When should chemotherapy be added to trastuzumab as first-line therapy for patients with HER2-positive metastatic disease and for how long should trastuzumab be continued?

OVERVIEW: Randomized trial data from the advanced disease setting has demonstrated that in women with HER2 overexpressing breast cancers, the combination of trastuzumab plus chemotherapy — using either doxorubicin-cyclophosphamide or paclitaxel — results in improved progression-free and overall survival compared to the same chemotherapy given without trastuzumab. A recent report by Vogel of trastuzumab monotherapy demonstrated comparable antitumor activity to what has been reported trastuzumab plus chemotherapy. Trastuzumab alone is frequently utilized as first-line therapy, particularly in women with non-life threatening metastases or with comorbid conditions. Trastuzumab is widely accepted as an integral part of first line therapy of women with metastatic disease, and a key clinical question is whether to add chemotherapy, as no randomized trial has directly compared these treatments. In the responding patient, another key issue is the duration of treatment. In the pivotal clinical trials, trastuzumab was continued until disease progression, and this is widely considered a minimal standard. However, many research leaders continue trastuzumab beyond progression, adding another chemotherapeutic agent in the hope of antitumor synergy. The optimal duration of therapy is being studied in clinical trials. The efficacy of trastuzumab in the advanced disease setting has led to a new generation of phase 3 randomized trials evaluating this agent in the adjuvant setting.

Would you recommend first-line trastuzumab therapy for the following women with ER-negative, HER2+(IHC 3+) metastatic breast cancer?

	Asymptomatic 43-year-old woman with bone metastases who received adjuvant AC-T	65%
	Asymptomatic 63-year-old woman with bone metastases who received adjuvant AC-T	65%
	Very ill 43-year-old woman with liver and lung metastases who received adjuvant AC	80%
	Very ill 63-year-old woman with liver and lung metastaseswho received adjuvant AC	70%
	Very ill 43-year-old woman with liver and lung metastases who received adjuvant AC-T	85%
	Very ill 63-year-old woman with liver and lung metastases who received adjuvant AC-T	80%

A 57-year-old woman has HER2-positive breast cancer and on first relapse is treated with paclitaxel/trastuzumab. After 4 months, she has had a good response and is doing well. Generally, how long would you continue therapy?

	Continue until progression	65%
	Stop before progression	35%

	Continue after progression and add another chemo agent	65%
	Continue until progression, then stop	25%
	Stop before progression	10%

SURVIVAL ADVANTAGE IN METASTATIC DISEASE

We found that trastuzumab-based combination therapy was effective in that it reduced the relative risk of death by 20% at a median follow-up of 30 months. Few studies of metastatic breast cancer have demonstrated a survival advantage of this magnitude in association with the addition of a single agent. ...Given the extremely poor prognosis of patients with HER2-positive metastatic breast cancer, the cardiotoxicity of trastuzumab must be weighed against its potential clinical benefit. We recommend a cautious approach to the use of trastuzumab in patients who have previously received anthracyclines and in those who are currently receiving anthracyclines. The adjuvant use of trastuzumab will be an important research topic, but since many patients with early-stage breast cancer can be cured by surgery and radiotherapy, the cardiotoxicity of trastuzumab will be a critical consideration. In this context, the risks of trastuzumab will necessitate great caution especially when combined with an anthracycline. Indeed, one large upcoming trial of adjuvant trastuzumab will evaluate a nonanthracycline-based regimen for this reason.

— Dennis J Slamon, MD, PhD et al.
N Engl J Med 2001;344(11):783-792.

TRASTUZUMAB AS ADJUVANT THERAPY

There is a powerful emotional and intellectual appeal to translate the survival gains from the use of trastuzumab in the advanced-disease setting to the adjuvant treatment of HER2-overexpressing breast cancer, particularly with those at greatest risk of recurrence and death. The undetermined long-term risk of cardiac problems from trastuzumab, however, demands caution, and use of the agent as adjuvant therapy is best restricted to participation in the several clinical trials that are now underway. Eligibility for these trials generally require tumors to have IHC 3+ or FISH-positive HER2 results and a pretreatment EF > 50%.

— John Horton, MB, ChB, FACP
Cancer Control 2001;8(1):103-110.

CLINICAL TRIALS OF ADJUVANT TRASTUZUMAB

For HER2/neu-overexpressing breast cancer patients, the adjuvant use of trastuzumab will become paramount; therefore, it must be evaluated in a randomized controlled trial. There is disagreement regarding the design of such a trial, largely because of the ubiquitous use of anthracyclines in the adjuvant setting and the opposing necessity of avoiding anthracycline plus trastuzumab combinations. Combination index values for various chemotherapeutic drugs in combination with trastuzumab demonstrate dramatic synergistic interactions with the platinum agents and with docetaxel (Taxotere; Aventis Pharmaceuticals, Inc, Parsippany, NJ). The greatest level of synergy has been demonstrated with the triple-drug combination of docetaxel, platinum, and trastuzumab in which synergy is demonstrated, even at low doses. The adjuvant trial design for the Breast Cancer International Research Group uses a control arm of doxorubicin/cyclophosphamide for four cycles followed by docetaxel for four cycles and the second arm contains the addition of trastuzumab to the taxane sequence. The third arm, a nonanthracycline-containing regimen, contains docetaxel, a platinum agent (either cisplatin or carboplatin), and trastuzumab. The rationale for the selection of this three-drug regimen is based on the biology of the system and preclinical and clinical findings that demonstrate a high potential for clinical synergy.

— Joseph A Sparano, MD
Semin Oncol 2001;(1Suppl 3):20-27.

TRASTUZUMAB-ASSOCIATED CARDIOTOXICITY

A problem in considering trastuzumab as adjuvant therapy is the unexpected risk of developing cardiac dysfunction, particularly when combined with the anthracycline doxorubicin. This would require careful monitoring in patients with early breast cancer who have potentially curable disease.

—Gerhard Schaller, MD et al.
Ann Oncol 2001;(Suppl 1):S97-S100.

INTEGRATING TRASTUZUMAB INTO THE ADJUVANT SETTING

…the significant cardiac toxicity observed with trastuzumab-anthracycline combinations has led to two main strategies for integrating trastuzumab in the adjuvant setting: (1) addition of trastuzumab to mostly anthracycline-based programs (sequential approach); and (2) biology-oriented strategy based on synergism between trastuzumab and chemotherapy agents. Large-scale clinical research programs are presently being developed and will create a challenge for clinical researchers. The adequate scientific hypothesis, related to the pivotal studies of trastuzumab in the adjuvant setting, require large sample sizes (several thousand patients) and a very strict selection of the patient population (tumors amplifying the HER2 gene). Success in a timely fashion requires global collaboration, dedication to high-standard clinical research, and awareness of all available protocols by oncologists and patients with breast cancer.

—Jean-Marc Nabholtz, MD, Dennis Slamon, MD, PhD
Semin Oncol 2001;28(Suppl1):1-12.

RATIONALE FOR ADJUVANT TRASTUZUMAB TRIALS

The data from NSABP B-15 have not been published in full but are contained within the background of the NSABP B-31 protocol. We see poorer outcomes in patients with node-positive, HER2-positive breast cancer, who only receive AC chemotherapy. Even patients with one to three positive nodes have only a 50-50 chance of being alive and free of disease at five to ten years. We must try to improve their survival rate, and trastuzumab is the best agent we have right now that is targeted specifically to this group of women.

—Edith A Perez, MD

ADJUVANT CLINICAL TRIALS OF TRASTUZUMAB

Intergroup trial 9831 is an adjuvant study that was activated in May 2000. We have enrolled 700 patients with node-positive, HER2-positive breast cancer. This trial will join the three other worldwide studies being conducted to help answer the question of whether trastuzumab adds benefit to chemotherapy in this group of poor-prognosis women. We are also testing the question of whether trastuzumab should be used sequentially or concurrently with chemotherapy.

NSABP B-31 has very similar eligibility criteria. The NSABP uses paclitaxel every three weeks, while we are utilizing paclitaxel weekly. Another difference between the two trials is that the NSABP starts tamoxifen — if indicated — concurrent with AC, whereas in the Intergroup trial, tamoxifen is started after the completion of the six months of chemotherapy. Additionally, we are submitting an amendment to our protocol to administer trastuzumab once every three weeks, whereas NSABP will maintain weekly trastuzumab for one year.

If someone uses adjuvant trastuzumab outside of a clinical trial setting, they’re essentially shooting in the dark. We do not yet understand for how long this therapy should be given, what schedule should be used in combination with chemotherapy, and the potential risks or benefits the patients may derive from such treatment.

—Edith A Perez, MD

CARDIOTOXICITY AND TRASTUZUMAB

Both adjuvant trastuzumab trials — NCCTG N9831 and NSABP B-31 — are carefully attending to cardiac tolerability. At this time, no red flags have been raised. In our adjuvant trial, we have attempted to ameliorate the risk of cardiotoxicity by not using trastuzumab concurrently with anthracyclines and by limiting the dose of doxorubicin to 240 milligrams per meter squared. In the pivotal trastuzumab metastatic study, the increased risk of cardiotoxicity in terms of congestive heart failure was seen when the cumulative dose of doxorubicin was greater than 300 milligrams per meter squared.

We are accumulating data to help us understand what AC chemotherapy leads to in terms of ejection fractions, because this has never been investigated thoroughly. We are developing a companion cardiac tolerability study, and the NSABP will be conducting a similar study as well. We are attempting to determine whether we can find plasma factors that predict clinical cardiotoxicity. There’s a lot of cardiology literature regarding the potential value of various factors, and we’re going to look at these in a prospective fashion to see if any correlate with clinical outcome. We are also going to look at the correlation between ejection fractions obtained by MUGA versus echocardiogram, evaluating ejection fractions before study entry, after AC, after paclitaxel, and nine and 18 months into treatment. If we see more than 5% cardiotoxicity in the investigational arms compared to the standard arm, we will stop the trial.

—Edith A Perez, MD

CONTINUATION OF TRASTUZUMAB AFTER DISEASE PROGRESSION IN THE METASTATIC SETTING

My standard practice is to use trastuzumab until progression or toxicity. Whether it should be continued after disease progression is an issue we’re wrestling with on a day-to-day basis, and nobody knows the answer. We will join Dr. Pusztai from MD Anderson in his trial to help us answer this question in patients who have progressed on a taxane-trastuzumab combination. The randomization will be to continue on trastuzumab and add vinorelbine or stop the trastuzumab and use vinorelbine alone. Everybody should embrace this study, because it will help us answer this very, very important question.

—Edith A Perez, MD

GENENTECH-HO648G; NCI-V95-0714: PHASE III RANDOMIZED STUDY OF CHEMOTHERAPY WITH VS WITHOUT MONOCLONAL ANTIBODY HER2 IN WOMEN WITH METASTATIC BREAST CANCER OVEREXPRESSING HER2/NEU AND PREVIOUSLY UNTREATED WITH CYTOTOXIC CHEMOTHERAPY CLOSED PROTOCOL

AC = doxorubicin or epirubicin, cyclophosphamide

ROCHE-BO16216; GENENTECH-H2223G: PHASE II/III RANDOMIZED STUDY OF ANASTROZOLE WITH OR WITHOUT TRASTUZUMAB (HERCEPTIN) IN POSTMENOPAUSAL WOMEN WITH HORMONE RECEPTOR-POSITIVE HER2-OVEREXPRESSING METASTATIC BREAST CANCER OPEN PROTOCOL

PROJECTED ACCRUAL: A total of 202 patients will be accrued within 24 months.

Treatment continues for at least 2 years in the absence of disease progression or unacceptable toxicity.

STUDY CONTACT: Bernd Langer, Chair, Ph: 41-61-68-80638 Roche Global Development - Palo Alto

NCCTG-983252: PHASE II RANDOMIZED STUDY OF PACLITAXEL, CARBOPLATIN AND TRASTUZUMAB (HERCEPTIN) AS FIRST-LINE CHEMOTHERAPY IN WOMEN WITH OVEREXPRESSED HER-2, METASTATIC BREAST CANCER. OPEN PROTOCOL

STUDY CONTACT Edith Perez, Chair, 507-284-5369 North Central Cancer Treatment Group

CLINICAL BENEFIT, DURATION OF RESPONSE AND CARDIOTOXICITY IN CHEMOTHERAPY VERSUS CHEMOTHERAPY PLUS TRASTUZUMAB REGIMENS

Derived from Slamon DJ et al. N E J M 2001;344(11):783-792. Abstract

CALGB 9840, CTSU: PHASE III RANDOMIZED STUDY OF PACLITAXEL VIA ONE HOUR INFUSION EVERY WEEK VERSUS THREE HOUR INFUSION EVERY 3 WEEKS WITH OR WITHOUT TRASTUZUMAB IN PATIENTS WITH INOPERABLE, RECURRENT, OR METASTATIC BREAST CANCER WITH OR WITHOUT OVEREXPRESSION OF HER2-NEU. OPEN PROTOCOL

PROJECTED ACCRUAL: A total of 580 patients will be accrued within 3 years.

T=paclitaxel; H=trastuzumab Trastuzumab patients are administered an initial loading dose. Courses repeat every 3 weeks in the absence of disease progression or unacceptable toxicity.

STUDY CONTACT: Andrew D Seidman, Chair, Ph: 212-636-5875 Cancer and Leukemia Group B

NSABP B-31 TRIAL: PHASE III RANDOMIZED STUDY OF DOXORUBICIN AND CYCLOPHOSPHAMIDE FOLLOWED BY PACLITAXEL WITH OR WITHOUT TRASTUZUMAB IN WOMEN WITH NODE-POSITIVE BREAST CANCER THAT OVEREXPRESSES HER2 OPEN PROTOCOL

AC=doxorubicin/cyclophosphamide; T=paclitaxel; H=trastuzumab ER/PR-positive patients receive tamoxifen for 5 years. Patients > 50 years old or who are ER/PR-negative or indeterminable and have received prior chemopreventive tamoxifen may be treated with tamoxifen at the investigator’s discretion. Lumpectomy patients undergo XRT x 5-6 weeks after chemotherapy and concurrently with trastuzumab.

STUDY CONTACT Edward H Ramond, Chair, Ph: 859-323-5038 National Surgical Adjuvant Breast and Bowel Project

SWS-SAKK-22/99, EU-99028: PHASE III RANDOMIZED STUDY OF FIRST-LINE TRASTUZUMAB ALONE FOLLOWED BY COMBINATION TRASTUZUMAB AND PACLITAXEL VERSUS FIRST-LINE COMBINATION TRASTUZUMAB AND PACLITAXEL IN WOMEN WITH HER2 OVEREXPRESSING METASTATIC BREAST CANCER OPEN PROTOCOL

PROJECTED ACCRUAL: Approximately 170-250 patients.

Treatment continues in both arms until unacceptable toxicity or disease progression.

STUDY CONTACT Aron Goldhirsch, Ph: 39-02-574-894-39 Instituto Europeo Di Oncologia

BCIRG-006: PHASE III RANDOMIZED STUDY OF ADJUVANT DOXORUBICIN, CYCLOPHOSPHAMIDE, AND DOCETAXEL WITH OR WITHOUT TRASTUZUMAB VERSUS TRASTUZUMAB, DOCETAXEL, AND EITHER CARBOPL ATIN OR CISPLATIN IN WOMEN WITH HER2-NEU-EXPRESSING NODE-POSITIVE OR HIGH-RISK NODE-NEGATIVE OPERABLE BREAST CANCER OPEN PROTOCOL

AC=doxorubicin/cyclophosphamide; T=docetaxel; H=trastuzumab ER/PR+ patients receive tamoxifen

STUDY CONTACT Linnea Chap, Chair, Ph: 310-206-6144 Jonsson Comprehensive Cancer Center, UCLA

CALGB-49808 TRIAL: PHASE III RANDOMIZED STUDY OF DOXORUBICIN AND CYCLOPHOSPHAMIDE WITH OR WITHOUT DEXRAZOXANE, FOLLOWED BY PACLITAXEL WITH OR WITHOUT TRASTUZUMAB, FOLLOWED BY SURGERY AND RADIOTHERAPY WITH OR WITHOUT TRASTUZUMAB IN WOMEN WITH HER2+ STAGE IIIA OR IIIB OR REGIONAL STAGE IV BREAST CANCER OPEN PROTOCOL

AC=doxorubicin/cyclophosphamide; T=paclitaxel; H=trastuzumab Treatment continues in all arms in the absence of distant disease progression.

STUDY CONTACT Mark L Graham, Chair, Ph: 919-859-6631 Cancer and Leukemia Group B

NCCTG-N9831: PHASE III RANDOMIZED STUDY OF DOXORUBICIN PLUS CYC LOPHOSPHAMIDE FOLLOWED BY PACLITAXEL WITH OR WITHOUT TRASTUZUMAB (HERCEPTIN) IN PATIENTS WITH HER2 OVEREXPRESSING BREAST CANCER OPEN PROTOCOL

AC=doxorubicin/cyclophosphamide; T=paclitaxel; H=trastuzumab All ER/PR-positive patients receive tamoxifen x 5 years.

STUDY CONTACTS Edith A Perez, Chair, 507-284-5369 North Central Cancer Treatment Group Nancy E Davidson, Chair, 410-955-8964 Eastern Cooperative Oncology Group Peter A Kaufman, Chai r, 603-650-6700 Cancer and Leukemia Group B Silvana Martino, Chair, 310-998-3961 Southwest Oncology Group

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