Rina-S Trial Adds Mesothelioma to Its Tumor Cohorts

A clinical trial run by Genmab is testing an experimental drug called Rina-S in people with advanced solid tumors, and mesothelioma is one of the cancer types it accepts. The study, known as RAINFOL-01, measures the safety, dosing, and antitumor activity of Rina-S across a range of tumors rather than mesothelioma alone.

The trial, listed on ClinicalTrials.gov as NCT05579366, is a Phase 1/2 study. It started in December 2022 and is currently recruiting. The investigational agent here is Rina-S, an antibody-drug conjugate, so this study sits apart from the mesothelioma trials that test immune checkpoint inhibitors.

What the Trial Is Testing

The study evaluates Rina-S, also identified in the record as rinatabart sesutecan, PRO1184, and GEN1184. Rina-S is a folate receptor alpha (FRalpha) targeted antibody-drug conjugate. An antibody-drug conjugate pairs an antibody, which homes in on a marker found on cancer cells, with a cell-killing payload, so the drug aims to deliver its payload to tumor cells that carry the folate receptor alpha target while sparing healthy tissue. The molecule joins an FRalpha-directed antibody to an exatecan payload, a topoisomerase I inhibitor, through a hydrophilic linker.

This is a basket study, which means it enrolls several different cancer types into separate cohorts and runs them in parallel. The conditions listed on the record include epithelial ovarian cancer, primary peritoneal cancer, fallopian tube cancer, endometrial cancer, non-small cell lung cancer, EGFR-mutated non-small cell lung cancer, breast cancer, cervical cancer, and mesothelioma.

The study is organized into multiple parts. Mesothelioma sits in Part B, the tumor-specific monotherapy dose-expansion stage, where participants receive Rina-S on its own. The trial record also describes combination cohorts in other parts that pair Rina-S with carboplatin, with bevacizumab, or with pembrolizumab, but those combinations apply to ovarian and other gynecologic cohorts, not to the mesothelioma cohort.

Who Can Participate

The trial is open to adults aged 18 and older. According to the eligibility criteria, participants must have a histologically or cytologically confirmed metastatic or unresectable solid malignancy, with the specific tumor type determined by the part they enter. Mesothelioma is one of the tumor types accepted in Part B.

The record notes a measurement detail specific to this cancer. Most tumor types in the study are assessed for measurable disease using RECIST v1.1, the standard ruler researchers use to track tumor size on scans. Pleural mesothelioma instead uses mRECIST v1.1, a modified version designed for the way mesothelioma grows along the lining of the lung.

The study excludes people with a history of non-infectious interstitial lung disease or pneumonitis that required steroids within the past two years, and people who have already received a topoisomerase 1 inhibitor-based antibody-drug conjugate.

What the Trial Measures

Across its earliest parts, including the Part B cohort that contains mesothelioma, the trial’s primary goal is safety and tolerability. The record lists the primary outcome for Parts A, B, and D as the incidence of treatment-emergent adverse events, a count of the side effects participants experience during treatment. Later expansion cohorts in other parts measure objective response rate, the share of participants whose tumors shrink by a defined amount.

Secondary measures across the study include best overall response, objective response rate, disease control rate, progression-free survival, overall survival, duration of response, and a set of pharmacokinetic readouts that track how the drug moves through the body.

Where It Is Running

The trial is a global study. The ClinicalTrials.gov record lists 66 sites across the United States, China, and Japan, with 37 locations in the United States, 20 in China, and 9 in Japan. The US sites span states including Arizona, California, Florida, Massachusetts, Michigan, Ohio, Tennessee, Texas, Virginia, and Washington, among others.

Because cohorts open and close as the study moves through its parts, not every site is enrolling every tumor type at the same time. People considering the trial should confirm with a specific site whether the mesothelioma cohort is open there before traveling.

Why This Trial Matters

Most of the experimental drugs in mesothelioma trials right now are immunotherapies that release the brakes on the immune system or cell therapies that re-engineer immune cells. Rina-S takes a different route. As an antibody-drug conjugate, it is built to find a target on the surface of cancer cells and deliver a chemotherapy-like payload directly to them.

Folate receptor alpha, the target this drug is built around, appears on several solid tumors, which is why the study casts a wide net across ovarian, endometrial, lung, breast, and other cancers. Including mesothelioma as a cohort lets researchers gather early signals on whether this class of drug is worth pursuing further in a disease that has few approved options.

Limitations to Consider

This is an early-phase study. Phase 1/2 trials are designed mainly to establish safety and the right dose, not to prove that a drug extends survival. The mesothelioma cohort sits within a much larger basket study, so the number of people with mesothelioma is a fraction of the overall 884-participant target.

The trial is also still recruiting, with an estimated primary completion in July 2027 and study completion in October 2027 per the record. Meaningful data specific to mesothelioma, if it emerges, will take time to mature and report.