Mirvetuximab soravtansine: A breakthrough in targeted therapy for platinum-resistant ovarian cancer

Ovarian cancer, ranked as the second leading cause of gynecologic malignancy-related deaths globally, poses a formidable challenge despite advances in early detection and treatment modalities. This paper explores the efficacy and safety of mirvetuximab soravtansine, the first folate receptor alpha (FRα)-targeting antibody-drug conjugate, in platinum-resistant ovarian cancer expressing FRα. A review of 4 key studies involving 453 participants consistently demonstrates mirvetuximab soravtansine's clinically meaningful antitumor activity and favorable safety profile. Clinical implications emphasize mirvetuximab soravtansine's pivotal role in targeted therapy, especially for high FRα-expressing tumors, potentially reshaping platinum-resistant ovarian cancer management. The combination therapy approach introduces a novel dimension, suggesting enhanced therapeutic outcomes. Even in heavily pretreated patients, mirvetuximab soravtansine's favorable tolerability positions it as a viable option. The reliability of archival tissue for FRα assessment simplifies patient selection, streamlining accessibility to targeted therapies. However, identified gaps, including limited diversity in patient populations, sparse quality of life data, and the need for long-term safety information, indicate areas for future research. Exploration of additional biomarkers predicting mirvetuximab soravtansine responsiveness is essential for personalized treatment.

Mirvetuximab Soravtansine in FRα-Positive, Platinum-Resistant Ovarian Cancer

BACKGROUND

Mirvetuximab soravtansine-gynx (MIRV), a first-in-class antibody-drug conjugate targeting folate receptor α (FRα), is approved for the treatment of platinum-resistant ovarian cancer in the United States.

METHODS

We conducted a phase 3, global, confirmatory, open-label, randomized, controlled trial to compare the efficacy and safety of MIRV with the investigator's choice of chemotherapy in the treatment of platinum-resistant, high-grade serous ovarian cancer. Participants who had previously received one to three lines of therapy and had high FRα tumor expression (≥75% of cells with ≥2+ staining intensity) were randomly assigned in a 1:1 ratio to receive MIRV (6 mg per kilogram of adjusted ideal body weight every 3 weeks) or chemotherapy (paclitaxel, pegylated liposomal doxorubicin, or topotecan). The primary end point was investigator-assessed progression-free survival; key secondary analytic end points included objective response, overall survival, and participant-reported outcomes.

RESULTS

A total of 453 participants underwent randomization; 227 were assigned to the MIRV group and 226 to the chemotherapy group. The median progression-free survival was 5.62 months (95% confidence interval [CI], 4.34 to 5.95) with MIRV and 3.98 months (95% CI, 2.86 to 4.47) with chemotherapy (P<0.001). An objective response occurred in 42.3% of the participants in the MIRV group and in 15.9% of those in the chemotherapy group (odds ratio, 3.81; 95% CI, 2.44 to 5.94; P<0.001). Overall survival was significantly longer with MIRV than with chemotherapy (median, 16.46 months vs. 12.75 months; hazard ratio for death, 0.67; 95% CI, 0.50 to 0.89; P = 0.005). During the treatment period, fewer adverse events of grade 3 or higher occurred with MIRV than with chemotherapy (41.7% vs. 54.1%), as did serious adverse events of any grade (23.9% vs. 32.9%) and events leading to discontinuation (9.2% vs. 15.9%).

CONCLUSIONS

Among participants with platinum-resistant, FRα-positive ovarian cancer, treatment with MIRV showed a significant benefit over chemotherapy with respect to progression-free and overall survival and objective response. (Funded by ImmunoGen; MIRASOL ClinicalTrials.gov number, NCT04209855.).

Safety profile of trastuzumab-emtansine (T-DM1) with concurrent radiation therapy: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

In recent years, the treatment landscape for breast cancer has undergone significant advancements, with the introduction of several new anticancer agents. One such agent is trastuzumab emtansine (T-DM1), an antibody drug conjugate that has shown improved outcomes in both early and advanced breast cancer. However, there is currently a lack of comprehensive evidence regarding the safety profile of combining T-DM1 with radiation therapy (RT). In this study, we aim to provide a summary of the available data on the safety of combining RT with T-DM1 in both early and metastatic breast cancer settings.

MATERIALS AND METHODS

This systematic review and meta-analysis project is part of the consensus recommendations by the European Society for Radiotherapy and Oncology (ESTRO) Guidelines Committee on integrating RT with targeted treatments for breast cancer. A thorough literature search was conducted using the PUBMED/MedLine, Embase, and Cochrane databases to identify original studies focusing on the safety profile of combining T-DM1 with RT.

RESULTS

After applying eligibility criteria, nine articles were included in the meta-analysis. Pooled data from these studies revealed a high incidence of grade 3 + radionecrosis (17%), while the rates of grade 3 + radiation-related pneumonitis (<1%) and skin toxicity (1%) were found to be very low.

CONCLUSION

Although there is some concern regarding a slight increase in pneumonitis when combining T-DM1 with postoperative RT, the safety profile of this combination was deemed acceptable for locoregional treatment in non-metastatic breast cancer. However, caution is advised when irradiating intracranial sites concurrently with T-DM1. There is a pressing need for international consensus guidelines regarding the safety considerations of combining T-DM1 and RT for breast cancer.

High risks adverse events associated with trastuzumab emtansine and trastuzumab deruxtecan for the treatment of HER2-positive/mutated malignancies: a pharmacovigilance study based on the FAERS database

BACKGROUND

T-DM1 and T-DXd are two promising antibody-drug conjugates for treating advanced HER2-positive breast cancer and HER2-mutated lung cancer. Understanding the differences in the adverse events (AEs) profile of both drugs may help clinicians make an appropriate treatment decision.

RESEARCH DESIGN AND METHODS

All data obtained from the FDA Adverse Event Reporting System (FAERS) database from Q1 2004 to Q3 2022 underwent disproportionality analysis and Bayesian analysis to detect and assess the AE signals of T-DM1 and T-DXd for comparison.

RESULTS

A total of 2,113 and 1,269 AE reports associated with T-DM1 and T-Dxd, respectively, were retrieved from FAERS database, in which, respondents were mostly elderly women. Their statistical differences (p < 0.001), poses high incidence of thrombocytopenia, including cardiotoxicity (p < 0.05) for T-DM1, while myelosuppression, interstitial lung disease (ILD), and pneumonitis for T-DXd. Splenomegaly, nodular regenerative hyperplasia, hepatic cirrhosis, portal hypertension, neuropathy peripheral, and spider nevus, are particular to T-DM1. Similarly, febrile neutropenia, pneumocystis jirovecii pneumonia, neutrophil count decreased, and KL-6 increased, are unique to T-DXd.

CONCLUSIONS

T-DXd is more likely to induce ILD/pneumonia and myelosuppression than T-DM1, whereas T-DM1 has higher risk of hepatotoxicity, cardiotoxicity, and thrombocytopenia than T-DXd. T-DM1-related hepatotoxicity may need redefinition. Clinicians may need to balance the benefits and risks of antibody-drug conjugates treatment for certain patients.

Ado-trastuzumab emtansine associated spider telangiectasia

INTRODUCTION

Breast cancer is the most common cancer in women. Human epidermal growth factor receptor 2 (HER2) positivity rate is 20% and generally has a poor prognosis. Ado-trastuzumab emtansine (T-DM1) is an antibody-drug conjugate consisting of HER2 target monoclonal antibody trastuzumab and microtubule inhibitor emtansine. The most common side effects are fatigue, diarrhea, anemia, and it is generally a safe and tolerable agent.

CASE REPORT

In our case, we reported our patient who developed mucosal and cutaneous telangiectasia after T-DM1 treatment and who had a complete response in metastases after skin lesions.

MANAGEMENT AND OUTCOME

While no side effects were observed during the use of T-DM1 for HER2 positive disease, nose bleeding and spider telangiectasia on the skin developed in the 9th month of the treatment. In these lesions, which did not require any treatment, no regression was observed during T-DM1 treatment.

DISCUSSION

We think that T-DM1, which was detected with a low incidence of skin toxicity in studies, may form telangiectatic lesions due to vascular dilatation through emtansine, and therefore care should be taken in the treatment of T-DM1.

A phase 1 study of LY3076226, a fibroblast growth factor receptor 3 (FGFR3) antibody-drug conjugate, in patients with advanced or metastatic cancer

Background We report a Phase 1 study of LY3076226, an antibody-drug conjugate composed of human IgG1 monoclonal antibody against the human FGFR3 attached with a cleavable linker to the maytansine derivative DM4 in patients with advanced or metastatic cancer. Methods This study was comprised of two parts: (A) dose escalation in patients with advanced or metastatic cancer and (B) dose expansion in patients with urothelial carcinoma with locally determined FGFR3 alterations. The dose range of LY3076226 tested was 0.2-5.0 mg/kg as an intravenous infusion on Day 1 of each 21-day cycle. The primary objective was to determine a recommended phase 2 dose (RP2D). Results Twenty-five patients were enrolled (Part A: 22, Part B: 3) and received ≥ 1 dose of LY3076226. No dose-limiting toxicities were reported. LY3076226 was generally well tolerated; most of the toxicities were Grade 1 or 2. Two patients experienced treatment-related Grade 3 toxicity (embolism and decreased platelet count). Four patients experienced serious adverse events (not treatment-related), all in Part A. Dose-proportional exposure was observed, with an estimated half-life of 2-7 days. No responses were seen with LY3076226 treatment. Stable disease persisting for > 6 months was observed in 1 patient receiving 3.2 mg/kg of LY3076226. Conclusion The study demonstrates acceptable safety and tolerability of LY3076226 up to the 5.0 mg/kg dose. Recruitment was stopped due to pipeline prioritization. Dose escalation of LY3076226 beyond 5.0 mg/kg in patients with advanced tumors may be possible. The trial was registered on August 19, 2015 under identifier NCT02529553 with ClinicalTrials.gov.

Acute eosinophilic pneumonia: a fatal reaction to ado-trastuzumab

Ado-trastuzumab emtansine (T-DM1) is a monoclonal antibody drug conjugate approved for the treatment of HER2-positive breast cancers. Presented here is a case report of a patient who developed fatal pulmonary toxicity in the form of acute eosinophilic pneumonia while undergoing treatment with T-DM1. Prior to beginning T-DM1 therapy, this patient had been treated with two HER2-targeted agents (trastuzumab, pertuzumab) per National Comprehensive Cancer Network (NCCN) guidelines. This case represents a novel presentation of toxicity associated with T-DM1 while perhaps demonstrating additive toxicity associated with multiple lines of HER2 targeted therapies.

Chemotherapy-related amenorrhea (CRA) after adjuvant ado-trastuzumab emtansine (T-DM1) compared to paclitaxel in combination with trastuzumab (TH) (TBCRC033: ATEMPT Trial)

PURPOSE

Chemotherapy-related amenorrhea (CRA) is a surrogate for ovarian toxicity and associated risk of infertility and premature menopause. Here, we compare CRA rate with paclitaxel (T)-trastuzumab (H) to that with ado-trastuzumab emtansine (T-DM1).

METHODS

Patients with T1N0 HER2 + early-stage breast cancer (eBC) enrolled on the ATEMPT trial and were randomized 3:1 to T-DM1 3.6 mg/kg IV every (q) 3 weeks (w) × 17 vs. T 80 mg/m² with H IV qw × 12 (4 mg/kg load → 2 mg/kg), followed by H (6 mg/kg IV q3w × 13). Enrollees who self-reported as premenopausal were asked to complete menstrual surveys at baseline and every 6-12 months for 60 months. 18-month CRA (no periods reported during prior 6 months on 18-month survey) was the primary endpoint of this analysis.

RESULTS

Of 512 ATEMPT enrollees, 123 who began protocol therapy and answered baseline and at least one follow-up menstrual survey were premenopausal at enrollment. 76 had menstrual data available at 18 months without having received a gonadotropin-releasing hormone agonist or undergone hysterectomy and/or oophorectomy. Median age was 45 (range 23-53) among 18 who had received TH and 46 (range 34-54) among 58 who had received T-DM1. The 18-month rate of CRA was 50% after TH and 24% after T-DM1 (p = 0.045).

CONCLUSION

Amenorrhea at 18 months was less likely in recipients of adjuvant T-DM1 than TH. Future studies are needed to understand how T-DM1 impacts risk of infertility and permanent menopause, and to assess amenorrhea rates when T-DM1 is administered after standard HER2-directed chemotherapy regimens.

Mirvetuximab Soravtansine Combination Yields Encouraging Response Rates in Ovarian Cancer

Mirvetuximab soravtansine in combination with bevacizumab (Avastin) to treat patients with platinum-agnostic ovarian cancer demonstrated a confirmed 64% overall response rate (ORR), regardless of platinum status, according to study results presented at the 2020 American Society of Clinical Oncology Virtual Scientific Program.

Prospective evaluation of the cardiac safety of HER2-targeted therapies in patients with HER2-positive breast cancer and compromised heart function: the SAFE-HEaRt study

Purpose

HER2-targeted therapies have substantially improved the outcome of patients with breast cancer, however, they can be associated with cardiac toxicity. Guidelines recommend holding HER2-targeted therapies until resolution of cardiac dysfunction. SAFE-HEaRt is the first trial that prospectively tests whether these therapies can be safely administered without interruptions in patients with cardiac dysfunction.

Methods

Patients with stage I–IV HER2-positive breast cancer candidates for trastuzumab, pertuzumab or ado-trastuzumab emtansine (TDM-1), with left ventricular ejection fraction (LVEF) 40–49% and no symptoms of heart failure (HF) were enrolled. All patients underwent cardiology visits, serial echocardiograms and received beta blockers and ACE inhibitors unless contraindicated. The primary endpoint was completion of the planned HER2-targeted therapies without developing either a cardiac event (CE) defined as HF, myocardial infarction, arrhythmia or cardiac death or significant asymptomatic worsening of LVEF. The study was considered successful if planned oncology therapy completion rate was at least 30%.

Results

Of 31 enrolled patients, 30 were evaluable. Fifteen patients were treated with trastuzumab, 14 with trastuzumab and pertuzumab, and 2 with TDM-1. Mean LVEF was 45% at baseline and 46% at the end of treatment. Twenty-seven patients (90%) completed the planned HER2-targeted therapies. Two patients experienced a CE and 1 had an asymptomatic worsening of LVEF to ≤ 35%.

Conclusion

This study provides safety data of HER2-targeted therapies in patients with breast cancer and reduced LVEF while receiving cardioprotective medications and close cardiac monitoring. Our results demonstrate the importance of collaboration between cardiology and oncology providers to allow for delivery of optimal oncologic care to this unique population.

Electronic supplementary material

The online version of this article (10.1007/s10549-019-05191-2) contains supplementary material, which is available to authorized users.

Trastuzumab Emtansine for Residual Invasive HER2-Positive Breast Cancer

BACKGROUND

Patients who have residual invasive breast cancer after receiving neoadjuvant chemotherapy plus human epidermal growth factor receptor 2 (HER2)-targeted therapy have a worse prognosis than those who have no residual cancer. Trastuzumab emtansine (T-DM1), an antibody-drug conjugate of trastuzumab and the cytotoxic agent emtansine (DM1), a maytansine derivative and microtubule inhibitor, provides benefit in patients with metastatic breast cancer that was previously treated with chemotherapy plus HER2-targeted therapy.

METHODS

We conducted a phase 3, open-label trial involving patients with HER2-positive early breast cancer who were found to have residual invasive disease in the breast or axilla at surgery after receiving neoadjuvant therapy containing a taxane (with or without anthracycline) and trastuzumab. Patients were randomly assigned to receive adjuvant T-DM1 or trastuzumab for 14 cycles. The primary end point was invasive disease-free survival (defined as freedom from ipsilateral invasive breast tumor recurrence, ipsilateral locoregional invasive breast cancer recurrence, contralateral invasive breast cancer, distant recurrence, or death from any cause).

RESULTS

At the interim analysis, among 1486 randomly assigned patients (743 in the T-DM1 group and 743 in the trastuzumab group), invasive disease or death had occurred in 91 patients in the T-DM1 group (12.2%) and 165 patients in the trastuzumab group (22.2%). The estimated percentage of patients who were free of invasive disease at 3 years was 88.3% in the T-DM1 group and 77.0% in the trastuzumab group. Invasive disease-free survival was significantly higher in the T-DM1 group than in the trastuzumab group (hazard ratio for invasive disease or death, 0.50; 95% confidence interval, 0.39 to 0.64; P<0.001). Distant recurrence as the first invasive-disease event occurred in 10.5% of patients in the T-DM1 group and 15.9% of those in the trastuzumab group. The safety data were consistent with the known safety profile of T-DM1, with more adverse events associated with T-DM1 than with trastuzumab alone.

CONCLUSIONS

Among patients with HER2-positive early breast cancer who had residual invasive disease after completion of neoadjuvant therapy, the risk of recurrence of invasive breast cancer or death was 50% lower with adjuvant T-DM1 than with trastuzumab alone. (Funded by F. Hoffmann-La Roche/Genentech; KATHERINE ClinicalTrials.gov number, NCT01772472 .).

Nodular Regenerative Hyperplasia Induced by Trastuzumab Emtansine: Role of Emtansine?

Trastuzumab is a monoclonal antibody targeted against the Human Epidermal Growth Factor Receptor 2 (HER2) overexpressed in some breast cancer. This targeted therapy significantly improves the prognosis of these cancers. Recently an anti-HER2 antibodydrug conjugate was shaped in order to facilitate the targeted delivery of potent cytotoxic drug to cancer cells and to reduce resistance. This formulation, called trastuzumab emtansine (T-DM1), consists of the monoclonal antibody trastuzumab linked to a cytotoxic drug (a derivative of maytansine) via a chemical linker. Little is known about adverse reactions due to this new formulation. Herein we described the case of a woman suffering from a HER2-positive breast cancer, treated with trastuzumab for 30 months followed by T-DM1 monotherapy. After 12 months of T-DM1 treatment, a nodular regenerative hyperplasia confirmed by liver biopsy occurred. T-DM1 was stopped and medical imagery showed a resolution of the nodular regenerative hyperplasia. Unfortunately, hepatic metastasis progressed. Few cases of nodular regenerative hyperplasia induced by T-DM1 have been described so far. Further studies are needed to explore pathogenesis of nodular regenerative hyperplasia with this new antibody-drug conjugate treatment.

Splenic Enlargement and Bone Marrow Hyperplasia in Patients Receiving Trastuzumab-Emtansine for Metastatic Breast Cancer

BACKGROUND

An association between trastuzumab-emtansine (T-DM1) and splenic enlargement is reported in preclinical data, and has been noted anecdotally in patients receiving T-DM1 at our institution. Use of whole-body MRI examinations (WB-MRI) allows for detailed bone marrow assessment and semi-automated splenic volume calculations.

OBJECTIVE

To retrospectively evaluate changes in splenic volume versus evidence of bone marrow hyperplasia and/or changes in portal venous pressure in patients receiving T-DM1 for metastatic breast cancer.

PATIENTS AND METHODS

Twelve metastatic breast cancer patients underwent 29 WB-MRIs before and during T-DM1 therapy. Splenic volume, portal vein diameter, bone marrow diffusion-weighted normalised signal intensity (nSI), quantitative water diffusivity (apparent diffusion coefficient, ADC) and fat fraction (rF%) were measured and correlated.

RESULTS

Splenic volume increases were observed in 92% of patients. Mean splenic volume increased from 144 cm³ (95% CI 110-177 cm³) to 209 cm³ (95% CI 161-257 cm³) on T-DM1 therapy (p = 0.006). Splenic volume increases correlated with treatment duration (r² = 0.43). Bone marrow hyperplasia was evidenced by an increase in bone marrow nSI (3.5 to 4.8, p = 0.12), and decreases in rF% (64.3% to 57.3%, p = 0.12) and ADC (655 μm²/s to 543 μm²/s, p = 0.11). No changes to portal vein diameter were seen.

CONCLUSIONS

Previously unreported increases in splenic volume and bone marrow hyperplasia are observed on WB-MRI in patients on T-DM1 therapy. Caution must be applied to avoid misinterpreting T-DM1-induced bone marrow hyperplasia as diffuse disease progression in bone.

Trastuzumab emtansine versus capecitabine plus lapatinib in patients with previously treated HER2-positive advanced breast cancer (EMILIA): a descriptive analysis of final overall survival results from a randomised, open-label, phase 3 trial

BACKGROUND

The antibody-drug conjugate trastuzumab emtansine is indicated for the treatment of patients with HER2-positive metastatic breast cancer previously treated with trastuzumab and a taxane. Approval of this drug was based on progression-free survival and interim overall survival data from the phase 3 EMILIA study. In this report, we present a descriptive analysis of the final overall survival data from that trial.

METHODS

EMILIA was a randomised, international, open-label, phase 3 study of men and women aged 18 years or older with HER2-positive unresectable, locally advanced or metastatic breast cancer previously treated with trastuzumab and a taxane. Enrolled patients were randomly assigned (1:1) via a hierarchical, dynamic randomisation scheme and an interactive voice response system to trastuzumab emtansine (3·6 mg/kg intravenously every 3 weeks) or control (capecitabine 1000 mg/m² self-administered orally twice daily on days 1-14 on each 21-day cycle, plus lapatinib 1250 mg orally once daily on days 1-21). Randomisation was stratified by world region (USA vs western Europe vs or other), number of previous chemotherapy regimens for unresectable, locally advanced, or metastatic disease (0 or 1 vs >1), and disease involvement (visceral vs non-visceral). The coprimary efficacy endpoints were progression-free survival (per independent review committee assessment) and overall survival. Efficacy was analysed in the intention-to-treat population; safety was analysed in all patients who received at least one dose of study treatment, with patients analysed according to the treatment actually received. On May 30, 2012, the study protocol was amended to allow crossover from control to trastuzumab emtansine after the second interim overall survival analysis crossed the prespecified overall survival efficacy boundary. This study is registered with ClinicalTrials.gov, number NCT00829166.

FINDINGS

Between Feb 23, 2009, and Oct 13, 2011, 991 eligible patients were enrolled and randomly assigned to either trastuzumab emtansine (n=495) or capecitabine and lapatinib (control; n=496). In this final descriptive analysis, median overall survival was longer with trastuzumab emtansine than with control (29·9 months [95% CI 26·3-34·1] vs 25·9 months [95% CI 22·7-28·3]; hazard ratio 0·75 [95% CI 0·64-0·88]). 136 (27%) of 496 patients crossed over from control to trastuzumab emtansine after the second interim overall survival analysis (median follow-up duration 24·1 months [IQR 19·5-26·1]). Of those patients originally randomly assigned to trastuzumab emtansine, 254 (51%) of 495 received capecitabine and 241 [49%] of 495 received lapatinib (separately or in combination) after study drug discontinuation. In the safety population (488 patients treated with capecitabine plus lapatinib, 490 patients treated with trastuzumab emtansine), fewer grade 3 or worse adverse events occurred with trastuzumab emtansine (233 [48%] of 490) than with capecitabine plus lapatinib control treatment (291 [60%] of 488). In the control group, the most frequently reported grade 3 or worse adverse events were diarrhoea (103 [21%] of 488 patients) followed by palmar-plantar erythrodysaesthesia syndrome (87 [18%]), and vomiting (24 [5%]). The safety profile of trastuzumab emtansine was similar to that reported previously; the most frequently reported grade 3 or worse adverse events in the trastuzumab emtansine group were thrombocytopenia (70 [14%] of 490), increased aspartate aminotransferase levels (22 [5%]), and anaemia (19 [4%]). Nine patients died from adverse events; five of these deaths were judged to be related to treatment (two in the control group [coronary artery disease and multiorgan failure] and three in the trastuzumab emtansine group [metabolic encephalopathy, neutropenic sepsis, and acute myeloid leukaemia]).

INTERPRETATION

This descriptive analysis of final overall survival in the EMILIA trial shows that trastuzumab emtansine improved overall survival in patients with previously treated HER2-positive metastatic breast cancer even in the presence of crossover treatment. The safety profile was similar to that reported in previous analyses, reaffirming trastuzumab emtansine as an efficacious and tolerable treatment in this patient population.

FUNDING

F Hoffmann-La Roche/Genentech.

Safety and Activity of Mirvetuximab Soravtansine (IMGN853), a Folate Receptor Alpha-Targeting Antibody-Drug Conjugate, in Platinum-Resistant Ovarian, Fallopian Tube, or Primary Peritoneal Cancer: A Phase I Expansion Study

Purpose This phase I expansion cohort study evaluated the safety and clinical activity of mirvetuximab soravtansine (IMGN853), an antibody-drug conjugate consisting of a humanized anti-folate receptor alpha (FRα) monoclonal antibody linked to the tubulin-disrupting maytansinoid DM4, in a population of patients with FRα-positive and platinum-resistant ovarian cancer. Patients and Methods Patients with platinum-resistant epithelial ovarian, fallopian tube, or primary peritoneal cancer received IMGN853 at 6.0 mg/kg (adjusted ideal body weight) once every 3 weeks. Eligibility included a minimum requirement of FRα positivity by immunohistochemistry (≥ 25% of tumor cells with at least 2+ staining intensity). Adverse events, tumor response (via Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1), and progression-free survival (PFS) were determined. Results Forty-six patients were enrolled. Adverse events were generally mild (≤ grade 2), with diarrhea (44%), blurred vision (41%), nausea (37%), and fatigue (30%) being the most commonly observed treatment-related toxicities. Grade 3 fatigue and hypotension were reported in two patients each (4%). For all evaluable patients, the confirmed objective response rate was 26%, including one complete and 11 partial responses, and the median PFS was 4.8 months. The median duration of response was 19.1 weeks. Notably, in the subset of patients who had received three or fewer prior lines of therapy (n = 23), an objective response rate of 39%, PFS of 6.7 months, and duration of response of 19.6 weeks were observed. Conclusion IMGN853 exhibited a manageable safety profile and was active in platinum-resistant ovarian cancer, with the strongest signals of efficacy observed in less heavily pretreated individuals. On the basis of these findings, the dose, schedule, and target population were identified for a phase III trial of IMGN853 monotherapy in patients with platinum-resistant disease.

SAFE-HEaRt: Rationale and Design of a Pilot Study Investigating Cardiac Safety of HER2 Targeted Therapy in Patients with HER2-Positive Breast Cancer and Reduced Left Ventricular Function

BACKGROUND

Human epidermal growth receptor 2 (HER2) targeted therapies have survival benefit in adjuvant and metastatic HER2 positive breast cancer but are associated with cardiac dysfunction. Current U.S. Food and Drug Administration recommendations limit the use of HER2 targeted agents to patients with normal left ventricular (LV) systolic function.

METHODS

The objective of the SAFE-HEaRt study is to evaluate the cardiac safety of HER2 targeted therapy in patients with HER2 positive breast cancer and mildly reduced left ventricular ejection fraction (LVEF) with optimized cardiac therapy. Thirty patients with histologically confirmed HER2 positive breast cancer (stage I-IV) and reduced LVEF (40% to 49%) who plan to receive HER2 targeted therapy for ≥3 months will be enrolled. Prior to initiation on study, optimization of heart function with beta-blockers and angiotensin converting enzyme inhibitors will be initiated. Patients will be followed by serial echocardiograms and cardiac visits during and 6 months after completion of HER2 targeted therapy. Myocardial strain and blood biomarkers, including cardiac troponin I and high-sensitivity cardiac troponin T, will be examined at baseline and during the study.

DISCUSSION

LV dysfunction in patients with breast cancer poses cardiac and oncological challenges and limits the use of HER2 targeted therapies and its oncological benefits. Strategies to prevent cardiac dysfunction associated with HER2 targeted therapy have been limited to patients with normal LVEF, thus excluding patients who may receive the highest benefit from those strategies. SAFE-HEaRt is the first prospective pilot study of HER2 targeted therapies in patients with reduced LV function while on optimized cardiac treatment that can provide the basis for clinical practice changes. The Oncologist 2017;22:518-525 IMPLICATIONS FOR PRACTICE: Human epidermal growth receptor 2 (HER2) targeted therapies have survival benefit in adjuvant and metastatic HER2 positive breast cancer but are associated with cardiac dysfunction. To our knowledge, SAFE-HEaRt is the first clinical trial that prospectively tests the hypothesis that HER2 targeted therapies may be safely administered in patients with mildly reduced cardiac function in the setting of ongoing cardiac treatment and monitoring. The results of this study will provide cardiac safety data and inform consideration of clinical practice changes in patients with HER2 positive breast cancer and reduced cardiac function, as well as provide information regarding cardiovascular monitoring and treatment in this population.

Phase I study of IMGN901, a CD56-targeting antibody-drug conjugate, in patients with CD56-positive solid tumors

Background IMGN901 is a CD56-targeting antibody-drug conjugate designed for tumor-selective delivery of the cytotoxic maytansinoid DM1. This phase 1 study investigated the safety, tolerability, pharmacokinetics, and preliminary activity of IMGN901 in patients with CD56-expressing solid tumors. Methods Patients were enrolled in cohorts of escalating IMGN901 doses, administered intravenously, on 3 consecutive days every 21 days. A dose-expansion phase accrued patients with small cell lung cancer (SCLC), Merkel cell carcinoma (MCC), or ovarian cancer. Results Fifty-two patients were treated at doses escalating from 4 to 94 mg/m(2)/day. The maximum tolerated dose (MTD) was determined to be 75 mg/m(2). Dose-limiting toxicities included fatigue, neuropathy, headache or meningitis-like symptoms, chest pain, dyspnea, and myalgias. In the dose-expansion phase (n = 45), seven patients received 75 mg/m(2) and 38 received 60 mg/m(2) for up to 21 cycles. The recommended phase 2 dose (RP2D) was established at 60 mg/m(2) during dose expansion. Overall, treatment-emergent adverse events (TEAEs) were experienced by 96.9 % of all patients, the majority of which were Grade 1 or 2. The most commonly reported Grade 3 or 4 TEAEs were hyponatremia and dyspnea (each 8.2 %). Responses included 1 complete response (CR), 1 clinical CR, and 1 unconfirmed partial response (PR) in MCC; and 1 unconfirmed PR in SCLC. Stable disease was seen for 25 % of all evaluable patients who received doses ≥60 mg/m(2). Conclusions The RP2D for IMGN901 of 60 mg/m(2) administered for 3 consecutive days every 3 weeks was associated with an acceptable tolerability profile. Objective responses were observed in patients with advanced CD56+ cancers.

[A Case of Advanced Breast Cancer in Which Marked Improvement of Joint Pain Was Obtained with Stepwise Dose Reduction of Trastuzumab Emtansine (T-DM1)]

A 51-year-old woman had previously received treatment for breast cancer at another hospital but had refused early and aggressive treatment. Therefore, she was treated with symptomatic therapy. As her disease progressed, the patient wished to receive palliative care, and was transferred to a palliative care hospital. However, based on her general condition, it was determined that aggressive treatment should not be abandoned, and she was referred to our hospital for treatment. During her initial visit, the patient was found to have left breast cancer with chest wall invasion, right breast metastasis, multiple liver and lung metastases, left pleural effusion accompanied by pleural dissemination, and left upper limb edema. There was no evidence of bone metastases. The patient's pain was managed with oral oxycodone sustained-release tablets (320 mg daily), using high-dose (80 mg) oral oxycodone hydrochloride hydrate as rescue medication. The results of immunohistochemical testing, confirmed by her previous hospital, were ER (-), PgR (-) and HER2/neu positive. First-line treatment was initiated with paclitaxel (PTX) plus trastuzumab (Tmab), and the response was rated as stable disease (SD). During the course of treatment, she developed drug-induced interstitial pneumonia, which was probably caused by the taxane. Therefore, the first-line treatment was discontinued and T-DM1 was initiated as second-line treatment. However, beginning with cycle 3 of the T-DM1 treatment, the patient began complaining of joint pain, mainly in the upper limbs. Therefore, the dose of oxycodone sustained-release tablets was increased to 600 mg per day. However, the patient's joint pain showed no improvement and it was considered unlikely that the pain was due to bone metastases. It was suspected that the pain was an adverse reaction to T-DM1, and the dose of T-DM1 was reduced by one step in cycle 7 of treatment. This resulted in a dramatic improvement of the patient's symptoms. Since oxycodone sustained-release tablets was being used at a high dose, sleepiness caused by the drug interfered with her activities of daily living. Consequently, as part of an opioid rotation scheme, topical fentanyl citrate was used concomitantly, and the initial daily oxycodone sustained-release tablets dose of 600 mg was reduced to 40 mg and administered in combination with fentanyl citrate (12mg). These findings suggest that uncontrollable joint pain can occur as an adverse reaction to T-DM1.

Trastuzumab emtansine and stereotactic radiosurgery: an unexpected increase in clinically significant brain edema

BACKGROUND

In the last 10 years, multiple new targeted agents have been developed for patients with human epidermal growth factor receptor 2-positive (HER2+) breast cancer. Up to 55% of patients with HER2+ breast cancer will develop brain metastases requiring some form of radiation therapy. The interaction between radiation and these targeted agents is unknown and previously unreported.

METHODS

In this series, we describe 4 patients who developed clinically significant brain edema at sites of treated brain metastases. These patients were treated with stereotactic radiosurgery and trastuzumab emtansine, the newest FDA-approved agent for metastatic HER2+ breast cancer. Additionally, we present rates of clinically significant radiation necrosis among all breast cancer patients treated during this same time period.

RESULTS

Using previously published clinical and preclinical data, we then hypothesize possible mechanisms for this striking interaction.

CONCLUSION

Increased awareness of potential interactions between targeted agents and radiation to the brain is crucial.

T-DM1 as a New Treatment Option for Patients with Metastatic HER2-positive Breast Cancer in Clinical Practice

AIM

To compare results of trastuzumab-emtansine (T-DM1) treatment in our clinical practice with data from phase III clinical trials.

PATIENTS AND METHODS

A retrospective chart review of all 23 patients with metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer who were started on T-DM1 until April 2014 was performed.

RESULTS

Four patients (17.4%) received T-DM1 as first-line, three (13.0%) as second-line, six (26.0%) as third-line, and 10 (43.5%) as fifth- or further-line therapy. Overall, the response rate (ORR) was 26.0%, disease control rate 78.3% and median progression-free survival (PFS) 8.4 months. The only toxicities of grade 3 or more were fatigue (21.7%), thrombocytopenia (4.3%) and elevation of liver enzymes (8.7%). ORR and PFS were similar to the TH3RESA and EMILIA trials. Compared to the EMILIA study, we recorded higher rates of newly-diagnosed cerebral metastasis and cerebral progression in patients with stable peripheral metastases.

CONCLUSION

T-DM1 is effective and well-tolerated even in intensively pre-treated patients.

Trastuzumab emtansine: a review of its use in patients with HER2-positive advanced breast cancer previously treated with trastuzumab-based therapy

Trastuzumab emtansine (Kadcyla™) is an antibody-drug conjugate consisting of the humanized anti-human epidermal growth factor receptor (HER) 2 antibody trastuzumab covalently linked to the highly potent microtubule inhibitory drug DM1 (a cytotoxic derivative of maytansine) via a stable thioether linker. Intravenous trastuzumab emtansine was recently approved for use in patients with HER2-positive, unresectable, locally advanced (in the EU) or metastatic (in the USA and EU) breast cancer who had previously received trastuzumab and a taxane (separately or in combination), making it the first antibody-drug conjugate approved in this indication. This article reviews the efficacy and tolerability of trastuzumab emtansine in these patients and summarizes its pharmacology. In the well-designed EMILIA study, trastuzumab emtansine significantly prolonged progression-free survival and overall survival, relative to treatment with lapatinib plus capecitabine, in patients with HER2-positive, unresectable, locally advanced or metastatic breast cancer who were previously treated with trastuzumab and a taxane. Trastuzumab emtansine was generally well tolerated in this study, with <6% of patients discontinuing treatment because of adverse events. Based on its efficacy and favourable tolerability, the US National Comprehensive Cancer Network guidelines recommend trastuzumab emtansine as the preferred option in patients with HER2-positive metastatic breast cancer who have received previous trastuzumab-based therapy.

What Can We Learn about Antibody-Drug Conjugates from the T-DM1 Experience?

Antibody conjugates are a diverse class of therapeutics that consist of a cytotoxic agent linked covalently to an antibody or antibody fragment directed toward a specific cell surface target expressed by tumor cells. The notion that antibodies directed toward targets on the surface of malignant cells could be used for drug delivery is not new. The history of antibody conjugates has been marked by hurdles identified and overcome. Early conjugates used mouse antibodies, drugs that either were not sufficiently potent, were immunogenic (proteins), or were too toxic, and linkers that were not sufficiently stable in circulation. Four main avenues have been explored using antibodies to target cytotoxic agents to malignant cells: antibody-protein toxin (or antibody fragment-protein toxin fusion) conjugates, antibody-chelated radionuclide conjugates, antibody-small molecule conjugates, and antibody-enzyme conjugates administered along with small molecule prodrugs that require metabolism by the conjugated enzyme to release the activated species. Technology is continuing to evolve regarding the protein and small molecule components, and it is likely that single chemical entities soon will be the norm for antibody-drug conjugates. Only antibody-radionuclide conjugates and antibody-drug conjugates have reached the regulatory approval stage, and there are more than 40 antibody conjugates in clinical trials. The time may have come for this technology to become a major contributor to improving treatment for patients with cancer.

Trastuzumab emtansine. An inadequately assessed combination of two cytotoxic drugs

There is no consensus on second-line treatment for women with metastatic or locally advanced breast cancer over-expressing HER-2 protein in whom treatment with a taxane + trastuzumab has failed. Capecitabine is one option. Adding lapatinib does not prolong survival. Trastuzumab emtansine (Kadcyla, Roche) has received EU marketing authorisation for use in this setting. It consists of two covalently bound drugs: trastuzumab, a monoclonal antibody that binds to HER-2 receptors, and DM1, a cytotoxic microtubule inhibitor. DM1 is derived from maytansine, a cytotoxic drug abandoned in the 1980s because it proved to be too toxic after systemic administration. Clinical evaluation of trastuzumab emtansine is based on an unblinded trial versus capecitabine + lapatinib in 991 patients. The use of lapatinib in all patients in the control group is questionable. An interim analysis suggested that overall survival was about 6 months longer with trastuzumab emtansine (30.9 versus 25.1 months). In addition to the adverse effects of trastuzumab (thrombocytopenia, heart failure, etc.), trastuzumab emtansine causes frequent and potentially life-threatening hepatic toxicity, peripheral neuropathy, and urinary tract infections. Trastuzumab emtansine appears to be less toxic to the skin and mucous membranes than the capecitabine + lapatinib combination. DM1 is metabolised by cytochrome P450 isoenzymes CYP3A4 and CYP3A5 and is also a P-glycoprotein substrate, creating a potential risk of multiple pharmacokinetic interactions. Trastuzumab emtansine appears to be teratogenic and embryotoxic. The international nonproprietary name of this drug is easily confused with trastuzumab. In practice, it is best to at least wait for the full results of the only available comparative trial of trastuzumab emtansine before drawing conclusions about its harm-benefit balance and its possible use if it represents a real therapeutic advance.

Trastuzumab emtansine: first global approval

Genentech and ImmunoGen are collaborating on the development of trastuzumab emtansine, a HER2 antibody-drug conjugate that comprises Genentech's trastuzumab antibody linked to ImmunoGen's anti-mitotic agent, mertansine (a maytansine derivative; also known as DM1). The conjugate combines two strategies: the anti-HER2 activity of trastuzumab, and the targeted intracellular delivery of mertansine, a tubulin polymerisation inhibitor which interferes with mitosis and promotes apoptosis. The linker in trastuzumab emtansine is a non-reducible thioether linker, N-succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC, designated MCC after conjugation). Trastuzumab emtansine (Kadcyla™) has been launched in the USA as second-line monotherapy for HER2-positive metastatic breast cancer, and has been filed for approval in the EU and Japan in this indication. Trastuzumab emtansine is in phase III development as first-line combination therapy or monotherapy for metastatic HER2-positive breast cancer, and as third-line monotherapy for metastatic HER2-positive breast cancer. Phase II development is underway for early-stage breast cancer and phase II/III development is underway in patients with HER2-positive gastric cancer. This article summarizes the milestones in the development of trastuzumab emtansine leading to this first approval for the treatment of patients with HER2-positive, metastatic breast cancer who previously received trastuzumab and a taxane, separately or in combination.

Novel formulations and new mechanisms of delivering chemotherapy

The identification of epidermal growth factor receptor mutations and anaplastic lymphoma kinase rearrangements and the development of targeted therapy for patients with these molecular alterations has been a tremendous advance in the treatment of advanced stage or metastatic non-small cell lung cancer (NSCLC). However, the majority of patients with advanced stage NSCLC will not have one of these molecular alterations and will receive chemotherapy as their primary therapy. Chemotherapy remains a critical component of therapy for resected and locally advanced NSCLC, as well as for patients with limited-stage and extensive stage small cell lung cancer (SCLC). A significant unmet need exists to develop novel chemotherapy agents and to improve the efficacy and toxicity of currently available agents. Several novel formulations of currently available chemotherapy agents are in development for NSCLC and SCLC. Antibody conjugates are therapeutic agents that employ a tumor-specific monoclonal antibody conjugated to a cytotoxic or radionuclide agent. After the monoclonal antibody binds to the tumor antigen, these agents are internalized, and the link between the antibody and the therapeutic agent is dissolved and the cytotoxic agent is release intracellularly. This enhanced delivery of chemotherapy to malignant tissues has the potential to improve efficacy and reduce toxicity. Antibody conjugates to therapeutic agents are currently available for other malignancies and are in development for NSCLC and SCLC.

Preclinical safety profile of trastuzumab emtansine (T-DM1): mechanism of action of its cytotoxic component retained with improved tolerability

Trastuzumab emtansine (T-DM1) is the first antibody-drug conjugate (ADC) approved for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. The therapeutic premise of ADCs is based on the hypothesis that targeted delivery of potent cytotoxic drugs to tumors will provide better tolerability and efficacy compared with non-targeted delivery, where poor tolerability can limit efficacious doses. Here, we present results from preclinical studies characterizing the toxicity profile of T-DM1, including limited assessment of unconjugated DM1. T-DM1 binds primate ErbB2 and human HER2 but not the rodent homolog c-neu. Therefore, antigen-dependent and non-antigen-dependent toxicity was evaluated in monkeys and rats, respectively, in both single- and repeat-dose studies; toxicity of DM1 was assessed in rats only. T-DM1 was well tolerated at doses up to 40 mg/kg (~4400 μg DM1/m(2)) and 30 mg/kg (~ 6000 μg DM1/m(2)) in rats and monkeys, respectively. In contrast, DM1 was only tolerated up to 0.2mg/kg (1600 μg DM1/m(2)). This suggests that at least two-fold higher doses of the cytotoxic agent are tolerated in T-DM1, supporting the premise of ADCs to improve the therapeutic index. In addition, T-DM1 and DM1 safety profiles were similar and consistent with the mechanism of action of DM1 (i.e., microtubule disruption). Findings included hepatic, bone marrow/hematologic (primarily platelet), lymphoid organ, and neuronal toxicities, and increased numbers of cells of epithelial and phagocytic origin in metaphase arrest. These adverse effects did not worsen with chronic dosing in monkeys and are consistent with those reported in T-DM1-treated patients to date.

Trastuzumab emtansine (T-DM1) for HER2-positive breast cancer

BACKGROUND

Trastuzumab emtansine (T-DM1), a novel drug developed for the treatment of HER2-positive breast cancer, is a human epidermal growth factor receptor (HER2) targeted antibody drug conjugate, composed of trastuzumab, a stable thioether linker, and the potent cytotoxic agent DM1 (derivative of maytansine). It has been shown that, in preclinical studies, it has anti-tumor activity in trastuzumab refractory cancer cells. In this review, we aim to show the clinical data about trastuzumab-DM1 (T-DM1) therapy and to discuss the therapy advantages for the management of patients with HER2-positive breast cancer.

SCOPE

T-DM1 showed positive results in clinical studies of HER2-positive metastatic breast cancer. PubMed database, ASCO and San Antonio Breast Cancer Symposium Meeting abstracts were searched up to September 2012 by using the terms 'trastuzumab emtansine (T-DM1) and anti-HER2 treatment'; papers which were considered relevant for the aim of this review were selected by the authors.

FINDINGS

The phase III randomized trial EMILIA has shown that T-DM1 provided objective tumor responses and significantly improved progression free survival and overall survival compared to lapatinib and capacitabine combination in HER2-positive metastatic breast cancer patients treated with a prior taxane and trastuzumab regimen. It is believed that T-DM1 will play a role in the management of patients with advanced and early stage HER2-positive breast cancer, but this awaits further study. In particular, the ongoing phase III trials MARIANNE and TH3RESA will further give information about the place of T-DM1 in the treatment algorithms for HER2-positive disease.

CONCLUSION

The trials of T-DM1 as a single agent and in combination with other chemotherapies have shown clinical activity and a favorable safety profile in patients with HER2-positive metastatic breast cancer. There are ongoing studies of T-DM1 showing an increasing tendency towards moving the study of these agents to earlier stages of HER2-positive breast cancer.

ADME of antibody-maytansinoid conjugates

The concept of treating cancer with antibody-drug conjugates (ADCs) has gained momentum with the favorable activity and safety of trastuzumab emtansine (T-DM1), SAR3419, and lorvotuzumab mertansine (IMGN901). All three ADCs utilize maytansinoid cell-killing agents which target tubulin and suppress microtubule dynamics. Each ADC utilizes a different optimized chemical linker to attach the maytansinoid to the antibody. Characterizing the absorption, distribution, metabolism, and excretion (ADME) of these ADCs in preclinical animal models is important to understanding their efficacy and safety profiles. The ADME properties of these ADCs in rodents were inferred from studies with radio-labeled ADCs prepared with nonbinding antibodies since T-DM1, SAR3419, IMGN901 all lack cross-reactivity with rodent antigens. For studies exploring tumor localization and activation in tumor-bearing mice, tritium-labeled T-DM1, SAR3419, and IMGN901 were utilized. The chemical nature of the linker was found to have a significant impact on the ADME properties of these ADCs-particularly on the plasma pharmacokinetics and observed catabolites in tumor and liver tissues. Despite these differences, T-DM1, SAR3419, and IMGN901 were all found to facilitate efficient deliveries of active maytansinoid catabolites to the tumor tissue in mouse xenograft models. In addition, all three ADCs were effectively detoxified during hepatobiliary elimination in rodents.

Trastuzumab emtansine for HER2-positive advanced breast cancer

BACKGROUND

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate incorporating the human epidermal growth factor receptor 2 (HER2)-targeted antitumor properties of trastuzumab with the cytotoxic activity of the microtubule-inhibitory agent DM1. The antibody and the cytotoxic agent are conjugated by means of a stable linker.

METHODS

We randomly assigned patients with HER2-positive advanced breast cancer, who had previously been treated with trastuzumab and a taxane, to T-DM1 or lapatinib plus capecitabine. The primary end points were progression-free survival (as assessed by independent review), overall survival, and safety. Secondary end points included progression-free survival (investigator-assessed), the objective response rate, and the time to symptom progression. Two interim analyses of overall survival were conducted.

RESULTS

Among 991 randomly assigned patients, median progression-free survival as assessed by independent review was 9.6 months with T-DM1 versus 6.4 months with lapatinib plus capecitabine (hazard ratio for progression or death from any cause, 0.65; 95% confidence interval [CI], 0.55 to 0.77; P<0.001), and median overall survival at the second interim analysis crossed the stopping boundary for efficacy (30.9 months vs. 25.1 months; hazard ratio for death from any cause, 0.68; 95% CI, 0.55 to 0.85; P<0.001). The objective response rate was higher with T-DM1 (43.6%, vs. 30.8% with lapatinib plus capecitabine; P<0.001); results for all additional secondary end points favored T-DM1. Rates of grade 3 or 4 adverse events were higher with lapatinib plus capecitabine than with T-DM1 (57% vs. 41%). The incidences of thrombocytopenia and increased serum aminotransferase levels were higher with T-DM1, whereas the incidences of diarrhea, nausea, vomiting, and palmar-plantar erythrodysesthesia were higher with lapatinib plus capecitabine.

CONCLUSIONS

T-DM1 significantly prolonged progression-free and overall survival with less toxicity than lapatinib plus capecitabine in patients with HER2-positive advanced breast cancer previously treated with trastuzumab and a taxane. (Funded by F. Hoffmann-La Roche/Genentech; EMILIA ClinicalTrials.gov number, NCT00829166.).

Cantuzumab mertansine in a three-times a week schedule: a phase I and pharmacokinetic study

PURPOSE

Cantuzumab mertansine (SB-408075; huC242-DM1) is a conjugate of the maytansinoid drug DM1 to the antibody huC242, which targets CanAg antigen. In previous studies, cantuzumab mertansine was considered safe and tolerable, but transaminitis precluded tolerance of higher doses. Based on those studies, it was suggested that treatment at intervals of the half-life of the intact immunoconjugate may allow a higher dose density. This provided the rationale for the three-times weekly treatment explored in this protocol.

METHODS

Patients with advanced solid tumors and documented CanAg expression were treated with escalating doses of cantuzumab mertansine IV administered three-times a week in a 3 out of 4 weeks schedule. Plasma samples were assayed to determine pharmacokinetic parameters.

RESULTS

Twenty patients (pts) with colon (11/20), rectal carcinomas (2/20), or other malignancies (7/20) were treated with doses ranging from 30 to 60 mg/m2 per day of cantuzumab mertansine IV three-times a week. The maximum tolerated dose (MTD) was 45 mg/m2, and the dose-limiting toxicity was grade 3 transaminitis. Hepatic, hematologic, and neurosensory effects occurred, but were rarely severe with repetitive treatment at doses of 45 mg/m2.

CONCLUSIONS

Treatment with cantuzumab mertansine at 45 mg/m2 per day three-times weekly x 3-every-4-week schedule proved that a dose-intense treatment with an immunoconjugate can be safely administered. The pharmacokinetic profile of the intact immunoconjugate indicates that the linker is cleaved with a half-life of about 2 days, resulting in faster clearance of the maytansinoid relative to the antibody. Therefore, with the development of second-generation immunoconjugates, there is a need for improvement of the immunoconjugate linker to take full advantage of the slow clearance of full-length antibody molecules.

Phase II trials of maytansine, low-dose chlorozotocin, and high-dose chlorozotocin as single agents against advanced measurable adenocarcinoma of the pancreas. Gastrointestinal Tumor Study Group

One hundred and five patients with advanced measurable pancreatic carcinoma were randomized to receive therapy with maytansine, low-dose chlorozotocin (120 mg/m2), or high-dose chlorozotocin (175 mg/m2). Objective response rates were as follows: maytansine, no responses among 48 patients; low-dose chlorozotocin, none among 27; and high-dose chlorozotocin, three among 30 (10%). Among patients with excellent performance status (Eastern Cooperative Oncology Group grade of 0-1) and no prior chemotherapy, response rates were as follows: maytansine, no responses among 17 patients; low-dose chlorozotocin, none among 14; and high-dose chlorozotocin, three among 28 (11%). The responses observed with high-dose chlorozotocin were transient (5-8 weeks) and were of no benefit to the patients. None of these agents given by the methods of this study can be recommended for patients with advanced pancreatic cancer.

Phase II evaluation of maytansine (NSC 153858) in advanced cancer. A Southeastern Cancer Study Group trial

Maytansine given in a 3-day course q3 weeks produced only five responses (3%) in 163 evaluable adults with advanced cancer. The dose schedule employed is not recommended for further study.

Phase II study of maytansine in the treatment of advanced or recurrent squamous cell carcinoma of the cervix. A Gynecologic Oncology Group study

Twenty-nine patients with advanced or recurrent squamous cell carcinoma of the cervix who had failed standard therapy were treated with maytansine 1.2 mg/m2 intravenously once every 3 weeks. Only one partial remission was observed among the 29 patients (3%). There were no complete remissions. Stable disease was observed in 18 (62%) and progressive disease in 10 (35%). Adverse effects were infrequent and mild to moderate and consisted primarily of myelosuppression, weakness, and nausea and vomiting. This study shows that maytansine at the dose and schedule tested is essentially inactive in the treatment of advanced or recurrent squamous cell carcinoma of the cervix.

Phase II study of maytansine in the treatment of advanced or recurrent adenocarcinoma of the ovary. A Gynecologic Oncology Group study

Twenty-nine patients with advanced or recurrent adenocarcinoma of the ovary no longer responsive to standard treatment measures were given maytansine 1.2 mg/m2 I.V. every 3 weeks. None of the 29 patients demonstrated an objective regression of disease. Eighteen (62%) demonstrated stable disease for 1 or more months, while 11 (38%) developed rapid progression of disease. Adverse effects consisted primarily of leukopenia (7/29), thrombocytopenia (9/29), and nausea and vomiting (14/29). Only one patient developed life-threatening toxicity (platelets less than 25,000 microliters), and no drug-related deaths were observed. Maytansine thus appears inactive in the treatment of adenocarcinoma of the ovary at the dose and schedule tested.

Phase II evaluation of dibromodulcitol, ICRF-159, and maytansine for sarcomas

Patients with objectively measurable soft tissue sarcomas, osteosarcomas, chondrosarcomas, and mesotheliomas were treated with dibromodulcitol (DBD) (180 mg/m2 p.o. days 1-10 q4 wks.). ICRF-159 (300 mg/m2 p.o. tid days 1-3 q4 wks), or maytansine (MAYT) (1.5 mg/m2 I.V. q3 wks.). Forty-five evaluable patients received DBD, 47 MAYT, and 37 ICRF-159. Only patients who had had their histopathologic diagnoses confirmed by a pathology reference panel were included in the final analysis. Two patients had objective partial responses: a patient with osteosarcoma who responded to DBD and a patient with fibrosarcoma who had a partial response of brief duration to ICRF-159. Approximately 70% of the patients treated with each drug were of ECOG performance status 0 or 1, and over half had moderate or worse toxicity. It seems unlikely that these drugs have significant therapeutic activity for common mesenchymal malignancies.

Phase II study of cisplatin, maytansine, and chlorozotocin in small cell lung carcinoma (EST 2578)

Seventy-three patients with small cell lung carcinoma refractory to standard chemotherapy were entered in this phase II randomized study of cisplatin, maytansine, and chlorozotocin. Of the 58 evaluable patients, only one partial response was observed among 21 patients given cisplatin, and no responses were seen among 19 given maytansine or 18 given chlorozotocin. One patient treated with chlorozotocin and two treated with cisplatin experienced life-threatening thrombocytopenia. One third of the maytansine-treated patients experienced moderate or severe neurologic toxicity. The overall median survival was 9.7 weeks. Chlorozotocin treatment was associated with inferior survival (7.7 weeks).