Targeted Cancer Vaccines Could Shift the Paradigm for HPV+ HNSCC

Ongoing research is developing increasingly targeted cancer vaccines to boost cure rates for patients with human papillomavirus (HPV)–positive head and neck squamous cell carcinoma (HNSCC), as well as develop more effective therapies for those with HPV-negative disease, according to Katharine A. Price, MD.¹

In an interview with OncLive®, Price discussed the current status of the HNSCC treatment paradigm, data informing the use of injectable HPV-targeted immunotherapy in patients with HPV16-positive disease, and the importance of broadening access to and education about preventive HPV vaccination.

Price highlighted the clinical implications of the phase 2 VERSATILE002 trial (NCT04260126), which evaluated the cancer vaccine Versamune HPV (formerly PDS0101) plus pembrolizumab (Keytruda) in patients with frontline HPV16-positive HNSCC.¹ This combination generated a median overall survival of 30 months among 53 patients with frontline recurrent/metastatic HNSCC. The investigator-assessed best overall response rate was 34% among patients with a PD-L1 combined positive score (CPS) of at least 1 (n = 53) and 48% among those with a CPS of at least 20 (n = 21).

She also noted the design of the phase 3 VERSATILE003 trial, which will investigate Versamune HPV plus pembrolizumab in patients with previously untreated, recurrent/metastatic HPV16-positive HNSCC.²

“I don’t think [these cancer vaccines] will be curative for patients who are not [in the curative setting] most of the time, but I think they will be an incremental step forward in improving outcomes and quality of life [QOL], if there are patients in whom we can delay the use of chemotherapy and other more toxic treatments,” Price said.

Price is an associate professor of oncology and a consultant in the Division of Medical Oncology in the Department of Oncology at Mayo Clinic in Rochester, Minnesota.

OncLive: What are the current and projected incidences of head and neck cancer and its related causes?

Price: Head and neck cancer [comprises] a heterogeneous group of cancers, so we can look at incidence—both current and projected—in different ways. If we start broadly and look worldwide at all HNSCC, we’ve seen an increase over the past decade; some data will say even as high as an approximately 60% increase compared with the decade before. In the United States [US] and in many other countries, a lot of that is driven by the increasing incidence of HPV-associated oropharynx cancer. [However, there is] still a high global burden of [head and neck] cancer overall.

In most areas of the world, tobacco use has declined over time, so we’ve seen a decreasing association of smoking-driven cancers, such as [laryngeal] cancer. There have been some declines, mostly related to the decreased use of tobacco. However, there are some concerning and unexplained slight rises in incidence. The one that’s caught our attention in the world of head and neck cancer is a slight increase in the incidence of oral tongue cancer in nonsmoking patients, mostly women. We don’t understand exactly why that [incidence is rising], and it’s still a small number, relatively speaking.

[Head and neck cancer is] an interesting landscape right now. The global burden of HNSCC and the burden in the US are still significant. There’s a lot of attention on health disparities, and I might be a bit more in tune with this because I practice in an area that serves a population that is highly rural. The incidence of HPV-driven cancers in rural areas is continuing to rise steeply, whereas the incidence in more urban areas is going up but has leveled off a bit. A lot of that is related to disparities in preventive HPV vaccination.

Are these preventive HPV vaccination disparities generally due to a lack of access or public opinion about vaccination in general?

If we separate it and consider preventive HPV vaccination as a tool to prevent HPV-associated head and neck cancers and you look at maps of the US, the [map of the] incidence and mortality from HPV-associated cancers can be superimposed on the map of preventive vaccination rates. The lowest preventive vaccination rates are in the Midwest and Southeast compared with the coasts. Those are areas where there are higher incidences of HPV-associated cancer. Those two [factors] are intertwined.

There are a lot of reasons for preventive HPV vaccination hesitancy or lack of uptake, and that’s a complicated issue. Health care access and delivery to more rural areas play a role in that. [A lesser role is played by a lack of] understanding the real reason for preventive HPV vaccination. When we look at access to care for a patient with cancer, rural areas are more challenging [areas to deliver treatment], and we see differences in outcomes [vs in more urban areas]. A lot of data have been published in the oral cavity cancer field about outcomes being different based on access to care and treatments in tertiary referral centers vs non-tertiary centers. These issues are all interconnected, and there’s not one fix for them; however, we should always be working to even out disparities in our health care system, both from a prevention and an access-to-care standpoint.

What is the current prognosis of patients with recurrent and metastatic head and neck cancer, and what is their associated QOL?

Approximately 20% of patients with HPV-associated cancers will have a recurrence after their original treatment. We can stratify that. Patients with large T4 tumors will be at higher risk [for recurrence, as will] patients with a higher nodal burden. Given that a lot of patients are being diagnosed with HPV-positive [head and neck] cancer and it’s the eighth most common cancer in men, we’re still dealing with a lot of patients who have recurrent and metastatic disease, which for most is an incurable cancer and will shorten their life expectancy.

For HPV-related cancers, QOL is a difficult issue because there are so many factors that go into it. Even [in the context of] a radiation and chemotherapy–based treatment, a patient’s functional outcomes will be different based on the location of their cancer and their radiation field. However, most patients with HPV-associated cancer have a good QOL after all that. Most patients will go back to their life, work, eating, etc.

There are a lot of research efforts—we’ve done some of this work at Mayo Clinic, and lots of other centers have [done this work as well]—investigating: who can we de-escalate therapy for? Some patients can receive de-escalated therapy, but some patients cannot. Having done some of the trials that have evaluated significantly de-escalating radiation therapy after surgery, for HPV-positive patients, QOL tracks with the amount of radiation therapy [they receive]. Higher radiation tends to be [associated with] longer-term adverse effects [AEs] that impact QOL.

We’ve made progress. A challenge [remains] patients who can’t [have treatment] de-escalated and are still stuck with significant treatment toxicities. Even in the time I’ve been practicing, [I have seen] slight shifts in treatment, such as shifts in radiation. Intensity-modulated radiation therapy was a big leap forward. Proton therapy was another incremental leap forward. We’ve seen improvement in toxicities with the migration of treatment trends and expertise over time, but [these are still a] challenge.

For HPV-negative cancers, survival benefits have not changed much over the years. That’s the group of patients that I wake up at night and worry about. For example, [the only treatment options for] patients with oral cavity cancer [are associated with high rates of morbidity]. Most of those patients undergo surgery and then require radiation or radiation and chemotherapy afterward. That group suffers a lot, and we need new treatments, creativity, and new treatment paradigms to try to improve outcomes.

What investigational therapies are of interest to you for patients with HPV-positive and HPV-negative disease?

I and others have done work evaluating the use of therapeutic vaccines for HPV-associated head and neck cancers. A lot of great data are emerging for that, and several randomized studies are [reading out] that will help inform [the use of these cancer vaccines]. The area of viral-driven cancers, such as HPV-associated cancers, is exciting.

Some of my colleagues, Ari Rosenberg, MD, [of UChicago Medicine in Illinois] and Cesar Perez, MD, [of Florida Cancer Specialists & Research Institute in Lake Nona] talked at the 2024 ASCO Annual Meeting about some new classes of therapies: antibody-drug conjugates and bispecific antibodies. The preliminary response rates [with these agents are high, and we are] seeing more durability of response. This seems to be the first big improvement in treatment, specifically for HPV-negative patients. We almost never see better response rates in HPV-negative vs HPV-positive patients, and [those improvements have been] encouraging.

There is a lot of excitement about those classes of drugs, particularly for the HPV-negative group, and they can also be applied to the HPV-positive group. Both of those groups will benefit. We’re going to see some exciting data coming out over the next couple years, and hopefully we will even have some of those [regimens] be incorporated into curative-intent treatment paradigms, particularly for HPV-negative patients.

Where might injectable HPV-targeted immunotherapy vaccines fit into the HNSCC treatment paradigm?

Several of these agents are being studied. If we consider the studies that have been done and the ones that are reading out, most of the promising data [with these agents] are in the first-line recurrent/metastatic setting in combination with checkpoint inhibition. There are some data about the use of these therapeutic vaccines in treatment-refractory patients, but as expected, the response rate [in that population] is much lower. There will be some data emerging about response to the therapeutic vaccine alone without immunotherapy. However, if we follow the trajectory of the ongoing trials, based on data with these agents, the first indication will probably be in the first-line recurrent/metastatic setting in combination with current immunotherapy for patients with a CPS of 1 or greater.

Some of the data from the 2024 ASCO Annual Meeting showed that [patients with a] CPS greater than or equal to 20 seemingly have more benefit [with therapeutic vaccines], just as they do with immunotherapy. Some of the [ongoing] trials [investigating therapeutic vaccines in patients with HNSCC] are restricting [enrollment] to that population. The VERSATILE003 trial will not restrict [enrollment to patients with a CPS of] 20 or higher, but it will [restrict enrollment to patients with] a CPS of 1 or higher. For patients with a PD-L1–negative CPS, there is still going to be a treatment void [with the emergence of these therapeutic vaccines].

One of the [populations in which] it would be interesting to see [the efficacy of these therapeutic vaccines is patients with] a biochemical or molecular recurrence. We’re finding a lot of these patients now because we’re using circulating tumor DNA [ctDNA] assays more frequently in routine practice. [These are] patients who have received curative-intent treatment and have no evidence of disease, but then start to have rising ctDNA levels. One could imagine a scenario where we treat those patients with a therapeutic vaccine, follow that level, and see if we can prevent or delay a more significant recurrence in the future.

My colleague, David M. Routman, MD, a radiation oncologist [at Mayo Clinic], is currently running a study [investigating the] therapeutic vaccine [PDS0101] alone or with pembrolizumab prior to curative-intent treatment with either surgical resection or chemoradiation [in patients with HPV-associated oropharynx cancer]. We’ll likely see these therapeutic vaccines be incorporated into other treatment paradigms and into the curative-intent setting. However, right now, the ongoing studies are focusing on [studying these therapeutic vaccines in] first-line, recurrent/metastatic disease.

Based on the data that have read out from VERSATILE002, what CPS subgroup may experience the greatest benefit with the Versamune HPV vaccine?

We always [need to strike] a balance between selecting the patients who are likely to have the most benefit vs [developing an agent] to offer to more patients. [Regarding] a new treatment in a setting where we don’t have a lot of great therapeutic options, I tend to favor being a little more broad and [testing] it in different patients until we have better predictors [of efficacy]. It’s almost a philosophical question of study design. [As oncologists who treat] a lot of patients and are heavily clinically involved, we want to be able to offer a new and different therapy to the patient sitting in front of us, as long as there’s reason to believe it would be beneficial.

In VERSATILE002, and the same will be for VERSATILE003, the CPS cutoff was 1 or higher. We saw responses in patients with a CPS lower than 20. The data will ultimately unfold, and we may end up with indications that are more restrictive; it will just depend on what the randomized data look like compared with immunotherapy alone.

What safety data were seen with the addition of the therapeutic vaccine to pembrolizumab in VERSATILE002?

We didn’t see any signal for worse AEs [with the therapeutic vaccine] or any safety signals compared with immunotherapy alone. Most of the AEs were grades 1 and 2, and even more importantly, most were just related to the vaccine injection site: redness, swelling, and a bit of discomfort for a couple days. We saw some systemic fatigue, mild nausea, and the occasional fever, but [these AEs were] minimal and did not seem to enhance the immunotherapy toxicity profile.

At least in the phase 2 [setting, the therapeutic vaccine] looked safe. If that holds up in the phase 3 setting, [the therapeutic vaccine will be] an important treatment to consider for patients who might not have robust [responses and will subsequently] develop recurrent/metastatic disease, or those who, if they develop recurrence early, are still recovering from their curative-intent treatment. There are clinical scenarios where it’d be helpful to know that there’s a treatment that’s not going to be too toxic.

How has the increased knowledge regarding HPV-associated cancers increased the necessity to advocate for preventive HPV vaccination?

Ask everybody who has influence in the cancer world or elsewhere, such as primary care, to be advocates for preventive HPV vaccination. We’re fortunate that we have a tool that can make a difference in the incidence over time of this disease, but it’s underutilized. Vaccination rates are not where they need to be. As the community that sees the result of not being vaccinated, we have a unique perspective on this and can use that voice to help patients [and health care providers] understand [the importance of HPV vaccination].

I’ve done a lot of talks and outreaches, both with health care providers in the primary care setting and with different groups of individuals—not necessarily patients with cancer, but just regular people and adolescents. There is a lot of misunderstanding about preventive HPV vaccination; most people I’ve talked to outside of the head and neck cancer world don’t even know that it’s a cancer-preventing vaccine. They think it’s just preventing sexually transmitted disease. A lot of messaging has been missed, and as a community, we can use our collective voice and influence to try to help [rectify that].

References

1. PDS Biotech VERSATILE-002 phase 2 clinical trial meets primary study endpoints in first line recurrent/metastatic HPV16-positive head and neck cancer. News release. PDS Biotechnology. May 9, 2024. Accessed August 19, 2024. https://pdsbiotech.com/index.php/investors/news-center/press-releases/press-releases1/131-2024-news/918-iotech002hase2linicalrialeetsrim20240509
2. PDS Biotech aligns with FDA on phase 3 trial in HPV16-positive first-line recurrent or metastatic head and neck cancer. News release. PDS Biotechnology. August 1, 2024. Accessed August 19, 2024. https://pdsbiotech.com/index.php/investors/news-center/press-releases/press-releases1/131-2024-news/933-iotechlignswithonhase3rialin16osit20240801