A Phase 1 interventional study of US-sourced oral Femara® + Letrozole SIE and EU sourced oral Femara® + Letrozole SIE in Hormone Receptor Positive Early Breast Cancer, sponsored by Rovi Pharmaceuticals Laboratories. Recruiting at 21 sites in 3 countries. Open to female participants aged 18 Years to 80 Years. Per ClinicalTrials.gov, last updated 2026-10-09.
Sponsored by Rovi Pharmaceuticals Laboratories · Phase 1, Interventional, and Treatment
Among 905 studies in Breast Neoplasms with a site in Spain — 164 open to participants now, 286 under way, 84 of them phase 3. Breast Neoplasms · Spain.
Among the 905 studies in Breast Neoplasms with a site in Spain, this one is the 449th largest by planned enrollment of the 805 interventional ones that give a count, is one of 28 that started in 2026, is one of 104 in phase 1, reaches primary completion later than 212 of the 285 other live ones, and was the 877th registered.
14,829 studies on the registry are indexed under Breast Neoplasms; 3,318 are open to participants now.
Browse Breast Neoplasms studies →164 of the 905 studies in Breast Neoplasms with a site in Spain are open now. Recruiting first, the newest first:
Fundacion para la Formacion e Investigacion Sanitarias de la Region de Murcia · Sites in Spain
Ages 18+
Spanish Breast Cancer Research Group · Sites in Spain
Ages 18+
Daiichi Sankyo · Sites in Spain, United States, Belgium and 5 more countries
Ages 18+
Kenko Imalytics S.L. · Sites in Spain
Ages 18+ · Women only
Spanish Breast Cancer Research Group · Sites in Spain
Ages 18+ · Women only
A study can be open while its sites in Spain have not opened yet or have stopped. Only those recruiting at a site in Spain →
Of the 2,398 Breast Neoplasms studies recruiting now, 1,569 (65%) set no upper age limit and 592 (25%) stop at 75 or younger; 103 take children under 18; 215 take healthy volunteers.
This study: 18 Years to 80 Years · female · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
905 studies; the count open now beside each. This study's row is marked.
A study in two phases is counted once above. Listed by phase, each with its combined phases: Phase 1 174 · Phase 2 326 · Phase 3 224 · Phase 4 13
First in 1996; this study’s year is marked. 28 started in 2026.
By drug class, each counting the studies that test any of its medicines:
This study's planned enrollment of 120 is above the median of 72 across 10,900 interventional studies indexed under Breast Neoplasms.
Median enrollment 151 across the 805 interventional studies, 200 across the 97 observational. Of the 575 that completed or were terminated, 291 (51%) have results posted.
This tab as a report to print or save as PDF → With an account.
533 of 905 have an industry lead sponsor. The 10 most frequent:
Rovi Pharmaceuticals Laboratories is the lead sponsor of 19 studies on the registry; 2 are open to participants now.
Rovi Pharmaceuticals Laboratories has 3 studies filed under Breast Neoplasms — fewer than ten, so there is no comparison to draw.
81 of the studies in Breast Neoplasms with a site in Spain that are under way reach primary completion within a year, 21 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT05646862Phase 3Hoffmann-La RocheA Study Evaluating the Efficacy and Safety of Inavolisib Plus Fulvestrant Compared With Alpelisib Plus Fulvestrant in Participants With HR-Positive, HER2-Negative, PIK3CA Mutated, Locally Advanced or Metastatic Breast Cancer Post CDK4/6i and Endocrine Combination Therapy | 2026-11-13 |
| NCT03820830Phase 3ETOP IBCSG Partners FoundationPalbociclib for HR Positive / HER2-negative Isolated Locoregional Recurrence of Breast Cancer | 2026-12 |
| NCT03595592Phase 3Fondazione MichelangeloNeoadjuvant Treatment of HER2 Positive Early High-risk and Locally Advanced Breast Cancer | 2026-12-15 |
| NCT05909397Phase 3PfizerVepdegestrant (ARV-471/PF-07850327) + Palbociclib vs Letrozole + Palbociclib in ER(+)/HER2(-) Advanced Breast Cancer | 2026-12-30 |
| NCT05894239Phase 3Hoffmann-La RocheA Study to Evaluate the Efficacy and Safety of Inavolisib in Combination With Phesgo Versus Placebo in Combination With Phesgo in Participants With PIK3CA-Mutated HER2-Positive Locally Advanced or Metastatic Breast Cancer | 2026-12-31 |
Add all 81 to your calendar (.ics) → With an account.
Among the 905 studies in Breast Neoplasms with a site in Spain, from their registry updates:
This tab as a report to print or save as PDF → With an account.
The study aims to compare the amount of the drug letrozole that gets into the bloodstream after multiple doses of the quarterly injection Letrozole SIE, versus multiple doses of the standard oral daily tablet of letrozole (Femara®), in women who have gone through menopause and have received treatment for hormone receptor-positive early breast cancer. Participants must have completed at least five years of hormone therapy with at least two of those years with letrozole before starting their participation in the study. Women who have completed four years of hormone therapy are also eligible if their doctor considers them at low risk of cancer returning.
The primary objective of the study is to evaluate the steady-state comparative bioavailability of quarterly injectable Letrozole SIE compared to United States (US)-sourced oral Femara® in the US-sourced arm and of quarterly injectable Letrozole SIE compared to European Union (EU)-sourced oral Femara® in the EU-sourced arm, in post-menopausal women treated with endocrine therapy for hormone-receptor positive (HR+) early breast cancer (EBC). The study also aims to characterize the elimination phase of Letrozole SIE after multiple doses.
The study consists of four periods: Screening, Treatment Period 1 (TP1), Treatment Period 2 (TP2) and Extension Period. After the Screening Period, participants will be randomized to two different arms: US-sourced oral Femara® or EU-sourced oral Femara® for 14 days to achieve the steady-state concentrations of letrozole in TP1. After receiving the latest oral letrozole dose, participants from both arms will start TP2. In TP2, quarterly injectable Letrozole SIE will be administered to achieve steady-state. After TP2, a subset of participants (up to 60 participants, regardless of which study arm they belong to) will continue in the study for the assessment of the elimination phase of Letrozole SIE after multiple doses during the Extension Period.
It is estimated that approximately 120 subjects should be randomized.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HER2
HER2 is a protein, made from the ERBB2 gene, that drives the growth of some cancers. A study may look for a level of the protein, extra copies of the gene, or a particular change in it.
In breast cancer, protein tests are read as HER2-positive, HER2-low or HER2-negative; other cancers use their own rules. Check which test result the study requires.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CYP3A (CYP3A4) inhibitors and inducers
CYP3A is a group of enzymes, mainly CYP3A4, in the liver and gut that break down many medicines. Some medicines, supplements and foods (grapefruit, St John’s wort) slow them down or speed them up, which changes how much of a study drug stays in the body.
Studies list them so they can be avoided or switched; bring a list of everything you take, including supplements.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Drug: US-sourced oral Femara® + Letrozole SIE
Drug: EU sourced oral Femara® + Letrozole SIE
US-sourced Femara® 2.5 mg/day oral for 14 days (treatment period 1) + quarterly injectable Letrozole SIE (treatment period 2)
EU-sourced oral Femara® 2.5 mg/day for 14 days (treatment period 1) + quarterly injectable Letrozole SIE (treatment period 2)
Area under the concentration-time curve within a dosing interval at Steady-State (SS AUCtau)
Individual and mean area under the concentration-time curve within a dosing interval at steady-state
Time frame: After multiple doses of Letrozole SIE until Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® on Day 14 TP1
Adverse Events
Incidence of adverse events (type, severity, seriousness, and relationship to study drug), including the incidence of treatment-emergent adverse events (TEAEs), the incidence of serious TEAEs, and the incidence of TEAEs leading to treatment discontinuation.
Time frame: From the time of obtaining signed informed consent until the final follow-up visit on Day 281 (or Day 421 for the subset of participants in the Extension Period)
Injection site reactions
Incidence of injection site reactions
Time frame: At pre-dose and 1 hour after each Letrozole SIE administration in TP2
Injection-related pain score
Changes in injection-related pain score by numeric rating scale (NRS). The NRS evaluates the intensity of injection-related pain experienced at the time of Letrozole SIE administration. It is scored from 0 to 10 (0 meaning no pain and 10 meaning the worst possible pain).
Time frame: From baseline TP2 to the follow-up visit on Day 281
Bone mineral density (BMD) by dual energy x-ray absorptiometry (DXA)
Changes in bone mineral density BMD by DXA
Time frame: From screening to Day 281 TP2
Average plasma drug concentration during a dosing interval at Steady-State (SS Cave)
Individual and mean steady-state average plasma drug concentration during a dosing interval
Time frame: After multiple doses of Letrozole SIE until Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® at Day 14 TP1
Minimum drug concentration at steady-state (Cmin ss)
Minimum drug concentration at steady-state
Time frame: After multiple doses of Letrozole SIE until Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® at Day 14 TP1
Maximum plasma concentration at steady-state (Cmax ss)
Maximum plasma concentration at steady-state
Time frame: After multiple doses of Letrozole SIE at Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® at Day 14 TP1
Letrozole blood level percent fluctuation
Individual and mean letrozole blood percent fluctuation
Time frame: After multiple doses of Letrozole SIE at Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® at Day 14 TP1
Time to peak observed concentration (Tmax)
Time to peak observed concentration
Time frame: After multiple doses of Letrozole SIE until Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® at Day 14 TP1
Steady-State (SS)
Characterization of the steady-state
Time frame: After multiple doses of Letrozole SIE until Day 281 TP2 and after multiple doses of US-sourced oral Femara® or EU-sourced oral Femara® at Day 14 TP1
Terminal rate constant (λz)
Individual and mean Terminal rate constant (λz) after multiple doses of Letrozole SIE in the subset of participants in the Extension Period
Time frame: After multiple doses of Letrozole SIE in TP2 until Day 421 in the Extension Period
Terminal half-life (t1/2)
Individual and mean Terminal half-life after multiple doses of Letrozole SIE in the subset of participants in the Extension Period
Time frame: After multiple doses of Letrozole SIE in TP2 until Day 421 in the Extension Period
Area under the curve extrapolated to infinity (AUC∞)
Individual and mean Area under the curve extrapolated to infinity after multiple doses of Letrozole SIE in the subset of participants in the Extension Period
Time frame: After multiple doses of Letrozole SIE in TP2 until Day 421 in the Extension Period
Area under the curve that is extrapolated (AUCextrap)
Percentage of area under the curve that is extrapolated after multiple doses of Letrozole SIE in the subset of participants in the Extension Period
Time frame: After multiple doses of Letrozole SIE in TP2 until Day 421 in the Extension Period
Hormone supression
Analysis of letrozole exposure and hormone suppression measuring the sex hormone estrone (E1), sulfate estrone (SE1), and estradiol (E2) plasma levels.
Time frame: From screening to the final follow-up visit on Day 281 (or Day 421 for the subset of participants in the Extension Period)
CYP2A6 genotyping
Proportion of participants in each CYP2A6 metabolizer phenotype category (normal, intermediate, slow)
Time frame: From screening to final follow-up visit Day 281 (or Day 421 for the subset of participants in the Extension Period)
Started Jun 2026 (actual). Primary completion is estimated for May 2028, 23 months after the start.
Of 389 industry-sponsored phase 1 interventional studies under Breast Neoplasms, half reached primary completion within 39 months of starting (the median), counting those still running; a quarter within 22 and three quarters within 56. This study's planned 23 months is below that.
Counting every sponsor, half of 761 studies reached it within 44 months; a quarter within 25 and three quarters within 65.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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Rovi Pharmaceuticals Laboratories