Researchers developed a new experimental drug called AZD5335 designed to fight ovarian cancer by targeting a specific protein found on cancer cells. Unlike an existing similar drug that only works well in patients with high levels of this protein, AZD5335 appears effective even in patients with lower levels. In laboratory and animal studies, the drug shrank tumors in 82% of cases, and it even worked against cancers that had become resistant to the older drug. When combined with other cancer treatments, AZD5335 showed even better results. While these early results are encouraging, the drug is still experimental and needs testing in human patients before doctors can prescribe it.

The Quick Take

  • What they studied: Whether a new experimental cancer drug called AZD5335 could effectively treat ovarian cancer in different types of patients, including those whose cancers didn’t respond to existing treatments
  • Who participated: The study used laboratory cancer cells and tumors grown from actual ovarian cancer patient samples implanted in mice. Seventeen different patient-derived tumor models were tested, plus two real cancer patients who received the drug as part of early clinical cases
  • Key finding: AZD5335 shrank tumors in 82% of the cases tested (14 out of 17 patient-derived models). Importantly, it worked well even in cancers with low levels of the target protein, and it successfully treated cancers that had stopped responding to an older similar drug
  • What it means for you: This research suggests AZD5335 could eventually help ovarian cancer patients who currently have limited treatment options, especially those whose cancers don’t have high levels of the target protein or whose cancers have become resistant to existing drugs. However, this is early-stage research, and much more testing in human patients is needed before this drug becomes available

The Research Details

Researchers created AZD5335 by combining two components: a targeting molecule that finds cancer cells with a specific protein called folate receptor alpha (FRα), and a cancer-killing drug called a topoisomerase-1 inhibitor. They tested this new drug in multiple ways: first in cancer cells grown in laboratory dishes, then in tumors from actual patients that were implanted into mice. They also tested it against an existing similar drug to see which worked better, especially in harder-to-treat cases.

The team examined how well AZD5335 worked depending on how much of the target protein each cancer had. They also tested whether combining AZD5335 with other standard cancer drugs or with a drug called a PARP inhibitor would work even better. Finally, they documented two real patients who received AZD5335 and tracked how their tumors responded.

This approach allowed researchers to move from basic laboratory testing toward understanding whether the drug might work in real patients, though much more human testing is still needed.

This research approach is important because it bridges the gap between laboratory discoveries and real-world treatment. By testing in patient-derived tumors (actual cancer tissue from real patients), the results are more likely to predict how the drug will work in actual patients compared to testing only in simplified laboratory conditions. Testing against an existing drug shows whether AZD5335 is truly better, not just whether it works at all.

Strengths of this research include testing in multiple patient-derived tumor models (17 different ones), which increases confidence in the findings, and including real patient cases. The study was published in a respected cancer research journal. However, this is still preclinical and early clinical research—the drug hasn’t been fully tested in large groups of human patients yet. The sample size of 17 patient-derived models is relatively small. Results from animal studies don’t always translate perfectly to humans, so larger human clinical trials are essential before drawing firm conclusions about safety and effectiveness in patients.

What the Results Show

AZD5335 demonstrated strong anti-tumor activity across the board. When given as a single dose to mice with patient-derived ovarian cancer tumors, the drug achieved an 82% response rate, meaning tumors shrank significantly in 14 out of 17 cases. This is a notably high success rate for early-stage cancer research.

A particularly important finding was that AZD5335 worked well even in cancers with low levels of the target protein (FRα). This is significant because the existing similar drug, Elahere, only works effectively in patients with high levels of this protein, limiting who can benefit from it. When directly compared in low-FRα tumors, AZD5335 outperformed an Elahere-like drug, suggesting it could help patients currently excluded from existing treatments.

The drug also showed promise against drug-resistant cancers. In tumors that had stopped responding to Elahere (acquired resistance), AZD5335 treatment resulted in complete tumor disappearance in some cases. This suggests the drug works through a different mechanism that can bypass resistance to older treatments.

When AZD5335 was combined with standard ovarian cancer drugs or with a PARP inhibitor (another type of cancer drug), the results were even more impressive, with enhanced tumor shrinkage and longer-lasting responses.

The two documented human patient cases provided encouraging early signals. One patient with high FRα expression and another with low FRα expression both showed significant tumor responses to AZD5335, supporting the laboratory findings that the drug works across different FRα expression levels. These case reports suggest the drug’s activity in laboratory models may translate to real patients, though individual cases cannot prove effectiveness.

This research builds on the success of Elahere, an FDA-approved drug that targets the same FRα protein but uses a different cancer-killing component (a microtubule inhibitor). While Elahere represents an important advance, it has limitations: it only works in patients with high FRα expression, and some patients develop resistance or experience safety concerns. AZD5335 appears to address these limitations by using a different cancer-killing mechanism (topoisomerase-1 inhibition) that may be safer and work in a broader patient population. The research suggests AZD5335 could be a next-generation improvement rather than a replacement for Elahere.

Several important limitations should be considered. First, this research was conducted primarily in laboratory and animal models, not in large groups of human patients. Animal studies don’t always predict human results perfectly due to differences in how bodies process drugs and respond to treatment. Second, the sample size of 17 patient-derived tumor models, while reasonable for early research, is relatively small. Third, only two human patients were documented, which is too few to draw firm conclusions about safety or effectiveness in people. Fourth, we don’t have detailed information about potential side effects from the animal studies or the two patient cases. Finally, the long-term durability of responses and optimal dosing schedules haven’t been fully established. Much larger human clinical trials are needed before this drug can be approved for patient use.

The Bottom Line

Based on this early-stage research, AZD5335 shows promise as a potential future treatment for ovarian cancer, particularly for patients with low FRα expression or those whose cancers have become resistant to existing drugs. However, confidence in these recommendations is currently low because human testing is still in very early stages. Patients should not expect this drug to be available soon—it will require years of additional clinical testing. Ovarian cancer patients interested in experimental treatments should discuss clinical trial opportunities with their oncologists, but should be cautious about any claims of effectiveness until larger human studies are completed.

This research is most relevant to ovarian cancer patients, particularly those with low FRα expression (who currently have fewer treatment options) and those whose cancers have become resistant to Elahere. Oncologists treating ovarian cancer should be aware of this development as a potential future option. Researchers and pharmaceutical companies developing cancer treatments should note this approach. However, this research is not yet relevant to the general public or to patients with other cancer types, as it’s specific to ovarian cancer and remains experimental.

This is very early-stage research. Based on typical drug development timelines, if AZD5335 continues to show promise, it would likely take 5-10 years or more before it could potentially become available to patients. The drug would need to progress through Phase 1 (safety testing in small patient groups), Phase 2 (effectiveness testing), and Phase 3 (large-scale comparison trials) before regulatory approval. Patients should not expect access to this drug in the near term.

Want to Apply This Research?

  • For ovarian cancer patients currently in clinical trials or monitoring their condition: track tumor marker levels (such as CA-125) weekly if available, and document any changes in symptoms, energy levels, or side effects in a simple daily log to share with your oncology team
  • If you’re an ovarian cancer patient: discuss with your oncologist whether you might be eligible for clinical trials testing new drugs like AZD5335, and ask about being added to trial notification lists so you’re informed when new studies open at your treatment center
  • For long-term tracking: maintain a health journal documenting treatment dates, imaging results, tumor marker levels, and symptom changes. Set monthly reminders to review this information with your healthcare team to assess how any treatments are working and adjust plans as needed

This research describes an experimental drug (AZD5335) that is not yet approved for patient use. The findings are based on laboratory studies and animal models, with only two documented human cases. Results from animal studies do not always translate to humans. This information is for educational purposes only and should not be interpreted as medical advice or a recommendation to seek this treatment. Ovarian cancer patients should discuss all treatment options, including experimental therapies and clinical trials, with their qualified oncologist. Do not delay or avoid standard cancer treatments based on this research. Clinical trial participation should only be considered under the guidance of your medical team.