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After the recent raft of posts on immunotherapy, it’s time to turn our attention back to oncogenic addiction. A couple of key topics have dominated colorectal cancer over the years, namely what causes EGFR resistance and why don’t patients with the BRAF V600 mutation do as well with RAF monotherapy compared to melanoma patients?
In today’s post, we take a more detailed look at BRAF mutant colon cancer in terms of what we’ve learned so far and what the potential therapeutic solutions are, which could influence patient outcomes in a positive way.
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