Predicting If an Immune Checkpoint Drug Will Work


Drugs that activate the immune system to attack cancer in a process known as immune checkpoint blockade (ICB) are a focus of intense investigation. A number of them are already approved by the U.S. Food and Drug Administration (FDA) for various cancers; namely, the anti-CTLA4 antibody ipilimumab (Yervoy), two anti-PD-1 antibodies: pembrolizumab (Keytruda) and nivolumab (Opdivo), and three anti-PD-L1 drugs: atezolizumab (Tecentriq), avelumab (Bavencio) and durvalumab (Imfinzi). These ICB drugs have the potential to induce durable cancer regressions, but the majority of cancer patients just do not respond to them at all.

Biomarkers, signature molecules in the blood or other tissue, can sometimes be used to predict a patient’s response to a given treatment. But no reliable biomarkers exist for ICB, and this is a serious concern. Patients who may really benefit from ICB could be overlooked, and patients who are not likely to respond may receive useless (and very expensive) ICB treatment.

Most potential response predictors that have already been identified are not yet useful for one or all of the following reasons: they are not extensively validated, their significance is still uncertain and may differ from one cancer (or even one patient) to another, or they are technically challenging for routine use. These markers are addressed below. Continue reading…


New Developments in Melanoma Treatment


Neoadjuvant (before-surgery) treatments for resectable melanoma

Neoadjuvant treatments are the mainstay in the care of patients with breast, colon, and other cancers, but have not traditionally been used in melanoma. This has changed now, with the publication of a report showing that patients with resectable stage III or IV BRAF-mutant melanoma benefit from treatment with the BRAF/MEK inhibitor drugs dabrafenib and trametinib prior to (and continued after) surgery. The randomized clinical trial that produced these findings was small, but the benefits were so obvious that the researchers had to close the control group—those patients who received a placebo instead of neoadjuvant treatment. 71% of the 14 patients in the trial who received BRAF/MEK inhibitors prior to surgery were disease-free after 18 months, whereas all seven patients in the control group experienced a recurrence. The trial is continuing without the control group: all patients will receive treatment prior to surgery

Adjuvant (after-surgery) treatments

Melanoma patients whose tumors are surgically removed experience a very high rate of recurrence. Until recently, adjuvant treatments to prevent recurrences were limited to the drug interferon alpha-2B and, more recently, ipilimumab (brand name Yervoy), an anti-CTLA-4 immune checkpoint drug approved by the U.S. Food and Drug Administration (FAD) for adjuvant treatment in 2015. Interferon treatment is extremely harsh, with many adverse effects, and is not often used anymore. Yervoy is often associated with autoimmune side effects, which are sometimes quite serious.

Enter nivolumab (Opdivo) the anti-PD-1 checkpoint drug approved by the FDA to treat metastatic melanoma and other cancers. A clinical trial showed that the recurrence-free survival (RFS) rate at 18 months with nivolumab was 66.4% compared to 52.7% for ipilimumab (Yervoy) in patients with resected stage IIIB/C or IV melanoma. This amounts to a 35% reduction in the risk of recurrence or death with the PD-1 inhibitor versus the CTLA-4 inhibitor. Not the least important factor is the much lower rate of side effects seen with nivolumab compared to ipilimumab. Nivolumab is now approved by the FDA as an adjuvant treatment after surgical resection of melanoma.

Pembrolizumab, a competing anti-PD-1 drug, also showed encouraging results in a randomized trial for stage III melanoma. The stakes in this trial were lower, since the control arm received a placebo (not ipilimumab!). Risk reduction was 43%, according to preliminary results of the trial.

For patients with BRAF-mutant stage III melanoma, adjuvant treatment with the BRAF/MEK inhibitors dabrafenib and trametinib was just recently granted a priority review by the FDA, signaling a likely approval soon. Recurrence-free 3-year survival was 58% for the combination versus 39% for placebo.

New treatments for metastatic melanoma

A Knowledge Blog post from last summer described new combination treatments for metastatic melanoma. There have been significant developments since then.

Several trials combined PD-1 blockers (pembrolizumab or nivolumab) with small molecules known as IDO inhibitors. The latter help shut down the activity of immune system cells known as regulatory T cells (T regs), which dampen the immune response triggered by anti-PD-1 drugs. Combination of pembrolizumab with the IDO inhibitor epacadostat increased the rate of responses to pembrolizumab from 32% to 56%. This is very comparable to the response rate seen with the FDA-approved combination of nivolumab and ipilimumab. However, the significant toxicities seen with addition of ipilimumab are not observed when IDO inhibitors are added. Several other competing IDO inhibitors are currently in trials with both pembrolizumab and nivolumab. Importantly, there is also hope that these drug combinations may abolish resistance to PD-1 blockers in previously treated melanoma patients.

Another promising combination has been tested in a small clinical trial of nivolumab with NKTR-214, a specifically modified form of the protein IL-2, which is a strong activator of the immune system. High-dose IL-2 is a drug that has long been approved for metastatic melanoma but is rarely used because of the extremely serious adverse effects. NKTR-214 is a modified (PEGylated) IL-2 that has much reduced side effects, and does not activate inhibitory T regs. Clinical trial results have been released for 11 melanoma patients treated with the combination. Of the patients enrolled, 73% have experienced objective responses, which is obviously much higher than what is seen with nivolumab alone. This trial is now enrolling patients who have or have not already been treated with immune drugs.

Patients who were treated with anti-PD-1 drugs and experience progression may consider enrolling in trials that add relatlimab (an anti-LAG3 immune drug) to nivolumab. In a trial that enrolled heavily pretreated patients who failed on previous treatment with anti-PD-1 drugs, the rate of response was 11.5%, but many more patients (38%) have achieved stable disease. The presence of LAG3 protein (but not PD-L1 protein) in the tumors was predictive of response.

There are other new drugs to watch. TLR9 agonists (activators) have shown early promising results in melanoma. TLR is a group of receptors that are strongly involved in innate immunity. A recent publication showed that intratumoral injection of a TLR9 activator with an antibody to OX40 (a protein on T cells) has extraordinary activity in a mouse cancer model. Trials that combine anti-OX40 and TLR9 agonists are forthcoming. However, two TLR9 agonists, SD-101 and IMO-2125, have shown very promising results in combination with anti-PD-1 or anti-CTLA4 drugs.

The other drug with early promise is ImmunoPulse IL-12 (pIL-12). In combination with pembrolizumab, it induced responses in 43% of patients who had not been previously treated with immune drugs. The important point is that patients in this trial were specifically selected to have a tumor profile that is associated with lack of response to pembrolizumab. pIL-12 is injected into tumors, so this intervention is appropriate for patients who have injectable tumors.

New BRAF/MEK inhibitors for melanoma have emerged: encorafenib and binimetinib produced a 3-year overall survival rate that is twice as high as seen with vemurafenib, a BRAF inhibitor. The comparison is not exactly meaningful because vemurafenib is not used as a single drug in BRAF-mutant melanoma these days, but this phase III trial was initiated back in 2013, prior to the approval of other BRAF/MEK combinations. The new combination may be approved mid-2018.

The triplet combinations for BRAF-mutant melanoma should be mentioned (immune plus targeted drugs). A trial that combined dabrafenib and trametinib with pembrolizumab reported early success, with a confirmed response rate of 67% in 15 patients who received the combination.


A Gut Feeling: Bacteria in Your Gut May Affect Cancer Treatment


The human gut contains hundreds of species bacteria, which are known to contribute to various bodily functions (such as digestion, of course!) but they also shape our immune system. Now, recent research has revealed how our microbiomes (the abundant bacteria living in our bodies) may affect the efficacy of immune checkpoint blockade (ICB) in cancer treatment.

How it started: about two years ago, an American group of scientists led by Thomas Gajewski of the University of Chicago noticed that melanoma (and some other cancers’) growth in mice was influenced heavily by the type of bacteria found in the mouse gut. They worked with mice purchased from two different vendors, and realized that mice from one vendor had consistently slower-growing tumors. Bifidobacterium bacteria present in the mouse gut were pinpointed to be the culprit, because transfer of Bifidobacterium to mice that did not have it was able to slow down melanoma growth. Treatment with an immune anti-PD-L1 drug was effective in mice that had the bacteria, but not in mice lacking it. Continue reading…


Melanoma News at ASCO 2017: Combination Treatments


There are many hopes that combining immune checkpoint inhibitor drugs, or combining them with drugs of other types (immunotherapy, targeted therapy, or chemotherapy) is the future of treatment for many kinds of cancer. Literally hundreds of clinical trials are actively exploring these combinations, and melanoma is the cancer for which trials of this type abound. Last month, the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago featured just a few presentations in this area, apparently because it is too early to report results from the many ongoing trials with drug combinations. Continue reading…


Metastatic Melanoma: Not Quite Curable…But Getting There


By 2050, the number of deaths due to malignant melanoma in the U.S. could be three times lower than peak levels reached before 1960. Researchers presented the data behind this prediction at the 2017 European Cancer Congress in January.

It is unclear how much of this anticipated decline in deaths can be attributed to the availability of new, effective treatments. However, it is obvious that much-increased awareness of sunlight exposure as the single factor most responsible for the development of skin melanoma has contributed to lower incidence of the disease.

In any case, the armament of treatments available for metastatic melanoma is currently such that this diagnosis has transformed from being almost universally fatal (even just a few years ago) into a being largely treatable. Since 2011, the U.S. Food and Drug Administration (FDA) has approved eight new drugs for melanoma. Continue reading…


Super Patient: Peter Fortenbaugh Faces the Uncertainty of Pioneering Melanoma Treatment


In spring of 2014, Peter Fortenbaugh noticed what appeared to be a tick that had bitten his lower calf. “It turned out not to be a tick, but it didn’t really go away,” he says.

The spot began to grow and bulge, and in October, Peter showed it to his primary care doctor, who referred him to a dermatologist to remove it. At the time, Peter recalls, it did not occur to him that the growth could be serious.

“I was actually very concerned about skin cancer because I spent a lot of time out in the sun sailing,” Peter says. “I put on a tremendous amount of sunscreen and protection, but never on my legs…I never connected the dots.”

However, a biopsy of the growth came back positive for melanoma. Peter, who lives in Palo Alto, California, with his wife and three children, immediately reached out to several doctors in the San Francisco Bay Area, and all had the same advice: “Take it out, take a biopsy.” Continue reading…


Testing for Tumor Mutations: Liquid Biopsy Versus Traditional Biopsy


Liquid biopsies, virtually unknown even a year or two ago, are becoming common tools in precision diagnostics for cancer. Here, I will try to explain some of the more important differences between liquid and “traditional” tumor biopsies.

Biopsies of solid tumors (e.g., lung, breast, or brain tumors) involve surgically removing a small part of a tumor and sending it to pathology lab. In the last few years, doctors have also started to send some tumor samples to special service labs that analyze tumor DNA for the presence of cancer-related mutations.

By definition, regular biopsies can be intrusive and are sometimes associated with side effects, such as bleeding or infection. However, they provide some really essential information; i.e., the histology and grade of the tumor and other tumor characteristics necessary to determine the best choice of treatment. For lung cancer, for example, a biopsy determines the type of tumor—adenocarcinoma, squamous cancer, small-cell lung cancer, or another, less common type. For breast cancer, a routine test will determine if the tumor expresses estrogen, progesterone receptors, and a protein called HER2. These tests are critically important in guiding treatment choices. If mutational analysis of cancer-related genes is also performed (which doesn’t always happen, unfortunately), it may guide treatment with targeted drugs. Continue reading…


Melanoma: New Drugs and New Challenges (Part 2 of 2)


Editor’s note: This is part 2 of a 2-part post on the latest research in melanoma. To learn about research into drug combinations for melanoma that may work better than single drugs, check out Melanoma: New Drugs and New Challenges (Part 1 of 2).

As always, the more new treatments become available in melanoma, the more new challenges arise. With eight new drugs approved for melanoma in the last five years, oncologists may sometimes face the difficult choice of what drugs to choose for a patient’s first-line treatment. Immune checkpoint drugs sometimes cause serious side effects, but progress is being made on how to treat these and also how to treat patients with pre-existing autoimmune conditions. New approaches are needed in efforts to prevent recurrence of melanomas diagnosed at earlier stages of disease progression. These and other challenges are discussed below. Continue reading…


Melanoma: New Drugs and New Challenges (Part 1 of 2)


New targeted and immunotherapy drugs have changed the diagnosis of metastatic melanoma from a death sentence into a disease that can potentially be managed and even cured. Nevertheless, these new drugs do not work in all patients, or they may stop working after a transient response. This post (part one of two) will describe ongoing efforts to find drug combinations with higher efficacy than single drugs and decipher the mechanisms underlying drug resistance. Continue reading…